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1
Sumida, Ciro Hideki, Lucas Henrique Fantin, Karla Braga, Marcelo Giovanetti Canteri, and Martin Homechin. "Control of root rot (Phytophthora cinnamomi) in avocado (Persea Americana) with bioagents." Summa Phytopathologica 46, no. 3 (September 2020): 205–11. http://dx.doi.org/10.1590/0100-5405/192195.
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ABSTRACT Despite the favorable edaphoclimatic conditions for avocado production in Brazil, diseases such as root rot caused by the pathogen Phytophthora cinnamomi compromise the crop. With the aim of managing root rot in avocado, the present study aimed to evaluate chemical and biological control with isolates of Trichoderma spp. and Pseudomonas fluorescens. Thus, three assays were conducted to assess: (i) mycelial inhibition of P. cinnamomi by isolates of Trichoderma spp. and P. fluorescens from different crop systems; (ii) effect of autoclaved and non-autoclaved metabolites of P. fluorescens, and (iii) chemical or biological treatment of avocado seedlings on the control of root rot under field conditions. The isolates of Trichoderma spp. from maize cultivation soil and the commercial products formulated with Trichoderma presented greater antagonism (p <0.05) to the pathogen P. cinnamomi in the in vitro tests. Similarly, non-autoclaved metabolites of P. fluorescens presented antagonistic potential to control P. cinnamomi. Under field conditions, the fungicide metalaxyl and the bioagents showed effectiveness in controlling P. cinnamomi, as well as greater root length and mass. Results demonstrated potential for the biological control of avocado root rot with Trichoderma spp. and P. fluorescens.
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Alvarado, Laureano, Sebastián Saa, Italo F. Cuneo, Romina Pedreschi, Javiera Morales, Alejandra Larach, Wilson Barros, Jeannette Guajardo, and Ximena Besoain. "A Comparison of Immediate and Short-Term Defensive Responses to Phytophthora Species Infection in Both Susceptible and Resistant Walnut Rootstocks." Plant Disease 104, no. 3 (March 2020): 921–29. http://dx.doi.org/10.1094/pdis-03-19-0455-re.
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Clonal rootstocks are one alternative used by the walnut industry to control damage caused by Phytophthora species, traditionally using plants grafted on susceptible Juglans regia rootstock. Vlach, VX211, and RX1 are clonal rootstocks with a degree of resistance to Phytophthora species. The resistance to pathogens in these rootstocks depends on the resistance mechanisms activated by the presence of the pathogen and subsequent development of responses in the host. In this work, we analyzed how plants of J. regia, Vlach, VX211, and RX1 responded to inoculation with Phytophthora cinnamomi or Phytophthora citrophthora isolates obtained from diseased English walnut plants from Chilean orchards. After inoculation, plants of Vlach, VX211, and RX1 showed canopy and root damage indexes that did not differ from noninoculated control plants. In contrast, plants of J. regia, which is susceptible to P. cinnamomi and P. citrophthora, died after inoculation. Vlach, VX211, and RX1 plants inoculated with P. cinnamomi or P. citrophthora showed greater root weight and volume and greater root growth rates than their respective controls. These results suggest that short-term carbohydrate dynamics may be related to the defense mechanisms of plants; they are immediately activated after inoculation through the production of phenolic compounds, which support the further growth and development of roots in walnut clonal rootstocks. To our knowledge, this is the first study that comprehensively characterizes vegetative and radicular growth and the dynamics of sugars and phenols in response to infection with P. cinnamomi or P. citrophthora in walnut rootstocks.
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Casonato, S. G., M. A. Manning, P. A. Rheinlander, and R. A. Fullerton. "Control of Phytophthora cinnamomi in Erica sessiliflora and Erica davisii." New Zealand Plant Protection 61 (August 1, 2008): 86–90. http://dx.doi.org/10.30843/nzpp.2008.61.6823.
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A field trial was conducted to test the efficacy of two fungicides (metalaxyl and phosphorous acid) and supplementary organic matter for the control of Phytophthora cinnamomi root rot in Erica sessiliflora and E davisii Five treatments were applied (1) untreated control (2) metalaxyl (3) phosphorous acid (4) metalaxyl plus phosphorous acid and (5) organic soil amendment Plants were assessed for plant health as an indication of possible P cinnamomi infection Phosphorous acid applied alone or in combination with metalaxyl resulted in a significant reduction in the number of diseased or dead E sessiliflora plants compared with the untreated control plants (P0011 and P0004 respectively) The mean health index of phosphorous acid treated E davisii plants was not different (P>005) to control plants Results suggest that this species of Erica has some tolerance to P cinnamomi Metalaxyl applications alone or organic matter treatments did not reduce disease relative to controls in either species
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Lawrence, Scott A., Hannah F. Robinson, Daniel P. Furkert, Margaret A. Brimble, and Monica L. Gerth. "Screening a Natural Product-Inspired Library for Anti-Phytophthora Activities." Molecules 26, no. 7 (March 24, 2021): 1819. http://dx.doi.org/10.3390/molecules26071819.
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Phytophthora is a genus of microorganisms that cause devastating dieback and root-rot diseases in thousands of plant hosts worldwide. The economic impact of Phytophthora diseases on crops and native ecosystems is estimated to be billions of dollars per annum. These invasive pathogens are extremely difficult to control using existing chemical means, and the effectiveness of the few treatments available is being jeopardized by increasing rates of resistance. There is an urgent need to identify new chemical treatments that are effective against Phytophthora diseases. Natural products have long been regarded as “Nature’s medicine chest”, providing invaluable leads for developing front-line drugs and agrochemical agents. Here, we have screened a natural product-inspired library of 328 chemicals against two key Phytophthora species: Phytophthora cinnamomi and Phytophthora agathidicida. The library was initially screened for inhibition of zoospore germination. From these screens, we identified twenty-one hits that inhibited germination of one or both species. These hits were further tested in mycelial growth inhibition studies to determine their half-maximal inhibitory concentrations (IC50s). Four compounds had IC50 values of approximately 10 µM or less, and our best hit had IC50s of approximately 3 µM against both Phytophthora species tested. Overall, these hits may serve as promising leads for the development of new anti-Phytophthora agrochemicals
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Zinati, Gladis M. "Compost in the 20th Century: A Tool to Control Plant Diseases in Nursery and Vegetable Crops." HortTechnology 15, no. 1 (January 2005): 61–66. http://dx.doi.org/10.21273/horttech.15.1.0061.
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The discovery of disease suppression in certain bark composts increased the interest in using compost as growing substrate to control root rot diseases caused by Phytophthora cinnamomi. Disease suppression mechanisms include antibiosis, competition, hyperparasitism, and induced systemic resistance. Although abiotic factors may influence disease suppression, the latter is often based on microbial interactions—the two common mechanisms being general for pythium (Pythium spp.) and phytophthora root rot (Phytophthora spp.) and specific for rhizoctonia (Rhizoctonia solani). The discovery of disease suppression agents in compost led to the development of biocontrol agent-fortified compost during the last decade of the 20th century. The suggested recommendations for future research and extension outreach may include 1) development of methods to manage bacterial and viral diseases through the use of compost; 2) exploration of the potential effects of fortified compost on insect pests suppression; 3) improvement of inoculation methods of composts with biocontrol agents to produce consistent levels of disease suppression at the commercial scale; 4) development of effective fortified compost teas for suppressing foliar diseases; 5) education of compost producers on methods of production of fortified compost that suppress specific diseases; and 6) education of end-users on uses of fortified compost and its by-products.
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Moon, Jae-Hyun, Sang-Jae Won, Chaw Ei Htwe Maung, Jae-Hyeok Choi, Su-In Choi, Henry B. Ajuna, and Young Sang Ahn. "Bacillus velezensis CE 100 Inhibits Root Rot Diseases (Phytophthora spp.) and Promotes Growth of Japanese Cypress (Chamaecyparis obtusa Endlicher) Seedlings." Microorganisms 9, no. 4 (April 13, 2021): 821. http://dx.doi.org/10.3390/microorganisms9040821.
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Root rot diseases, caused by phytopathogenic oomycetes, Phytophthora spp. cause devastating losses involving forest seedlings, such as Japanese cypress (Chamaecyparis obtusa Endlicher) in Korea. Plant growth-promoting rhizobacteria (PGPR) are a promising strategy to control root rot diseases and promote growth in seedlings. In this study, the potential of Bacillus velezensis CE 100 in controlling Phytophthora root rot diseases and promoting the growth of C. obtusa seedlings was investigated. B. velezensis CE 100 produced β-1,3-glucanase and protease enzymes, which degrade the β-glucan and protein components of phytopathogenic oomycetes cell-wall, causing mycelial growth inhibition of P. boehmeriae, P. cinnamomi, P. drechsleri and P. erythoroseptica by 54.6%, 62.6%, 74.3%, and 73.7%, respectively. The inhibited phytopathogens showed abnormal growth characterized by swelling and deformation of hyphae. B. velezensis CE 100 increased the survival rate of C. obtusa seedlings 2.0-fold and 1.7-fold compared to control, and fertilizer treatment, respectively. Moreover, B. velezensis CE 100 produced indole-3-acetic acid (IAA) up to 183.7 mg/L, resulting in a significant increase in the growth of C. obtusa seedlings compared to control, or chemical fertilizer treatment, respectively. Therefore, this study demonstrates that B. velezensis CE 100 could simultaneously control Phytophthora root rot diseases and enhance growth of C. obtusa seedlings.
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Jung, T., and G. Dobler. "First Report of Littleleaf Disease Caused by Phytophthora cinnamomi on Pinus occidentalis in the Dominican Republic." Plant Disease 86, no. 11 (November 2002): 1275. http://dx.doi.org/10.1094/pdis.2002.86.11.1275c.
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Pinus occidentalis Sw. is an endemic species of the Caribbean island of Hispaniola (Dominican Republic and Haiti). It shows an extreme ecological plasticity and grows on a wide range of soil types from 0 to 3,175 m in elevation with annual mean temperatures ranging from 6 to 25°C and annual precipitation of 800 to 2,300 mm. P. occidentalis is a major component of forests above 800 m in elevation and forms pure climax forests above 2,000 m (4). For more than 10 years, stands of P. occidentalis in the Sierra (Cordillera Central) growing on a wide range of site conditions have suffered from a serious widespread disease. Symptoms include yellowing and dwarfing of needles, a progressive defoliation and dieback of the crown, and finally, death of weakened trees often caused by attacks by secondary bark beetles. Mature stands are mainly affected, but the disease is also present in plantations and natural regeneration that is older than 10 years. Disease spread is rapid, and occurs mainly along roads and from diseased trees downslope following the path of water runoff. Initially, Leptographium serpens was isolated from necrotic roots and was thought to be the causal agent (1). However, the symptoms of the disease more closely resemble those of littleleaf disease of P. echinata and P. taeda in the southeastern United States, which is caused by the aggressive fine-root pathogen Phytophthora cinnamomi Rands (3). Moreover, spread and dynamics of the disease are similar to the diebacks of Chamaecyparis lawsoniana in Oregon and Eucalyptus spp. in western Australia, which are caused by the introduced soilborne pathogens Phytophthora lateralis and Phytophthora cinnamomi, respectively. Soil samples containing the rhizosphere and fine roots of diseased P. occidentalis trees were collected in February 2002 at five sites near Celestina and Los Montones (Dominican Republic) and transported to the Bavarian State Institute of Forestry. The pathogen was baited from the soil by floating 3- to 7-dayold leaves of Quercus robur seedlings over flooded soil and placing the leaves on selective PARPNH agar (2). Phytophthora cinnamomi was isolated from the soil of all five sites. Crossing with A1 and A2 tester strains of Phytophthora cinnamomi confirmed that all isolates belong to the A2 mating type. In cross sections of necrotic fine roots, characteristic structures of Phytophthora cinnamomi such as nonseptate hyphae and chlamydospores could be observed. Our results indicate that the disease of P. occidentalis is caused by the introduced pathogen Phytophthora cinnamomi. Because of the ecological and economical importance of P. occidentalis, the disease poses a major threat to forestry in the Dominican Republic. Future research should include the mapping of the disease, pathogenicity tests on P. occidentalis and alternative pine species, in particular P. caribaea, screening for resistance in the field, and testing of systemic fungicides such as potassium phosphonate, which is known to be effective against Phytophthora cinnamomi. References: (1) G. Dobler. Manejo y Tablas de Rendimiento de Pinus occidentalis. Plan Sierra, San José de las Matas, Dominican Republic, 1999. (2) T. Jung et al. Plant Pathol. 49:706, 2000. (3) S. W. Oak and F. H. Tainter. How to identify and control littleleaf disease. Protection Rep. R8-PR12, USDA Forest Service Southern Region, Atlanta, Georgia, 1988. (4) L. Sprich. Allg. Forst. Jagdztg. 168:67, 1997.
