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

KrishiKosh

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Title BIOLOGICAL CONTROL OF Colletotrichum gloeosporioides Penz., CAUSING MANGO ANTHRACNOSE AND MOLECULAR CHARACTERIZATION OF POTENTIAL BIOCONTROL AGENTS
 
Creator ANU ANIE MATHEWS
 
Contributor ESWARA REDDY, N.P
 
Subject BIOLOGICAL, CONTROL, Colletotrichum, gloeosporioides, Penz, CAUSING, MANGO, ANTHRACNOSE, MOLECULAR, CHARACTERIZATION, POTENTIAL, BIOCONTROL, AGENTS
 
Description Mango 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.
 
Date 2016-08-08T15:02:02Z
2016-08-08T15:02:02Z
2007
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/71584
 
Language en
 
Relation D8199;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD