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1
Matheron, Michael E. "Biology and Management of Downy Mildew of Lettuce." College of Agriculture, University of Arizona (Tucson, AZ), 2015. http://hdl.handle.net/10150/579516.
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Matheron, M. E., J. C. Matejka, and M. Porchas. "Field Testing of Potential New Fungicides for Control of Lettuce Diseases, 1993." College of Agriculture, University of Arizona (Tucson, AZ), 1994. http://hdl.handle.net/10150/214718.
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Several diseases caused by plant pathogenic fungi can cause economic losses to lettuce growers in Arizona. Leaf drop of lettuce is caused by Sclerotinia minor and S. sclerotiorum, while downy and powdery mildew are caused by Bremia lactucae and Erysiphe cichoracearum, respectively. Cool and moist environmental conditions favor development of leaf drop and downy mildew, while warmer and dry weather is conducive for development of powdery mildew. Potential new fungicides were evaluated for control of these diseases during the winter of 1992-93. For leaf drop, two nonregistered materials, Fluazinam and Topsin M, controlled disease at least well as the standard registered fungicides. Fluazinam and Aliette provided equivalent control of downy mildew, while Fluazinam but not Aliene significantly reduced the severity of powdery mildew on lettuce.
3
Boshoff, Jane. "Biological control of Pythium wilt and root rot in hydroponically grown lettuce." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-02272007-163651/.
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Matheron, M., J. McGrady, M. Butler, M. Rethwisch, J. Matejka, and P. Tilt. "Effect of Sunstainable Versus Conventional Fertilization Practices on Populations of Pythium and Fusarium on Roots of Lettuce in 1990 Field Test." College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/221453.
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This report focuses upon our efforts to evaluate the effect of sustainable versus conventional fertilization practices on subsequent populations of soil-borne pathogens on lettuce roots. The different fertilization treatments included conventional fertilizer, composted cow manure, and a biological soil conditioner. Near plant maturity, lettuce roots were collected from the field and the populations of Pythium and Fusarium were determined. The lowest population of both of these pathogens was found in the plots fertilized with composted cow manure, while the highest levels of Pythium and Fusarium were detected in the plots treated with conventional fertilizer. Further field studies are planned to confirm these initial findings. Of the two pathogens assayed, Pythium is of greatest concern because of its ability to destroy roots and reduce plant growth and vigor. Species of Fusarium are commonly found in soil and on plant roots and usually do not cause damage to plants unless the plants are under stress.
5
Matheron, M. E., and J. C. Matejka. "Sclerotinia Leaf Drop of Lettuce - Screening New Fungicides for Disease Control in 1986." College of Agriculture, University of Arizona (Tucson, AZ), 1987. http://hdl.handle.net/10150/221404.
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In western Arizona, the incidence and severity of lettuce drop, caused by the fungus Sclerotinia sclerotiorum, can be significant during February, March and April. During 1986 a field trial was established to test new fungicides for disease control. Disease severity in the inoculated lettuce planting was significantly reduced by Baycor, Spotless and CGA-449, as well as the registered fungicides Ronilan and Rovral. Further testing of Baycor, Spotless and CQA-449 will be performed next year.
6
McGrady, John, Vince Rubatzky, Norm Oebker, Tim Hartz, Marvin Butler, Phil Tilt, and Sherry Hagerman. "Cultural Alternative for Avoidance of Lettuce Infectious Yellows Virus (LIYV)." College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/221452.
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Matheron, M. E., and J. C. Matejka. "Effect of Fungicides Applied at Different Rates on Control of Sclerotinia Leaf Drop of Lettuce -- 1990 Field Test." College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/221455.
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Leaf drop of lettuce, caused by the plant pathogenic fungi Sclerotinia sclerotiorum and S. minor, is found every year in some lettuce fields in Arizona. When environmental conditions are favorable, disease incidence and resulting crop loss can be significant. During the 1989 -90 lettuce season in western Arizona, different fungicides and rates of materials were evaluated in the field for disease control Ronilan and Rovral, the two fungicides currently registered for use on lettuce for control of Sclerotinia leaf drop, provided significant disease suppression and increased yields at all rates tested. Bravo and Botran did not control the disease.
8
Matheron, Michael E., and Martin Porchas. "Downy and Powdery Mildew of Lettuce: Comparison of Chemical Management Tools in 1997." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/221600.
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Downy and powdery mildew are caused by the plant pathogenic fungi Bremia lactucae and Erysiphe cichoracearum, respectively. Cool and moist environmental conditions favor development of downy mildew, while warmer and dry weather is conducive for development of powdery mildew. Potential new fungicides were evaluated for management of these diseases in 1997. A very low level of downy mildew occurred during this trial; however, all treatments significantly reduced the number of leaf lesions compared to nontreated lettuce plants. Powdery mildew was quite intense at crop maturity and was significantly lower, compared to nontreated lettuce, on plants treated with Microthiol Special, BAS 490 + Bravo Weather Stik, Quadris, and two additional treatments not usually found to reduce this disease.
9
Wilcox, Mark, and Michael Matheron. "Field Evaluation of Head Lettuce Cultivars for Susceptibility to Sclerotinia Leaf Drop in 1997." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/221601.
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Leaf drop of lettuce is caused by the plant pathogenic fungi Sclerotinia minor and S. sclerotiorum. Cool and moist environmental conditions favor disease development. Sixteen diffirent cultivars of head lettuce were evaluated in the field for susceptibility to Sclerotinia leaf drop in plots inoculated with sclerotia of Sclerotinia minor or S. sclerotiorum. Significant differences were detected among the tested cultivars in the amount of lettuce plants killed by Sclerotinia minor. On the other hand, there were no significant differences among tested cultivars in the number of plants destroyed by Sclerotinia sclerotiorum
10
Matheron, Michael E., and Martin Porchas. "Field Evaluation of Potential New Fungicides for Control of Lettuce Downey and Powdery Mildew in 1994 and 1995." College of Agriculture, University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/221462.
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Downy and powdery mildew are caused by the plant pathogenic fungi Bremia lactucae and Erysiphe cichoracearum, respectively. Cool and moist environmental conditions favor development of downy mildew, while warmer and dry weather is conducive for development of powdery mildew. Potential new fungicides were evaluated for control of these diseases during 1994 and 1995. In 1994, downy mildew did not occur in the test plots; however, powdery mildew was severe and was controlled most effectively by Microthiol. In the 1995 study, both downy and powdery mildew developed in the test plots. The highest level of downy mildew control was achieved with three experimental compounds, Fluazinam, Dimethomorph, and BAS-490. The most effective fungicides for control of powdery mildew in 1995 were BAS-490 and Microthiol.
11
Matheron, Michael E., Iraj J. Misaghi, Martin Porchas, and Dominic DeCianne. "Field Evaluation of Potential New Fungicides for Control of Sclerotinia Leaf Drop of Lettuce in 1994 and 1995." College of Agriculture, University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/221473.
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Leaf drop of lettuce is caused by the plant pathogenic fungi Sclerotinia minor and S. sclerotiorum. Cool and moist environmental conditions favor disease development. Potential new fungicides were evaluated in field trials for control of this disease in 1994 and 1995. In the 1994 trial, Fluazinam and Topsin M provided significant decrease of disease and significant increase inmarketable yield compared to no treatment in plots infested with Sclerotinia minor or S. sclerotiorum. In 1995, Fluazinam, Topsin M, and two compounds from Ciba significantly reduced disease caused by Sclerotinia minor and increased marketable yield of treated lettuce when compared to nontreated plots.
12
Matheron, Michael E., and Martin Porchas. "Evaluation of New Fungicides for Management of Downy and Powdery Mildew of Lettuce in 1998." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/221659.
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Bremia lactucae and Erysiphe cichoracearum, respectively, cause downy and powdery mildew of lettuce. Cool moist environmental conditions favor the development of downy mildew, whereas warm and dry weather is conducive for powdery mildew. Several potential new fungicides were evaluated for control of these diseases of lettuce in 1998. The final severity of downy mildew in this trial was low. In addition to the standard compounds maneb, Aliette and Trilogy, several fungicides currently in development significantly reduced the severity of downy mildew compared to nontreated plants. These chemistries included Acrobat, RH -7281, an Unknown, Actigard, EF1295, Curzate, Quadris, BAS 500, QST 153, BAS 505 and BAS 490. Untreated lettuce plants were heavily infected with powdery mildew. In addition to the standard materials Microthiol Special and Trilogy, powdery mildew was significantly reduced on plants treated with BAS 490, BAS 505, EF1295, BAS 500 and Quadris. The possible availability of one or more of these chemistries under development for lettuce could help in efforts to develop and maintain a fungicide resistance management program for plant medicines of importance for this crop.
13
Matheron, Michael E., and Martin Porchas. "New Fungicides Evaluated for Control of Sclerotinia Leaf Drop of Lettuce in 1997 and 1998." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/221661.
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Sclerotinia leaf drop of lettuce is caused by two different species of this fungal pathogen, Sclerotinia minor and S. sclerotiorum. Cool and moist environmental conditions favor this disease. Some new fungicides in development were evaluated for control of leaf drop on lettuce during the winter vegetable growing seasons of 1996-97 and 1997-98. Sclerotia of each pathogen were applied to plots after thinning and just before the first of two applications of test compounds. The final severity of leaf drop in these trials was high. Significant reduction in disease or increase in marketable heads compared to nontreated plants was usually achieved by application of the standard compounds Ronilan and Rovral as well as the new fungicides BAS 500 and an "unidentified" material. The future registration and subsequent availability of one or both of these new chemistries for lettuce could provide equivalent disease control to that of the current standard materials with 0.2 to 0.25 lb active ingredient (a.i.) per acre instead of the current 1.0 lb a.i. per acre required with the standard compounds.
14
Kerns, David L., and Tony Tellez. "Tank Mixing New Insecticide Chemistries with a Pyrethroid Insecticide for Control of Lepidopterous Pests in Head Lettuce, 1997." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/221679.
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Confirm, Success and Proclaim were evaluated for lepidopterous insect control in lettuce with and without the addition of Mustang 1.5EW. Success and Proclaim used alone were highly efficacious toward cabbage looper and Heliothinae and did not appear to benefit greatly from the addition of Mustang. However, Confirm's activity towards Heliothinae was significantly improved by the addition of Mustang. Additionally, on large framed plants where coverage is difficult, Confirm benefitted from the addition of a pyrethroid for control of loopers.
15
Gracia, Javier. "Lettuce stunt : effect of Pythium populations and interactions between Pythium tracheiphilum and nematodes." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59387.
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This research has focused on the determination of natural populations in the fields, the effect of different inoculum densities on lettuce growth and a study of the association of this fungus with two nematodes (Pratylenchus penetrans Cobb and Meliodogyne hapla Chitwood). Under conditions of artificial infestation of soil the results were satisfactory, but in trials with naturally infested soil the fungus could not be detected. The effect of different inoculum densities was measured at different stages of growth, and only in those plants inoculated 2 weeks after seeding were differences significant and consistent. Some evidence of the detrimental effect of wounding the root system prior to attack by the fungus led to studies of the relationship between this fungus with either P. penetrans or M. hapla. In the first case a negative interaction seemed to exist; no significant increase of the damage caused to the lettuce was observed. In contrast, when the root-knot nematodes and P. tracheiphilum were combined there was a marked reduction of lettuce growth. The interaction was found to be additive.
16
Sultan, Youneskhan 1957. "Rhythm of zoospore production of pythium on lettuce cultured hydroponically." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276687.
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Zoospore production of Pythium dissotocum Drechs. in the nutrient solution of hydroponically-grown lettuce, in the greenhouse, was shown to be cyclic. The number of zoospores detected in the nutrient solution was lowest around noontime, (11:00-14:00 hr) and highest around 20:00 hr. Growth chamber studies were conducted to determine the effect of different light periods on zoospore production. Under continuous light or continuous darkness, the population of zoospores in the nutrient solution decreased. But under 12 hours light, and 12 hours darkness or two periods of light each for 3 hours, zoospore populations decreased during the light period but increased during the dark period.
17
Matheson, Michael E., and Joseph C. Matejka. "Sclerotinia Leaf Drop on Lettuce -- Evaluation of New Fungicides for Disease Control." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/214265.
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Leaf drop of lettuce, caused by Sclerotinia sclerotiorum, is a sporadic, but destructive, disease in Arizona. Field trials were established during 1987 and 1988 to evaluate potential new fungicides for disease control. Ronilan and Rovral, the two materials currently registered for use on lettuce for Sclerotinia leaf drop, were consistently among the most effective fungicides for disease control. Levels of disease control equivalent to that provided by Rovral and Ronilan were observed with CGA-449, SC-0854 SDS-65311, Bay HWG 1608, and Spotless. These field tests have identified several potential new fungicides for control of leaf drop of lettuce caused by S. sclerotionan.
18
Pier, J. W., T. A. Doerge, and T. McCreary. "Fungicides Evaluated for Control of Sclerotinia Leaf Drop of Lettuce in 1991 Field Test." College of Agriculture, University of Arizona (Tucson, AZ), 1992. http://hdl.handle.net/10150/214510.
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Matheron, Michael E., and Martin Porchas. "Management of Sclerotinia Leaf Drop on Lettuce: Efficacy of Fungicides in 1996 Field Trial." College of Agriculture, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/214737.
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Leaf drop of lettuce is caused by the plant pathogenic fungi Sclerotinia minor and S. sclerotiorum. Cool and moist environmental conditions favor disease development. Potential new fungicides were evaluated in a field trial for management of this disease in 1996. For plots containing Sclerotinia minor, all compounds and rates tested significantly reduced the number of diseased heads compared to plots not treated with a fungicide. All treatments except Ronilan at the 0.5 lb. a. i./A rate yielded a significantly higher number of marketable heads compared to nontreated plots infested with S. minor. For plots containing S. sclerotiorum, all materials except the Ciba compound at the low and high rates decreased the number of diseased heads and increased the number of marketable heads compared to nontreated plots.
20
Matheron, Michael E., and Martin Porchas. "Management of Downy and Powdery Mildew on Lettuce: Efficacy of Fungicides in 1996 Field Trial." College of Agriculture, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/214738.
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Downy and powdery mildew are caused by the plant pathogenic fungi Bremia lactucae and Erysiphe cichoracearum, respectively. Cool and moist environmental conditions favor development ofdowny mildew, while warmer and dry weather is conducive for development of powdery mildew. Potential new fungicides were evaluated for management of these diseases in 1996. Both downy and powdery mildew developed in the test plots. All tested materials significantly reduced the severity of downy mildew compared to plants not treated with a fungicide. Compared to nontreated control plants as well as some tested materials and rates, significant reduction of powdery mildew was achieved with Azoxystrobin 80WDG + Latron B-1956, BAS 490 02F, Ciba G /MZ + Mancozeb 75DF, Dithane 75DF + Latron CS-7, Propamocarb 6EC (high rate), R11-7281 2F + Larron CS-7, and Microthiol 80WDG.
21
Nelson, Merritt R., Joseph C. Matejka, and Judith K. Brown. "Use of Stylet Oil to Slow the Spread of Lettuce Infectious Yellows Virus." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/214262.
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The use of stylet oil to slow the spread of the whitefly- transmitted vines, lettuce infectious yellows, shows sufficient promise to plan for expanded research efforts. The main positive results were a slower buildup of virus infection and a larger number of marketable heads in the block of lettuce sprayed with oil. Weight (in grams) of individual heads could be correlated with time of infection in that the lowest weights and marketability ratings occurred in plants infected earliest in the season. Whether they were front treated or untreated plots, marketable heads weighed an average of 784 grams; unmarketable heads weighed 491 grams. The key difference is that, on the average, five marketable heads of lettuce were in the oil- treated plots for every three in the untreated plots. A follow-up experiment will be conducted in 1989 to determine if these preliminary positive results indicate that stylet oil treatment may be a practical control method for slowing the spread of L1YV.
22
Matheron, M. E., and J. C. Matejka. "Sclerotinia Leaf Drop of Lettuce - Testing New Fungicides and Formulations of Ronilan for Disease Control." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/214477.
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Leaf drop of lettuce, caused by the fungus Sclerotinia sclerotionunb is a sporadic but potentially destructive disease in Arizona During the 1988-89 lettuce season in western Arizona, different fungicides and formulations of materials were evaluated in the field for disease control. All tested compounds provided significant disease suppression and increased yields, provided that a sufficient rate of fungicide was applied. Ronilan and Rovral, the two fungicides currently registered for use on lettuce for Sclerotinia leaf drop, were the most effective fungicides in this test, performing significantly better than the two experimental materials. The SODF formulation of Ronilan provided significantly better disease control than the SOW formulation of the same compound.
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Matheron, M. E., R. Leonard, and G. Major. "Fungicides Evaluated for Control of Rhizoctonia Bottom Rot of Lettuce in 1991 Field Trials." College of Agriculture, University of Arizona (Tucson, AZ), 1992. http://hdl.handle.net/10150/214512.
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Bottom rot of lettuce, caused by the soil -borne fungus Rhizoctonia solani, can cause economic losses on early season lettuce harvested in November. First evidence of the disease is the appearance of brown, sunken, necrotic areas on the midribs of leaves touching the soil. Under favorable environmental conditions, the pathogen grows from leaf to leaf inside the head. If the fungus invades the leaves of the marketable head it and all similarly infected heads are left in the field resulting in economic losses. Field trials were established to evaluate the potential level of disease control obtainable by applying Ronilan or Rovral to lettuce beds immediately after thinning. No significant reduction in loss of marketable heads was observed in these trials, although there was a trend toward lower levels of bottom rot when either fungicide was in place.
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Kalonji, Kabengele Muzela J. B. "Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings." Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/29549.
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Lettuce (Lactuca sativa L.) seedlings diseases caused by soilborne pathogens are characterised by root rot, stem rot and damping-off of the seedlings that can occur at any time during growth. Fusarium solani, Pythium ultimum and Rhizoctonia solani are known to be the important destructive pathogens of lettuce, causing severe yield losses in South Africa. The aim of this research was to evaluate the effects of three selected fungicides to control these pathogens on lettuce seedlings. In this study the fungicides metalaxyl (Apron®), fludioxonil (Celest®) and mefenoxam (Subdue®) were applied at two concentrations as single and double doses on lettuce seedlings to determine their efficacy to control the pathogens Fusarium solani, Pythium ultimum and Rhizoctonia solani after significant reduction of mycelia growth was observed in vitro. Cultures of P. ultimum (UPGH024), R. solani (UPGH122) and F. solani (UPGH122) were obtained from the culture collection of the Department of Microbiology and Plant Pathology, University of Pretoria and cultivated on PDA for 2 days at 25ºC. Pasteurised soil was artificially inoculated with these pathogens. For the first experiment lettuce seeds were planted in polystyrene seedling trays at a depth of 1.0 cm. There were four replications of 50 seeds per treatment. In Experiment 2 pots (12 cm x 7 cm) were filled with pasteurised growing medium and 3-week old seedlings were transplanted. There were three replications of six pots containing three plants each. Seedling trays and pots were drenched with fungicides and placed in a randomised block design in a controlled environment room at 20- 26°C with a 12h-light/dark regime. The seedling trays and pots were rotated daily in the room. Seedling trays and pots were watered daily to maintain field capacity. The seedlings were able to grow larger in the pots than in seedling trays. It was confirmed that the treatment with fludioxonil (Celest®) at double and single dose inhibited the growth of the three fungi F. solani, P. ultimum and R. solani on lettuce seedlings without causing phytotoxicity. All three fungicides significantly reduced the diseases caused by the three pathogens. These findings are consistent with previous reports that fludioxonil, metalaxyl and mefenoxam can control oomycete fungi. There are few registered fungicides for the control of Fusarium solani, Pythium ultimum and Rhizoctonia solani on lettuce, therefore further work will aim to confirm these results in the field.Dissertation (MInstAgrar)--University of Pretoria, 2008.
Microbiology and Plant Pathology
unrestricted
25
Mercier, Julien. "Studies of the phylloplane microflora of lettuce and its interactions with pesticides and Sclerotinia sclerotiorum." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65425.
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Waddy, Elisabeth. "The effect of chlorine rinse on the microbial growth and storage quality of fresh broccoli and lettuce." Online version, 1999. http://www.uwstout.edu/lib/thesis/1999/1999waddye.pdf.
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Tchervenivanova, Eli. "Development of a model to predict sporulation of Bremia lactucae in lettuce." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23943.
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The effect of temperature and duration of leaf wetness (DLW) on sporulation of Bremia lactucae was determined for lettuce cv. Ithaca. A single spore isolate of B. lactucae was produced and was identified using lettuce differential lines each of which had known gene for resistance. Potted lettuce plants were inoculated with the isolate and incubated at 15 C, at 100% relative humidity for 24 h and then at a relative humidity lower than 70%. Seven days later, the plants were submitted to five different temperatures (5, 10, 15, 20 and 25 C) and six durations of leaf wetness (4, 6, 8, 10, 12 and 14 h). The number of spores produced was determined at the end of each wet period. After 4 h of incubation no spores were observed at any of the temperatures. Highest number of spores was found at 10 and 15 C for more than 10 h of DLW. The rate of sporulation rapidly increased between 8 and 10 h for all the temperatures, including 25 C, where the amount of spores produced was very low. The observed number of spores was transformed into proportion of maximum sporulation (PMS) by providing each data by the maximum number of spores observed for each experiment. The Richards model was used to describe sporulation as a function of leaf wetness duration and the rate and maximum value expressed as a function of temperature. This approach resulted in a three-dimensional equation that explained 87% of the variation in the PMS. Spore viability was also estimated for each temperature and DLW. It was zero after 6 h of incubation and reached almost the maximum after 10 h for all the temperatures. The sporulation model was validated under field conditions and it predicted high, medium, low, or no sporulation in 8 out of 11 times.
28
Klerks, Michel M. "Quantitative detection of Salmonella enterica and the specific interaction with Lactuca sativa /." Netherlands : Wageningen University, 2007. http://purl.fcla.edu/UF/lib/Klerks_thesis.pdf.
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Thesis (Doctoral)--Wageningen University, The Netherlands, 2007.Vita. "Prepositions (stellingen)" ([1] leaf) inserted. Includes bibliographical references. Also available via the Internet on the university's web site.
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Toussaint, Vicky. "Ecology of Xanthomonas campestris pv. vitians in relation to development of bacterial leaf spot of lettuce by Vicky Toussaint." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37850.
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In Quebec, bacterial leaf spot of lettuce was observed for the first time in 1994. Since this first mention, the disease has been observed each year and the severity varied with environmental conditions. Little information was available on this disease because until recently it was only sporadically observed around the world following the first mention in 1918. In this project, we found that two groups of Xanthomonas caused the bacterial leaf spot of lettuce according to the BIOLOG profiles. From the results of strain characterization, a semi-selective medium has been developed to detect and quantify X. campestris pv. vitians. This medium is made of maltose, tryptone, methyl green, phosphate salts, amoxicillin, cephalothin, cycloheximide and trace elements. It allowed us to carry out studies on the ecology of the pathogen and on the disease epidemiology. The effect of weather conditions on bacterial population size and the bacterial leaf spot development has been studied. Weather parameters influencing the bacterial population were the number of hours with temperature higher than 28°C, the number of hours with wind velocity lower than 1 km per hour, the number of hours with relative humidity lower than 45% and the minimum relative humidity. The weather parameters that significantly discriminated between disease increase categories were the mean solar radiation, the number of hours with relative humidity higher than 90%, the mean relative humidity and the maximum temperature. Looking at the relationship between X. campestris pv. vitians population size and host plant development, it was shown that both bacterial population size and disease severity increased with leaf age. Mathematical models were developed to show these relationships. This information will be useful in disease management to decide when to apply bactericides and when to harvest. Finally, an exploratory study was conducted looking at the effects of nutrients on the size of saprophytic bacterial
30
Pretorius, Rudolph Johannes. "A plant health management system for aphididae on lettuce under variable shadehouse conditions in the central Free State, South Africa." Thesis, Bloemfontein : Central University of Technology, Free State, 2008. http://hdl.handle.net/11462/114.
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Thesis (M. Tech) --Central University of Technology, Free State, 2008Aphids (Hemiptera: Aphididae) are amongst the most destructive insects in agricultural crop production systems. This reputation stems from their complex life cycles which are mostly linked to a parthenogenetic mode of reproduction, allowing them to reach immense population sizes within a short period of time. They are also notorious as important and efficient vectors of several plant viral diseases. Their short fecund life cycles allow them to be pests on crops with a short growth period, e.g. lettuce (Lactuca sativa L.). It is common practice to provide this crop with some degree of protection from environmental extremes on the South African Highveld. Shadehouses are popular in this regard, but aphids are small enough to find their way into these structures, and their presence on lettuce is discouraged due to phytosanitary issues. In addition, the excessive use of insecticides is criticized due to the negative influence on human health, and because aphids can rapidly develop resistance. This necessitates the use of alternative control options in order to suppress aphid numbers. Biological control is popular in this regard and the use of predatory ladybirds (Coleoptera: Coccinellidae) is a popular choice. This study investigated the aphid and coccinellid species complex encountered under varying shadehouse conditions on cultivated head lettuce in the central Free State Province (South Africa). Their seasonality was also examined, along with variations in their population size throughout a one-year period. Finally, the impact of varying aphid populations on some physical characteristics of head lettuce was examined, and recommendations for aphid control (using naturally occurring coccinellid predators) were made. Two shadehouse structures were evaluated during this study. One was fully covered with shade netting and designed to exclude the pugnacious ant, Anoplolepis custodiens (Hymenoptera: Formicidae), while the other was partially covered with shade netting (on the roof area) allowing access to the ants. Six cycles of head lettuce were planted and sampled four times during each cycle. These were scheduled to monitor the seedling, vegetative and heading stage of lettuce. Four important aphid species were recorded on the lettuce, namely Acyrthosiphon lactucae, Nasonovia ribisnigri, Myzus persicae and Macrosiphum euphorbiae. Both structures harboured similar aphid and coccinellid species, but their population dynamics differed. A. lactucae dominated in the absence of A. custodiens in the fully covered structure (whole study), while N. ribisnigri dominated in the partially covered structure in the presence of these ants during the warmer months (December – January). M. euphorbiae replaced this species as the dominant species in the absence of A. custodiens (April – September). M. persicae occured during the winter (May – August) in the fully covered structure. Promising coccinellid predators were Hippodamia variegata and Scymnus sp. 1, and to a lesser extent, Exochomus flavipes and Cheilomenes lunata. However, the fully covered structure hampered the entrance of the larger adult coccinellid species, resulting in their lower occurrence. Aphid and coccinellid activity peaked during the summer months (October – January), and the fully covered structure attained the highest aphid infestation levels and coccinellid larval numbers during this time. On the other hand, aphid numbers were higher in the partially covered structure during the cooler months of the year (April – July) and this structure also harboured more adult coccinellids. In most cases, aphid infestation levels did not affect the amount of leaves formed. However, symptomatic damage in terms of head weight reduction did occur under severe infestation levels. Specific environmental conditions within a shadehouse structure concurrently contributed to this reduction, with less favourable conditions accelerating this condition. Results from this study have shown that even though the type of shadehouse structure does not influence the insect species complex found on lettuce, it does have an influence on detrimental and beneficial insect population dynamics. Aphid species infesting lettuce have been identified, along with coccinellid predators that could potentially be used in their control. Both types of structures had advantages and disadvantages, and therefore, decisions concerning shadehouses should not be focused on which type of structure to use, but rather which type of structure to use during different seasons of the year.
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Trembley, Marcella L. "The effect of mechanical weed cultivation on crop yield and quality, disease incidence and phenology in snap bean, carrot and lettuce crops." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0003/MQ29801.pdf.
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Gumede, Halalisani. "The development of a putative microbial product for use in crop production." Thesis, Rhodes University, 2008. http://eprints.ru.ac.za/1352/.
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Carignan, Sylvie. "Evaluation of the potential of the exotic larval parasitoid Peristenus digoneutis Loan as a biological control agent against the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), in lettuce and celery crops in muck soils of southwestern Quebec." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23387.
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In the agricultural muck soil area of southwestern Quebec, two native parasitoids, Peristenus pallipes and P. pseudopallipes (Hymenoptera: Braconidae) were found to parasitize nymphs of the tarnished plant bug Lygus lineolaris (Hemiptera: Miridae), on various flowering plants and on cultivated lettuce. Parasitism levels (ranging from 1.3% to 92.3%) varied with host plant species sampled, and with methods used for the calculation of percentage parasitism. The percentage parasitism of tarnished plant bug populations was expressed as pooled values from all samples in the season (method 1), and by the Southwood and Jepson's graphical method (method 2). Phenology of parasitism, defined as the time during which female parasitoids are active in the field, was evaluated for both native parasitoid species. The cold-hardiness of P. digoneutis, a European nymph parasitoid introduced in northern United States, was evaluated in the laboratory by measuring the supercooling point and cumulative cold damage at sub-zero temperatures. When compared to the native P. pallipes and P. pseudopallipes the exotic parasitoid showed the same capacity to withstand cold temperatures. Prior to introduction, the evaluation of the impact of P. digoneutis on indigenous species will require a rapid identification to species level. The development of immature stages of P. digoneutis was studied to find taxonomic and developmental differences between the three species. At $21 pm1 sp circ$C, the egg matures in five days, and there are three larval instars, the first two molting inside the host while the third emerges from the host, three to four weeks after egg deposition. Adult characters of the pre-imaginal stage can be used to distinguish the exotic P. digoneutis from the two native species since mouth sclerites of the final instar larvae of P. digoneutis, P. pallipes and P. pseudopallipes do not possess reliable distinguishing characters. (Abstract shortened by UMI.)
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Borges, Luciana Maestro [UNESP]. "Controle de viroses em alface por meio de métodos integrados de manejo da cultura." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/103246.
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borges_lm_dr_botfca.pdf: 958343 bytes, checksum: 2ae20dca03a02b69b0046c575acb7680 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O trabalho teve como objetivos avaliar diversas progenies de alface da geracao [(Brasil 303 x Tinto) Elisa] F5 RC1, previamente selecionadas para tolerancia a Lettuce mosaic virus - (LMV-II), Lettuce mottle virus (LeMoV) e Tospovirus e o efeito de diferentes praticas culturais no controle de fitovirus na cultura da alface, em duas epocas do ano (outono/inverno e primavera/verao). Os fatores avaliados foram: cobertura do solo (palha de arroz e sem cobertura), cultivo protegido (tunel coberto com filme PEBD aditivado antivirus de 150 æm e tunel coberto com tela anti-afideo) e 18 progenies, avaliando os seguintes aspectos agronomicos: area de projecao da copa, massa fresca da parte aerea da planta, produtividade, fechamento de cabeça, tempo de inicio do pendoamento e incidencia de fitoviroses. A avaliacao da incidencia de fitovirus na cultura foi realizada atraves de observacao visual dos sintomas, sendo que amostras de plantas que apresentavam sintomas foram coletadas e examinadas atraves de testes moleculares de diagnose especificos para LMV-II, LMV-IV, LeMoV e Tospovirus. Para algumas amostras sintomaticas negativas ainda foram realizados testes de RT-PCR para possivel deteccao de Cucumber mosaic virus. (CMV), testes de inoculacao mecanica em hospedeiras diferenciadoras e analises de microscopia eletronica. Quanto aos aspectos agronomicos das progenies, observou-se que o tratamento palha de arrozapresentou resultado superior aos demais tratamentos para as caracteristicas massa fresca e produtividade e igual desempenho ao tratamento solo nu para as caracteristicas fechamento de cabeça e tempo de inicio de pendoamento. Dentre as 2 progenies testadas, se destacaram as de numero 6 e 7 por apresentarem maior tolerancia a viroses e caracteristicas agronomicas equivalentes a cultivar comercial utilizada como controle. Na avaliacao visual de fitoviroses...
The research aimed to evaluate various progenies, obtained from the crossing of [(Brasil 303 x Tinto) Elisa] F5 RC1, previously selected for tolerance to Lettuce mosaic virus - (LMV-II), Lettuce mottle virus (LeMoV) and tospovirus and the effect of different phytovirus control practices in lettuce, in two periods of the year (autumn/winter and spring/summer). The factors evaluated were: soil covering (straw of rice and bare soil); protected development with a tunnel covered with an anti-virus PEBD treated film of 150 ìm and a tunnel covered with anti-aphid screen; and 18 progenies, evaluating the following agronomic aspects: area of top projection, fresh mass of the aerial part of the plant, productivity, closing of head and time at the beginning of tasselling and incidence of phytovirosis. The evaluation of phytovirus incidence in the crop was accomplished through visual observation of symptoms. Samples of plants showing symptoms were collected and taken to the laboratory for molecular tests to specifically detect LMV-II, LMV-IV, LeMoV and tospovirus. For some negative symptomatic samples, tests of RT-PCR were accomplished to detect possible infection by Cucumber mosaic virus- (CMV), and mechanical inoculation tests in differential plant, and electronic microscopic analysis. As for the agronomic aspects of the progenies, it was observed that the rice straw treatment presented better results than other the treatments for the fresh mass and productivity parameters, and equal performance on the bare soil treatment for the parameters closing of head and time at the beginning of tasseling. Among the tested progenies, number 6 and 7 were distinguished for presenting better tolerance to phytovirosis and agronomic characteristics equivalent to the commercial cultivar used as control. In the visual evaluation of phytovirosis, it was verified that 3,65%...
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McHale, T. "Sclerotinia disease of lettuce crops." Thesis, Liverpool John Moores University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380665.
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Moura, Mônika Fecury 1979. "Potyvirus: caracterização parcial de espécies em plantas daninhas associadas a cultura do pimentão, avaliação de genótipos de alface e análise subcelular do eIF4E e de proteínas do Lettuce mosaic virus /." Botucatu, 2013. http://hdl.handle.net/11449/105378.
Full textAbstract:
Orientador: Renate Krause SakateCoorientador: Marcelo Agenor Pavan
Banca: Ivan de Godoy Maia
Banca: Valcir Atsushi Yuki
Banca: Romulo Fujito Kobori
Resumo: Os potyvírus constituem cerca de 90% das espécies conhecidas da família Potyviridae. No Brasil ocasionam sérios entraves em alface (Lactuca sativa L.) e em pimentão (Capsicum annuum L.), onde se pode citar o Lettuce mosaic virus - LMV e o Pepper yellow mosaic virus (PepYMV), respectivamente. Com o intuito de melhor compreender o reservatório natural de potyvírus em plantas invasoras, amostras foram coletadas em áreas produtoras de pimentão e analisadas utilizando-se antissoro anti-potyvirus (Agdia). Entre estas plantas positivas, destacou-se Solanum americanum Mill, onde foi verificada infecção mista do Cucumber mosaic virus e do Potato virus Y, e Commelina benghalensis L. em que foi encontrado um possível novo potyvírus com a maior identidade de nucleotídeos da proteína capsidial (62%) com a espécie Hardenbergia mosaic virus. Este potyvírus não foi transmitido por extrato vegetal, bem como por afídeos para plantas de pimentão e Nicotiana tabaccum TNN. Na região codificadora para a proteína capsidial do potyvirus não foi encontrado o domínio DAG, relacionado a transmissão por afídeos. Visando encontrar possíveis fontes de resistência ao Lettuce mosaic virus - LMV, genótipos foram inoculados com o isolado LMV-AF-199 (LMV-Most) e o fator de iniciação de tradução eucariótico eIF4E destes genótipos analisado. Em Calona e Salinas-88, conhecidas previamente como portadoras dos genes recessivos mol1 e mol2 foram observados sintomas em todas as plantas inoculadas e verificado o padrão típico do eIF4E1 e eIF4E2, respectivamente... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The Potyvirus genus corresponds to 90% of known species of the Potyviridae family. In Brazil potyviruses causes serious problems in lettuce (Lactuca sativa L) and in pepper crops (Capsicum annuum L.), which we can highlight Lettuce mosaic virus - LMV and Pepper yellow mosaic virus (PepYMV), respectively. To increase knowledge about the natural reservoir of potyviruses in weeds, samples were collected from a pepper producer area and analyzed for potyvirus using antiserum anti-potyvirus (Agdia). Solanum americanum Mill was identified as a host for Cucumber mosaic virus and Potato virus Y. In Commelina benghalensis L. a possible new species of potyvirus was found with higher nucleotide identity of the coat protein (62%) with Hardenbergia mosaic virus. This potyvirus could not be transmitted by aphids to sweetpepper and... (Complete abstract click electronic access below)
Doutor
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Moura, Mônika Fecury [UNESP]. "Potyvirus: caracterização parcial de espécies em plantas daninhas associadas a cultura do pimentão, avaliação de genótipos de alface e análise subcelular do eIF4E e de proteínas do Lettuce mosaic virus." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/105378.
Full textAbstract:
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moura_mf_dr_botfca.pdf: 469933 bytes, checksum: eccaa27134acf7a66cc0606cbff1deaa (MD5)Os potyvírus constituem cerca de 90% das espécies conhecidas da família Potyviridae. No Brasil ocasionam sérios entraves em alface (Lactuca sativa L.) e em pimentão (Capsicum annuum L.), onde se pode citar o Lettuce mosaic virus – LMV e o Pepper yellow mosaic virus (PepYMV), respectivamente. Com o intuito de melhor compreender o reservatório natural de potyvírus em plantas invasoras, amostras foram coletadas em áreas produtoras de pimentão e analisadas utilizando-se antissoro anti-potyvirus (Agdia). Entre estas plantas positivas, destacou-se Solanum americanum Mill, onde foi verificada infecção mista do Cucumber mosaic virus e do Potato virus Y, e Commelina benghalensis L. em que foi encontrado um possível novo potyvírus com a maior identidade de nucleotídeos da proteína capsidial (62%) com a espécie Hardenbergia mosaic virus. Este potyvírus não foi transmitido por extrato vegetal, bem como por afídeos para plantas de pimentão e Nicotiana tabaccum TNN. Na região codificadora para a proteína capsidial do potyvirus não foi encontrado o domínio DAG, relacionado a transmissão por afídeos. Visando encontrar possíveis fontes de resistência ao Lettuce mosaic virus - LMV, genótipos foram inoculados com o isolado LMV-AF-199 (LMV-Most) e o fator de iniciação de tradução eucariótico eIF4E destes genótipos analisado. Em Calona e Salinas-88, conhecidas previamente como portadoras dos genes recessivos mol1 e mol2 foram observados sintomas em todas as plantas inoculadas e verificado o padrão típico do eIF4E1 e eIF4E2, respectivamente...
The Potyvirus genus corresponds to 90% of known species of the Potyviridae family. In Brazil potyviruses causes serious problems in lettuce (Lactuca sativa L) and in pepper crops (Capsicum annuum L.), which we can highlight Lettuce mosaic virus – LMV and Pepper yellow mosaic virus (PepYMV), respectively. To increase knowledge about the natural reservoir of potyviruses in weeds, samples were collected from a pepper producer area and analyzed for potyvirus using antiserum anti-potyvirus (Agdia). Solanum americanum Mill was identified as a host for Cucumber mosaic virus and Potato virus Y. In Commelina benghalensis L. a possible new species of potyvirus was found with higher nucleotide identity of the coat protein (62%) with Hardenbergia mosaic virus. This potyvirus could not be transmitted by aphids to sweetpepper and... (Complete abstract click electronic access below)
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Borges, Luciana Maestro 1972. "Controle de viroses em alface por meio de métodos integrados de manejo da cultura /." Botucatu, [s.n.], 2006. http://hdl.handle.net/11449/103246.
Full textAbstract:
Orientador: Marcelo Agenor PavanBanca: Rumy Goto
Banca: Norberto da Silva
Banca: Alexandre de Moura Guimarães
Banca: Eliezer Rodrigues de Souto
Resumo: O trabalho teve como objetivos avaliar diversas progenies de alface da geracao [(Brasil 303 x Tinto) Elisa] F5 RC1, previamente selecionadas para tolerancia a "Lettuce mosaic virus" - (LMV-II), "Lettuce mottle virus" (LeMoV) e Tospovirus e o efeito de diferentes praticas culturais no controle de fitovirus na cultura da alface, em duas epocas do ano (outono/inverno e primavera/verao). Os fatores avaliados foram: cobertura do solo (palha de arroz e sem cobertura), cultivo protegido (tunel coberto com filme PEBD aditivado antivirus de 150 æm e tunel coberto com tela anti-afideo) e 18 progenies, avaliando os seguintes aspectos agronomicos: area de projecao da copa, massa fresca da parte aerea da planta, produtividade, fechamento de "cabeça", tempo de inicio do pendoamento e incidencia de fitoviroses. A avaliacao da incidencia de fitovirus na cultura foi realizada atraves de observacao visual dos sintomas, sendo que amostras de plantas que apresentavam sintomas foram coletadas e examinadas atraves de testes moleculares de diagnose especificos para LMV-II, LMV-IV, LeMoV e Tospovirus. Para algumas amostras sintomaticas negativas ainda foram realizados testes de RT-PCR para possivel deteccao de "Cucumber mosaic virus". (CMV), testes de inoculacao mecanica em hospedeiras diferenciadoras e analises de microscopia eletronica. Quanto aos aspectos agronomicos das progenies, observou-se que o tratamento "palha de arroz"apresentou resultado superior aos demais tratamentos para as caracteristicas massa fresca e produtividade e igual desempenho ao tratamento "solo nu" para as caracteristicas fechamento de "cabeça" e tempo de inicio de pendoamento. Dentre as 2 progenies testadas, se destacaram as de numero 6 e 7 por apresentarem maior tolerancia a viroses e caracteristicas agronomicas equivalentes a cultivar comercial utilizada como controle. Na avaliacao visual de fitoviroses...
