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Journal articles on the topic 'Seedling pathogens'
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1
García-Guzmán, Graciela, and Julieta Benítez-Malvido. "Effect of litter on the incidence of leaf-fungal pathogens and herbivory in seedlings of the tropical tree Nectandra ambigens." Journal of Tropical Ecology 19, no. 2 (2003): 171–77. http://dx.doi.org/10.1017/s0266467403003195.
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Effects of litter cover on insect herbivory, leaf-fungal damage, and seedling performance (survival, growth in height and leaf number), were assessed on established Nectandra ambigens seedlings in three sites of a Mexican tropical rain forest. Naturally occurring seedlings were measured for height, leaf number and standing levels of leaf damage by herbivores and pathogens. Thereafter, seedlings were exposed for 1 y to three litter treatments: (1) litter addition, (2) control and (3) continuous litter removal. There was a significant effect of site on the proportion of surviving seedlings and on the relative growth rates in terms of leaf number. Overall, seedlings with higher initial leaf number showed higher survival and produced more leaves after 12 mo than seedlings with lower initial leaf number. Litter addition resulted in seedlings with lower relative growth rates in height and higher levels of damage by herbivores and pathogens. On average, leaf area damaged by pathogens was < 6% and herbivory was < 27%. Seedlings with higher levels of herbivory showed higher levels of pathogen attack. Herbivory and pathogen attack had no effect on seedling performance. This study reveals the importance of litter-cover on the interactions between seedlings, herbivores and pathogens, as well as on the performance of tropical seedlings.
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Bakker, Matthew G., Jyotsna Acharya, Thomas B. Moorman, Alison E. Robertson, and Thomas C. Kaspar. "The Potential for Cereal Rye Cover Crops to Host Corn Seedling Pathogens." Phytopathology® 106, no. 6 (2016): 591–601. http://dx.doi.org/10.1094/phyto-09-15-0214-r.
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Cover cropping is a prevalent conservation practice that offers substantial benefits to soil and water quality. However, winter cereal cover crops preceding corn may diminish beneficial rotation effects because two grass species are grown in succession. Here, we show that rye cover crops host pathogens capable of causing corn seedling disease. We isolated Fusarium graminearum, F. oxysporum, Pythium sylvaticum, and P. torulosum from roots of rye and demonstrate their pathogenicity on corn seedlings. Over 2 years, we quantified the densities of these organisms in rye roots from several field experiments and at various intervals of time after rye cover crops were terminated. Pathogen load in rye roots differed among fields and among years for particular fields. Each of the four pathogen species increased in density over time on roots of herbicide-terminated rye in at least one field site, suggesting the broad potential for rye cover crops to elevate corn seedling pathogen densities. The radicles of corn seedlings planted following a rye cover crop had higher pathogen densities compared with seedlings following a winter fallow. Management practices that limit seedling disease may be required to allow corn yields to respond positively to improvements in soil quality brought about by cover cropping.
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Adachi, Naoto, Shoichi Tsukamoto, Yasuhiro Inoue, and Koji Azegami. "Control of Bacterial Seedling Rot and Seedling Blight of Rice by Bacteriophage." Plant Disease 96, no. 7 (2012): 1033–36. http://dx.doi.org/10.1094/pdis-03-11-0232-re.
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In Japan, rice seed are immersed in pesticide solutions to prevent seedborne diseases that attack greenhouse seedlings. However, disposal of large quantities of waste pesticide solutions after treatment is costly. As an alternative treatment, bacteriophages (phages) that are highly specific to the target bacteria are considered as potential biocontrol agents. Here, we isolated three phage strains that lyse Burkholderia glumae and B. plantarii, the causative pathogens of seedling rot and seedling blight, respectively. Two phages could lyse both bacteria and clearly suppress these diseases. One of these phages (BGPP-Ar) suppressed these diseases more effectively than existing pesticides: the ratio of seedlings exhibiting disease to the total number of seedlings examined after treatment with BGPP-Ar 1.0 × 108 plaque-forming units (PFU)/ml was 0.0 for seedling rot and 2.0 for seedling blight; after treatment with ipconazole/copper (II) hydroxide, the ratios were 14.3 and 15.0, respectively. BGPP-Ar was highly effective in suppressing seedling rot of rice, even at the low concentration of 1.0 × 105 PFU/ml. The best phage treatment effect for sterilizing seed is achieved indoors to avoid phage inactivation by UV irradiation. Treatment effect was demonstrated on seed infected with pathogens. Therefore, we consider that phage treatment was effective in this study.
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Norghauer, Julian M., David M. Newbery, Leho Tedersoo, and George B. Chuyong. "Do fungal pathogens drive density-dependent mortality in established seedlings of two dominant African rain-forest trees?" Journal of Tropical Ecology 26, no. 3 (2010): 293–301. http://dx.doi.org/10.1017/s0266467410000076.
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Abstract:Where one or a few tree species reach local high abundance, different ecological factors may variously facilitate or hinder their regeneration. Plant pathogens are thought to be one of those possible agents which drive intraspecific density-dependent mortality of tree seedlings in tropical forests. Experimental evidence for this is scarce, however. In an African rain forest at Korup, we manipulated the density of recently established seedlings (~5–8 wk old; low vs. high-density) of two dominant species of contrasting recruitment potential, and altered their exposure to pathogens using a broad-spectrum fungicide. Seedling mortality of the abundantly recruiting subcanopy tree Oubanguia alata was strongly density-dependent after 7 mo, yet fungicide-treated seedlings had slightly higher mortality than controls. By contrast, seedling mortality of the poorly recruiting large canopy-emergent tree Microberlinia bisulcata was unaffected by density or fungicide. Ectomycorrhizal colonization of M. bisulcata was not affected by density or fungicide either. For O. alata, adverse effects of fungicide on its vesicular arbuscular mycorrhizas may have offset any possible benefit of pathogen removal. We tentatively conclude that fungal pathogens are not a likely major cause of density dependence in O. alata, or of early post-establishment mortality in M. bisulcata. They do not explain the latter's currently very low recruitment rate at Korup.
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Nowicki, Bogdan. "The fungi causin damping-off of carrot seedlings." Acta Agrobotanica 48, no. 2 (2013): 43–48. http://dx.doi.org/10.5586/aa.1995.014.
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When 136 samples of dying carrot seedlings from several fields were analyzed <em>Alternaria rudicina</em> proved to be the most common seedling pathogen (41%), followed by some <em>Fusarium</em> species (27%, mostly <em>F. avenaceum</em>).The less common seedling pathogens were <em>Pythium</em> spp. (13%), <em>Phoma</em> spp.(2,5%) and <em>Botrytis cinerea</em> (1,4%). Some other fungi (<em>Bipolaris sorokiniana, Sclerotinia sclerotiorum, Stemphylium botryosym</em> and <em>Ulocladium consortiale</em>) were found in less than 1% of seedlings examined.
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Rahman, M. A., R. Jannat, A. M. Akanda, M. A. R. Khan, and M. T. Rubayet. "Role of Chitosan in Disease Suppression, Growth and Yield of Carrot." European Journal of Agriculture and Food Sciences 3, no. 3 (2021): 34–40. http://dx.doi.org/10.24018/ejfood.2021.3.3.266.
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An attempt was made for controlling of Rhizoctonia canker caused by Rhizoctonia solani and southern blight caused by Sclerotium rolfsii in pot and field experiments under inoculated condition and also to increase the growth promoting factors and yield of carrot through the application of chitosan. Before setting the experiments in the field, laboratory experiments were carried out to select virulent isolates of R. solani and S. rolfsii and effective dose of chitosan on mycelial growth inhibition of virulent isolates of test pathogens. In the pathogenicity test, R. solani isolate R-1 and S. rolfsii isolate S-1 were found to be the most virulent against carrot seedlings. In vitro application of 1.0% chitosan was found to inhibit 100% mycelial growth of both tested pathogens. The field experiment was laid out following randomized complete block design with four treatments, where no treatment was done in T1, pathogen was inoculated in T2 and seed treatment and soil amendment with 1.0% chitosan was done in T3 and T4, respectively, in pathogen inoculated condition. Application of 1.0% chitosan as seed treatment or soil amendment significantly reduced post-emergence seedling mortality, incidence of diseases and enhanced seedling growth and also yields of carrot. On the contrary, post-emergence seedling mortality, incidence of Rhizoctonia canker and southern blight of carrot were highest in treatment T2 where soil was inoculated with pathogens. Chitosan could be used as an alternative of fungicide to suppress Rhizoctonia canker and southern blight in sustainable agriculture and improvement the yield of carrot.
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Limtong, Savitree, Parichat Into, and Panchapond Attarat. "Biocontrol of Rice Seedling Rot Disease Caused by Curvularia lunata and Helminthosporium oryzae by Epiphytic Yeasts from Plant Leaves." Microorganisms 8, no. 5 (2020): 647. http://dx.doi.org/10.3390/microorganisms8050647.
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Seedling rot disease in rice leads to significant loss in the production of seedlings. This research was conducted to explore yeasts that could be used as biological control agents against rice seedling rot disease caused by Curvularia lunata and Helminthosporium oryzae. In total, 167 epiphytic yeast strains were evaluated, revealing that 13 of these yeast strains demonstrated antagonistic activities against fungal pathogens and either C. lunata DOAC 2313 or H. oryzae DOAC 2293. The volatile organic compounds (VOCs) and biofilm produced were possible antagonistic mechanisms in vitro for all the antagonistic yeast strains. Using nursery trays in a greenhouse, this study evaluated the control of rice seedling rot disease caused by these two fungal pathogens using antagonistic yeasts, identified in the present study and from our previous study. Torulaspora indica DMKU-RP31 and Wickerhamomyces anomalus YE-42 were found to completely control rice seedling rot disease caused by both of these fungal pathogens. Furthermore, W. anomalus DMKU-RP04 revealed 100% disease control when the disease was caused by H. oryzae. This is the first report on using antagonistic yeasts to control rice seedling rot disease caused by C. lunata and H. oryzae. These three antagonistic yeasts also showed promising potential for development as biocontrol agents against rice seedling rot disease caused by fungi.
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Irawan, Arif, Ilaa Anggraeni, and Margaretta Christita. "Identification Causes Leaf Spot Disease in Cempaka (Magnolia elegans (Blume.) H.Keng) Seedling and Its Control Techniques." Jurnal Wasian 2, no. 2 (2015): 87. http://dx.doi.org/10.20886/jwas.v2i2.843.
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This research purposes to identify the pathogen causing leaf spot in cempaka seedling and its control technique. Identify cause of disease is necessary to know precise technique control. Identification of disease was conducted in macroscopic appearances and microscopically to determine pathogens. Identification is done by using the determination key of fungi. The results showed that the early signs of leaf spot disease on cempaka seedlings in the nursery are streaks or spots on the leaf surface with distinct boundaries. Leaf spots are formed generally brown surrounded by darker boundaries. The result shows leaf spot disease on cempaka seedling was caused by fungal pathogen Colletotrichum sp. Techniques for controlling the disease can be done by isolating the infected seeds, reducing the intensity of canopy, and using the appropriate fungicides.
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Diniz, Fábio Oliveira, Múcio Silva Reis, Eduardo Fontes Araújo, Luiz Antônio dos Santos Dias, Tuneo Sediyama, and Camilla Atsumi Zanuncio Sediyama-Bhering. "Incidence of pathogens and field emergence of soybean seeds subjected to harvest delay." Journal of Seed Science 35, no. 4 (2013): 478–84. http://dx.doi.org/10.1590/s2317-15372013000400009.
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This study aimed at evaluating seed health quality, as well as seedling emergence in the field, of eight soybean cultivars (UFV-16, Splendor, Vencedora, Confiança, UFV-18, UFV-TN 105, Garantia, and Celeste) subjected to different harvest periods. To this, seeds were harvested at the growth stages R8, R8+15 days, and R8+30 days, and then submitted to health test and to the test of seedling emergence in field. Results showed that although seeds harvested at 15 and 30 days after the stage R8 had shown a significant increase of fungi infection, especially by Fusarium spp., Phomopsis spp., and Epicoccum spp., the percent seedling emergence in the field was reduced only to seeds harvested 30 days after the reproductive stage R8. Cultivars have shown differentiated behavior between each other in relation to the percent incidence rate of fungi and seedling emergence in the field; and the seeds least infected by fungi were those allowing the highest percent emergence of seedlings in the field.
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Navitasari, Lisa, Loekas Soesanto, and Ahadiyat Yugi Rahayu. "PENGARUH APLIKASI PSEUDOMONAS FLUORESCENS P60 TERHADAP MUTU PATOLOGIS, MUTU FISIOLOGIS, DAN PERTUMBUHAN BIBIT PADI IR 64." Jurnal Hama dan Penyakit Tumbuhan Tropika 13, no. 2 (2013): 179–90. http://dx.doi.org/10.23960/j.hptt.213179-190.
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Effect of Pseudomonas fluorescens P60 on pathological and physiological quality and growth of rice IR 64 seedlings. The research objectives were (1) detection and identification of seed-borne pathogens of IR 64 rice, (2) testing Pseudomonas fluorescents P60 in inhibiting the in vitro growth of seed-borne pathogens colonies, (3) testing P. fluorescents P60 for pathological and physiological seed quality, and (4) testing P. fluorescents P60 on the growth of seedlings in the greenhouse. The results showed that some seed-borne pathogens can be found both on farmers’ IR 64 rice and factory’s; they were Aspergillus flavus, Alternaria padwickii, Pseudomonas glumae, and P. syringae. Application of P. flourescens P60 was able to inhibit the in vitrogrowth of colonies of all seed-borne pathogens, except P. syringae. Related to pathological quality, the effect of P. flourescens P60 on percentage of seed-borne pathogens attack did not significantly different from that of benomil but smaller than distilled water. On the physiological quality of seeds, treatment of P. flourescens P60 has the same effect with benomil and distilled water, with germination rate was more than 80%. In the greenhouse study,treatment of seed immersion time in P. flourescens P60 suspension showed that the effect of immersion time as long as15 minutes and 25 minutes on seedling height, root length, and seedling dry weightdid not significantly different. were. However, 25 minutes immersion time resulted in fresh seedling weight and root dry weight higher than that of 15 minutes immersion time.
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Hidayati, Nur, Siti Husna Nurrohmah, and Fithry Ardhany. "Isolasi, identifikasi dan karakterisasi penyebab penyakit bercak daun pada semai pinus di perum perhutani BKPH Purworejo, KPH Kedu Selatan." Jurnal Pemuliaan Tanaman Hutan 14, no. 1 (2020): 21–32. http://dx.doi.org/10.20886/jpth.2020.14.1.21-32.
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Pinus merkusii, a multiuse tree, is cultivated at Indonesian Plantation. Pinus plantation have been threatened by rust/spot leaf disease. The pathogen has infected pinus seedlings at Perum Perhutani, BKPH Purworejo, KPH Kedu Selatan and cause high mortality. The aims of this research to identify pathogen causing rust/spot leaf thus information how to control can be observed. Pathogens were isolated from infected leaves, and grown on the potato dextrose agar (PDA) and observed macroscopis and microscopis and identified. The pathogens also were inoculated to healthy seedlings (Postulat Koch Test). The result shows that pathogen causing rust/spot leaf on seedlings pine is Pestalotia sp with characteristic white colony, hypha has aservuli with conidia that have 25 septums and at the edge, some structure looks like feather whipped 3-5. Potulat Koch test indicated that inoculated healthy seedling shows similar symptom with infected seedlings. Rust/spot leaf has similar sympto and sign. Spot or rust appear on leaves started from edge and spread to base. At first, spots were formed in small size and separate each other but they developed and became larger and wider and fused.
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Hwang, S. F., B. D. Gossen, G. D. Turnbull, K. F. Chang, and R. J. Howard. "Seedbed preparation, timing of seeding, fertility and root pathogens affect establishment and yield of alfalfa." Canadian Journal of Plant Science 82, no. 2 (2002): 371–81. http://dx.doi.org/10.4141/p01-121.
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Invasion by grasses and weedy species occurs when plant density in alfalfa fields falls below critical levels. Several soil-borne fungal pathogens can reduce stand density in alfalfa by impeding seedling establishment and by killing older plants weakened by other stresses. Surveys of alfalfa fields were conducted in 1997, and pathogenic fungi from rotted roots were isolated and identified. Isolates of selected pathogens were applied with the seed in field trials to assess the impact of fertilizer and seeding system (conventional vs. sod-seeding, spring vs. dormant-fall seeding) on seedling emergence and subsequent productivity when disease pressure was high. The impact of various fungicide seed treatments was also assessed. Seed treatment improved seedling emergence and initial forage productivity in one of three trials; however, it had little effect on long-term forage yield. Addition of sulphur fertilizer had little effect on seedling emergence or survival, but improved forage productivity at all three trial sites. Sod-seeded plots suffered more winterkill and were less vigorous than plots seeded into a tilled seedbed. Seedling emergence was lower when seedlings were planted in the fall than in the spring. However, fall-seeded treatments showed a less adverse response to inoculum treatments and, in some cases, these seedlings were able to take advantage of early-season moisture to produce higher yields than their spring-seeded counterparts. Key words: Medicago, Fusarium, Pythium, Phoma, fungicide, seed treatment, fertilizer, tillage
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Cleavitt, Natalie L., Timothy J. Fahey, and John J. Battles. "Regeneration ecology of sugar maple (Acer saccharum): seedling survival in relation to nutrition, site factors, and damage by insects and pathogens." Canadian Journal of Forest Research 41, no. 2 (2011): 235–44. http://dx.doi.org/10.1139/x10-210.
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The possible regeneration failure of sugar maple ( Acer saccharum Marsh.) as part of their decline has been not well explored using field studies. We sought to clarify the roles of maternal effects and dynamics of early-season survival in contributing to the previously documented pattern of larger seedlings and higher seedling densities on a Ca-treated watershed (CAL) at Hubbard Brook Experimental Forest. We used a reciprocal seed planting experiment at four sites, two sites per watershed blocked by elevation. Regardless of maternity, sugar maple seedlings planted in CAL had higher survival than seedlings in the reference watershed. However, this advantage was not as clearly linked to the Ca amendment as in our previous work, probably, in part, because Ca availability has decreased over time. Maternal effects on seed chemistry and some seedling traits were detected, but these were not strong determinants of survival. Site was a good predictor of early seedling survival with litter layer depth, pathogen prevalence, and soil chemistry all contributing to the explanatory power of site. The strength of Ca,addition effects on sugar maple regeneration from seed depends on initial soil characteristics, application amounts, and interactions of the amendment with other factors such as leaf litter cycling, weather, and pathogens.
