BIOLOGICAL CONTROL OF Colletotrichum gloeosporioides Penz., CAUSING MANGO ANTHRACNOSE AND MOLECULAR CHARACTERIZATION OF POTENTIAL BIOCONTROL AGENTS

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dc.contributor.advisorESWARA REDDY, N.P
dc.contributor.authorANU ANIE MATHEWS
dc.date.accessioned2016-08-08T15:02:02Z
dc.date.available2016-08-08T15:02:02Z
dc.date.issued2007
dc.description.sponsorshipMango is one of the most important fruit crops of India and accounts for more than 50 per cent of world’s mango production. Andhra Pradesh ranks first in area and production of mangoes in India. Anthracnose caused by Colletotrichum gloeosporioides is an important disease of mango causing 30-60% losses especially in humid climate. Several reports suggest the development of resistance by the pathogen to different fungicides. Hence in the present study, an attempt was made to isolate native potential antagonists against C.gloeosporioides causing anthracnose of mango and to evaluate their efficiency in combinations with different fungicides both under in vitro and in vivo. A total of 24 antagonistic microflora (15 fungi and 9 bacteria) were obtained from phylloplane and fructoplane of mango using leaf/fruit wash method. All were found effective in inhibiting the growth of C.gloeosporioides in dual culture, but at varying degrees. Among the 15 fungal isolates, two Trichoderma isolates viz., T1 and T7 and one fungal isolate, F11 inhibited the growth of C.gloeosporioides to the extent of 79.931%, 71.38% and 71.00% respectively. Among the nine bacterial isolates, B1 isolate gave the highest inhibition per cent of 63.09%. These results were further confirmed by spread plate technique, which showed 100% inhibition of C.gloeosporioides by all isolates. Sensitivity of C.gloeosporioides to different fungicides viz., carbendazim, hexaconazole, propiconazole, prochloraz, thiophanate-methyl, captan, thiram, mancozeb and copper oxychloride were assessed in poisoned food technique. All fungicides, except mancozeb inhibited the pathogen completely. Compatibility of the three potential fungal antagonists viz., T1, T7 and F11 with above said fungicides were evaluated in poisoned food technique and bacterial isolate B1 using spectrophotometric method. F11 isolate was incompatible with all fungicides except mancozeb. B1 isolate gave very low OD values at 600 nm compared to control in case of hexaconazole, captan, thiram and copper oxychloride indicating its incompatibility with those fungicides. T1 and T7 isolates were 100% per cent compatible with mancozeb, but gave different degrees of compatibility with other fungicides. T7 was compatible with thiram (76.44%), whereas T1 was incompatible (18.11%). Based on its high inhibition per cent and relatively higher compatibility with thiram, T7 isolate was selected as the best potential fungicide compatible antagonist. Isolates T1 and T7 were identified as T.koningii and T.fasciculatum respectively at Indian Type Culture Collection, IARI, New Delhi. In vivo screening of T.fasciculatum (107 spores/ml) alone and in combination with thiram @ 750 ppm was assessed by pre-inoculation and postinoculation methods. In general, treatments under post-inoculation method gave minimum lesion diameter compared to pre-inoculation method. Based on in vitro results, the inhibition of C.gloeosporioides by T.fasciculatum may be due to combined action of competition due to fast growth, production of volatile and non-volatile metabolites and mycoparasitism. The molecular characterization of nine potential Trichoderma isolates using RAPD with five random primers viz., OPA3, OPA5, OPA8, OPA9 and OPA10 gave high polymorphism. All the five primers produced unique bands in case of T.koningii. However, the primer OPA8 amplified a unique band of approximately 800 bp in case of T.fasciculatum. All the isolates were classified into three clusters based on dendrogram formed using UPGMA analysis. In ITS-PCR all the isolates produced a single band ranging from 560 to 657 bp which confirmed the generic status of Trichoderma.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/71584
dc.language.isoenen_US
dc.publisherACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABADen_US
dc.relation.ispartofseriesD8199;
dc.subPlant Pathology
dc.subjectBIOLOGICAL, CONTROL, Colletotrichum, gloeosporioides, Penz, CAUSING, MANGO, ANTHRACNOSE, MOLECULAR, CHARACTERIZATION, POTENTIAL, BIOCONTROL, AGENTSen_US
dc.these.typeM.Sc
dc.titleBIOLOGICAL CONTROL OF Colletotrichum gloeosporioides Penz., CAUSING MANGO ANTHRACNOSE AND MOLECULAR CHARACTERIZATION OF POTENTIAL BIOCONTROL AGENTSen_US
dc.typeThesisen_US
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