Abstract: The research aimed to evaluate various progenies, obtained from the crossing of [(Brasil 303 x Tinto) Elisa] F5 RC1, previously selected for tolerance to "Lettuce mosaic virus" - (LMV-II), "Lettuce mottle virus" (LeMoV) and tospovirus and the effect of different phytovirus control practices in lettuce, in two periods of the year (autumn/winter and spring/summer). The factors evaluated were: soil covering (straw of rice and bare soil); protected development with a tunnel covered with an anti-virus PEBD treated film of 150 ìm and a tunnel covered with anti-aphid screen; and 18 progenies, evaluating the following agronomic aspects: area of top projection, fresh mass of the aerial part of the plant, productivity, closing of "head" and time at the beginning of tasselling and incidence of phytovirosis. The evaluation of phytovirus incidence in the crop was accomplished through visual observation of symptoms. Samples of plants showing symptoms were collected and taken to the laboratory for molecular tests to specifically detect LMV-II, LMV-IV, LeMoV and tospovirus. For some negative symptomatic samples, tests of RT-PCR were accomplished to detect possible infection by "Cucumber mosaic virus"- (CMV), and mechanical inoculation tests in differential plant, and electronic microscopic analysis. As for the agronomic aspects of the progenies, it was observed that the "rice straw" treatment presented better results than other the treatments for the fresh mass and productivity parameters, and equal performance on the "bare soil" treatment for the parameters closing of "head" and time at the beginning of tasseling. Among the tested progenies, number 6 and 7 were distinguished for presenting better tolerance to phytovirosis and agronomic characteristics equivalent to the commercial cultivar used as control. In the visual evaluation of phytovirosis, it was verified that 3,65%...
Doutor
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Ubalijoro, Eliane. "Characterization of resistance to lettuce mosaic virus in Lactuca sativa." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22821.
Full textAbstract:
Lettuce mosaic virus (LMV) is an economically important pathogen with worldwide distribution. LMV infection in L. sativa can cause significant yield losses. Resistance to LMV in L. sativa is conferred by the recessive gene mo. We attempted to position the mo gene on the L. sativa map. The ultimate goal is a better understanding of plant-virus interactions. To do so, Random Amplified Polymorphic DNA (RAPD) markers were screened in the near isogenic lines (NILs) Vanguard and Vanguard 75. These NILs differ in the presence of the mo gene in Vanguard 75. Polymorphic markers were screened for linkage to mo in two F$ sb2$ populations segregating for resistance to LMV. The F$ sb2$ populations used were derived from 2 crosses, the first one between the L. sativa cultivars Dwarf 2 (resistant to LMV via the presence of mo) and Saffier and the second one between two breeding lines 87-25M-1 (momo) and 87-1090M-1 (MoMo). In order to develop a highly stringent antibody detection system to phenotype plants infected with LMV, a plasmid construct was developed which overproduces LMV coat protein. This construct will be used in the future to produce enough recombinant LMV coat protein for antibody production. To further characterize mo, a selection of cultivars resistant and susceptible to LMV according to the literature were subjected to various temperature changes to determine the environmental influences on virus movement.
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McCabe, Matthew. "Molecular breeding of lettuce (Lactuca sativa L.) : an evaluation of transgene expression." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387660.
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Suzuki, Gerson Shinya [UNESP]. "Comportamento de genótipos de alface com o alelo mo10 ao Lettuce mosaic virus e Lettuce mottle virus." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/113793.
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000806750.pdf: 405498 bytes, checksum: d7b936b62c9737ef848ca34aff10a7e8 (MD5)A alface (Lactuca sativa L.), pertencente à família Asteraceae, é uma das hortaliças mais consumidas no Brasil. Um dos principais problemas fitossanitários para essa cultura são as fitoviroses, em especial o Lettuce mosaic virus (LMV), que causa elevados prejuízos aos produtores em diversas regiões do país, além do Lettuce mottle virus (LeMoV), que vem crescendo em importância nos últimos anos. Como forma de controle, o uso de variedades resistentes é maneira mais eficaz de contornar os danos causados por vírus. Na maioria das variedades resistentes de alface faz-se o uso de genes recessivos, em sua maioria envolvidos na interação planta-vírus, são os chamados codificadores de fatores de iniciação de tradução eucarióticos (eIFs). Diante disso, este trabalho teve como objetivo avaliar dois genótipos de alface (169501 e 169501C), quanto a resistência ao LMV e ao LeMoV. Foram realizadas transmissões via extrato vegetal nos dois genótipos de alface com LMV e LeMoV em diferentes intervalos de tempo. Para LMV também foram realizadas transmissões por afídeos. As duas variedades testadas se mostraram resistentes ao LMV nas duas formas de transmissão, mas apresentaram sintomas quando inoculadas com LeMoV. Em reações de RT-PCR com oligonucleotídeos específicos, foram comprovadas a ausência de LMV e a infecção por LeMoV nas plantas inoculadas. O isolado de LMV após análise do sequenciamento da porção N’ terminal da ...
Lettuce (Lactuca sativa L.) belongs to the Asteraceae family and is one of the most consumed vegetables in Brazil. One of the major disease problems in this crop are plant viruses, especially the Lettuce mosaic virus (LMV) that cause losses to producers in various regions of the country, but also Lettuce mottle virus (LeMoV). As a form of control, the use of resistant varieties is the most effective way to overcome the damage caused by plant viruses. Most of the resistant varieties of lettuce makes the use of recessive genes, mostly involved in plant-virus interactions and characterized as eukaryotic translation initiation factor (eIFs). Thus, this study aimed to evaluate two lettuce genotypes (169501 and 169501C) for resistance to LMV and LeMoV. LMV and LeMoV were sap transmitted at different time of intervals. For LMV also transmissions with aphids were carried out. The two varieties tested were resistant to LMV in both forms of transmission, but showed symptoms when inoculated with LeMoV. In RT-PCR with specific primers, LMV was not detected but LeMoV yes, confirming the infection in the inoculated plants. The isolate of LMV used in the tests was not classified as belonging to subgroups Most ...
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Suzuki, Gerson Shinya 1984. "Comportamento de genótipos de alface com o alelo mo10 ao Lettuce mosaic virus e Lettuce mottle virus /." Botucatu, 2014. http://hdl.handle.net/11449/113793.
Full textAbstract:
Orientador: Renate Krause SakateBanca: Marcelo Agenor Pavan
Banca: Massaharu Marubayashi
Resumo: A alface (Lactuca sativa L.), pertencente à família Asteraceae, é uma das hortaliças mais consumidas no Brasil. Um dos principais problemas fitossanitários para essa cultura são as fitoviroses, em especial o Lettuce mosaic virus (LMV), que causa elevados prejuízos aos produtores em diversas regiões do país, além do Lettuce mottle virus (LeMoV), que vem crescendo em importância nos últimos anos. Como forma de controle, o uso de variedades resistentes é maneira mais eficaz de contornar os danos causados por vírus. Na maioria das variedades resistentes de alface faz-se o uso de genes recessivos, em sua maioria envolvidos na interação planta-vírus, são os chamados codificadores de fatores de iniciação de tradução eucarióticos (eIFs). Diante disso, este trabalho teve como objetivo avaliar dois genótipos de alface (169501 e 169501C), quanto a resistência ao LMV e ao LeMoV. Foram realizadas transmissões via extrato vegetal nos dois genótipos de alface com LMV e LeMoV em diferentes intervalos de tempo. Para LMV também foram realizadas transmissões por afídeos. As duas variedades testadas se mostraram resistentes ao LMV nas duas formas de transmissão, mas apresentaram sintomas quando inoculadas com LeMoV. Em reações de RT-PCR com oligonucleotídeos específicos, foram comprovadas a ausência de LMV e a infecção por LeMoV nas plantas inoculadas. O isolado de LMV após análise do sequenciamento da porção N' terminal da ...