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AVAN, Meltem, Gülsüm PALACIOĞLU, Tülin SARIGÜL ERTEK, et al. "Sugar beet root rot caused by oomycetous pathogens in Turkey and their control by seed treatmen." TURKISH JOURNAL OF AGRICULTURE AND FORESTRY 44, no. 6 (2020): 631–41. http://dx.doi.org/10.3906/tar-1910-55.
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The aim of this study was to determine the oomycetous pathogens causing root rot on sugar beet and test their control by seed treatment in Konya Province, Turkey. Oomycetous fungus-like pathogens of sugar beet were investigated using 866 plant samples collected at 2 growth stages, early seedling and late root, from fields in the Konya region of Turkey and 1 sample from the Thrace region. Herein, 10 oomycetous species belonging to 3 genera: Aphanomyces cochlioides, Phytophthora cryptogea, Ph. pseudocryptogea, Ph. megasperma, Ph. inundata, Pythium aphanidermatum, Py. helicoides, Py. heterothallicum, Py. sylvaticum, and Py. ultimum var. ultimum (Globisporangium ultimum var. ultimum) were discovered at various times with in the 2 growth periods, all of which were the first records for Turkey. A. cochlioides was the most serious pathogen, both in terms of its wide distribution and aggressiveness. The pathogen produced more than 90% disease severity when tested by soil infestation at the seedling stage, although it also occurred at the late root growth stage. Pythium species were also ascommon, such as A. cochlioides, the majority of which were very aggressive, producing more than 84% disease severity at the seedling stage, except for Py. aphanidermatum. Half-strength potato dextrose agar medium was found to be very useful for the isolation of all of the pathogens from the plant samples at both stages. Morphological features of all of the pathogens were abundantly produced when the pathogens were grown on amended grated carrot agar medium and culture disks of fungal growth of this medium were submerged in sterile and nonsterile soil extracts. Out of the 15 fungicide mixes tested, 2 mixes, thiram+metalaxyl+hymexazole and thiram+metalaxyl+hymexazole+ pyraclostrobin reduced seedling root rot caused by both A. cochlioides and Pythium ultimum var. ultimum, while the standard seed treatment fungicide mix of thiram+hymexazole was not effective against either of the pathogens.
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Santamaría, O., D. R. Smith, and G. R. Stanosz. "Interaction Between Diplodia pinea and D. scrobiculata in Red and Jack Pine Seedlings." Phytopathology® 101, no. 3 (2011): 334–39. http://dx.doi.org/10.1094/phyto-07-10-0180.
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Sphaeropsis sapinea sensu lato is a conifer fungal pathogen that causes shoot blight and stem cankers. Recently, the former S. sapinea has been divided into two species, Diplodia pinea and D. scrobiculata. The aims of the study were to determine the contribution of each species in disease development on red and jack pines by means of co-inoculations and molecular identifications, and to evaluate how the presence of each species affects the development and aggressiveness of the other. Symptom severity (distance below the inoculation site at which necrotic needles were observed) and identification length (the maximum distance from inoculation site from which either D. pinea or D. scrobiculata was identified using molecular methods) were recorded 4 weeks after inoculating wounded seedlings with agar plugs colonized by these pathogens. The results suggested that D. pinea was much more aggressive on both hosts than D. scrobiculata. When a seedling was co-inoculated with these pathogens, the symptom development appeared to be mainly due to D. pinea. The presence of D. pinea also interfered with the establishment of D. scrobiculata in the plant tissue. However, D. scrobiculata showed antagonism toward D. pinea. When both pathogens co-occurred in a single seedling, symptom severity caused by D. pinea was less than when D. pinea alone was present.
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Feng, Wenzhuo, Akira Nukaya, Mamoru Satou, et al. "Use of LAMP Detection to Identify Potential Contamination Sources of Plant-Pathogenic Pythium Species in Hydroponic Culture Systems of Tomato and Eustoma." Plant Disease 102, no. 7 (2018): 1357–64. http://dx.doi.org/10.1094/pdis-10-17-1679-re.
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Hydroponic culture systems are subject to high risks of diseases caused by zoosporic plant pathogens. Control is generally difficult because of the rapid spread of zoospores in the nutrient solutions. In Japan, tomato and eustoma, which are cultivated using the D-tray and nutrient film techniques, respectively, are susceptible to diseases caused by Pythium aphanidermatum and P. irregulare. We used loop-mediated isothermal amplification to identify potential contamination sources of these two pathogens by monitoring their presence in the water supply wells, seedling terraces, nutrient solutions, diseased plants, and ground soils of a tomato greenhouse complex and a eustoma greenhouse complex. The results indicated that the pathogens may enter the culture systems from the soils around the greenhouses. Entry most likely occurs when seedlings are moved from the seedling terraces to the greenhouses, and sterilization of the hydroponic systems may not be sufficient. Therefore, monitoring pathogens in the culture systems and ground soils is very important for the management and prevention of these diseases.
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Ridout, Mary, and George Newcombe. "Sydowia polyspora is both a Foliar Endophyte and a Preemergent Seed Pathogen in Pinus ponderosa." Plant Disease 102, no. 3 (2018): 640–44. http://dx.doi.org/10.1094/pdis-07-17-1074-re.
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Poor seedling performance and reduced seed emergence are often ascribed to known pathogens that cause low seedling recruitment and poor seed emergence in forest nurseries and regeneration plantings. On the other hand, foliar endophytes are often overlooked as a source of poor emergence or tree seedling disease. Here, we show that an endophytic fungus common to the foliar microbiome of Pinus ponderosa acts as a cryptic pathogen in delaying emergence. In a series of experiments, we inoculated seed of P. ponderosa with a suspension of Sydowia polyspora 12 h prior to sowing. S. polyspora reduced seed emergence of its host, P. ponderosa, by as much as 30%. A tetrazolium chloride viability assay showed that S. polyspora reduces emergence by preventing germination; seed remained viable. In sum, pathogens affecting tree seed emergence and seedling recruitment may be endophytic as well as in seed and soil and deserve greater attention in studies of natural regeneration.
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Moya-Elizondo, Ernesto A., Barry J. Jacobsen, Andrew C. Hogg, and Alan T. Dyer. "Population Dynamics Between Fusarium pseudograminearum and Bipolaris sorokiniana in Wheat Stems Using Real-Time qPCR." Plant Disease 95, no. 9 (2011): 1089–98. http://dx.doi.org/10.1094/pdis-11-10-0794.
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Fusarium pseudograminearum and Bipolaris sorokiniana are causal agents of Fusarium crown rot and common root rot, respectively, of wheat and cause significant losses worldwide. Understanding the population dynamics between these two pathogens at late stages of wheat development is needed. The effect of F. pseudograminearum and B. sorokiniana inocula applied singly or in mixtures at seeding to spring wheat ‘Hank’ was measured using seedling stand, grain yield, and pathogen populations in the first internode at heading, milk, and harvest stage of wheat development using real-time quantitative polymerase chain reaction. High and low rates of F. pseudograminearum inoculum reduced B. sorokiniana populations in field trials but B. sorokiniana inoculations did not affect F. pseudograminearum populations. Populations of both pathogens increased from heading until harvest, with F. pseudograminearum colonizing lower internodes earlier than B. sorokiniana. Neither pathogen prevented infection by the other in the first internode of wheat stems. Inoculations increased incidence of infection and co-infection relative to natural settings observed for both pathogens. At the seedling stage, both fungi, individually or combined, reduced the seedling stands when compared with a noninoculated control for the three location–years. Grain yield and F. pseudograminearum populations were inversely correlated, while B. sorokiniana populations were not correlated with yield.
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Standing, Taryn-Ann, Erika du Plessis, Stacey Duvenage, and Lise Korsten. "Internalisation potential of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica subsp. enterica serovar Typhimurium and Staphylococcus aureus in lettuce seedlings and mature plants." Journal of Water and Health 11, no. 2 (2013): 210–23. http://dx.doi.org/10.2166/wh.2013.164.
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The internalisation potential of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella enterica subsp. enterica serovar Typhimurium in lettuce was evaluated using seedlings grown in vermiculite in seedling trays as well as hydroponically grown lettuce. Sterile distilled water was spiked with one of the four human pathogenic bacteria (105 CFU/mL) and used to irrigate the plants. The potential for pathogen internalisation was investigated over time using light microscopy, transmission electron microscopy and viable plate counts. Additionally, the identities of the pathogens isolated from internal lettuce plant tissues were confirmed using polymerase chain reaction with pathogen-specific oligonucleotides. Internalisation of each of the human pathogens was evident in both lettuce seedlings and hydroponically grown mature lettuce plants. To our knowledge, this is the first report of S. aureus internalisation in lettuce plants. In addition, the levels of background microflora in the lettuce plants were determined by plate counting and the isolates identified using matrix-assisted laser ionisation–time of flight (MALDI–TOF). Background microflora assessments confirmed the absence of the four pathogens evaluated in this study. A low titre of previously described endophytes and soil inhabitants, i.e., Enterobacter cloacae, Enterococcus faecalis, Lysinibacillus fusiformis, Rhodococcus rhodochrous, Staphylococcus epidermidis and Staphylococcus hominis were identified.