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Shearer, BL, and M. Dillon. "Impact and Disease Centre Characteristics of Phytophthora cinnamomi Infestations of Banksia Woodlands on the Swan Coastal Plain, Western Australia." Australian Journal of Botany 44, no. 1 (1996): 79. http://dx.doi.org/10.1071/bt9960079.
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Phytophthora cinnamomi Rands was isolated from either dead plants or soil at 46 disease centres in Banksia woodland at national parks and reserves on the Swan Coastal Plain. Phytophthora cryptogea Pethybridge & Lafferty was also isolated from roots of dead Acacia pulchella R.Br. in one disease centre infected with P. cinnamomi. Dead plants were infected with Armillaria luteobubalina Watling & Kile in four disease centres on the Spearwood Dune System, and these centres were excluded from further analysis. Phytophthora cinnamomi diseased areas ranged from 0.01 to 30 ha in size (mean 1.6 ± s.e. 0.7 ha). The total area infested for the 46 disease centres was 71.5 ha. Impact of P. cinnamomi was high in 17% of disease centres and low in 11% of disease centres. Age of plant death was a mixture of old and recent in 85% of disease centres. Mainly old deaths occurred in only 4% of disease centres. The proportion of species dying in infested areas varied between 10-64% (mean 28 ± s.e. 2%) and was positively correlated with impact type. It was found that infestation decreased species number; on average, there were seven fewer species in infested compared to non-infested areas. Four plant species associated with moist sandy sites tended to occur more frequently in centres of high impact than by chance alone. Occurrence of P. cinnamomi was related to soil association with soils of 60% of the disease centres belonging to the Bassendean or Southern River associations of the Bassendean Dune System. Sixteen percent of disease centres occurred in the Cannington, Guildford and Serpentine River associations of the Pinjarra Plain. No disease centres of P. cinnamomi were found on soils of the Speanvood and Quindalup Dune Systems. A water table was found within 3 m of the soil surface in 48% of the centres. Disturbance was associated with all disease centres. Firebreaks were associated with 72% of disease centres. Banksia woodland remnants on the Bassendean Dune System and the Pinjarra Plain are highly vulnerable to infection by P. cinnamomi and their conservation requires control of existing infestatinns and protection from introduction af the pathogen.
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Matei, Petruta, Jesús Martín-Gil, Beatrice Michaela Iacomi, Eduardo Pérez-Lebeña, María Barrio-Arredondo, and Pablo Martín-Ramos. "Silver Nanoparticles and Polyphenol Inclusion Compounds Composites for Phytophthora cinnamomi Mycelial Growth Inhibition." Antibiotics 7, no. 3 (August 16, 2018): 76. http://dx.doi.org/10.3390/antibiotics7030076.
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Phytophthora cinnamomi, responsible for “root rot” or “dieback” plant disease, causes a significant amount of economic and environmental impact. In this work, the fungicide action of nanocomposites based on silver nanoparticles and polyphenol inclusion compounds, which feature enhanced bioavailability and water solubility, was assayed for the control of this soil-borne water mold. Inclusion compounds were prepared by an aqueous two-phase system separation method through extraction, either in an hydroalcoholic solution with chitosan oligomers (COS) or in a choline chloride:urea:glycerol deep eutectic solvent (DES). The new inclusion compounds were synthesized from stevioside and various polyphenols (gallic acid, silymarin, ferulic acid and curcumin), in a [6:1] ratio in the COS medium and in a [3:1] ratio in the DES medium, respectively. Their in vitro response against Phytophthora cinnamomi isolate MYC43 (at concentrations of 125, 250 and 500 µg·mL−1) was tested, which found a significant mycelial growth inhibition, particularly high for the composites prepared using DES. Therefore, these nanocomposites hold promise as an alternative to fosetyl-Al and metalaxyl conventional systemic fungicides.
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Thinggaard, K., and B. Toppe. "First Report of Phytophthora cinnamomi Root Rot, Stem, and Leaf Blight on Ivy." Plant Disease 81, no. 8 (August 1997): 960. http://dx.doi.org/10.1094/pdis.1997.81.8.960c.
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Phytophthora cinnamomi was isolated from varieties of Hedera helix pot plants in 1989 in two Danish greenhouse nurseries. The symptoms were brown, rotten roots and stems, and brown areas developing from the base of the leaves. The fungus was isolated directly from roots, stems, leaves, and soil, and by baiting the nutrient solutions of the watering systems with needles of Cedrus deodara. The fungus was isolated on Phytophthora selective agar medium containing hymexazol and identified with the keys of Kröber (1) and Stamps et al. (2). The fungus was characterized by coralloid hyphal swellings, chlamydospores, lack of oogonia in single culture, and production of numerous, ovoid sporangia with a nonpapillate, wide pore. The sporangia produced many zoospores after 2 days flooding with autoclaved pond water on V8 juice agar, followed by internal proliferation. The fungus was also isolated in Norway in 1993 from ivy pot plants. The fungus was widespread in Danish and Norwegian pot plant nurseries in 1997 and caused losses in most varieties, especially at temperatures above 23°C. Effective fungicides are not available for use in Denmark and the disease is easily spread with cuttings, and through the watering system with recirculation of the nutrient solution. A Danish isolate of P. cinnamomi originating from roots of H. helix was used in a pathogenicity test. Five-week-old cuttings were inoculated by adding zoospores (5 per ml) to the recirculating nutrient solution. Control plants were on a separate bench with nutrient solution without the fungus. After 1 week, symptoms of root rot were observed, and 2 weeks after inoculation, 75% of plants expressed severe symptoms on roots, stems, and leaves. P. cinnamomi was reisolated from roots, stems, and leaves of diseased plants, but was not isolated from the control plants. The reisolate was morphologically identical to the original isolate. This is the first report of P. cinnamomi from ivy in Europe. References: (1) H. Kröber. Mitt. Biol. Bundesanst. Land Forstwirtsch. Berlin-Dahlem 225:73, 1985. (2) D. J. Stamps et al. 1990. Mycol. Pap. No. 162. CAB Int. Mycol. Inst., Kew, England.
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Sánchez, M. E., S. Andicoberry, and A. Trapero. "Phytophthora Root Rot of Aleppo Pine Seedlings in a Forest Nursery in Spain." Plant Disease 86, no. 5 (May 2002): 563. http://dx.doi.org/10.1094/pdis.2002.86.5.563c.
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Since 1993, more than 120,000 ha of former agricultural lands has been forested in southern Spain. However, there is a lack of information about the etiology of the diseases affecting nursery seedlings in the region. During 1998 and 1999, death of Aleppo pine (Pinus halepensis) seedlings was associated with episodes of excess water. The plants were grown in containers in fertilized peat under shade cloth and remained waterlogged for long periods. A few weeks before their scheduled planting in the field, the plants exhibited needle wilting, extensive root necrosis, and root death. Phytophthora species were suspected as the cause of the mortality, and several species of the genus Phytophthora have been reported to cause damping-off of seedlings of Pinus spp. Only P. citrophthora, however, has been associated with Aleppo pine (1). In a nursery in southern Spain, P. drechsleri mating type A2 was isolated consistently from rotted roots of Pinus halepensis seedlings. Fungal identification was based on temperature-growth relationships and sporangial and gametangial characteristics (1). The optimum growth temperature was 24°C, with a rapid decline in growth rate above 30°C. Sporangia were persistent, terminal, nonpapillate, ovoid, and averaged 41 ± 4 × 29 ± 3 μm. The isolates were self-sterile, and antheridia and oogonia were only observed in pairings with A1 testers of P. drechsleri. Oogonia appeared smooth, spherical, and 33 ± 2 μm in diameter, with amphigynous antheridia that were 14 ± 1 μm long. Pathogenicity tests were conducted on 1-year-old seedlings of Pinus halepensis inoculated with two isolates of P. drechsleri collected from Aleppo pine and Quercus ilex seedlings, respectively, and two isolates of P. cinnamomi from Q. ilex. Inoculated and noninoculated control plants were waterlogged 2 days per week. After 18 weeks, both species of Phytophthora produced extensive root necrosis that resulted in needle wilting. Control plants did not develop needle symptoms and only had a low level of root necrosis. No difference in pathogenicity was observed between the isolates of either species. However, disease severity was less with isolates of P. drechsleri from Q. ilex than with those from Aleppo pine. To our knowledge, this is the first report of P. drechsleri causing root rot of Aleppo pine seedlings in forest tree nurseries in Spain and also demonstrates the potential for P. cinnamomi to cause damping-off on this pine species. Reference: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996.
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Swiecki, T. J., E. A. Bernhardt, and M. Garbelotto. "First Report of Root and Crown Rot Caused by Phytophthora cinnamomi Affecting Native Stands of Arctostaphylos myrtifolia and A. viscida in California." Plant Disease 87, no. 11 (November 2003): 1395. http://dx.doi.org/10.1094/pdis.2003.87.11.1395b.
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Ione manzanita (Arctostaphylos myrtifolia) is a rare, endemic, evergreen shrub restricted to Ione formation soils (infertile, acidic, sedimentary oxisols) in the foothills of the Sierra Nevada. The widely distributed A. viscida (whiteleaf manzanita) intermixes with A. myrtifolia at the margins of Ione formation soils. In 2002, we observed extensive mortality within two mixed stands of A. myrtifolia and A. viscida near Ione, CA. At one site, nearly all plants of both species in a 0.25-ha area had died recently. At a second site, most of the A. myrtifolia and A. viscida plants on several hectares died at least 5 years earlier. Dying plants of both species exhibited wilting and desiccation of the foliage; dark brown discoloration and necrosis of the root crown, taproot, and some large roots; and loss of fine roots. Plants of all age classes were affected. We consistently isolated a Phytophthora sp. from symptomatic plants of both species using PARP (1) and acidified potato dextrose agar. We recovered the same Phytophthora sp. from soil collected under dead plants using green pears to bait flooded soil samples. The pathogen was not recovered from soil collected under healthy plants 50 m from the nearest dead plant. Based on the morphology of the hyphae, chlamydospores, sporangia, and the sequence of the internal transcribed spacer rDNA, we identified the pathogen as P. cinnamomi Rands (GenBank Accession No. AY267370; ATCC No. MYA-2989). To test pathogenicity, we poured zoospore suspensions (4 × 104 zoospores per pot) on the soil of eight pots with rooted A. myrtifolia cuttings and four pots with rooted A. viscida cuttings (1 14-month-old plant per pot). The soil in inoculated and uninoculated control pots (eight A. myrtifolia and two A. viscida) was flooded for 20 to 23 h. All inoculated A. myrtifolia developed severe root and crown rot, and seven of eight died within 17 days. All inoculated A. viscida developed severe root rot, and three of four developed 5- to 10-cm long basal cankers. After 17 days, we isolated P. cinnamomi from inoculated A. myrtifolia (eight of eight) and A. viscida (two of four) but not from controls, which remained healthy. We tested pathogenicity in native soil by transplanting rooted cuttings (eight A myrtifolia and six A. viscida) into pots of naturally infested soil from one of the disease centers. Controls (four and three plants, respectively) were planted in soil collected from under healthy plants. Pots were flooded for 12 to 13 h for 11 days (A. myrtifolia) or 6 weeks (A. viscida) after transplanting. All plants grown in naturally infested soil developed root and crown rot, and all A. myrtifolia and one A. viscida died within 5 weeks of transplanting. Plants grown in field soil collected near healthy plants remained asymptomatic. We isolated P. cinnamomi from all eight A. myrtifolia and three A. viscida plants grown in infested soil but not from the controls. To our knowledge, this is the first report of root and crown rot caused by P. cinnamomi on A. myrtifolia and A. viscida. P cinnamomi was first isolated in the state in 1942 (2), but it has not previously been reported to caused significant mortality in natural stands of California native species. This disease will significantly impact conservation of the already threatened A. myrtifolia. References: (1) D. C. Erwin and O. K. Ribeiro, Phytophthora Diseases Worldwide. American Phytopathological Society, St. Paul, MN 1996. (2) V. A. Wager. Hilgardia 14:519, 1942.
