STUDIES ON FRUIT ROT OF CHILLI CAUSED BY Colletotrichum capsici (SYD.) BUTLER AND BISBY AND ITS MANAGEMENT

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dc.contributor.advisorSARADA JAYALAKSHMI DEVI, R
dc.contributor.authorVENKATA RAMESH, KOTA
dc.date.accessioned2020-02-25T04:47:58Z
dc.date.available2020-02-25T04:47:58Z
dc.date.issued2019
dc.descriptionD5876en_US
dc.description.abstractThe present investigation was undertaken with an aim to know the variability among Colletotrichum capsici isolates causing chilli anthracnose and fruit rot in Andhra Pradesh and Telangana and its integrated management. Among the districts surveyed during 2014-15 in AP, highest (50.84 %) incidence was observed in Guntur and lowest (33.01 %) incidence was observed in Chittoor district. Mean per cent incidence was 43.61 % in AP and 40.84 % in Telangana. Highest and lowest incidences of of 54.63 % and 33.54 % were recorded in Warangal and Ranga Reddy districts. Studies on the seed mycoflora of fruit rot infected fruits revealed that Colletotrichum capsici was the predominant fungus observed in 64.53 % and 58.83 % of samples of Andhra Pradesh and Telangana states, respectively. Other mycoflora associated with infected seeds were C. gloeosporioides, Cercospora spp. Aspergillus spp., Alternaria spp., Fusarium spp. and Penicillium spp. Forty isolates (Cc 1 to Cc40) of C. capsici were isolated and their pathogenicity was proved on detatched fruits by pin prick method. Isolates were also identified by molecular means through species specific primers. Morphological and cultural variability existed among the isolates. Colony colour of greyish white to black, fluffy or suppressed growth, margins regular or irregular, colour of the conidial mass is grey or orange. Based on the pathogenic variability, isolates were divided the isolates into five groups. Isolate Cc 20 from Chittoor with lowest pathogenic ability is in Group I where as three isolates Cc 3, Cc 5 and Cc 39 with highest pathogenic ability were in Group V. Molecular variability studies using RAPD divided the isolates into three clusters (I-III) in the phylogenetic tree dendrogram at 0.49 co efficient of similarity. The topology of the dendrogram suggested that most isolates were more than 20% different xiv from each other, and indicated the existence of both local and geographical polymorphism among the isolates. Cross inoculation studies of three isolates of C. capsici from betelvine, chilli and turmeric, revealed the presence of pathogenic variability and host preference among the isolates from different hosts. Isolates were more pathogenic when they were inoculated on their original hosts. Results of the In vitro evaluation of fungicide revealed that mancozeb and difenoconazole inhibited 77.78 % and 75.93 % of mycelial growth at 100 ppm concentration. Among the fungal and bacterial bioagents tested, T. longibrachiatum Tl 1 (78.15 %) and P. fluorescens Pf 1 (64.81 %) were effective in inhibiting the mycelial growth. In IDM experiment involving the effective fungicides and bioagents in different modules, in nursery, highest germination (85.40 %) and low seedling mortality (3.00 %) was recorded in chemical module whereas highest seed vigour index was recorded in integrated module (731.40). From the data of the main field for two years and their pooled analysis, pertaining to the effectiveness of different modules (T1, T2, T3, T4) the three modules (T1, T2, T3) significantly reduced the disease and increased the yield compared to control (T4). Among the three effective modules, integrated module (T3) recorded highest yield where as the biological module T1 recorded the lowest dry chilli yield. Residues of fungicides were detected through LC MS/MS and GC MS/MS studies in dry chilli samples collected from different fields during harvesting season. Among the fungicides, tebuconazole and carbendazim were most commonly detected. All the fungicide residues detected in the present study were lesser than the prescribed MRL’s. From the above results it can be concluded that the risk of residues of fungicides in dry chillies is very limited (none of the fungicides detected were above MRL’s). From the present study, it can be concluded that fruit rot of chilli is an important limiting factor for chilli production with highest incidence up to 54.63 per cent recorded in Warangal district. Isolates differed in their morphology, cultural studies, pathogenic levels and also in molecular studies. However, there is no correlation between the three different types of studies and the geographical distribution of the isolates. The aerial spread of the pathogen along with seed infection and movement of the seed to different areas might be the reason for such distribution. C. capsici isolates can cross infect between the crop and are more aggressive on their original host. Mancozeb, difenoconazole in fungicides and T. longibrachiatum and P. fluorescens were effective in in vitro studies and integrated module, involving the bioagents, fungicides and SAR inducing chemicals successfully reduced the disease compared to control and recorded the highest yield. Fungicide residue studies revealed that the fungicides, tebuconazole and carbendazim were most commonly detected but were found to be lesser than the MRL levels.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/5810143516
dc.keywordsFRUIT ROT CHILLI, Colletotrichum capsici BUTLER, BISBY MANAGEMENTen_US
dc.language.isoen_USen_US
dc.publisherAcharya N G Ranga Agricultural University, Gunturen_US
dc.research.problemSTUDIES ON FRUIT ROT OF CHILLI CAUSED BY Colletotrichum capsici (SYD.) BUTLER AND BISBY AND ITS MANAGEMENTen_US
dc.subPlant Pathologyen_US
dc.subjectnullen_US
dc.themeSTUDIES ON FRUIT ROT OF CHILLI CAUSED BY Colletotrichum capsici (SYD.) BUTLER AND BISBY AND ITS MANAGEMENTen_US
dc.these.typePh.Den_US
dc.titleSTUDIES ON FRUIT ROT OF CHILLI CAUSED BY Colletotrichum capsici (SYD.) BUTLER AND BISBY AND ITS MANAGEMENTen_US
dc.typeThesisen_US
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