Abstract: Lettuce (Lactuca sativa L.) belongs to the Asteraceae family and is one of the most consumed vegetables in Brazil. One of the major disease problems in this crop are plant viruses, especially the Lettuce mosaic virus (LMV) that cause losses to producers in various regions of the country, but also Lettuce mottle virus (LeMoV). As a form of control, the use of resistant varieties is the most effective way to overcome the damage caused by plant viruses. Most of the resistant varieties of lettuce makes the use of recessive genes, mostly involved in plant-virus interactions and characterized as eukaryotic translation initiation factor (eIFs). Thus, this study aimed to evaluate two lettuce genotypes (169501 and 169501C) for resistance to LMV and LeMoV. LMV and LeMoV were sap transmitted at different time of intervals. For LMV also transmissions with aphids were carried out. The two varieties tested were resistant to LMV in both forms of transmission, but showed symptoms when inoculated with LeMoV. In RT-PCR with specific primers, LMV was not detected but LeMoV yes, confirming the infection in the inoculated plants. The isolate of LMV used in the tests was not classified as belonging to subgroups Most ...
Mestre
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Singh, Rampal. "Characterization of virus disease resistance in Lactuca sativa." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55529.
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Little is known about the mechanism of virus disease resistance in plants. The aim of the work presented here was to answer whether disease resistance is offered within the cell or at the level of intercellular movement of the virus. The protoplast system was used for this purpose. Conditions were optimized to isolate viable protoplasts from the leaves of Lactuca sativa cultivars. Protoplasts and leaves from resistant and susceptible Lactuca sativa cultivars were inoculated separately with turnip mosaic virus (TuMV) and lettuce mosaic virus (LMV), Virus multiplication was examined over time using enzyme-linked immunosorbent assay. Resistant cv. Kordaat did not support TuMV multiplication in protoplasts as well as in leaves. The results indicated that resistance to TuMV is available within the cell. The results ruled out the possibility of involvement of cell to cell movement and resistance to TuMV seems to be constitutive. On the other hand, protoplasts and leaves from both resistant and susceptible lettuce cultivars supported LMV multiplication. This suggested that resistance to LMV may not be offered within the cell. The results also indicated that the resistance to LMV was partly due to a hypersensitive response though virus was still able to spread systemically. To contribute towards mapping of the Tu resistance gene, the genotype of F$ sb2$ individuals was determined by screening an F$ sb3$ population from 71 F$ sb2$ individuals of a cross between cv. Calmar and cv. Kordaat for TuMV-infection. These data were useful for the production of bulks around the Tu locus to facilitate the search for new molecular markers linked to the Tu gene.
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Littlefield, Joanne. "A New Plant Disease Hits the U.S. "Winter Salad Bowl": Fusarium Wilt of Lettuce." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2003. http://hdl.handle.net/10150/622230.
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Dufresne, Philippe J. "Development and validation of molecular markers for the detection of disease resistance alleles in Lactuca sativa." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=78352.
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In this study, RAPD (Randomly Amplified Polymorphic DNA) and SCAR (Sequence Amplified Characterized Region) markers found within 5 centiMorgans of known disease resistance loci in L. sativa were tested for their potential use in MAS. Out of thirty RAPD and SCAR markers evaluated, ten were found to be reliable predictors of disease resistance or susceptibility across a wide range of commercial and reference cultivars. Direct sequencing of seven selected markers did not reveal any significant similarity with known sequences. Three SNPs (Single Nucleotide Polymorphism) associated with two markers found in close proximity to corky root (cor) and Lettuce mosaic virus resistance (mo12) genes were identified. This information was used in the development of a non-electrophoresis PCR-based assay called FRET (Fluorescence Resonance Energy Transfer) hybridization probes assay.
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Montesclaros, Luz B. "Mapping of molecular markers surrounding the Tu gene conferring resistance to turnip mosaic virus in Lactuca sativa L." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23923.
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In lettuce (Lactuca sativa), the dominant gene Tu confers resistance to turnip mosaic virus (TuMV) infection. In order to eventually clone and characterize the Tu gene using a map-based cloning strategy, the chromosome region in which Tu is located needs to be saturated with molecular markers. Random polymorphic DNA (RAPD) markers were screened using bulked segregant analysis. Nine new RAPD markers, UBC431$ rm sb{420}, UBC431 sb{940}, UBC434 sb{360}, UBC434 sb{1000}, UBC439 sb{520}, UBC448 sb{685:750}, UBC135 sb{240}, OP108 sb{410} and OP108 sb{1305},$ were identified as linked to Tu. Each marker was mapped relative to Tu using F$ sb2$ individuals previously known to be recombinant in the area surrounding the Tu locus. Three new markers, UBC431$ rm sb{420}, UBC439 sb{520} and UBC135 sb{240}$ are within a 5 cM area of Tu. As the number of DNA markers on the map increased map expansion and difficulties in determining a unique order were encountered. To increase the confidence in the estimate of genetic distances, a population of 500 F$ sb2$ plants was screened in order to identify more recombinant individuals around the Tu locus. The population was screened using markers UBC431$ sb{420}$ and UBC135$ sb{240}.$ Thirty-three recombinants were identified in an interval of 6.6 cM. Two markers, UBC346$ sb{1067}$ and OP108$ sb{634},$ tightly flanking Tu were converted to sequence characterized amplified regions (SCAR 346 and SCAR L08). No polymorphism was detected among the SCARs generated. The area surrounding Tu now includes 24 RAPD markers in an interval of 44 cM.
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Robbins, Marjorie. "The location of Tu on the genetic map of Lactuca sativa and the identification of random amplified polymorphic DNA markers flanking and tightly linked to Tu /." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69684.
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In Lactuca sativa, the dominant gene Tu confers resistance to infection by turnip mosaic virus (TuMV). Tu and Dm5/8, a gene for resistance to Bremia lactucae, are linked in L. sativa. The area surrounding Dm5/8 on the genetic map of L. sativa contains restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers. The orientation of Tu relative to Dm5/8 was not known. Locating Tu would indicate which markers are on the map of lettuce close to Tu. To locate Tu on the L. sativa genetic map, F$ sb3$ families from recombinant F$ sb2$ in the Dm5/8 area of a cross between TuMV-resistant (Cobbham Green) and susceptible (Calmar) cultivars were inoculated with TuMV and phenotyped for Tu by indirect enzyme-linked immunosorbent assay. Polyclonal antibodies for immunodetection were produced using turnip mosaic virus coat protein expressed in E. coli. Phenotypic ratios within F$ sb3$ families were used to determine individual F$ sb2$ genotypes for Tu. With these genotypes, Tu was located on the genetic map of L. sativa relative to data present for Dm5/8 and surrounding markers, between OPM18 and OPY13. Using bulked segregant analysis, bulks created for the Dm5/8 locus were screened for genetic polymorphisms by the RAPD technique. Five new RAPD markers, UBC346, UBC517, UBC563, UBC599, and UBC675 were found linked to Tu after mapping relative to F$ sb2$ genotypes for Tu and other RAPD markers. The resulting three-point mapping information indicates that Tu is flanked by two markers, OPM18/OPL08 and UBC346, at respective genetic distances of 0.4 and 0.7 cM.
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Sala, Fernando Cesar. "Reação de alface (Lactuca sativa L.) a Thielaviopsis basicola (Berk. & Broome) Ferraris." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-23082006-160804/.