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Zwart, Drew C., and Soo-Hyung Kim. "Biochar Amendment Increases Resistance to Stem Lesions Caused by Phytophthora spp. in Tree Seedlings." HortScience 47, no. 12 (December 2012): 1736–40. http://dx.doi.org/10.21273/hortsci.47.12.1736.
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Soil amendment with biochar is thought to confer multiple benefits to plants including induction of systemic resistance to plant pathogens. Pathogens in the genus Phytophthora cause damaging diseases of woody species throughout the world. The objective of this study was to test 1) whether biochar amendment induces resistance to canker causing Phytophthora pathogens; and 2) how this resistance is related to the amount of biochar amendment in two common landscape tree species: Quercus rubra (L.) and Acer rubrum (L.). Seedlings of Q. rubra and A. rubrum were planted in peatmoss-based potting mix uniformly amended with 0%, 5%, 10%, or 20% biochar by volume. Plants in each treatment group were stem wound-inoculated with an isolate of Phytophthora cinnamomi Rands (host: Q. rubra) or P. cactorum (Leb. and Cohn) Schröeter (host: A. rubrum) using standard agar-plug inoculation procedures. Amendment of potting media with 5% biochar reduced horizontal expansion of lesions in both hosts, whereas the same treatment significantly reduced vertical expansion of lesions in A. rubrum (P < 0.05). In addition, 5% biochar resulted in a higher midday stem water potential in Q. rubra (P = 0.066) and significantly greater stem biomass in A. rubrum compared with inoculated control plants (0% biochar, P < 0.05). Our results suggest that biochar amendment has the potential to alleviate disease progression and physiological stress caused by Phytophthora canker pathogens and there is likely an optimal level of biochar incorporation into the root media beyond which the effects may be less pronounced.
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Tuo, Xinxin, Jie Yang, Yedong Zhang, and Peiyi Wang. "Synthesis of N-Methylmorpholinium Derivatives Possessing a 1,3,4-Oxadiazole Core as Feasible Antibacterial Agents against Plant Bacterial Diseases." Journal of Chemistry 2021 (September 1, 2021): 1–10. http://dx.doi.org/10.1155/2021/5415950.
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To develop a kind of quaternary ammonium compounds that can safely apply in agriculture for managing the plant bacterial diseases, herein, a series of N-methylmorpholinium derivatives possessing a classical 1,3,4-oxadiazole core were prepared and the antibacterial activities both in vitro and in vivo were screened. Bioassay results revealed that compounds 3l and 3i showed the strongest antibacterial activity toward pathogens Xanthomonas oryzae pv. oryzae and X. axonopodis pv. citri with the lowest EC50 values of 1.40 and 0.90 μg/mL, respectively. Phytotoxicity test trials indicated that target compounds bearing a bulky N-methylmorpholinium pendant are safe for plants. The following in vivo bioassays showed that compound 3l could control the rice bacterial blight disease, thereby affording good control efficiencies of 55.95% (curative activity) and 53.09% (protective activity) at the dose of 200 μg/mL. Preliminary antibacterial mechanism studies suggested that target compounds had strong interactions with the cell membrane of bacteria via scanning electron microscopy imaging. Additionally, this kind of framework also displayed certain antifungal activity toward Fusarium oxysporum and Phytophthora cinnamomi. Given the above privileged characteristics, this kind of 1,3,4-oxadiazole-tailored N-methylmorpholinium derivatives could stimulate the design of safe quaternary ammonium bactericides for controlling plant bacterial diseases.
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Garibaldi, A., D. Bertetti, A. Poli, L. Bizioli, and M. L. Gullino. "First Report of Root Rot Caused by Phytophthora cinnamomi on Mountain Laurel (Kalmia latifolia) in Italy." Plant Disease 96, no. 9 (September 2012): 1381. http://dx.doi.org/10.1094/pdis-04-12-0402-pdn.
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Kalmia latifolia L., common name Mountain Laurel, is an evergreen shrub that is becoming increasingly popular in gardens. It is also grown as a potted plant for its round flowers that range from light pink to white and occur in clusters in late spring. During July 2011, 3-year-old plants of K. latifolia ‘Olympic Fire’ showed extensive chlorosis and root rot on several commercial nurseries close to Maggiore Lake (Verbano-Cusio-Ossola Province) in northwestern Italy. Twigs wilted and died and leaves dropped, although in some cases, wilted leaves persisted on stems. The whole root system was affected with vascular tissues on the lower stem exhibiting brown discoloration, followed by plant death. The disease was severe and widespread, affecting 5% of approximately 3,500 plants. Tissue fragments of 1 mm2 were excised from the margins of the lesions and plated. A Phytophthora-like organism was consistently isolated on an oomycete-selective medium (BNPRA + HMI at 25 μg/ml) (4) after disinfesting root pieces for 1 min in a 1% NaOCl solution. The pathogen was identified based on morphological and physiological features as Phytophthora cinnamomi (2). Oogonia didn't form in single culture. On V8 agar, the microorganism was characterized by coenocytic coralloid hyphae, with spherical lateral and terminal swellings 23 to 46 (average 34) μm in diameter (n = 50), single or in clusters, and produced spherical, terminal chlamydospores 35 to 47 (average 40) μm in diameter (n = 50). No sporangia were produced after growing pure cultures in sterilized soil extracts nor were they produced on V8 agar. The internal transcribed spacer (ITS) region of the rDNA of a single isolate was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 898-bp segment showed a 99% homology with the sequence of P. cinnamomi (GU799638). The nucleotide sequence has been assigned the GenBank Accession No. JQ951607. Pathogenicity of one isolate obtained from infected plants was confirmed by inoculating 18-month-old plants of K. latifolia ‘Olympic Fire’. The isolate was grown for 50 days in a mixture of 70:30 wheat/hemp kernels and then mixed into a substrate containing sphagnum peat moss/pumice/pine bark/clay (50:20:20:10 v/v) at a rate of 3 g/l. One plant per 2-l pot was transplanted into the substrate and constituted the experimental unit. Five plants were inoculated. Noninoculated plants represented the control treatment and the trial was repeated once. All plants were kept in a greenhouse at 24 to 27°C. Two of five plants inoculated developed symptoms of chlorosis, wilting, and root rot after 70 days and remaining plants after about 80 days. P. cinnamomi was reisolated consistently from inoculated plants but not from controls that remained symptomless. To our knowledge, this is the first report of P. cinnamomi on K. latifolia in Italy and in Europe. The disease has been reported in the United States (3). The economic importance of the disease is uncertain because of the limited number of nurseries that grow this crop in Italy, although its importance could increase as the popularity of K. latifolia increases. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. American Phytopathological Society, St Paul, MN, 1996. (3) L. F. Grand. North Carolina Agric. Res. Serv. Techn. Bull. 240, 1985. (4) H. Masago et al. Phytopathology 67:425, 1977.
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Kobliha, J., and J. Stejskal. "Recent fir hybridization research in the light of Czech-American cooperation." Journal of Forest Science 55, No. 4 (March 25, 2009): 162–70. http://dx.doi.org/10.17221/114/2008-jfs.
Full textAbstract:
The project is based on control pollination of different fir species in the sense of interspecific hybridization. The aim of this procedure is a new bred material for specific needs of forestry and Christmas tree production. Concrete breeding aims are represented in this sense by resistance to limiting environmental conditions (e.g. drought) and by resistance to diseases and pests. The experiment follows a traditional hybridization program of the department focused on the genus <I>Abies</I> and recently it has been extended by the Czech-U.S. cooperation (North Carolina State University Raleigh). For hybridization mainly Mediterranean fir species are used together with Asian species (e.g. <I>Abies koreana</I>) and of course American species (above all <I>Abies fraseri</I>). Hybridizations will be followed by <I>Phytophthora cinnamomi</I> screenings that have high priority. Hybrid progenies will undergo early testing and their vegetative propagation for cloning purposes is being considered.
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Elshafie, Hazem S., Lucia Caputo, Laura De Martino, Shimaa H. Sakr, Vincenzo De Feo, and Ippolito Camele. "Study of Bio-Pharmaceutical and Antimicrobial Properties of Pomegranate (Punica granatum L.) Leathery Exocarp Extract." Plants 10, no. 1 (January 14, 2021): 153. http://dx.doi.org/10.3390/plants10010153.
Full textAbstract:
Pomegranate (Punica granatum L.) fruits are important sources of vitamins and minerals and widely used in the dietary supplement industry. An aqueous extract of its leathery exocarp (LEP) was obtained by a solid-phase micro-extraction method. The antifungal activity was examined against the phytopathogenic fungi, Fusarium oxysporum, Phytophthora cinnamomi, Penicillium digitatum and Botrytis cinerea, and the antibacterial activity was evaluated against Escherichia coli, Xanthomonas campestris,Bacillus megaterium and Clavibacter michiganensis. The antimicrobial assays showed, in some cases, a promising antimicrobial effect compared to the synthetic drugs. The possible anti-acetylcholinesterase and antioxidant activities of the LEP extract were investigated by the Ellman’s assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, respectively, and their results showed that the LEP extract has an effective anti-acetylcholinesterase inhibitory effect and an antioxidant activity. Thus, the LEP extract could be valid as a candidate for further studies on the use of pomegranate in neurodegenerative diseases as a food preservative and a suitable substitute to control several phytopathogens.
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Belisario, A., M. Maccaroni, A. M. Vettraino, and A. Vannini. "First Report of Phytophthora nicotianae and P. citricola Associated with English Walnut Decline in Europe." Plant Disease 87, no. 3 (March 2003): 315. http://dx.doi.org/10.1094/pdis.2003.87.3.315b.
Full textAbstract:
English (Persian) walnut (Juglans regia), among the most widely cultivated species of Juglans worldwide, is cultivated primarily for fruit production but also for timber. In the last 10 years, walnut decline causing leaf yellowing, sparse foliage, overall decline, and plant death has increased in Italian commercial orchards. In Italy, Phytophthora cactorum, P. cambivora, P. cinnamomi, and P. cryptogea are associated with this disease (1,4). Over the last 5 years, P. cinnamomi was the most widely isolated and destructive species (1). Recently, a different species of Phytophthora was isolated from diseased roots and soil from around lateral roots of 10 declining trees in two orchards in the Veneto Region of northern Italy. Another species of Phytophthora was isolated consistently from rotted roots of declining walnut trees in two orchards in the Campania Region of southern Italy. Phytophthora spp. were isolated directly from plant material or Rhododendron spp. leaf baiting on soil samples with PARBhy selective medium (10 mg of pimaricin, 250 mg of ampicillin [sodium salt], 10 mg of rifampicin, 50 mg of hymexazol, 15 mg of benomyl, 15 g of malt extract, 20 g of agar in 1,000 ml of H2O). Two species of Phytophthora were identified based on morphological and cultural characteristics (2). The species from trees in the Veneto Region was identified as P. nicotianae. All isolates produced papillate, spherical to obturbinate, occasionally caducous sporangia with short pedicels, terminal and intercalary chlamydospores, and were mating type A2. The species isolated from trees in the Campania Region was identified as P.citricola. Isolates were homothallic, produced semipapillate, persistent, obclavate to obpyriform sporangia, occasionally with two apices, and antheridia paragynous. Identifications were confirmed by comparing restriction fragment length polymorphism patterns of the internal transcribed spacer region of rDNA with those obtained from previously identified species of Phytophthora. Pathogenicity of two isolates each of P. citricola and P. nicotianae was tested on 2-year-old potted walnut seedlings. Inocula were prepared by inoculating sterilized millet seeds moistened with V8 broth with plugs of mycelium and incubated for 4 weeks at 20°C in the dark. Infested seeds were added to potting soil at a rate of 3% (wt/vol). One day later, pots were flooded for 48 h to promote sporulation. Ten noninoculated seedlings were used as the control. Symptoms were assessed 2 months after inoculation. Seedlings inoculated with P. nicotianae developed necrosis of feeder and lateral roots, but only limited infection of taproots. Seedlings inoculated with P. citricola developed necroses at the insertion points of lateral roots. All four isolates produced visible damage to lateral roots on inoculated plants. P. nicotianae and P. citricola were reisolated from respectively infected roots. Results from these inoculations confirmed P. nicotianae and P. citricola as root pathogens of English walnut. Both species were associated with walnut decline as reported in the United States (3). To our knowledge, this is the first report of P. nicotianae and P. citricola on J. regia in Europe. References: (1) A. Belisario et al. Petria 11:149. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) M. E. Matheron and S. M. Mircetich. Phytopathology 75:977, 1985. (4) A. M. Vettraino et al. Plant Dis. 86:328, 2002.