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Lokesh, S., B. Bharath, V. Raghavendra, and M. Govindappa. "Importance of plant growth-promoting rhizobacteria in enhancing the seed germination and growth of watermelon attacked by fungal pathogens." Acta Agronomica Hungarica 55, no. 2 (2007): 243–49. http://dx.doi.org/10.1556/aagr.55.2007.2.12.
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In the present study, seven isolates of plant growth-promoting rhizobacteria were used for seed treatment to suppress seedling diseases caused by fungi. Their effect on the seed germination and seedling vigour of watermelon was also studied. Among them INR-7 was able to inhibit a broad range of fungal species, GBO3 and IPC-11 were found to be effective against Fusarium spp. and Didymella bryoniae , while isolates SE-34 and T-4 were effective against Myrothecium species and also reduced the development of symptoms on the seedlings. Isolates GBO3, IPC-11 and INR-7 increased seed germination and seedling vigour to the greatest extent.
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Nahar, MS, MA Rahman, MG Kibria, ANM Rezaul Karim, and SA Miller. "Use of tricho-compost and tricho-leachate for management of soil-borne pathogens and production of healthy cabbage seedlings." Bangladesh Journal of Agricultural Research 37, no. 4 (2013): 653–64. http://dx.doi.org/10.3329/bjar.v37i4.14390.
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Tricho-compost, a Trichoderma based compost fertilizer, was developed by mixing a definite concentration of spore suspension of a Trichoderma harzianum strain with measured amounts of processed raw materials, such as cowdung, poultry refuse, water hyacinth, vegetable wastes, sawdust, maize bran, and molasses. Tricho-leachate, a liquid by-product of the Tricho-compost, was obtained during decomposition of Tricho-compost materials. These bioproducts were tested both in the laboratory and in seedbed nurseries to evaluate their effectiveness against soil-borne pathogens for growing cabbage seedlings. Application of Tricho-compost and Tricho-leachate reduced the seedling mortalities of cabbage caused by Sclerotium rolfsii by about 98%. In laboratory tests, Trichoderma harzianum, after re-isolation from Tricho-compost and tricho-leachate, was also found to be highly effective to arrest the growth of S. rolfsii. T. harzianum destroyed the radial growth of S. rolfsii mycelium by 59.7% after five days, and effected total destruction of the mycelium in 10 days. In seedbed nurseries, soil applications of Tricho-compost and Tricho-leachate significantly increased the seedling germination rate and reduced the incidence of soil-borne diseases and infestation of root-knot nematodes. Field experiment showed that combined application of Tricho-compost and Tricho-leachate reduced the seedling mortalities by 40.9% to 64.5% in Gazipur and 53.3% to 62.1% in Bogra. Application of Tricho-leachate at 500 ml per sq. metre increased plant weight by about 55.6%, and reduced the seedling mortality by about 84.0% in Gazipur. Seedbed nurseries treated with Tricho-compost and Tricho-leachate had only Pythium spp as a soil-borne pathogen, whereas the control plot had as many as four soil-borne pathogens -Pythium, Rhizoctonia, Sclerotium and Fusarium spp. Use of richo-compost and Tricho-leachate also reduced the infestation of root-knot nematode by about 80.7% to 91.0%. The results clearly showed that use of Tricho-compost and Tricho-leachate is highly effective for production of healthy cabbage seedlings. DOI: http://dx.doi.org/10.3329/bjar.v37i4.14390 Bangladesh J. Agril. Res. 37(4): 653-664, December 2012
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Pittaway, PA. "Opportunistic association between Pythium species and weed residues causing seedling emergence failure in cereals." Australian Journal of Agricultural Research 46, no. 3 (1995): 655. http://dx.doi.org/10.1071/ar9950655.
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Field trials were conducted to establish the link between weed residue management, Pythium infectivity and cereal seedling emergence failure. The herbicide glyphosate was used to manage weed-free and weed residue treatments, and the systemic fungicide metalaxyl was used to protect seedlings from pythiaceous attack. Seedling vigour and emergence were enhanced by the application of metalaxyl, and by the total suppression of weed growth. Invasion of cereal seedlings by pythiaceous fungi was greatest when seed was sown into cloddy seedbeds within 1-3 days after herbicide application. Debilitated weeds enhanced the activity of pythiaceous pathogens, promoting the invasion of cereals sown into the residues. If sowing is delayed for 3 weeks after herbicide application, pythiaceous activity will be reduced by saprophytic competitors colonizing the residues, resulting in improved seedling vigour and establishment.
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Walcott, Ron R. "Detection of Seedborne Pathogens." HortTechnology 13, no. 1 (2003): 40–47. http://dx.doi.org/10.21273/horttech.13.1.0040.
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Plant pathogens present a serious threat to seedling establishment and the potential for plant disease epidemics under greenhouse conditions is great. Hence, pathogen exclusion by detection and elimination of infested seedlots remains a requisite tactic for seedling production and disease management. Unfortunately, the numbers of contaminated seed within a lot may be low and infested seed may be asymptomatic making their detection difficult. To address these issues seed detection assays have been developed, but many of them have shortcomings that reduce their effectiveness. Examples of frequently used seed assays include visual examination, selective media, seedling grow-out and serological assays which, while appropriate for some pathogens, often display inadequate levels of sensitivity and specificity. Recently, the polymerase chain reaction (PCR) has emerged as a tool for detecting microorganisms in many diverse environments. Thus far, it is clear that DNA-based detection systems exhibit higher levels sensitivity than conventional techniques. Unfortunately, PCR-based seed tests require the extraction of PCR-quality DNA from target organisms in backgrounds of saprophytic organisms and inhibitory seed-derived compounds. The inability to efficiently extract PCR-quality DNA from seeds has restricted the acceptance and application of PCR for seed detection. To overcome these limitations several modified PCR protocols have been developed including selective target colony enrichment followed by PCR (BIO-PCR) and immunomagnetic separation and PCR. These techniques seek to selectively concentrate or increase target organism populations to enhance detection and have been successfully applied for detecting bacteria in seed. Other techniques with great potential for rapid detection of seedborne pathogens include magnetic capture hybridization and PCR, and DNA-chip technology. Ultimately, PCR will be available for the detection of all seedborne pathogens and may supersede conventional detection methods.
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Gossen, Bruce D., Robert L. Conner, Kan-Fa Chang, et al. "Identifying and Managing Root Rot of Pulses on the Northern Great Plains." Plant Disease 100, no. 10 (2016): 1965–78. http://dx.doi.org/10.1094/pdis-02-16-0184-fe.
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Pulse crops (annual grain legumes such as field pea, lentil, dry bean, and chickpea) have become an important component of the cropping system in the northern Great Plains of North America over the last three decades. In many areas, the intensity of damping-off, seedling blight, root rot, and premature ripening of pulse crops is increasing, resulting in reduction in stand establishment and yield. This review provides a brief description of the important pathogens that make up the root rot complex and summarizes root rot management on pulses in the region. Initially, several specific Fusarium spp., a range of Pythium spp., and Rhizoctonia solani were identified as important components of the root rot disease complex. Molecular approaches have recently been used to identify the importance of Aphanomyces euteiches on pulses, and to demonstrate that year-to-year changes in precipitation and temperature have an important effect on pathogen prevalence. Progress has been made on management of root rot, but more IPM tools are required to provide effective disease management. Seed-treatment fungicides can reduce damping-off and seedling blight for many of the pathogens in this disease complex, but complex cocktails of active ingredients are required to protect seedlings from the pathogen complex present in most commercial fields. Partial resistance against many of the pathogens in the complex has been identified, but is not yet available in commercial cultivars. Cultural practices, especially diversified cropping rotations and early, shallow seeding, have been shown to have an important role in root rot management. Biocontrol agents may also have potential over the long term. Improved methods being developed to identify and quantify the pathogen inoculum in individual fields may help producers avoid high-risk fields and select IPM packages that enhance yield stability.
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Solé, Raphaële, Sofia Gripenberg, Owen T. Lewis, et al. "The role of herbivorous insects and pathogens in the regeneration dynamics of Guazuma ulmifolia in Panama." Nature Conservation 32 (February 6, 2019): 81–101. http://dx.doi.org/10.3897/natureconservation.32.30108.
