Record Details

STUDIES ON Choanephora TWIG BLIGHT (Choanephora cucurbitarum (Berk & Rav.) Thaxt. OF CHILLI (Capsicum frutescens L.) AND ITS MANAGEMENT

KrishiKosh

View Archive Info
 
 
Field Value
 
Title STUDIES ON Choanephora TWIG BLIGHT (Choanephora cucurbitarum (Berk & Rav.) Thaxt. OF CHILLI (Capsicum frutescens L.) AND ITS MANAGEMENT
 
Creator CHANDRAKALA, J
 
Contributor VIDYASAGAR, B
 
Subject diseases, fungi, biological development, choanephora cucurbitarum, biological phenomena, planting, developmental stages, chillies, polysaccharides, pathogens
 
Description Choanephora cucurbitarum is a facultative saprobe that belongs to the Sub
division Zygomycotina, Order: Mucorales and Family Choanephoraceae and it is
responsible for causing twig blight in chilli. It is a fungal plant pathogen and has a wide
host range (Abel Motaal et al., 2010). The disease was first reported by Dastur (1920) in
India and it became endemic in certain monocropping areas. A little is known about
chilli twig blight, hence the present investigation has been initiated to study the
symptoms and management of disease.
A preliminary survey was conducted in 6 major chilli growing districts of
Telangana district representing 13 mandals and 38 villages during kharif 2013-14 for
the prevalence of Choanephora twig blight diseases in chilli.
Khammam recorded maximum disease incidence varying from 20 to 32% in all
five villages surveyed where as in Karimnagar and Warangal district the disease
incidence was 18 and 15% respectively. There was no incidence of twig blight disease
in chilli in Medak, Ranga Reddy and Nizambad districts.
The pathogen was isolated from the leaf and proved for its pathogenecity. The
drooping multisporous sporangia were subglobose in shape and 90.15 - 100 μm in size.
The sporangia were non columellate and dehisce into two half releasing the spores.
Sporangiospores were elliptic, fusiform or ovoid in shape, light brown or dark brown in
color and are characterized by longitudinal striatures on the surface of wall and 12-19 x
7.23-9.5 μm by size. The sporangiophore (conidiophore) from which the monosporous
sporangiola arose was long slender, branched at the apex with primary vesicle from
which secondary vesicles were produced on the stalks which bears sporangiospores
(conidia). Monosporous sporangiola were elliptical, fusiform or ovoid, striate and
measured 11-19 × 4-12 μm. Zygospores of C. cucurbitarum appear not to have been
observed prior to the present study. The mycelial and morphological characters were
similar to that described by Wolf, 1917. On the basis of morphological and cultural
characters, growth habitat and temperature relations, the fungus was identified as
Choanephora cucurbitarum.
The pathogen restricts its attack on young green twigs as well as petiole, fruit
stalk and flower bases. The affected areas on twig first develop as water soaked, brown
coloured lesion which enlarge rapidly encircling the twig. The portion of twig above the
affected region becomes wilted, blighted and dried up. The fungus develops stiff thread
like sporangiophores with black headed asexual reproductive structures on diseased
lesions.
Prominent hairy growth of Choanephora cucurbitarum on the infected tissue
was found in the morning hours. This is visible with a hand lens. Usually whitish
mycelia and monosporous sporangial were produced on the lesions. The disease
gradually spreads to more and more branches even to the stem causing severe damage
under warm and humid conditions that favor the disease development.
Studies on the effect of different pH, media and temperature on the radial
growth were carried out. The suitable pH for mycelial growth of C. cucurbitarum was at
pH 4.5. Among the eight media tesed, PDA was found more suitable for growth of C.
cucurbitarum. The temperature of 25
o
C was found favourable for the radial growth of
C. cucurbitarum.
Four isolates of Trichoderma spp and 8 fungal antagonists isolates were isolated
from rhizosphere and phylloplane of chilli respectively and tested the efficacy against
test pathogen Choanephora cucurbitarum by dual culture technique. Among these,
Trichoderma viride isolate-1 was found most effective in inhibiting the test pathogen
followed Fusarium spp.
Seven fungicides viz., azoxystrobin, carbendazim, captan, copper oxychloride,
chlorothalonil, hexaconazole and mancozeb were tested at six concentrations i.e. 0.05,
0.1, 0.15, 0.2, 0.25 and 0.3% respectively under in vitro conditions. Among them captan
at 0.15% at least concentration inhibited the mycelia growth of Choanephora
cucurbitarum.
Ten varieties were screened against the test pathogen C. cucurbitarum and out of
them LCA-334 and G-4 showed disease severity index with 27 and 24 per cent
respectively.
The potential biocontrol agent and effective fungicide were screened under
greenhouse conditions against twig blight of chilli caused by Choanephora
cucurbitarum with different combinations. The treatment, T2 (captan @ 0.15%)
recorded was found to most effective in reducing the disease incidence by 66.47%
followed by T7 (Trichoderma viride + captan + Neem oil) 28.9% when compared to
control (13.95%).
 
Date 2017-01-03T10:50:55Z
2017-01-03T10:50:55Z
2016
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/94089
 
Language en
 
Relation D10019;
 
Format application/pdf
 
Publisher PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY RAJENDRANAGAR, HYDERABAD