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A alface é a principal hortaliça folhosa do Brasil. A podridão negra das raízes causada pelo fungo Thielaviopsis basicola vem limitando o cultivo da alface americana ´Lucy Brown`. Os objetivos desta pesquisa foram: determinar a reação das cultivares comerciais de alface à T. basicola; elucidar a herança da resistência de alface ao patógeno e selecionar alface americana resistente ao patógeno a partir de variantes da Lucy Brown`. Inocularam-se 37 cultivares de alface usando o isolado patogênico L1 de T. basicola, na fase juvenil. Para todos os ensaios a avaliação foi feita na fase juvenil através de uma escala de notas de acordo com a severidade da doença de 1 (ausência de sintomas) a 5 (mais de 90% das raízes severamente afetadas). A seleção de progênies resistentes ao patógeno foi feita a partir de variantes da ´Lucy Brown` pelo método genealógico usando um critério qualitativo para uniformidade, qualidade da cabeça e adaptação para o cultivo nas condições de verão. As cultivares do tipo crespa e batávia foram resistentes ao patógeno. As do tipo lisa e americana apresentaram variação inter-varietal quanto à reação a T. basicola. A herança da reação de alface a T. basicola foi devido a um gene dominante, designado de Tb. As progênies elites S4 derivadas da alface ´Lucy Brown` foram resistentes ao patógeno, uniformes e estáveis para o mérito hortícola no cultivo de verão.Lettuce is the major leafy crop in Brazil. Lettuce black root rot (LBRR) caused by Thielaviopsis basicola is one the most limiting disease for the crisphead lettuce cv. Lucy Brown. Research focuses were: cultivars reaction to the pathogen; resistance inheritance elucidation and selections of LBRR resistant variants from cv. Lucy Brown. About 37 cultivars were screened using L1 pathogenic strain of T. basicola at juvenile stage. The reaction reading was made for all trials at juvenile stage using a severity disease scale from 1 (absence of symptoms) to 5 (with more than 90% of root rots). Selection of LBRR variants derived from Lucy Brown was made by pedigree selection and using selective criteria of line uniformity, heading qualities and adaptation for summer season slotting planting. Leaf lettuce Grand Rapids and Batavia types were resistant. There was inter-varietal occurrence of crisphead and butterhead resistance and other susceptible to LBRR. The inheritance to LBRR resistance in lettuce was due to a dominant gene designated as Tb. Elite LBRR resistant S4 lines derived from the crisphead cv. Lucy Brown were identified by their uniformity and stability for summer crop adaptation.
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Leclerc-Potvin, Carole. "Identification of Ty3gypsy-like sequences in A. thaliana, L. sativa, Lycopersicon, and Z. mays." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27361.
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The nucleotide sequence of a cloned RAPD DNA marker (OPI08) linked to a disease resistance gene in L. sativa (lettuce) revealed homology with the conserved domain of the reverse transcriptase of Ty3/gypsy retrotransposons. To further characterize the presence of Ty3/gypsy-like sequences in plants, sets of degenerate primers deduced from archetype retrotransposons were used for PCR amplification of a sequence domain characteristic of the reverse transcriptase and the integrase of Ty3/gypsy retrotransposons. The nucleotide sequence of two cloned DNA fragments of Z. mays (maize) and A. thaliana proved to be homologous with the conserved domains of the reverse transcriptase and the integrase of Ty3/gypsy retrotransposons. Southern blot analysis also demonstrated homology of the Z. mays clone to Lycopersicon (tomato) and L. sativa. This is the first report of Ty3/gypsy-like sequences in A. thaliana, and L. sativa. This research brings to six the number of plant species where this type of element has been reported, in contrast to the large number of plant Ty1/copia transposable elements described. It is not known whether these elements are actively transposing in plant genomes.
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Teixeira-Yañez, Liliane de Diana. "Resistência genética, fungicidas e solarização para o controle de Thielaviopsis basicola (Berk. & Broome) Ferraris na cultura de alface (Lactuca sativa L.)." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/11/11135/tde-05052005-160132/.
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A alface é a hortaliça folhosa mais consumida no Brasil. Seu cultivo vem sendo severamente afetado pelo fungo Thielaviopsis basicola, que ocasiona podridão radicular e subdesenvolvimento de plantas. Não existem maiores estudos sobre o controle desse patógeno nas condições brasileiras. Os objetivos deste trabalho foram: a determinação da ocorrência de T. basicola em plantios comerciais de alface e outras folhosas do Estado de São Paulo, do efeito da temperatura sobre a patogenicidade in vitro dos isolados obtidos e a avaliação da viabilidade de seu controle através do emprego de cultivares de alface resistentes, de fungicidas e da solarização, com e sem incorporação de matéria orgânica. Quatorze isolados de T. basicola foram obtidos de raízes necróticas de alface, chicória e rúcula. O efeito da temperatura sobre a patogenicidade in vitro dos isolados foi determinado, inoculando-se sementes de alface semeadas em agar-água. Foram realizados dois ensaios. No primeiro, quatorze cultivares de alface foram inoculadas com o isolado L1, a 21 e 30ºC. No segundo, a cv. Elisa foi inoculada com os quatorze isolados de T. basicola, a 21 e 27ºC. O isolado L1 foi mais agressivo a 21ºC do que a 30ºC, ocasionando maiores severidade da doença e restrição do comprimento de plântulas em todas as cultivares. Todos os isolados causaram podridão radicular e reduziram o comprimento de plântulas a 21 e 27ºC, destacando-se o isolado A2 como o mais agressivo. De modo geral, os isolados foram mais agressivos a 27 que a 21ºC, exceto L1 e L2. A reação de cultivares de alface a três isolados de T. basicola foi avaliada in vivo. Primeiramente, treze cultivares foram confrontadas com o isolado L1 e, posteriormente, seis dessas cultivares foram inoculadas com os isolados A2 e CH. As cultivares do tipo lisa foram suscetíveis e as do tipo crespa, resistentes, exceto a cv. Verônica. Quanto às cultivares do tipo americana, houve variação na reação ao patógeno. O efeito de fungicidas sobre o crescimento micelial e a esporulação in vitro foi determinado para três isolados de T. basicola. Nove fungicidas foram testados para o isolado L1 e sete para os isolados A2 e CH, nas concentrações de 0; 0,1; 1, 10 e 100 ppm de ingrediente ativo. O fungicida carbendazim foi o mais efetivo. A eficiência de sete fungicidas foi avaliada no controle de T. basicola in vivo. Todos os produtos testados foram eficientes, destacando-se o tebuconazole e o triadimenol. O controle de T. basicola através da solarização, associada ou não à incorporação de 10 ton / ha de torta de mamona ou de cama de frango, também foi avaliado. A solarização do solo com e sem incorporação de matéria orgânica controlou efetivamente o patógeno. Os melhores resultados foram obtidos com a incorporação da torta de mamona seguida de solarização, que permitiu a produção de plantas com maiores comprimento e massa fresca e evitou o aparecimento de qualquer sintoma de necrose radicular.Lettuce is the most used leafy vegetable in Brazil. Its crop is being severely affected by Thielaviopsis basicola, fungus which causes root rot and stunting in plants. There are no control studies about this pathogen for the brazillian conditions. This research aimed: to determine the T. basicola occurence in São Paulo State commercial lettuce and other leafy vegetables crops, the temperature effect on isolates pathogenicity in vitro and control viability evaluation by lettuce resistant varieties, fungicides and solarization with and without organic matter amendments. Fourteen T. basicola isolates were got from lettuce, chicory and arugula necrotic roots. Temperature effect on the isolates pathogenicity in vitro was determined in inoculated seeds sown on the surface of water agar medium. Two trials were carried out. In the first one, fourteen lettuce varieties were inoculated with L1 isolate at 21 and 30ºC. In the second, only cv. Elisa was inoculated with fourteen T. basicola isolates, at 21 and 27ºC. The isolate L1 was the most aggressive at 21ºC than 30ºC, causing higher disease severity and seedling length restriction of all varieties. All isolates induced root rot and reduced seedlings length at 21 and 27ºC, but A2 isolate was the most aggressive one. All isolates were more aggressive at 27 rather than 21ºC, except L1 and L2 isolates. Lettuce varieties reactions to three T. basicola isolates were evaluated in vivo. First about thirteen varieties were challenged with L1 isolate and later, six of them were inoculated with A2 and CH isolates. Butterhead types were susceptible and Grand Rapids types were resistant, except cv. Veronica. Iceberg type varieties varied in their reaction to pathogen. Fungicide effect on mycelial growth and sporulation in vitro was determined for three T. basicola isolates. Nine fungicides were tested for L1 isolate and seven for A2 and CH isolates, at concentrations of 0; 0,1; 1; 10 and 100 ppm of active ingredient. Carbendazim was the most effective. Seven fungicides efficacy was evaluated to control of T. basicola in vivo. All tested products were efficient, but tebuconazole and triadimenol were the best ones. The control of T. basicola through soil solarization with and without chicken litter and coarse castor bean meal amendments, at 10 ton / ha, also was evaluated. Soil solarization alone and combined with organic matter amendments were both effective ways to control the pathogen. The best results were got with incorporation of coarse castor bean meal followed by solarization, which allowed increase in fresh weight and length of plants, and avoided root rot symptoms.