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A significant proportion of the mortality of rainforest trees occurs during early life stages (seeds and seedlings), but mortality agents are often elusive. Our study investigated the role of herbivorous insects and pathogens in the early regeneration dynamics of Guazumaulmifolia (Malvaceae), an important tree species in agroforestry in Central America. We reared pre-dispersal insect seed predators from G.ulmifolia seeds in Panama. We also carried out an experiment, controlling insects and pathogens using insecticide and/or fungicide treatments, as well as seed density, and compared survivorship of G.ulmifolia seeds and seedlings among treatments and relative to untreated control plots. We observed (1) high pre-dispersal attack (92%) of the fruits of G.ulmifolia, mostly by anobiine and bruchine beetles; (2) negligible post-dispersal attack of isolated seeds by insects and pathogens; (3) slow growth and high mortality (&gt; 95%) of seedlings after 14 weeks; (4) low insect damage on seedlings; and (5) a strong positive correlation between seedling mortality and rainfall. We conclude that for G.ulmifolia at our study site the pre-dispersal seed stage is by far the most sensitive stage to insects and that their influence on seedling mortality appears to be slight as compared to that of inclement weather. Thus, the regeneration of this important tree species may depend on effective primary dispersal of seeds by vertebrates (before most of the seed crop is lost to insects), conditioned by suitable conditions in which the seedlings can grow.
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Murillo-Williams, Adriana, and Palle Pedersen. "Early Incidence of Soybean Seedling Pathogens in Iowa." Agronomy Journal 100, no. 5 (2008): 1481–87. http://dx.doi.org/10.2134/agronj2007.0346.
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James,, R. A., J. A. Kirkegaard, and R. Munns. "Contribution of Rhizoctonia to reduced seedling growth of direct-drilled wheat: studies with intact cores." Australian Journal of Agricultural Research 48, no. 8 (1997): 1231. http://dx.doi.org/10.1071/a97029.
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Wheat seedlings were grown in intact cores of soil removed from 2 field experiments in southern New South Wales where the soil-borne pathogen Rhizoctonia solani had been implicated as a cause of slower seedling growth in direct-drilled soil compared with cultivated soil. Experiments were conducted with intact cores in controlled environments using fumigation to assess the role of Rhizoctonia in the growth responses. Seedling growth was lower in direct-drilled cores than cultivated cores from both sites at a very early stage. The growth reductions were completely removed by fumigation, confirming previous reports that biological factors rather than physical factors were responsible for reduced growth. In cores from the Galong site, Rhizoctonia symptoms were severe at the 5-leaf stage (8 on a scale of 0-10) and the reduction in leaf growth at earlier stages coincided with the appearance of Rhizoctonia symptoms on the roots. Seedling growth was not reduced until the severity was >5. This corresponded with a root-cutting experiment where shoot growth was unaffected until 3 of the 5 seminal roots of healthy seedlings were removed. Pre-sowing soil disturbance to a depth of 5 cm in unfumigated soil increased shoot growth from 47 to 84% of the fumigated controls with no further improvement when the depth of disturbance was increased to 10 cm, suggesting the pathogens responsible were confined to the 0-5 cm layer and were not completely eliminated by disturbance. Pre-sowing disturbance had no effect on shoot growth in fumigated soil. In cores from the Harden site, Rhizoctonia symptoms were moderate at the 5-leaf stage; however, reductions in leaf and root growth at earlier stages occurred 7 days before any symptoms of Rhizoctonia or other pathogens were visible on the roots. The results suggest that other inhibitory organisms are present at the Harden site and cause significant reductions in seedling growth in the absence of visible disease symptoms. Pythium spp. pathogenic to wheat are known to be present at the site but their role has not been confirmed. Further studies are required to identify the inhibitory organisms and to determine the mechanisms by which they reduce early seedling growth.
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Wiyono, Hadi, and Salim Widono. "Vigor of Plantlet from Microplantlet Treated by Filtrate and Cell Suspension of Some Isolates of Bacillus and Resistance to Banana Wilt Pathogen after Acclimatization." International Journal of Phytopathology 2, no. 2 (2013): 70–75. http://dx.doi.org/10.33687/phytopath.002.02.0086.
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Blood Disease Bacterium (BDB) and Fusarium oxysporum f.sp. cubense (FOC) is a couple wilt pathogen of banana. These pathogens are the most important constraint in cultivation of banana in Indonesia. In the integrated control strategy of the disease, the use of healthy seedlings produced from tissue culture technique is recommended. The seedling produced by tissue culture technique however leads to lower vigor and susceptibility to the disease due to the aseptic work in vitro causing the beneficial bacterial endophytic to be eliminated. Therefore, the utility of the beneficial endophytic bacteria should be studied for recovering the vigor and resistance of the seedling. Three isolates of endophytic Bacillus (B04, B05, B10) have been effective as growth promoter of microplantlet and antagonist of BDB and FOC in vitro. Here then, this article reports the study results of the vigor of the plantlet (treated microplantlet by filtrate or cell suspension of the Bacillus) after 3 months in acclimatization. The results were similar to the previous results on microplantlet in vitro, that Bacillus isolates B04, B05, and B10 were capable of promoting the growth and inducing the resistance to wilt pathogens on banana plantlets. The treatments with bacterial cell inoculums were more effective than those bacterial filtrate. Isolate B10 was most potential followed by B05 and B04 respectively.
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Loliam, B., T. Morinaga, and S. Chaiyanan. "Biocontrol ofPhytophthora infestans, Fungal Pathogen of Seedling Damping Off Disease in Economic Plant Nursery." Psyche: A Journal of Entomology 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/324317.
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This research aims to control Seedling damping off disease in plants by using antagonistic actinomycetes against the causative fungi.Phytophthora infestanswas isolated from the infected tomato plant seedling obtained from an economic plant nursery in Amphoe Pak Chong, Nakhon Ratchasima Province, Thailand. The chitinolyticStreptomyces rubrolavendulaeS4, isolated from termite mounds at the grove of Amphoe Si-Sawat, Kanchanaburi Province, Thailand, was proven to be the most effective growth inhibition of fungal pathogens tested on potato dextrose agar. Tomato and chili seedlings that colonized with antagonisticS. rubrolavendulaeS4 were grown inP. infestansartificial inoculated peat moss. Percents of noninfested seedling in fungal contaminated peat moss were compared to the controls with uninoculated peat moss. InP. infestanscontaminated peat moss, the percents of survival of tomato and chili seedling were significantly increased () from 51.42 to 88.57 and 34.10 to 76.71 for theS. rubrolavendulaeS4 treatment, respectively. TheS. rubrolavendulaeS4 also showed high efficiency equivalent to fungicide, metalaxyl with no significant difference (). It was clearly demonstrated thatS. rubrolavendulaeS4 can prevent the tomato and chili seedling damping off disease in economic plant nurseries.
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Adhikari, Tika B., C. M. Joseph, Guoping Yang, Donald A. Phillips, and Louise M. Nelson. "Evaluation of bacteria isolated from rice for plant growth promotion and biological control of seedling disease of rice." Canadian Journal of Microbiology 47, no. 10 (2001): 916–24. http://dx.doi.org/10.1139/w01-097.
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Of 102 rhizoplane and endophytic bacteria isolated from rice roots and stems in California, 37% significantly (P [Formula: see text] 0.05) inhibited the growth in vitro of two pathogens, Achlya klebsiana and Pythium spinosum, causing seedling disease of rice. Four endophytic strains were highly effective against seedling disease in growth pouch assays, and these were identified as Pseudomonas fluorescens (S3), Pseudomonas tolaasii (S20), Pseudomonas veronii (S21), and Sphingomonas trueperi (S12) by sequencing of amplified 16S rRNA genes. Strains S12, S20, and S21 contained the nitrogen fixation gene, nifD, but only S12 was able to reduce acetylene in pure culture. The four strains significantly enhanced plant growth in the absence of pathogens, as evidenced by increases in plant height and dry weight of inoculated rice seedlings relative to noninoculated rice. Three bacterial strains (S3, S20, and S21) were evaluated in pot bioassays and reduced disease incidence by 50%73%. Strain S3 was as effective at suppressing disease at the lowest inoculum density (106 CFU/mL) as at higher density (108 CFU/mL or undiluted suspension). This study indicates that selected endophytic bacterial strains have potential for control of seedling disease of rice and for plant growth promotion.Key words: biological control, plant growth promotion, endophytes, rice, seedling disease.
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Sigobodhla, T. E., S. Dimbi, and A. J. Masuka. "First Report of Pythium myriotylum Causing Root and Stem Rot on Tobacco in Zimbabwe." Plant Disease 94, no. 8 (2010): 1067. http://dx.doi.org/10.1094/pdis-94-8-1067c.
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Pythium species have a wide host range and are important pathogens of many agricultural crops. In Zimbabwe, 15 isolates of Pythium have been obtained from symptomatic tobacco (Nicotiana tabacum) in the new float seedling production system. This production system now accounts for 25 to 30% of the tobacco industry's annual requirement of 975 million seedlings. Disease symptoms are observed usually 5 to 6 weeks after sowing as wilting and yellowing of leaves followed by rotting of the roots, and in severe cases, seedling death. Up to 70% seedling loss has been reported in commercial seedbeds. In a study to fulfill Koch's postulates and to determine the susceptibility of 16 commercially grown tobacco cultivars, seedlings were produced in float trays and inoculated individually with 1 ml of Pythium (Isolate Py 19) spores (1 × 104 CFU/ml) and mycelium pipetted around the base of the stem of each seedling 9 weeks after sowing. First symptoms appeared 7 to 10 days after inoculation as yellowing and wilting of leaves. When seedlings were pulled, the lower portion of the stem and roots were brown and rotted. Seedling mortality averaged 29% and disease incidence was 96 to 100% among cultivars. All 16 tobacco cultivars were susceptible to Pythium root and stem rot and there were no significant (P > 0.05) differences in their susceptibility to the disease. The pathogen was reisolated from the inoculated seedlings. The representative isolate (Py 19) sent to Centraalbureau voor Schimmelcultures, the Netherlands was identified as Pythium myriotylum Drechsler (CBS Accession No. 125021) (2). P. aphanidermatum, causing black stem rot, and P. debaryanum and P. ultimum, responsible for damping-off (3), have been reported in the predominant conventional soil-based tobacco seedling production system, but do not cause economic losses. However, stem and root rot caused by P. myriotylum threaten the float seedling production system in Zimbabwe, although a chemical curative control of the disease has been recommended and is now widely practiced. P. myriotylum has previously been reported in the tobacco float seedling production system in South Carolina (1). To our knowledge, this constitutes the first published report of P. myriotylum on tobacco in Zimbabwe. References: (1) M. G. Anderson et al. Plant Dis. 81:227, 1997. (2) Centraalbureau voor Schimmelcultures. Retrieved from http://www.cbs.knaw.nl , 2010. (3) A. J. Masuka et al. List of Plant Diseases in Zimbabwe. Department of Research and Extension and Tobacco Research Board. Harare, Zimbabwe, 2003.
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Suharti, Tati, Triwidodo Arwiyanto, and Tri Joko. "Pertumbuhan dan Perkembangan Bibit Akor yang Diinokulasi Bakteri Patogen Terbawa Benih." Jurnal Fitopatologi Indonesia 14, no. 5 (2019): 159. http://dx.doi.org/10.14692/jfi.14.5.159.
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Growth and Development of Inoculated in Northern Black Wattle Seedling with Seed Borne Bacterial PathogensNorthern black wattle (Acacia auriculiformis) is a fast growing species that has multipurpose benefits such as pulpwood, solid wood, firewood, charcoal and pellet. Seed-borne bacterial pathogens were reported to reduce seed germination and seedling growth. The objective of this study was to evaluate effect of seed borne bacterial pathogen of A. auriculiformis on seed germination and 12 weeks-old seedling growth. Bacterial seed inoculation was performed by soaking the seed into respective bacterial suspension for 2 hours. The tested bacteria were Acinetobacter sp., Alcaligenes faecalis, Burkholderia cepacia complex, Escherichia hermannii, Paenochrobactrum sp., Pseudomonas stutzeri, Ralstonia sp., and Salmonella bongori. The results showed that all tested bacteria could reduce seed germination, but those does not affect seedling growth significantly. All tested bacteria excluding Acinetobacter sp. could inhibit seedling growth and development.
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Weiland, Jerry E., Anna L. Leon, Robert L. Edmonds, et al. "The effects of methyl bromide alternatives on soil and seedling pathogen populations, weeds, and seedling morphology in Oregon and Washington forest nurseries." Canadian Journal of Forest Research 41, no. 9 (2011): 1885–96. http://dx.doi.org/10.1139/x11-103.
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Five fumigation treatments (a conventional methyl bromide – chloropicrin application and four reduced-rate alternative fumigant treatments) and a nonfumigated treatment were evaluated at two forest nurseries in Oregon and one forest nursery in Washington for their effects on soil pathogen populations, weeds, and seedling morphology during a 2-year study. The effect of plastic tarp composition on fumigant efficacy was also evaluated (virtually impermeable film versus high-density polyethylene). All fumigant treatments reduced soil populations of Fusarium and Pythium for up to 7 months after fumigation and resulted in seedlings with significantly less pathogen colonization than those from the nonfumigated treatment. All fumigant treatments were more effective against pathogen inoculum buried at 15 cm rather than at 30 cm. Fusarium commune Skovgaard, O’Donnell et Nirenberg, Fusarium oxysporum Schlect. emend. Snyder & Hansen, isolates from the Gibberella fujikuroi Saw. complex, Pythium irregulare Buisman, Pythium aff. spiculum B. Paul 2006, Pythium sylvaticum Campbell & Hendrix, and Pythium ‘vipa’ Hermansen & Klemsdal were the most commonly isolated pathogens. Weed biomass and weeding times were significantly reduced by fumigation, but only at the Washington nursery with high weed pressure. No significant differences were observed in efficacy between the conventional methyl bromide – chloropicrin treatment and any of the reduced rate fumigants or between the two types of plastic tarp. Conifer seedling height, diameter, shoot volume, and root volume were significantly greater in all fumigated treatments compared with the nonfumigated treatment.
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Eck, Jenalle L., Simon M. Stump, Camille S. Delavaux, Scott A. Mangan, and Liza S. Comita. "Evidence of within-species specialization by soil microbes and the implications for plant community diversity." Proceedings of the National Academy of Sciences 116, no. 15 (2019): 7371–76. http://dx.doi.org/10.1073/pnas.1810767116.
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Microbes are thought to maintain diversity in plant communities by specializing on particular species, but it is not known whether microbes that specialize within species (i.e., on genotypes) affect diversity or dynamics in plant communities. Here we show that soil microbes can specialize at the within-population level in a wild plant species, and that such specialization could promote species diversity and seed dispersal in plant communities. In a shadehouse experiment in Panama, we found that seedlings of the native tree species, Virola surinamensis (Myristicaceae), had reduced performance in the soil microbial community of their maternal tree compared with in the soil microbial community of a nonmaternal tree from the same population. Performance differences were unrelated to soil nutrients or to colonization by mycorrhizal fungi, suggesting that highly specialized pathogens were the mechanism reducing seedling performance in maternal soils. We then constructed a simulation model to explore the ecological and evolutionary consequences of genotype-specific pathogens in multispecies plant communities. Model results indicated that genotype-specific pathogens promote plant species coexistence—albeit less strongly than species-specific pathogens—and are most effective at maintaining species richness when genetic diversity is relatively low. Simulations also revealed that genotype-specific pathogens select for increased seed dispersal relative to species-specific pathogens, potentially helping to create seed dispersal landscapes that allow pathogens to more effectively promote diversity. Combined, our results reveal that soil microbes can specialize within wild plant populations, affecting seedling performance near conspecific adults and influencing plant community dynamics on ecological and evolutionary time scales.
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Haeussler, Sybille, John C. Tappeiner II, and Brian J. Greber. "Germination, survival, and early growth of red alder seedlings in the central Coast Range of Oregon." Canadian Journal of Forest Research 25, no. 10 (1995): 1639–51. http://dx.doi.org/10.1139/x95-178.
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Effects of forest disturbance and soil moisture levels on establishment of red alder (Alnusrubra Bong.) seedlings were studied at four sites representing a climatic moisture gradient within the central Coast Range of Oregon. On average, there was no difference in seedling emergence between recent clearcuts and second-growth forests, but emergence was much higher on mineral soil than on organic seedbeds. Emergence, on both types of seedbed, was positively correlated with spring soil moisture conditions (R2 = 0.60). Seedling survival, on the other hand, differed greatly between clearcut and forest. In clearcuts, heat and drought injuries were the primary causes of seedling mortality. In the forest, seedlings had poor vigour and quickly succumbed to pathogens, herbivores, and rain splash. First-year survival rates were strongly correlated with minimum summer soil moisture levels (R2 = 0.71). Height growth of seedlings on clearcuts (2–5 cm after 1 year; 8–23 cm after 2 years) was much slower than rates typically described for red alder. Best establishment occurred on skid trails and landings, suggesting that young seedlings may suffer less from heat or moisture stress on these heavily disturbed microenvironments.
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Mihail, J. D., and S. M. Alcorn. "Seedling Establishment of Direct-seeded Guayule." Journal of the American Society for Horticultural Science 115, no. 2 (1990): 234–40. http://dx.doi.org/10.21273/jashs.115.2.234.
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The establishment of stands from directly sown seed may be a way to reduce the current high costs associated with guayule (Parthenium argentatum Gray) cultivation. These field studies were conducted to examine the combined effects of shade and fungicides on the survival of guayule seedlings established from directly sown seed. Soil in the experimental plot was a loam of pH 7.25. The following fungicides: a) Terraclor Super X, b) Ridomil 5G, c) Ridomil PC llG, d) Tilt 3.6E, e) Terracoat, and f) Vitavax + PCNB were tested alone and in combination with the nonwoven polyester shadecloth, Reemay, to identify treatments enhancing seed germination and seedling establishment. In all cases, seedling emergence in microplots covered with Reemay was significantly higher than in noncovered microplots. Terraclor Super X, Ridomil 5G, and Ridomil PC 1 lG were effective only when used in combination with the shadecloth. The long-term survival of guayule seedlings was strongly affected by severe climatic events. Since Reemay-protected seedlings were larger and more robust, they were more likely to survive the climatic extremes than unprotected seedlings. Two new guayule seedling pathogens were recorded -pythium dissotocum Drechsler and P. paroecandrum Drechsler. Chemical names used: 5-ethoxy-3-(trichloromethyl)-1,2,4-thiadiazole (Terrazole) + pen. tachloronitrobenzene (PCNB); N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-alamine methyl ester Ridomil + PCNB; 7. bromo-5-chloro-quinolin-8-yl-acrylate; Terrazole 5,6-dihydro-2-methyl-l,4 -oxathiin-3-carboxanilide + PCNB.
