STUDIES ON BIOLOGICAL CONTROL OF FUSARIAL WILT OF CHILLIES
KrishiKosh
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Title |
STUDIES ON BIOLOGICAL CONTROL OF FUSARIAL WILT OF CHILLIES
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Creator |
MADHAVI, M
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Contributor |
PRAMOD CHANDRA, C
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Subject |
STUDIES, BIOLOGICAL, CONTROL, FUSARIAL, WILT, CHILLIES
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Description |
Wilt of chilli (Capsicum annuum) caused by F. solani is an important and destructive soil borne disease causing yield losses in most popular cultivars of chilli especially in Northern Telangana zone of Andhra Pradesh during both kharif and rabi seasons during recent years. Detailed investigations were carried out on biological control of this disease by developing mutants of Trichoderma viride, T. harzianum and Pseudomonas fluorescens and studying the role of mutants on the antagonistic activity against the pathogen. The studies also included testing of the mutant biocontrol agents against commonly used fungicides, insecticides and herbicides. An attempt has also been made to develop disease management strategy using biocontrol agents and agrochemicals. Symptoms of the disease was as pale yellowing of the leaves of seedlings followed by withering and chlorosis of leaves, subsequently, the affected plants gradually wilt and die with vascular discoloration and marked reduction in root system. The fungus associated with the disease was isolated and identified as Fusarium solani (Mart.) Sacc. and pathogenicity was proved under glasshouse conditions. Of the four dosages of gamma radiation 50, 75, 100 and 125 K rad to which wild slant cultures of T. viride, T. harzianum and P. fluorescens exposed, exposure at 125 K rad produced eight and three each of T. viride and T. harzianum, carbendazim tolerant mutants. Wherein, the mutants tolerated higher concentrations of carbendazim as indicated by their growth on fungicide amended medium. While, gamma irradiation did not induce any distinguishable mutants of P. fluorescens. The mutants of T. viride and T. harzianum differed from their wild types in colony morphology, growth habit and rates, sporulation, antagonism against F. solani and tolerance to carbendazim. Among the eight and three mutants of each of T. viride and T. harzianum, mutants TvM1 and ThM1 recorded a faster growth rate of 82 mm within 72 h and could antagonize the test pathogen F. solani by forming zone of inhibition within 96 h, with 90.85 and 90.24 per cent inhibitions respectively compared to the rest of the mutants and wild types. While the bacterial biocontrol agent P. fluorescens (commercial isolate) inhibited the growth of F. solani to an extent of 65.9 per cent. Scanning electron microscopic studies revealed a perfect phenomenon of mycoparasitism involving chemotrophic stimulus, coiling, secretion of extra cellular enzymes and lysis of the pathogen’s mycelium / hyphae. Of the different pesticides tested against the mutants, carbendazim, fipronil and fluchloralin were found to be compatible with the mutants of T.viride, T. harzianum and P. fluorescens at their recommended and half the recommended dosages. An IDM strategy was developed for fusarial wilt of chilli based on glasshouse experiments. Results obtained in pot culture experiments revealed that, seed and soil application of TvM1 + ThM1 + P. fluorescens combined with soil drenching with carbendazim + fipronil + fluchloralin recorded significantly highest germination of chilli seedlings with no wilt incidence coupled with maximum shoot and root lengths and fresh and dry weights of chilli seedlings. The treatment not only controlled wilting but also enhanced the growth of chilli seedlings. |
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Date |
2016-08-19T13:35:29Z
2016-08-19T13:35:29Z 2006 |
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Type |
Thesis
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Identifier |
http://krishikosh.egranth.ac.in/handle/1/73016
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Language |
en
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Relation |
D7777;
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Format |
application/pdf
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Publisher |
ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
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