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Bowers, John H., and James C. Locke. "Effect of Formulated Plant Extracts and Oils on Population Density of Phytophthora nicotianae in Soil and Control of Phytophthora Blight in the Greenhouse." Plant Disease 88, no. 1 (January 2004): 11–16. http://dx.doi.org/10.1094/pdis.2004.88.1.11.
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Formulated plant extracts and oils were investigated for control of diseases caused by Phytophthora spp. Soil infested with chlamydospores of Phytophthora nicotianae was treated by incorporating 1, 5, and 10% aqueous emulsions of formulations containing clove oil, neem oil, pepper extract and mustard oil, cassia extract, synthetic cinnamon oil, or the fungicide metalaxyl. Population densities of P. nicotianae were determined at 0 (before treatment), 1, 3, 7, 14, and 21 days after treatment. Treatment of the soil with 5 and 10% aqueous emulsions resulted in significant (P < 0.05) differences among treatment mean values at each assay date. After 1 day, population densities were reduced to below the limit of detection (<0.04 CFU/cm3) in soil treated with 10% aqueous emulsions of two pepper extract-mustard oil formulations and two cassia extract formulations, and near the limit of detection for a synthetic cinnamon oil formulation. Over time, populations of P. nicotianae were detected in the assay; however, after 21 days, populations of P. nicotianae in soil treated with one of the pepper extract-mustard oil formulations still were not detected. Formulations of clove oil, another pepper extract-mustard oil combination, the two cassia extracts, and the synthetic cinnamon oil reduced populations 98.4 to 99.9% after 21 days compared with the nontreated control soil. The neem oil formulation and metalaxyl did not reduce pathogen populations at any rate tested. In the greenhouse after 35 days, 10% aqueous emulsions of a pepper extract-mustard oil formulation, a cassia extract, and the synthetic cinnamon oil formulation suppressed disease development in periwinkle 93.0 to 96.7% compared with the nontreated infested soil. The observed reduction in the pathogen population and significantly more healthy plants in the greenhouse indicates that these formulations of plant extracts and oils could have important roles in biologically based management strategies for control of diseases caused by P. nicotianae.
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Martins, João, Aitana Ares, Vinicius Casais, Joana Costa, and Jorge Canhoto. "Identification and Characterization of Arbutus unedo L. Endophytic Bacteria Isolated from Wild and Cultivated Trees for the Biological Control of Phytophthora cinnamomi." Plants 10, no. 8 (July 30, 2021): 1569. http://dx.doi.org/10.3390/plants10081569.
Full textAbstract:
Arbutus unedo L. is a resilient tree with a circum-Mediterranean distribution. Besides its ecological relevance, it is vital for local economies as a fruit tree. Several microorganisms are responsible for strawberry tree diseases, leading to production constrictions. Thus, the development of alternative plant protection strategies is necessary, such as bacterial endophytes, which may increase their host’s overall fitness and productivity. As agricultural practices are a driving factor of microbiota, this paper aimed to isolate, identify and characterize endophytic bacteria from strawberry tree leaves from plants growing spontaneously in a natural environment as well as from plants growing in orchards. A total of 62 endophytes were isolated from leaves and identified as Bacillus, Paenibacillus, Pseudomonas, Sphingomonas and Staphylococcus. Although a slightly higher number of species was found in wild plants, no differences in terms of diversity indexes were found. Sixteen isolates were tested in vitro for their antagonistic effect against A. unedo mycopathogens. B. cereus was the most effective antagonist causing a growth reduction of 20% in Glomerella cingulata and 40% in Phytophthora cinnamomi and Mycosphaerella aurantia. Several endophytic isolates also exhibited plant growth-promoting potential. This study provides insights into the diversity of endophytic bacteria in A. unedo leaves and their potential role as growth promoters and pathogen antagonists.
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Stejskal, J., J. Kobliha, and J. Frampton. "Results of Czech-American cooperation in interspecific fir hybridization in 2008 and 2009." Journal of Forest Science 57, No. 3 (March 21, 2011): 114–22. http://dx.doi.org/10.17221/80/2010-jfs.
Full textAbstract:
This Czech-American research collaboration is investigating interspecific hybridization among various fir species produced via control pollination. Its aim is the development of newly bred material for specific needs of Christmas tree production. The specific target of the breeding is increased growth rate, development of resistance to diseases, insect pests, and limiting environmental conditions (e.g. drought). Experimentation follows a traditional hybridization program of the Czech department focusing on the genus Abies and a long-term breeding program of the American department aimed at Christmas tree production. For hybridization, mainly Mediterranean fir species are used together with American species (especially Abies fraseri) and other species (e.g. Abies koreana). Generally overcoming 5% of viable seeds in the sample can be considered a success. Only few of our hybrid combinations have complied with this condition so far. In 2008 the hybrid combination CZ1 × NC73 brought 16% of viable seeds. In 2009 the most successful hybrid combination CZ1 × FF81 brought 6% of viable seeds. These crossing experiments will initially be followed by Phytophthora cinnamomi resistance screening trials.
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Feng, C. T., W. C. Ho, and Y. C. Chao. "Basal Petiole Rot and Plant Kill of Zamioculcas zamiifolia Caused by Phytophthora nicotianae." Plant Disease 90, no. 8 (August 2006): 1107. http://dx.doi.org/10.1094/pd-90-1107b.
Full textAbstract:
Zamioculcas zamiifolia (Lodd.) Engl., commonly called ‘ZZ’ plant, is a monocotyledonous plant in the Araceae. It is a new introduction in the foliage plant industry worldwide and is an increasing popular ornamental foliage plant in Taiwan. In 2003, basal petiole rot and death of ZZ plants were found in two nurseries in southern Taiwan with 18% of the plants diseased at one nursery. Early symptoms were water soaking of the petiole base and a slight yellowing of the leaflets followed by browning of leaflets. As the disease progressed, the petiole base became dark brown, shriveled, collapsed, and eventually rotted. The surface of the roots and rhizomes of diseased plants were initially blackish brown followed by root rots and mortality of plants. A Phytophthora species was consistently isolated from diseased petioles, rhizomes, and roots on a selective medium (4). Two single zoospore isolates (2), each from a different nursery, were used for morphological and pathogenicity tests. The isolates were grown on vegetable juice agar (10% V8 juice, 0.02% CaCO3, and 2% agar [VJA]) at 28°C with 12-h irradiation for 10 days. Sporangia were nondeciduous, terminal or intercalary, and attached to irregularly or sympodially branched sporangiophores. Papillate sporangia were spherical to broadly ovoid or obpyriform, averaged 37.3 × 30.2 μm, and ranged from 23 to 55 μm in length by 17 to 46 μm in diameter, with a length/breadth ratio of 1.24 and a range of 1.1 to 1.4. Chlamydospores with walls 1 to 4 μm thick were terminal or intercalary, spherical, averaged 30.6 μm in diameter, and ranged from 18 to 46 μm. On the basis of the morphological characteristics above, Phytophthora nicotianae Breda de Haar. (synonym P. parasitica Dastur) was identified (1). Paired with known A1 and A2 mating types of P. cinnamomi on VJA, both P. nicotianae cultures were A2, forming oospores after 14 days in darkness at 28°C. Disease-free ZZ plants were propagated by rhizomes in 242-cm3 round pots with 500 g of sterilized potting medium (vermiculite/peat moss/perlite = 1:2:1). Plants with 30 cm long petiole were used for inoculation. For the pathogenicity test, both isolates were grown on VJA plates sealed with Parafilm at 28°C in darkness. After 10 days, aerial mycelia with sporangia were scraped off the plates, placed in 10 ml of sterile distilled water at 8°C for 15 min to release zoospores. A zoospore suspension was adjusted to 104 zoospores/ml following enumeration with a microliter pipette (3) and 200 ml of the suspension was added to each pot, or rhizomes and roots were dipped in 400 ml of the suspension for 60 min and planted immediately. Ten plants were inoculated with either method and water was added to inoculated control plants. Water soaking of the petiole bases developed in 7 days and mortality occurred in 10 days in a screenhouse after plants were inoculated with either method. Control plants remained healthy and no petiole, root, or rhizome rots developed. P. nicotianae was isolated from the advancing lesions of the inoculated plants and both experiments were repeated. To our knowledge, this is the first report of basal petiole rot and plant kill of Zamioculcas zamiifolia caused by P. nicotianae. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) W. C. Ho and W. H. Ko. Bot. Bull. Acad. Sin. 38:41, 1997. (3) W. H. Ko et al. Phytopathology 63:1206, 1973. (4) W. H. Ko et al. Trans. Br. Mycol. Soc. 71:496, 1978.
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Vettraino, A. M., A. Belisario, M. Maccaroni, N. Anselmi, and A. Vannini. "First Report of Phytophthora cryptogea in Walnut Stands in Italy." Plant Disease 86, no. 3 (March 2002): 328. http://dx.doi.org/10.1094/pdis.2002.86.3.328c.
Full textAbstract:
English (Persian) walnut (Juglans regia L.) is among the most widely cultivated species in pure and mixed plantations of broadleaved trees in Italy. A decline of walnut of increasing occurrence has been reported recently in new plantations in central and northern Italy. Symptoms of the decline were typically characterized by yellowing of the foliage, defoliation, and plant death. Dark, flame-shaped necroses were often present at the collar. Phytophthora cactorum, P. cambivora, and P. cinnamomi were among the species associated with necrotic tissues of the collar and main roots (1). Furthermore, a Phytophthora sp. was isolated from soil removed from the lateral root zone of 6 of 15 declining trees in 3 walnut plantations, 2 in northern Italy and 1 in central Italy. Isolations were made by baiting with Rhododendron leaves and plating on PARBhy selective medium (3). The species isolated was identified as P. cryptogea on the basis of morphological and cultural characteristics (2). All isolates produced oval to obpyriform, nonpapillate sporangia and were mating type A2. Identification of the isolates was confirmed by comparing the restriction fragment length polymorphism patterns of the internal transcribed spacer region of ribosomal DNA with those obtained from previously identified Phytophthora species. Pathogenicity tests on potted 2-year-old walnut seedlings were conducted using two isolates of P. cryptogea. Inoculum was prepared by growing isolates on sterilized millet seeds added to soil at 2.5% (wt/vol). Sporulation was induced by 24-h flooding of the soil. Symptoms were assessed 1 month after inoculation. Ten uninoculated seedlings were used as controls. Inoculated seedlings showed no symptoms on the tap root, but there were extensive necroses of lateral roots ranging from 14 to 75% (average 38.6 ± 6.7 SE) of total lateral root (dry weight) compared with values of 0 to 11% (average 3 ± 1.5 SE) for uninoculated seedlings. P. cryptogea was easily reisolated from infected lateral roots and from the soil of inoculated pots. The inoculation trials confirmed P. cryptogea as a feeder-root pathogen of walnut in Italy. To our knowledge, this is the first report of P. cryptogea on English walnut in Italy. This species often has been associated with walnut decline in the United States (2) and on other woody plants in Italy (3). References: (1) A. Belisario et al. Petria 11:127, 2001. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Association, St. Paul, MN, 1996. (3) A. M. Vettraino et al. Plant Pathol. 50:90, 2001.