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., Sutarman, and Andriani Eko Prihatiningrum. "PENYAKIT HAWAR DAUN PINUS MERKUSII DI BERBAGAI PERSEMAIAN KAWASAN UTAMA HUTAN PINUS JAWA TIMUR." JURNAL HAMA DAN PENYAKIT TUMBUHAN TROPIKA 15, no. 1 (2015): 44. http://dx.doi.org/10.23960/j.hptt.11544-52.
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Leaf blight disease of Pinus merkusii in various nurseries of pine forest in major area of East Java. This study aims to: (i) obtain isolates of pathogens, (ii) determine disease on seedling growth during the critical period and the young plants, (iii) determine the effect of pathogenic isolates on disease severity, and (iv) determine the effect of altitude on severity of seedling’s leaf blight disease of Pinus merkusii from various nursery locations in East Java. The experiment was conducted in February-August 2014 at nine locations in the nursery and one young pine plantation site. Disease index data were analyzed using Microsoft Office Excel 2007 software to determine the regression model of the relationship between the index of disease with the independent variables and with Anova followed by Duncan test to find out the effect of altitude difference to the index of disease. Pathogen that causes late blight is Pestalotia theae Sawada. In the critical period, seedling disease index increased from 7.38 to an average of 26.96 in the nursery RPH Celaket; while on the young plants in the field in RPH Kemiri disease index ranged 28-31. Differences in altitude did not affect disease index difference. Based on disease index, three isolates of pathogens that require serious attention are Wagir isolates (985 m asl., the most virulent), Ngantang (500 m asl.), and South Pujon (1200 m asl.).
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Howell, C. R. "Cotton Seedling Preemergence Damping-Off Incited by Rhizopus oryzae and Pythium spp. and Its Biological Control with Trichoderma spp." Phytopathology® 92, no. 2 (2002): 177–80. http://dx.doi.org/10.1094/phyto.2002.92.2.177.
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Planting the cotton cv. Sure-Grow 747 in cotton seedling disease plots during the 2001 growing season resulted in high levels of preemergence damping-off among the seedlings. Four cotton pathogens, Pythium aphanidermatum, P. ultimum, an unidentified Pythium sp., and Rhizopus oryzae, were isolated from diseased seed embryos and seedlings. Disease incited by the Pythium spp. could be controlled by seed treatment with Metalaxyl, but disease incited by R. oryzae could not. Seed treatment with Metalaxyl in naturally infested field soil was only partially effective; therefore, symptoms in 47% of the diseased seedlings could be attributed to R. oryzae. Susceptibility to disease appeared to be related to release in the spermosphere, by the germinating seeds, of compounds that stimulate pathogen propagule germination, because exudates from seed of the suscept Sure-Grow 747 and extracts from wheat bran induced pathogen germination and growth, whereas exudates from resistant cv. Stoneville 213 did not. However, even Stoneville 213 became susceptible when infested soil was amended with wheat bran. Seed treatment with preparations of Trichoderma virens parent, mutant, and hybrid strains gave effective biological control of preemergence damping-off. Disease control was attributable to metabolism by the biocontrol agent of pathogen germination stimulants released by the seed, because amendment of pathogen-infested soil with the propagule germination stimulants in wheat bran negated the protective effect of the seed treatment.
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Huang, Fengmin, Minxia Liang, Yi Zheng, et al. "Soil nitrogen availability intensifies negative density-dependent effects in a subtropical forest." Journal of Plant Ecology 13, no. 3 (2020): 281–87. http://dx.doi.org/10.1093/jpe/rtaa012.
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Abstract Aims The importance of density-dependent mortality in maintaining tree species diversity is widely accepted. However, density-dependent effects may vary in magnitude and direction with different abiotic conditions in forests. Theoretical predictions surmise that density-dependent effects may vary with soil available nitrogen (AN), but this still needs to be tested. Methods We analyzed the density-dependent effects on survival of newly germinated seedlings for 18 common species based on a long-term seedling census across environmental gradients in a subtropical forest. We also conducted a root lesion detection experiment for five species to investigate the potential effects of pathogens on variation in density-dependent disease between rich and poor AN environments. Important Findings The seedling dynamics analysis revealed that the strength of density-dependent effects increased with AN, shifting from neutral or positive with low AN to negative with high AN. Three of the five tree species had stronger density-dependent effects on root lesions in rich AN environments than in poor AN environments, which is consistent with the results of a long-term seedling dynamics analysis. We also found higher species diversity in rich AN environments, which may be promoted by the stronger negative density-dependent effects. Both the seedling dynamic analysis and root lesion detection experiment revealed stronger negative density-dependent effects in higher AN environment, resulting from stronger disease pressure by soil pathogens. Our study emphasized the importance of considering context dependence when testing the density dependence hypotheses.
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Tarigan, Gema, Mardiana Wahyuni, and Guntoro . "EFEKTIVITAS BIOFUNGISIDA Trichoderma koningii TERHADAP PENCEGAHAN PENYAKIT JAMUR AKAR PUTIH DI PEMBIBITAN BATANG BAWAH TANAMAN KARET (Hevea brasiliensis)." Jurnal Agro Estate 3, no. 1 (2019): 10–17. http://dx.doi.org/10.47199/jae.v3i1.16.
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One of the main obstacles in rubber cultivation is the white root fungus (JAP) attack which caused by Rigidophorus ligonosus. This pathogen infects rubber plants from the nursery until the mature plants. Efforts to control the disease have been carried out by chemical, technical culture and use of biological agencies. This research was conducted at the STIP-AP Medan in January 2017 to June 2017, this study used a non-factorial Randomized Block Design (RBD) with four replications and four treatments. Using Trichoderma koningii with somes doses were 20 grams, 30 grams, and 40 grams/seedling. The results of this study indicate that the biofungicide application of Trichoderma koningii 30 g/seedling produces the greatest inhibition of the rubber plants seedling nursery against the growth of pathogens Rigidoporus lignosus.
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Long, Yanxin, Xiaodong Yang, Yuee Cao, et al. "Relationship between Soil Fungi and Seedling Density in the Vicinity of Adult Conspecifics in an Arid Desert Forest." Forests 12, no. 1 (2021): 92. http://dx.doi.org/10.3390/f12010092.
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Research Highlights: 1. Soil fungi have a higher influence on seedling density compared to soil environmental factors; 2. Host-specific pathogens and beneficial fungi affect seeding density via different influencing mechanisms. Background and Objectives: The growth and development of seedlings are the key processes that affect forest regeneration and maintain community dynamics. However, the influencing factors of seedling growth around their adult conspecifics are not clear in arid desert forests. Probing the intrinsic relations among soil fungi, soil environmental factors (pH, water content, salinity, and nutrition), and seedling density will improve our understanding of forest development and provide a theoretical basis for forest management and protection. Materials and Methods: Four experimental plot types, depending on the distance to adult conspecifics, were set in an arid desert forest. Soil environmental factors, the diversity and composition of the soil fungal community, and the seedlings’ density and height were measured in the four experimental plot types, and their mutual relations were analyzed. Results: Seedling density as well as the diversity and composition of the soil fungal community varied significantly among the four plot types (p < 0.05). Soil environmental factors, especially soil salinity, pH, and soil water content, had significant influences on the seedling density and diversity and composition of the soil fungal community. The contribution of soil fungi (72.61%) to the variation in seedling density was much higher than the soil environmental factors (27.39%). The contribution of detrimental fungi to the variation in seedling density was higher than the beneficial fungi. Conclusions: Soil fungi mostly affected the distribution of seedling density in the vicinity of adult conspecifics in an arid desert forest. The distribution of seedling density in the vicinity of adults was mainly influenced by the detrimental fungi, while the adults in the periphery area was mainly influenced by the beneficial fungi.
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CUI, YUE, DA LIU, and JINRU CHEN. "Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli on Vegetable Seeds Contaminated by Direct Contact with Artificially Inoculated Soil during Germination." Journal of Food Protection 83, no. 7 (2020): 1218–26. http://dx.doi.org/10.4315/jfp-20-021.
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ABSTRACT Contaminated vegetable seeds have been identified as a potential source of foodborne bacterial pathogens. This study was undertaken to observe the behavior of Salmonella and enterohemorrhagic Escherichia coli (EHEC) on vegetable seeds, contaminated by direct contact with artificially inoculated soil, during germination. Sterile sandy soil inoculated with lyophilized cells of four individual strains of Salmonella or EHEC (three O157:H7 strains and one O104:H4 strain) was mixed with sanitized seeds (2 g) of alfalfa, fenugreek, lettuce, and tomato at 20°C for 1 h. The contaminated seeds were germinated on 1% water agar at 25°C for 9 days in the dark. Populations of Salmonella and EHEC on various tissues (seed coat, root, cotyledon, and stem, etc.) of sprouts and seedlings were determined every other day over the germination period. Overall, 70.4 and 72.4% of collected tissue samples (n = 544) tested positive for Salmonella and EHEC, respectively. In general, the mean populations of Salmonella and EHEC on sprout and seedling tissues increased with the prolongation of germination time. Seed coats had the highest bacterial counts (4.00 to 4.06 log CFU/0.01 g), followed by the root (3.36 to 3.38 log CFU/0.01 g), cotyledon (3.13 to 3.38 log CFU/0.01 g), and stem tissues (2.67 to 2.84 log CFU/0.01 g). On average, tissue sections of fenugreek sprouts and lettuce seedlings had significantly higher (P &lt; 0.05) numbers of Salmonella and EHEC cells than that of alfalfa sprouts and tomato seedlings. Data suggest that the growth and dissemination of Salmonella and EHEC cells on alfalfa, fenugreek, lettuce, and tomato sprout and seedling tissues are influenced by the type of vegetable seeds and sprout and seedling tissues involved. The study provides useful information on the fate of two important foodborne bacterial pathogens on selected vegetable seeds, contaminated by direct contact with inoculated soil, during the germination process. HIGHLIGHTS
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Gehring, Catherine A. "Seed reserves and light intensity affect the growth and mycorrhiza development of the seedlings of an Australian rain-forest tree." Journal of Tropical Ecology 20, no. 3 (2004): 345–49. http://dx.doi.org/10.1017/s0266467403001160.
