BIOLOGICAL CONTROL OF ROOT ROT OF CLUSTER BEAN (Cyamopsis tetragonoloba L. Taub.).
KrishiKosh
View Archive InfoField | Value | |
Title |
BIOLOGICAL CONTROL OF ROOT ROT OF CLUSTER BEAN (Cyamopsis tetragonoloba L. Taub.).
|
|
Creator |
MUSAED NAJI EISSA NASSER
|
|
Contributor |
PRAMOD CHANDRA KUMAR, C
|
|
Subject |
BIOLOGICAL, CONTROL, ROOT, ROT, CLUSTER, BEAN
|
|
Description |
Cluster bean or guar (Cyamopsis tetragonoloba L. Taub.) is an economically important vegetable crop. It is consumed as vegetable in India. Gum extracted from seeds has a varied range of industrial applications. Cluster bean cultivation is gaining importance in and around Hyderabad and Andhra Pradesh in view of its commercial value. In recent years the crop yield are declining due to biotic and abiotic stresses. Of the biotic stresses, the diseases caused by fungi, bacteria and viruses are of economic importance. Among the fungal diseases, root rot disease caused by Sclerotium rolfsii Sacc. has become the constraint resulting in yield losses year after year . A detailed study was carried out on the biological control of this disease by analysing quantitative and qualitative rhizosphere microflora, in vitro screening of native rhizosphere microflora, exotic and commercial formulations of fungal and bacterial biocontrol agents, compatibility of potential antagonists with commonly used fungicides. The studies also included testing of the potential antagonists and compatible fungicides either applied alone or in combination against test pathogen under glasshouse conditions. The disease symptoms were initially characterized at seedling stage. Thirty days old plants showed root rot symptoms in warm conditions. The wilted plants showed gradually or sometimes sudden yellowing, withering and drying of leaves followed by drying of entire plant. The wilted plants showed light brown discolouration on the plant tip and whitish mycelial growth on the collar region and root due to the blocking of xylem and phloem. Wilting of the plant with dropping of the leaves occured when 30-32◦ C temperature prevailed during daytime. The infected plants usually wilted within 3 to 5 days, after the appearance the first root rot symptoms. The fungus associated with the disease was isolated and identified as Sclerotium rolfsii Sacc. and its pathogenicity was proved under glasshouse conditions. Nine fungi were isolated consistently from the rhizosphere of cluster bean (cv. Pusa Navbahar) plants at 15 DAP, 30DAP and 45 DAP stages by serial dilution method. Of these, Penicillium citrinum was found to be the predominant in the rhizosphere of cluster bean (cv. Pusa Navbahar) compared to Emericella sp with least per cent occurrence. Quantitative analysis of rhizosphere microflora of cluster bean revealed that the population of fungi and bacteria gradually increased from 15 DAP (seedling) to 30 DAP (vegetative) to 45 DAP (flowering) stages. In vitro screening of cluster bean rhizosphere microflora against S. rolfsii resu1ted in identifying potential native antagonists like Trichoderma viride (Native 1 Tv) followed by Trichoderma viride (Native 2 Tv). Among the native, exotic and commercial biocontrol agents, T. viride (Native 1 Tv), T. harzianum (DOR Th) and B. subtilis (DOR Bs) were found to be the best among all the isolates tested in inhibiting the growth of test pathogen. The non Trichoderma groups of fungi were less effective in inhibiting the pathogen growth. In compatibility studies, T. viride (Native 1 Tv), T. harzianum (DOR Th) and B. subtilis (DOR Bs) were found to be compatible with azoxystrobin at its recommended and half recommended dosages. The efficacy of potential antagonists and compatible fungicide either alone or combination as a seed or soil application were tested in pot culture against the test pathogen wherein the treatment T14 involving combined seed treatment/soil application of B. subtilis (DOR Bs) and azoxystrobin (0.1%) was found to be superior by recording significantly in highest per cent germination of cluster bean (cv. Pusa Navbahar) seedlings and least per cent disease incidence (15.08) compared to other treatments. |
|
Date |
2016-08-08T14:17:46Z
2016-08-08T14:17:46Z 2008 |
|
Type |
Thesis
|
|
Identifier |
http://krishikosh.egranth.ac.in/handle/1/71541
|
|
Language |
en
|
|
Relation |
D8173;
|
|
Format |
application/pdf
|
|
Publisher |
ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
|
|