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Valencia, A. L., R. A. Chorbadjian, and B. A. Latorre. "First Report of Nothofagus macrocarpa Dieback Caused by Phytophthora citrophthora and P. nicotianae in Chile." Plant Disease 95, no. 9 (September 2011): 1193. http://dx.doi.org/10.1094/pdis-03-11-0258.
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The genus Nothofagus, family Nothofagaceae, comprises 36 species of trees that are native to the Southern Hemisphere. N. macrocarpa (DC.) F.M. Vásquez & R.A. Rodríguez (Roble de Santiago) is an important deciduous tree, endemic to central Chile (32 to 35°S), and found above 800 m altitude. There is an increasing interest in N. macrocarpa as an ornamental. However, a general dieback (40 to 50% prevalence) was observed at a commercial nursery in Santiago in 2009, limiting its multiplication. Symptoms are wilting, partial defoliation, reddish brown cankers on the crowns, and root necrosis. The purpose of this work was to study the etiology of the dieback in nurseries. Phytophthora was isolated from the roots and cankers of symptomatic plants (n = 3) and soil samples (using apples and avocados as baits) on amended corn meal agar (3) at 20°C for 5 days in the dark. Morphologically, P. citrophthora (Smith & Smith) Leonian, and P. nicotianae Breda de Haan were identified (2). On V8 juice agar (V8) (1), P. citrophthora formed petaloid colonies, grew between 5 and 30°C (optimum of 25°C), and produced deciduous, mono- or bipapillated sporangia of (28.1) 45.0 to 64.1 × (18.8) 32.0 to 39.2 μm. On V8, P. nicotianae produced cottony colonies, grew between 10 and 30°C (optimum of 25°C), and produced spherical, intercalary chlamydospores (mean diameter of 19.6 μm) and persistent, papillate, spherical to ovoid, ellipsoid, obpyriform sporangia of (33.2) 47.5 to 67.6 × (24.1) 30.0 to 48.9 μm. Isolates of P. citrophthora were sexually sterile, but P. nicotianae formed oogonia with amphigenous antheridia in dual cultures with P. cinnamomi (A2 compatibility type). BLAST analysis of the internal transcribed spacer (ITS) region of rDNA of isolates identified as P. citrophthora (IMI 399056 and IMI 399054, GenBank Accession Nos. JF699756 and JF699755) and P. nicotianae (IMI 399055, Accession No. JF699757), amplified by PCR using ITS universal primers (4), revealed 100% similarity with reference isolates of P. citrophthora (Accession Nos. GU259324.1 and GU259317.1) and P. nicotianae (Accession No. GU983635.1). P. citrophthora (n = 2) and P. nicotianae (n = 1) were pathogenic when wounded detached twigs (n = 5) of N. macrocarpa and N. obliqua were inoculated with 20 μl of a mycelial suspension (106 CFU/ml) of either Phytophthora spp. Twigs were placed in a moist chamber at 20°C for 12 days prior to determine the length of the necrotic lesions that developed. An equal number of noninoculated twigs were left as control. Reisolation of P. citrophthora and P. nicotianae from inoculated material was 100%. The length of the necrotic lesions (13 to 80 mm) from inoculated N. macrocarpa and N. obliqua was significantly greater (P < 0.05) compared with the controls. Regardless of Phytophthora isolates, necrotic lesions (53.9 ± 15.8 mm) in infected N. macrocarpa were significantly longer than in N. obliqua (28.6 ± 13.1 mm) (P < 0.0001). To our knowledge, this is the first report of P. citrophthora and P. nicotianae associated with dieback on N. macrocarpa in Chile. Therefore, there is a potential risk of Phytophthora dieback in N. macrocarpa in nature. References: (1) J. Ampuero et al. Plant Dis. 92:1529, 2008. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) B. A. Latorre and R. Muñoz. Plant Dis. 77:715, 1993. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.
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Vargas, M., C. Loyola, N. Zapata, V. Rivera, G. Secor, M. Bolton, and A. France. "First Report of Root Rot of Chicory Caused by Phytophthora cryptogea in Chile." Plant Disease 96, no. 4 (April 2012): 591. http://dx.doi.org/10.1094/pdis-03-11-0245.
Full textAbstract:
Chicory (Cichorium intybus L. var sativum Bisch.), a relatively new high-value crop in Chile, was introduced for commercial production of inulin. Inulins are polysaccharides extracted from chicory tap roots that are used in processed foods because of their beneficial gastrointestinal properties. Approximately 3,000 ha of chicory are grown for local processing in the BioBio Region near Chillan in south central Chile. Recently, a severe rot of 1 to 3% of mature roots in the field and after harvest has been observed in most fields, which caused yield and quality losses. Typical symptoms include a brown discoloration and a soft, watery decay of the root. Tissue pieces from symptomatic roots were placed on water agar and clarified V8 juice agar medium amended with antibiotics (1) for isolation of the causal pathogen. A Phytopthora sp. had been consistently isolated from root lesions, and axenic cultures were obtained using single-hypha transfers. The species was provisionally identified as Phytopthora cryptogea (Pethybridge and Lafferty, 1919) on the basis of morphological and cultural characteristics (1). Mycelia grew between 5 and 30°C with optimal growth at 20 to 25°C and no growth at 35°C. All isolates produced hyphal swellings and nonpapillate, persistent, internally proliferating, and ovoid to obpyriform sporangia with mean dimensions of 45 × 31 μm in sterile soil extract. The isolates were of A1 mating type because they produced oospores only when paired with reference isolates of P. cinnamomi A2 on clarified V8 juice agar amended with thiamine, tryptophan, and β-sitosterol (1) after 20 days at 20°C in the dark. On the basis of morphological and sequence data from cytochrome c oxidase subunit 1 and 2, internal transcribed spacer 2, and β-tubulin (GenBank Accession Nos. JQ037796 to JQ037798, respectively), the pathogen was identified as P. cryptogea. Pathogenicity tests were conducted using three isolates of P. cryptogea by placing a 7-mm-diameter disk from a 1-week-old V8 agar culture on 10 wounded and nonwounded healthy chicory roots (2). Control roots were mock inoculated with agar plugs. The inoculated roots were incubated at 20°C in a moist chamber. Root rot symptoms, identical to those observed both in field and storage, developed after 4 to 6 days only on wounded sites inoculated with the pathogen, and P. cryptogea was reisolated from these inoculated plants. Mock-inoculated roots remained healthy. This experiment was completed twice and similar results were obtained. To our knowledge, this is the first report of Phytophthora root rot of chicory caused by P. cryptogea in Chile. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) M. E. Stanghellini and W. C. Kronland. Plant Dis. 66:262, 1982.
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Cacciola, S. O., G. E. Agosteo, and G. Magnano di San Lio. "Collar and Root Rot of Olive Trees Caused by Phytophthora megasperma in Sicily." Plant Disease 85, no. 1 (January 2001): 96. http://dx.doi.org/10.1094/pdis.2001.85.1.96a.
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Olive (Olea europea L.) is grown on about 154,000 ha in Sicily (southern Italy). In the summer of 1999, a few 3-year-old olive trees with decline symptoms were observed in a recently planted commercial orchard in the Enna province (Sicily). The trees were propagated on wild olive (O. europea L. var. sylvestris Brot.) rootstock. Aerial symptoms, consisting of leaf chlorosis, wilting, defoliation, and twig dieback followed in most cases by plant death, were associated with root rot and basal stem cankers. A Phytophthora sp. was consistently isolated from rotted rootlets and trunk cankers using the BNPRAH (benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol) selective medium. Pure cultures were obtained by single-hypha transfers. The species isolated from symptomatic olive trees was identified as P. megasperma Drechsler on the basis of morphological and cultural characteristics. All isolates were homothallic, with paragynous antheridia. The diameter of oospores varied from 28 to 42 μm (mean ± SE = 36.3 ± 0.4) when they were produced on potato-dextrose agar (PDA) and from 30 to 43 μm (mean ± SE = 37.8 ± 0.4) when they were produced in saline solution. Sporangia were non-papillate. Optimum and maximum temperatures for radial growth of the colonies on PDA were 25 and 30°C, respectively. At 25°C, radial growth rate was about 6 mm per day. The identification was confirmed by the electrophoresis of mycelial proteins on a polyacrylamide slab gel. The electrophoretic banding patterns of total soluble proteins and three isozymes (esterase, fumarase, and malate dehydrogenase) of the isolate from olive were identical to those of two isolates of P. megasperma obtained from cherry and from carrot in Italy and characterized previously (1). Conversely, they were clearly distinct from the electrophoretic patterns of four isolates of P. megasperma var. sojae Hildebr. from soybean (= P. sojae Kauf. & Ger.), from those of three isolates from asparagus tentatively identified as P. megasperma sensu lato (1) and from those of reference isolates of various species producing non-papillate sporangia, including P. cambivora (Petri) Buisman, P. cinnamomi Rands, P. cryptogea Pethybr. & Laff., P. drechsleri Tucker, and P. erythroseptica Pethybr. Pathogenicity of the isolate from olive was tested in the greenhouse at 18 to 25°C using 18-month-old rooted cuttings of olive cv. Biancolilla. Cuttings were inoculated on the lower stem by inserting a 3-mm plug taken from actively growing colonies on PDA into an incision made with a sterile scalpel. The wound was sealed with waterproof tape. Agar plugs with no mycelium were placed into the stem of cuttings used as a control. The bark was stripped and lesion areas were traced and measured 60 days after inoculation. The isolate from olive produced a brown necrotic lesion (mean size = 500 mm2) around the inoculation wound and was reisolated from the lesion. Conversely, the wound healed up on control plants. P. megasperma has previously been recognized as a pathogen of olive in Greece and Spain (3). However, this is the first report of P. megasperma causing root and collar rot of olive in Italy. References: (1) S. O. Cacciola et al. Inf. Fitopatol. 46:33, 1996. (2) D. C. Erwin and O. K. Ribeiro, 1996. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN. (3) M. E. Sánchez-Hernádez et al. Plant Dis. 81:1216, 1997.
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Benson, D. M., and Frank A. Blazich. "Control of Phytophthora Root Rot of Rhododendron chapmanii A. Gray with Subdue." Journal of Environmental Horticulture 7, no. 2 (June 1, 1989): 73–75. http://dx.doi.org/10.24266/0738-2898-7.2.73.
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Abstract Rooted cuttings of Chapman's rhododendron (Rhododendron chapmanii) in soilless medium were challenged with inoculum of the soi1borne fungus, Phytophthora cinnamomi (Rands). A portion of the plants received a soil drench of Subdue 2EC (metalaxyl) at 0.16 ml/L (2.0 oz/100 gal) at 2 month intervals. Chapman's rhododendron was highly susceptible to P. cinnamomi, but five of six plants treated with Subdue did not develop symptoms of Phytophthora root rot. In the one plant which developed root rot symptoms, P. cinnamomi was recovered in culture.
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Mcnab, W. Henry. "Evidence that Castanea Dentata Persists on Xeric, Mid-Elevation Sites in the Southern Appalachians." Journal of North Carolina Academy of Science 133, no. 1-2 (March 1, 2017): 23–31. http://dx.doi.org/10.7572/jncas-d-16-00004.1.
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Abstract: Castanea dentata (American chestnut) persists today in the southern Appalachian forests of North Carolina as sparsely occurring sprouting root systems. The introduction of two exotic fungal diseases into North America, root rot (Phytophthora cinnamomi) in the early 1800s and chestnut blight (Cryphonectria parasitica) in the early 1900s, eliminated C. dentata as a dominant canopy species. Identifying and understanding the characteristics of sites where C. dentata persists could offer insights for management and restoration. Using a regional forest inventory and analysis (FIA) database, I studied the ecology of C. dentata on 831 forested sample plots in 21 mountainous counties of western North Carolina. The purpose of my study was to determine if the presence of C. dentata was associated with common topographic variables and the co-occurrence of other tree species that could be used in a regression model for evaluation of sites for potential management activities. I found that C. dentata occurred on only 3.5% of the sample plots. Its presence was directly associated with elevation >900 m, positively related to the co-occurring species Quercus prinus (chestnut oak) and Q. rubra (northern red oak), and negatively related to Liriodendron tulipifera (yellow-poplar). Logistic regression revealed poor performance of formulations with multiple significant biological variables (i.e., tree species) because of multicollinearity effects with elevation. Good model performance was achieved with a two-variable formulation using elevation and a weighted averages score derived from direct gradient analysis and ordination of moisture affinities of the 30 tree species in the study plots. An explanation for the effect of elevation on occurrence of C. dentata on sites >900 m is unknown, but the arborescent species scores suggest probable xeric to subxeric plot moisture regimes. Limitations of the FIA data for my study were many including few plots with C. dentata, lack of plot soil characteristics and history of disturbance from fire. Results from my study may have application to rank forest sites for investigation of biological control of C. parasitica through hypovirulence and for identifying stands for application of silvicultural practices to reduce environmental stress and increase survival of existing root systems.
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Downer, A. J., J. A. Menge, and E. Pond. "Association of Cellulytic Enzyme Activities in Eucalyptus Mulches with Biological Control of Phytophthora cinnamomi." Phytopathology® 91, no. 9 (September 2001): 847–55. http://dx.doi.org/10.1094/phyto.2001.91.9.847.
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A series of samples were taken from mulched and unmulched trees starting at the surface of mulch or soil to a 15 cm soil depth, forming a vertical transect. Saprophytic fungi isolated from the soil samples on rose bengal medium and surveyed visually were most abundant in mulches and at the interface of mulch and soil (P < 0.05). Microbial activity as assayed by the hydrolysis of fluorescein diacetate was significantly greater in mulch layers than in soils. Cellulase and laminarinase enzyme activities were greatest in upper mulch layers and rapidly decreased in soil layers (P < 0.05). Enzyme activities against Phytophthora cinnamomi cell walls were significantly greater in mulch than in soil layers. When Phytophthora cinnamomi was incubated in situ at the various transect depths, it was most frequently lysed at the interface between soil and mulch (P < 0.001). Roots that grew in mulch layers were significantly less infected with Phytophthora cinnamomi than roots formed in soil layers. In mulched soil, roots were commonly formed at the mulch-soil interface where Phytophthora populations were reduced, whereas roots in unmulched soil were numerous at the 7.5 cm depth where Phytophthora cinnamomi was prevalent. Enzyme activities were significantly and positively correlated with each other, microbial activity, and saprophytic fungal populations, but significantly and negatively correlated with Phytophthora recovery.
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Onsando, J. M., and C. N. Gathungu. "CONTROL OF AVOCADO ROOT ROT CAUSED BY PHYTOPHTHORA CINNAMOMI." Acta Horticulturae, no. 218 (January 1988): 351–54. http://dx.doi.org/10.17660/actahortic.1988.218.45.
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Akıllı Şimşek, Seçil, Yakup Zekai Katırcıoğlu, and Salih Maden. "Türkiye’de Orman, Park ve Fidanlıklarda Görülen Phytophthora Kök Çürüklüğü Hastalıkları ve Korunma Önlemleri." Turkish Journal of Agriculture - Food Science and Technology 6, no. 6 (June 26, 2018): 770. http://dx.doi.org/10.24925/turjaf.v6i6.770-782.1928.
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Phytophthora species, as a member of Oomycetes are important plan diseases occurring on almost all of the annual and perennial plants and rapidly killing the plants by producing root, collar rots and leaf blights. The first Phytophthora study on forest trees in Turkey was made on oak species which is the most widespread tree in the country. Seven Phytophthora species, namely P. cinnamomi, P. citricola, P. cryptogea, P. gonapodyides, P. quercina, Phytophthora sp. 1 and Phytophthora sp. 2’ were found to cause dieback and death on oaks, P. quercina being the most frequently encountered. The second most common tree having Phytophthora infections is sweet chestnut and root rots caused by Phytophthora were determined everywhere chestnut grow in the country. Four species were found on chestnut and the most frequently occurring two species are P. cambivora and P. cinnamomi occurring in the inner part and in the coastal areas of the country respectively. The third and fourth species, P. plurivora and P. cryptogea were observed in the decreasing order respectively. From the above mentioned species, P. cambivora and P. cryptogea were also reported from black pine at one location in the newly reforested location. From the other forest trees; various Phytophthora species were reported; P. lacustris from narrow leaved ash, P. plurivora, P. occultans from boxwood, P. citrophthora and P. cactorum from horse chestnut, P. nicotianae from Ailanthus sp. Phytophthora diseases were also found in a few nurseries growing forest an ornamental trees. P. cinnamomi, P. cryptogea, P. cactorum, P. citricola, P. megasperma and P. syringae were found to cause disease on various forest tree saplings. Elaborate information on Phytophthora diseases is being given in the review.
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D'Souza, Nola K., Ian J. Colquhoun, Bryan L. Shearer, and Giles E. St J. Hardy. "The potential of five Western Australian native Acacia species for biological control of Phytophthora cinnamomi." Australian Journal of Botany 52, no. 2 (2004): 267. http://dx.doi.org/10.1071/bt03089.
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Five Acacia species native to Western Australia were assessed for their potential to protect the highly susceptible species Banksia grandis Wield from infection by the plant pathogen Phytophthora cinnamomi Rands. In a rehabilitated bauxite pit at Jarrahdale 55 km south-east of Perth and in a glasshouse trial, B. grandis planted either alone or with A. pulchella R.Br., A. urophylla Benth., A. extensa Lindl., A. lateriticola Maslin or A. drummondii Lindl., was soil inoculated with P. cinnamomi. It could only be shown that A. pulchella significantly protected B. grandis from P. cinnamomi infection in the rehabilitated bauxite pit trial up to 1 year after inoculation. This confirms the potential of this species for biological control of the pathogen in infested plant communities. The observed protection was not the result of a decrease in soil temperature or moisture. Protection was not emulated in a glasshouse trial where optimum environmental conditions favoured P. cinnamomi. Despite a delay in infection of B. grandis planted with Acacia spp., none of the five species definitively protected B. grandis from P. cinnamomi. However, in the glasshouse trial, A. pulchella, A. extensa, A. lateriticola and A. drummondii did significantly reduce the soil inoculum of P. cinnamomi, indicating a possible biological control effect on the pathogen. The mechanisms of biological control are discussed and the implications for management of rehabilitated bauxite mined areas and forests severely affected by P. cinnamomi are considered.
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Hu, Jiahuai, Chuanxue Hong, Erik L. Stromberg, and Gary W. Moorman. "Mefenoxam Sensitivity in Phytophthora cinnamomi Isolates." Plant Disease 94, no. 1 (January 2010): 39–44. http://dx.doi.org/10.1094/pdis-94-1-0039.
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Phytophthora cinnamomi is a destructive root pathogen of numerous woody plant species in the ornamental plant nursery. Sixty-five isolates of P. cinnamomi were evaluated for mefenoxam sensitivity on 20% clarified V8 agar amended with mefenoxam at 0 or 100 μg/ml. In the presence of mefenoxam at 100 μg/ml, eight isolates were intermediately sensitive, with mycelium growth ranging between 11 and 18% of the nonamended control, and 57 isolates were highly sensitive, with little or no mycelium growth. Five intermediately sensitive and five sensitive isolates were chosen to characterize their responses to mefenoxam at 0, 0.1, 1, 10, and 100 μg/ml. For intermediately sensitive isolates, the mefenoxam concentration causing 50% inhibition of mycelium growth (EC50 values) ranged between 0.03 and 0.08 μg/ml; EC50 values for sensitive isolates varied from 0.01 to 0.02 μg/ml. Five intermediately sensitive and seven sensitive isolates were selected further to assess in vivo sensitivity to mefenoxam using Lupinus angustifolius ‘Russell Hybrids’. Lupine seedlings were treated with distilled water or mefenoxam at label rate (Subdue MAXX, 1 fl. oz. of product per 100 gal.) and then, 2 days later, inoculated with a 5-mm-diameter mycelial plug of P. cinnamomi on each cotyledon. Mefenoxam-treated plants averaged more than 96% less disease than water-treated plants. Mefenoxam provided adequate protection of lupines from infection by all 12 isolates regardless of their in vitro levels of sensitivity to mefenoxam. The ability to develop mefenoxam resistance was assessed in P. cinnamomi isolates with different mefenoxam sensitivity by UV mutagenesis and adapting mycelium to increasing concentrations of mefenoxam. Both UV mutagenesis and mycelium adaptation generated isolates with reduced sensitivity to mefenoxam. These isolates, however, did not grow as quickly as their corresponding parent. This study suggests that P. cinnamomi populations from ornamental nurseries in Virginia are sensitive to mefenoxam.
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Scott, P. M., P. A. Barber, and G. E. St J. Hardy. "Novel phosphite and nutrient application to control Phytophthora cinnamomi disease." Australasian Plant Pathology 44, no. 4 (July 2015): 431–36. http://dx.doi.org/10.1007/s13313-015-0365-4.
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Downer, A. J., J. A. Menge, and E. Pond. "Effects of Cellulytic Enzymes on Phytophthora cinnamomi." Phytopathology® 91, no. 9 (September 2001): 839–46. http://dx.doi.org/10.1094/phyto.2001.91.9.839.
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Two enzyme systems, cellulase (β-1,4-glucanase) and laminarinase (β-1,3-glucanase), were added to soil extracts to simulate (in vitro) lytic components found in mulches suppressive to Phytophthora cinnamomi. Concentration ranges of each enzyme were incubated with Phytophthora cinnamomi mycelium, zoospores, zoospores cysts, and zoospore-infected excised roots to evaluate the roles of each enzyme in potential control of avocado root rot disease. Cellulase significantly retarded the development of zoosporangia and chlamydospores when mycelia were incubated in soil extract containing the enzyme at concentrations greater than 10 units/ml. Zoospore production was also reduced by cellulase but not by laminarinase. Laminarinase had little effect on zoosporangia or chlamydospore formation. At high concentrations, laminarinase was consistently more effective at preventing encystment than cellulase. Chlamydospores preformed in root tips were immune to the lytic effects of all treatments except cellulase at 100 units/ml. Zoospores placed in enzyme solutions and plated on a selective medium survived high cellulase concentrations and formed colonies, but there were fewer surviving zoospores when laminarinase was present at greater than 10 units/ml. Low concentrations of cellulase stimulated infection of excised roots, however, low concentrations of laminarinase prevented infection. Cellulase and laminarinase have different effects on the structures of the Phytophthora cinnamomi life history, however, each enzyme may have a role in reduction of inoculum.
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Saiz-Fernández, Iñigo, Ivan Milenković, Miroslav Berka, Martin Černý, Michal Tomšovský, Břetislav Brzobohatý, and Pavel Kerchev. "Integrated Proteomic and Metabolomic Profiling of Phytophthora cinnamomi Attack on Sweet Chestnut (Castanea sativa) Reveals Distinct Molecular Reprogramming Proximal to the Infection Site and Away from It." International Journal of Molecular Sciences 21, no. 22 (November 12, 2020): 8525. http://dx.doi.org/10.3390/ijms21228525.
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Phytophthora cinnamomi is one of the most invasive tree pathogens that devastates wild and cultivated forests. Due to its wide host range, knowledge of the infection process at the molecular level is lacking for most of its tree hosts. To expand the repertoire of studied Phytophthora–woody plant interactions and identify molecular mechanisms that can facilitate discovery of novel ways to control its spread and damaging effects, we focused on the interaction between P. cinnamomi and sweet chestnut (Castanea sativa), an economically important tree for the wood processing industry. By using a combination of proteomics, metabolomics, and targeted hormonal analysis, we mapped the effects of P. cinnamomi attack on stem tissues immediately bordering the infection site and away from it. P. cinnamomi led to a massive reprogramming of the chestnut proteome and accumulation of the stress-related hormones salicylic acid (SA) and jasmonic acid (JA), indicating that stem inoculation can be used as an easily accessible model system to identify novel molecular players in P. cinnamomi pathogenicity.