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Interspecific variation in seed size can affect seedling establishment in the light-limited understorey of rain forests. Large seeds with extensive seed reserves may allow seedlings to (1) persist in the deep shade, thereby increasing the likelihood of exposure to a canopy gap (Leishman & Westoby 1994, Saverimuttu & Westoby 1996); (2) promote growth, thereby allowing seedlings to reach higher light strata or to develop sufficient photosynthetic tissue to meet their energy needs in low light (Foster 1986); and (3) allow compensation for tissue losses to herbivores and pathogens (Armstrong & Westoby 1993, Foster 1986, Harms & Dalling 1997). However, comparisons of shade tolerance among species that vary in seed size have produced conflicting results; short-term seedling survival was strongly positively associated with seed size in several studies (Grime & Jeffrey 1965, Leishman & Westoby 1994), but only weakly in others (Augspurger 1984, Grubb & Metcalfe 1996).
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Wang, Qing, Stefanie Vera Buxa, Alexandra Furch, Wolfgang Friedt, and Sven Gottwald. "Insights Into Triticum aestivum Seedling Root Rot Caused by Fusarium graminearum." Molecular Plant-Microbe Interactions® 28, no. 12 (2015): 1288–303. http://dx.doi.org/10.1094/mpmi-07-15-0144-r.
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Fusarium graminearum is one of the most common and potent fungal pathogens of wheat (Triticum aestivum), known for causing devastating spike infections and grain yield damage. F. graminearum is a typical soil-borne pathogen that builds up during consecutive cereal cropping. Speculation on systemic colonization of cereals by F. graminearum root infection have long existed but have not been proven. We have assessed the Fusarium root rot disease macroscopically in a diverse set of 12 wheat genotypes and microscopically in a comparative study of two genotypes with diverging responses. Here, we show a ‘new’ aspect of the F. graminearum life cycle, i.e., the head blight fungus uses a unique root-infection strategy with an initial stage typical for root pathogens and a later stage typical for spike infection. Root colonization negatively affects seedling development and leads to systemic plant invasion by tissue-adapted fungal strategies. Another major outcome is the identification of partial resistance to root rot. Disease severity assessments and histological examinations both demonstrated three distinct disease phases that, however, proceeded differently in resistant and susceptible genotypes. Soil-borne inoculum and root infection are considered significant components of the F. graminearum life cycle with important implications for the development of new strategies of resistance breeding and disease control.
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Hamman, Brigitte, D. B. Egli, and Gwen Koning. "Seed Vigor, Soilborne Pathogens, Preemergent Growth, and Soybean Seedling Emergence." Crop Science 42, no. 2 (2002): 451. http://dx.doi.org/10.2135/cropsci2002.0451.
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Hamman, Brigitte, D. B. Egli, and Gwen Koning. "Seed Vigor, Soilborne Pathogens, Preemergent Growth, and Soybean Seedling Emergence." Crop Science 42, no. 2 (2002): 451–57. http://dx.doi.org/10.2135/cropsci2002.4510.
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Hagedorn, C., W. D. Gould, and T. R. Bardinelli. "Rhizobacteria of Cotton and Their Repression of Seedling Disease Pathogens." Applied and Environmental Microbiology 55, no. 11 (1989): 2793–97. http://dx.doi.org/10.1128/aem.55.11.2793-2797.1989.
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Marcinkowska, Joanna. "Fungi of the genus Fusarium as pathogens of soybean seedlings." Acta Agrobotanica 38, no. 2 (2013): 123–35. http://dx.doi.org/10.5586/aa.1985.011.
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Twenty isolates of fungi of the genus <i>Fusarium</i> collected in the period 1980-1982 from various organs of diseased soybean plants were investigated. Eight of them proved pathogenic to soybean seedlings. The species <i>F. culmorum</i> was most numerously represented among the isolated (4 of 8) pathogens. Isolates of <i>F. sambucinum</i> were also pathogenic (2 of 4) and those of <i>F. soloni</i> (1 of 3), too. The only isolate of <i>F. avenaceum</i> also caused seedling blight. Two isolates of <i>F. oxysporum</i> and two of <i>F. arthrosporioides</i> were not pathogenic. Numerous isolates affected seed gernination and one greatly inhibited growth of the infected seedlings. Pathogenicity was tested in the laboratory in Petri plates on isolate cultures and on filter paper imbibed with fungal inoculum and, in the greenhouse on a peat and perlite substrate. The degree of infection and the character of the disease symptoms depended on the experimental conditions. The results of experiments in plates and in the greenhouse supplemented one another.
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Alaba Olaitan Adeji and Adefoyeke Olufunmilayo Aduramigba-Modupe. "Botanical alternatives in management of fungal pathogens of seedling blight of cashew (Anacardium occidentale L.)." GSC Biological and Pharmaceutical Sciences 14, no. 1 (2021): 193–98. http://dx.doi.org/10.30574/gscbps.2021.14.1.0274.
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Introduction: Cashew (Anacardium occidentale L.) is an important tree crop and seedling survival is pertinent to successful establishment. Cashew seedling is infected by blight pathogens causing more than 60% seedling lost, however pesticides residues related issues and high cost of chemical necessitate efficacy trials of aqueous extracts of Mangifera indica, Azadirachta indica and Hyphtis suaveolens evaluated in-vitro on associated pathogens. Methods: Flora of blight-infected cashew seedlings was randomly collected from Cocoa Research Institute of Nigeria (CRIN) nursery between July and October, 2019. Mycoflora analysis was carried out in the plant pathology (Mycology) laboratory of CRIN. Antifungal assay of powdered Mangifera indica, Azadirachta indica and Hyphtis suaveolens were screened using aqueous extracts at 1:4 (w/v). Potato Dextrose Agar (PDA) amended with 1ml of 100%, 75%, 50%, 25%, and 0% of the extracts and Mancozeb (synthetic fungicide) as standard, 5mm mycelia mat disc of 10day old each of Lasiodiplodia theobromae, Fusarium pallidoroseum and Macrophomina sp. were placed at the centre of the amended media in triplicate and incubated 5-7days using complete randomized design (CRD). Mycelia extension inhibition and percentage growth inhibition (R) obtained. Results: Aspergillus niger, A. flavus, Fusarium oxysporium, F. pallidoroseum, Lasiodiplodia theobromae., Pythium sp., Rhizopus sp., Macrophomina sp. and Rhizotonia sp. were isolated. Fusarium pallidoroseum, L. theobromae and Macrophomina sp. screened with the varied concentrations of botanicals showed reduction in mycelia diameter; Mangifera indica (31.50%), A. indica (48.70%) and H. suaveolens (25.86%) on F. pallidoroseum favorably competed with mancozeb (39%) at 25% concentration while only M. indica was significant on L.theobromae(64.12%)and Macrophomina sp.(40.29%) and significantly different from control (0%). Conclusion: Aqueous extracts of M. indica, A. indica and H. suaveolens showed fungicidal potential on F. pallidoroseum and M. indica was significant on L. theobromae and Macrophomina sp.
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Rodríguez, Claudia, and Maria Alice Garcia. "Seed-bank dynamics of the tropical weedSida rhombifolia(Malvaceae): incidence of seedling emergence, predators and pathogens." Seed Science Research 19, no. 4 (2009): 241–48. http://dx.doi.org/10.1017/s0960258509990146.
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AbstractArrowleaf sida (Sida rhombifolia) is a tropical weed that grows in disturbed areas. Its control by hand pulling and mowing are only partially effective because arrowleaf sida is difficult to pull and quickly sprouts after cutting. We studied the seed-bank dynamics ofS. rhombifoliain the region of Campinas, São Paulo State, Brazil for 2 years, following a known number of seeds placed artificially at five burial depths. Predators and pathogens were responsible for the loss ofc.40% of the seeds during the first year of the experiment. The importance of predation declined with depth. Mortality due to fungal attack did not differ among the burial depths, except for seeds placed at the surface (where it was negligible). Seedling emergence only occurred during the first year, after the beginning of the rainy period and when the study area was still free of a dense vegetation cover. Seedlings did not emerge from depths greater than 5 cm. We conclude that seedling emergence and death are significant causes of seed losses from the seed bank ofS. rhombifoliabut their relative importance is highly dependent on depth of burial.