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Ochoa Fuentes, Yisa María, Anselmo Hernández Pérez, Juan Carlos Delgado Ortiz, Ernesto Cerna Chavez, Luis Alberto Aguirre Uribe, and Luis Mario Tapia-Vargas. "Control orgánico in vitro de Phytophthora cinnamomi con aceites esenciales de orégano y clavo." Revista Mexicana de Ciencias Agrícolas 10, no. 4 (June 24, 2019): 961–68. http://dx.doi.org/10.29312/remexca.v10i4.1739.
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Michoacán es el principal estado productor de aguacate en el mundo; sin embargo, las enfermedades radiculares diezman y dañan los árboles ocasionando su muerte. El objetivo de la presente investigación fue evaluar el control orgánico del crecimiento in vitro de Phytophthora cinnamomi con aceites esenciales de orégano (Lippia berlandieri) y clavo (Syzygium aromaticum). En los meses de octubre y noviembre de 2016, se recolectaron muestras de raíces en árboles con síntomas de la enfermedad en aguacate (Persea americana Mill. var. Hass), en la huerta experimental del INIFAP ubicada en San Juan Nuevo Parangaricutiro, Michoacán. Los aislados se identificaron morfológica y molecularmente. Se evaluó el control de P. cinnamomi con aceites esenciales de orégano y clavo determinando la concentración media inhibitoria y sus límites fiduciales al 95% mediante una regresión Probit por el método de máximas verosimilitud. Los análisis se realizaron utilizando el programa estadístico R 3.4. De acuerdo con los resultados obtenidos, en relación con la inhibición del crecimiento hay una reducción en el crecimiento de P. cinnamomi. Los aceites esenciales de clavo (Syzygium aromaticum) y orégano (Lippia berlandieri) son una alternativa natural para el control del oomiceto P. cinnamomi por su actividad fungicida a bajas concentraciones y pueden incluirse en programas de manejo integrado de enfermedades.
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Ruiz-Gómez, Francisco J., and Cristina Miguel-Rojas. "Antagonistic Potential of Native Trichoderma spp. against Phytophthora cinnamomi in the Control of Holm Oak Decline in Dehesas Ecosystems." Forests 12, no. 7 (July 17, 2021): 945. http://dx.doi.org/10.3390/f12070945.
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Phytophthora root rot caused by the pathogen Phytophthora cinnamomi is one of the main causes of oak mortality in Mediterranean open woodlands, the so-called dehesas. Disease control is challenging; therefore, new alternative measures are needed. This study focused on searching for natural biocontrol agents with the aim of developing integrated pest management (IPM) strategies in dehesas as a part of adaptive forest management (AFM) strategies. Native Trichoderma spp. were selectively isolated from healthy trees growing in damaged areas by P. cinnamomi root rot, using Rose Bengal selective medium. All Trichoderma (n = 95) isolates were evaluated against P. cinnamomi by mycelial growth inhibition (MGI). Forty-three isolates presented an MGI higher than 60%. Twenty-one isolates belonging to the highest categories of MGI were molecularly identified as T. gamsii, T. viridarium, T. hamatum, T. olivascens, T. virens, T. paraviridescens, T. linzhiense, T. hirsutum, T. samuelsii, and T. harzianum. Amongst the identified strains, 10 outstanding Trichoderma isolates were tested for mycoparasitism, showing values on a scale ranging from 3 to 4. As far as we know, this is the first report referring to the antagonistic activity of native Trichoderma spp. over P. cinnamomi strains cohabiting in the same infected dehesas. The analysis of the tree health status and MGI suggest that the presence of Trichoderma spp. might diminish or even avoid the development of P. cinnamomi, protecting trees from the worst effects of P. cinnamomi root rot.
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Miranda-Fontaíña, M. E., J. Fernández-López, A. M. Vettraino, and A. Vannini. "Resistance of Castanea Clones to Phytophthora Cinnamomi: Testing and Genetic Control." Silvae Genetica 56, no. 1-6 (December 1, 2007): 11–21. http://dx.doi.org/10.1515/sg-2007-0002.
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Summary The resistance of chestnut clones to Phytophthora cinnamomi was evaluated by a soil inoculation experiment under controlled environmental conditions, as well as by excised and intact stem tests. One-year-old plants of fifty different clones were inoculated with two isolates of Phytophthora cinnamomi and evaluated fourteen weeks after inoculation. There were significant differences among clones for all root and collar rot variables. There were significant differences for isolates of P. cinnamomi but only for the collar rot variables. A total of 84% of plants grown in infested soil showed symptoms of root rot but only 50% of the plants with root rot, showed also had collar rot. The roots of resistant clones were able to confine the colonization, in roots and from roots to collar. Percentage circumference of collar rot was the best indicator or descriptor of sensitivity, a 50% of clones were resistant or highly resistant clones, with respectively less than 20% and than 10% circumference of collar rot. Percentage of survival of plants is not sufficient to indicate resistance to the pathogen, as mortality may be affected by environmental conditions or by other pathogens. The clonal heritability of collar rot variables ranged between 0.54 and 0.71. The plants grown on inoculated soil showed a reduction in growth. The phenotypic and genotypic correlations between soil infestation characteristics and the length of necrosis in both intact and excised stem tests were positive and highly significant and indicated similar resistance rankings of the clones.
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Tynan, K. M., C. J. Wilkinson, J. M. Holmes, B. Dell, I. J. Colquhoun, J. A. McComb, and G. E. St J. Hardy. "The long-term ability of phosphite to control Phytophthora cinnamomi in two native plant communities of Western Australia." Australian Journal of Botany 49, no. 6 (2001): 761. http://dx.doi.org/10.1071/bt00062.
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This study examined the ability of foliar applications of the fungicide phosphite to contain colonisation of Phytophthora cinnamomi in a range of plant species growing in natural plant communities in the northern sandplain and jarrah (Eucalyptus marginata) forest of south-western Australia. Wound inoculation of plant stems with P. cinnamomi was used to determine the efficacy of phosphite over time after application. Colonisation by P. cinnamomi was reduced for 5–24 months after phosphite was applied, depending on the concentration of phosphite used, plant species treated and the time of phosphite application. Plant species within and between plant communities varied considerably in their ability to take up and retain phosphite in inoculated stems and in the in planta concentrations of phosphite required to contain P. cinnamomi. As spray application rates of phosphite increased from 5 to 20 g L–1, stem tissue concentrations increased, as did the ability of a plant species to contain P. cinnamomi. However, at application rates of phosphite above 5 g L–1 phytotoxicity symptoms were obvious in most species, with some plants being killed. So, despite 10 and 20 g L–1 of phosphite being more effective and persistent in controlling P. cinnamomi, these rates are not recommended for application to the plant species studied. The results of this study indicate that foliar application of phosphite has considerable potential in reducing the impact of P. cinnamomi in native plant communities in the short-term. However, in order to maintain adequate control, phosphite should be sprayed every 6–12 months, depending on the species and/or plant community.
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Bregant, Carlo, Antonio A. Mulas, Giovanni Rossetto, Antonio Deidda, Lucia Maddau, Giovanni Piras, and Benedetto T. Linaldeddu. "Phytophthora mediterranea sp. nov., a New Species Closely Related to Phytophthora cinnamomi from Nursery Plants of Myrtus communis in Italy." Forests 12, no. 6 (May 27, 2021): 682. http://dx.doi.org/10.3390/f12060682.
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Monitoring surveys of Phytophthora related diseases in four forest nurseries in Italy revealed the occurrence of fourteen Phytophthora species to be associated with collar and root rot on fourteen plants typical of Mediterranean and alpine regions. In addition, a multilocus phylogeny analysis based on nuclear ITS and ß-tubulin and mitochondrial cox1 sequences, as well as micromorphological features, supported the description of a new species belonging to the phylogenetic clade 7c, Phytophthora mediterranea sp. nov. Phytophthora mediterranea was shown to be associated with collar and root rot symptoms on myrtle seedlings. Phylogenetically, P. mediterranea is closely related to P. cinnamomi but the two species differ in 87 nucleotides in the three studied DNA regions. Morphologically P. mediterranea can be easily distinguished from P. cinnamomi on the basis of its smaller sporangia, colony growth pattern and higher optimum and maximum temperature values. Data from the pathogenicity test showed that P. mediterranea has the potential to threaten the native Mediterranean maquis vegetation. Finally, the discovery of P. cinnamomi in alpine nurseries, confirms the progressive expansion of this species towards cold environments, probably driven by climate change.
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Weiland, Jerry E., Carolyn F. Scagel, Niklaus J. Grünwald, E. Anne Davis, Bryan R. Beck, and Val J. Fieland. "Variation in Disease Severity Caused by Phytophthora cinnamomi, P. plurivora, and Pythium cryptoirregulare on Two Rhododendron Cultivars." Plant Disease 102, no. 12 (December 2018): 2560–70. http://dx.doi.org/10.1094/pdis-04-18-0666-re.
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Rhododendrons are an important crop in the ornamental nursery industry, but are prone to Phytophthora root rot. Phytophthora root rot is a continuing issue on rhododendrons despite decades of research. Several Phytophthora species are known to cause root rot, but most research has focused on P. cinnamomi, and comparative information on pathogenicity is limited for other commonly encountered oomycetes, including Phytophthora plurivora and Pythium cryptoirregulare. In this study, three isolates each of P. cinnamomi, P. plurivora, and Py. cryptoirregulare were used to inoculate rhododendron cultivars Cunningham’s White and Yaku Princess at two different inoculum levels. All three species caused disease, especially at the higher inoculum level. P. cinnamomi and P. plurivora were the most aggressive pathogens, causing severe root rot, whereas Py. cryptoirregulare was a weak pathogen that only caused mild disease. Within each pathogen species, isolate had no influence on disease. Both P. cinnamomi and P. plurivora caused more severe disease on Cunningham’s White than on Yaku Princess, suggesting that the relative resistance and susceptibility among rhododendron cultivars might be similar for both pathogens. Reisolation of P. cinnamomi and P. plurivora was also greater from plants exhibiting aboveground symptoms of wilting and plant death and belowground symptoms of root rot than from those without symptoms. Results show that both P. cinnamomi and P. plurivora, but not Py. cryptoirregulare, are important pathogens causing severe root rot in rhododendron. This study establishes the risks for disease resulting from low and high levels of inoculum for each pathogen. Further research is needed to evaluate longer term risks associated with low inoculum levels on rhododendron health and to explore whether differences among pathogen species affect disease control.
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Meadows, I. M., D. C. Zwart, S. N. Jeffers, T. A. Waldrop, and W. C. Bridges. "Effects of Fuel Reduction Treatments on Incidence of Phytophthora Species in Soil of a Southern Appalachian Mountain Forest." Plant Disease 95, no. 7 (July 2011): 811–20. http://dx.doi.org/10.1094/pdis-07-10-0505.
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The National Fire and Fire Surrogate Study was initiated to study the effects of fuel reduction treatments on forest ecosystems. Four fuel reduction treatments were applied to three sites in a southern Appalachian Mountain forest in western North Carolina: prescribed burning, mechanical fuel reduction, mechanical fuel reduction followed by prescribed burning, and a nontreated control. To determine the effects of fuel reduction treatments on Phytophthora spp. in soil, incidences were assessed once before and twice after fuel reduction treatments were applied. Also, the efficiency of the baiting bioassay used to detect species of Phytophthora was evaluated, and the potential virulence of isolates of Phytophthora spp. collected from forest soils was determined. Phytophthora cinnamomi and P. heveae were the only two species recovered from the study site. Incidences of these species were not significantly affected by fuel reduction treatments, but incidence of P. cinnamomi increased over time. In the baiting bioassay, camellia leaf disks were better than hemlock needles as baits. P. cinnamomi was detected best in fresh soil, whereas P. heveae was detected best when soil was air-dried and remoistened prior to baiting. Isolates of P. heveae were weakly virulent and, therefore, potentially pathogenic—causing lesions only on wounded mountain laurel and rhododendron leaves; however, isolates of P. cinnamomi were virulent and caused root rot and mortality on mountain laurel and white pine plants.
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Longmuir, Amy L., Peter L. Beech, and Mark F. Richardson. "Draft genomes of two Australian strains of the plant pathogen, Phytophthora cinnamomi." F1000Research 6 (November 8, 2017): 1972. http://dx.doi.org/10.12688/f1000research.12867.1.
Full textAbstract:
Background: The oomycete plant pathogen, Phytophthora cinnamomi, is responsible for the destruction of thousands of species of native Australian plants, as well as several crops, such as avocado and macadamia, and has one of the widest host-plant ranges of the Phytophthora genus. The currently available genome of P. cinnamomi is based on an atypical strain and has large gaps in its assembly. To further studies of the pathogenicity of this species, especially in Australia, more robust assemblies of the genomes of more typical strains are required. Here we report the genome sequencing, draft assembly, and preliminary annotation of two geographically separated Australian strains of P. cinnamomi. Findings: Some 308 million raw reads were generated for the two strains. Independent genome assembly produced final genomes of 62.8 Mb (in 14,268 scaffolds) and 68.1 Mb (in 10,084 scaffolds), which are comparable in size and contiguity to other Phytophthora genomes. Gene prediction yielded > 22,000 predicted protein-encoding genes within each genome, while BUSCO assessment showed 82.5% and 81.8% of the eukaryote universal single-copy orthologs to be present in the assembled genomes, respectively. Conclusions: The assembled genomes of two geographically distant isolates of Phytophthora cinnamomi will provide a valuable resource for further comparative analysis and evolutionary studies of this destructive pathogen, and further annotation of the presented genomes may yield possible targets for novel pathogen control methods.
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Longmuir, Amy L., Peter L. Beech, and Mark F. Richardson. "Draft genomes of two Australian strains of the plant pathogen, Phytophthora cinnamomi." F1000Research 6 (February 28, 2018): 1972. http://dx.doi.org/10.12688/f1000research.12867.2.
Full textAbstract:
Background: The oomycete plant pathogen, Phytophthora cinnamomi, is responsible for the destruction of thousands of species of native Australian plants, as well as several crops, such as avocado and macadamia, and has one of the widest host-plant ranges of the Phytophthora genus. The current reference genome of P. cinnamomi is based on an atypical strain and has large gaps in its assembly. To further studies of the pathogenicity of this species, especially in Australia, robust genome assemblies of more typical strains are required. Here we report the genome sequencing, draft assembly, and preliminary annotation of two geographically separated Australian strains of P. cinnamomi. Findings: Some 308 million raw reads were generated for the two strains, DU054 and WA94.26. Independent genome assembly produced final genome sequences of 62.8 Mb (in 14,268 scaffolds) and 68.1 Mb (in 10,084 scaffolds), which are comparable in size and contiguity to other Phytophthora genomes. Gene prediction yielded > 22,000 predicted protein-encoding genes within each genome, while BUSCO assessment showed 94.4% and 91.5% of the stramenopile single-copy orthologs to be present in the assembled genomes, respectively. Conclusions: The assembled genomes of two geographically distant isolates of Phytophthora cinnamomi will provide a valuable resource for further comparative analyses and evolutionary studies of this destructive pathogen, and further annotation of the presented genomes may yield possible targets for novel pathogen control methods.
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El-Tarabily, Khaled A., Melissa L. Sykes, Ipek D. Kurtböke, Giles E. St J. Hardy, Aneli M. Barbosa, and Robert F. H. Dekker. "Synergistic effects of a cellulase-producing Micromonospora carbonacea and an antibiotic-producing Streptomyces violascens on the suppression of Phytophthora cinnamomi root rot of Banksia grandis." Canadian Journal of Botany 74, no. 4 (April 1, 1996): 618–24. http://dx.doi.org/10.1139/b96-078.
Full textAbstract:
Three polyvalent Streptomyces phages were used to isolate four Micromonospora species (M. carbonacea, M. chalcea, M. purpureochromogenes, and M. inositola) from mine-site rhizosphere soils in Western Australia. Streptomyces violascens was isolated using selective isolation techniques from the same soils. The Micromonspora spp. were examined for their ability to produce cellulases. Micromonospora carbonacea, M. chalcea, and M. purpureochromogenes, which were found to produce the enzyme, caused lysis of Phytophthora cinnamomi hyphae. Glasshouse trials showed that the use of the cellulase-producing M. carbonacea isolate, in conjunction with the antibiotic-producing S. violascens isolate, had a synergistic effect on the suppression of the Phytophthora root rot and in promoting growth of Banksia grandis. The importance of using a number of antagonists with different antagonistic abilities to control plant pathogenic fungi is discussed. Keywords: biological control, Micromonospora carbonacea, Streptomyces violascens, cellulases, Phytophthora cinnamomi.
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Dai, Tingting, Aohua Wang, Xiao Yang, Xiaowei Yu, Wen Tian, Yue Xu, and Tao Hu. "PHYCI_587572: An RxLR Effector Gene and New Biomarker in A Recombinase Polymerase Amplification Assay for Rapid Detection of Phytophthora cinnamomi." Forests 11, no. 3 (March 11, 2020): 306. http://dx.doi.org/10.3390/f11030306.
Full textAbstract:
Phytophthora cinnamomi is a devastating pathogen causing root and crown rot and dieback diseases of nearly 5000 plant species. Accurate and rapid detection of P. cinnamomi plays a fundamental role within the current disease prevention and management programs. In this study, a novel effector gene PHYCI_587572 was found as unique to P. cinnamomi based on a comparative genomic analysis of 12 Phytophthora species. Its avirulence homolog protein 87 (Avh87) is characterized by the Arg-Xaa-Leu-Arg (RxLR) motif. Avh87 suppressed the pro-apoptotic protein BAX- and elicitin protein INF1-mediated cell death of Nicotiana benthamiana. Furthermore, a recombinase polymerase amplification-lateral flow dipstick detection assay targeting this P. cinnamomi-specific biomarker was developed. While successfully detected 19 P. cinnamomi isolates of a global distribution, this assay lacked detection of 37 other oomycete and fungal species, including P. parvispora, a sister taxon of P. cinnamomi. In addition, it detected P. cinnamomi from artificially inoculated leaves of Cedrus deodara. Moreover, the RPA-LFD assay was found to be more sensitive than a conventional PCR assay, by detecting as low as 2 pg of genomic DNA in a 50-µL reaction. It detected P. cinnamomi in 13 infested soil samples, while the detection rate was 46.2% using PCR. Results in this study indicated that PHYCI_587572 is a unique biomarker for detecting P. cinnamomi. Although PHYCI_587572 was identified as an effector gene based on the RxLR motif of Avh87 and the avirulence activity on Nicotiana, its exact genetic background and biological function on the natural hosts of P. cinnamomi warrant further investigations.
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Morales-Rodríguez, C., A. M. Vettraino, and A. Vannini. "Efficacy of Biofumigation with Brassica carinata Commercial Pellets (BioFence) to Control Vegetative and Reproductive Structures of Phytophthora cinnamomi." Plant Disease 100, no. 2 (February 2016): 324–30. http://dx.doi.org/10.1094/pdis-03-15-0245-re.
Full textAbstract:
The efficacy of biofumigation with Brassica carinata pellets (BioFence) to control vegetative and reproductive structures of Phytophthora cinnamomi was investigated in vitro at different doses and temperatures. Biofumigation was effective in inhibiting mycelial growth (culture diameter) and chlamydospore and zoospore germination, and was lethal at 24 mg of pellet per plate (approximately 0.4 mg/liter). The 50% effective concentration values showed that efficacy of B. carinata pellets in inhibiting or killing the vegetative and reproductive structures of P. cinnamomi was maximum at 15°C and decreased as temperature rose to 25°C. However, the fungicide effect was independent of the temperature. In vivo biofumigation of Quercus cerris seedlings with BioFence confirmed efficacy by reducing the inoculum density (CFU/g) of P. cinnamomi, thus protecting the host from root infection. The use of BioFence provides an alternative to synthetic pesticides to control P. cinnamomi within disease management programs in agroforestry systems.
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Cahill, David M., James E. Rookes, Barbara A. Wilson, Lesley Gibson, and Keith L. McDougall. "Phytophthora cinnamomi and Australia's biodiversity: impacts, predictions and progress towards control." Australian Journal of Botany 56, no. 4 (2008): 279. http://dx.doi.org/10.1071/bt07159.
Full textAbstract:
Phytophthora cinnamomi continues to cause devastating disease in Australian native vegetation and consequently the disease is listed by the Federal Government as a process that is threatening Australia’s biodiversity. Although several advances have been made in our understanding of how this soil-borne pathogen interacts with plants and of how we may tackle it in natural systems, our ability to control the disease is limited. The pathogen occurs widely across Australia but the severity of its impact is most evident within ecological communities of the south-west and south-east of the country. A regional impact summary for all states and territories shows the pathogen to be the cause of serious disease in numerous species, a significant number of which are rare and threatened. Many genera of endemic taxa have a high proportion of susceptible species including the iconic genera Banksia, Epacris and Xanthorrhoea. Long-term studies in Victoria have shown limited but probably unsustainable recovery of susceptible vegetation, given current management practices. Management of the disease in conservation reserves is reliant on hygiene, the use of chemicals and restriction of access, and has had only limited effectiveness and not provided complete control. The deleterious impacts of the disease on faunal habitat are reasonably well documented and demonstrate loss of individual animal species and changes in population structure and species abundance. Few plant species are known to be resistant to P. cinnamomi; however, investigations over several years have discovered the mechanisms by which some plants are able to survive infection, including the activation of defence-related genes and signalling pathways, the reinforcement of cell walls and accumulation of toxic metabolites. Manipulation of resistance and resistance-related mechanisms may provide avenues for protection against disease in otherwise susceptible species. Despite the advances made in Phytophthora research in Australia during the past 40 years, there is still much to be done to give land managers the resources to combat this disease. Recent State and Federal initiatives offer the prospect of a growing and broader awareness of the disease and its associated impacts. However, awareness must be translated into action as time is running out for the large number of susceptible, and potentially susceptible, species within vulnerable Australian ecological communities.
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Morales, Javiera, Ximena Besoain, Italo F. Cuneo, Alejandra Larach, Laureano Alvarado, Alejandro Cáceres-Mella, and Sebastian Saa. "Impact of Nitrogen Fertilization on Phytophthora cinnamomi Root-related Damage in Juglans regia Saplings." HortScience 54, no. 12 (December 2019): 2188–94. http://dx.doi.org/10.21273/hortsci14299-19.
Full textAbstract:
Excessive nitrogen (N) use in agriculture has been associated with increased severity of the damage caused by Phytophthora species. In this study, we investigated the impact in vitro and in vivo of N about Phytophthora cinnamomi. The preliminary in vitro assay showed the effect of different N sources on the mycelial growth of P. cinnamomi. This assay indicated that ammonium nitrate (NH4NO3) and ammonium sulfate [(NH4)2SO4] allowed for greater control of P. cinnamomi mycelia in comparison with calcium nitrate [Ca(NO3)2] and potassium nitrate (KNO3) when used with 1000 ppm N. The in vivo assay showed the severity of P. cinnamomi in 5-month-old Juglans regia saplings grown under greenhouse conditions. We selected NH4NH3 as the source for N for the greenhouse assay, considering the inhibitory effect on the ingrowth of P. cinnamomi and the intensive use of this fertilizer in agriculture. Walnut saplings were fertilized with 0, 35, 70, 140, 210, and 1050 ppm N and were inoculated with zoospores of P. cinnamomi 45 d after the application of nitrogen treatment (DAA). They were harvested at 90 DAA. We found that a 70-ppm N fertilization reduced the development of P. cinnamomi, resulting in lower root and canopy damage indices (DIs) than the unfertilized inoculated treatments and fertilized treatments greater than 140 ppm. The results of the in vitro and in vivo assay agree that increased N concentrations were associated with reduced mycelium growth of P. cinnamomi, providing further evidence that N fertilization can mitigate this disease. Greater root and canopy damage was observed in saplings fertilized with 1050 ppm N, regardless of whether they were inoculated with P. cinnamomi, as a result of N phytotoxicity (verified through foliar analysis). In contrast, inoculated and unfertilized saplings (N0) also showed high root and canopy DIs associated either with the inoculation with P. cinnamomi or the no fertilization treatment. We postulate that 70 ppm N is the best fertilization rate for J. regia saplings because the positive effects of N on growth are maximized and the damage caused by P. cinnamomi is mitigated.