Studies on variability and management of Verticillium fungicola causing dry bubble disease in Agaricus bisporus
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Date
2018
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CCSHAU
Abstract
Verticillium fungicola is a serious pathogen causing dry bubble disease in button mushroom
(Agaricus bisporus). Present investigations were carried out on both host and pathogen by covering
aspects of variability in pathogen, host-pathogen interaction and management of the disease. The isolates
of V. fungicola were collected from different mushroom farms of Haryana state, coded as MHS (Hisar),
BFT (Fatehabad), NJN (Jind), RHT (Rohtak), TPN (Panipat), BSN (Sonipat), FDB (Fridabad) and SKK
(Kurukshetra) and pathogenicity was proved on A. bisporus. All isolates showed morphological,
physiological and pathological variations. The isolates BSN, TPN, FDB, SKK and RHT are fall in the fast
growing category having radial growth of 44.66, 43.86, 43.33, 42.16 and 41.50 mm, respectively and
whitish colonies with dark yellow underside on PDA at pH 6.5 and 25±1ºC temperature after 12 days of
incubation. Similarly, during screening of the isolates, only BSN, TPN, FDB, SKK and RHT showed
disease symptoms on fruiting bodies of all the strains of A. bisporous included in the study and other
mushroom spp. i.e. A. bitorquis, Pleurotus sajor-caju and P. florida, except A. bisporus strain U-3 and
Calocybe indica where no disease appeared. During interaction between A. bisporus and the virulent
isolate (BSN) of V. fungicola, both are easily distinguishable at interaction regions on the basis of hyphal
width i.e. ranged from 4.0 to 6.5 μm and 1.5 to 4.5 μm, respectively. Pathogen grows inter- as well as
intra-cellularly on host hyphae, thereby causing coiling and lysis of host mycelia. During enzymatic
bioassay in dual culture, the mycopathogen showed production of different hydrolytic enzymes i.e.
amylase, cellulase and chitinase but not lipase and pectinase by formation of clear zonation on substrate.
In in vitro studies three bacterial isolates i.e. BI, BII and BIII were isolated from casing soil
for their antagonism against V. fungicola. The maximum growth inhibition of V. fungicola was 78.64%
with BII isolate followed by 63.94% and 61.10% in BI and BIII, respectively after 12 days of
incubation. The efficacy of neem products i.e. neem seed kernel extract, neem oil and neem leaf
extracts, at three concentrations (2.5, 5.0 and 7.5 μl/ml) were determined against V. fungicola. The
radial growth inhibition recorded was 50.02% at 7.5 μl/ml in case of neem seed kernel extract,
followed by 40.99% and 34.94% in neem leaf extract and neem oil, respectively. Salicylic acid and
jasmonic acid with different concentrations (0.1, 0.2 and 0.4 mM) were used and growth inhibition was
44.96% recorded at concentration 0.4 mM with salicylic acid, followed by jasmonic acid (23.42%)
when evaluated against V. fungicola. In In vivo both salicylic acid and jasmonic acid resulted in
reduction of lesions size on A. bisporus to the extent of 69.69% and 39.93%, respectively at
concentration of 0.4mM. Similarly, the number of lesions reduction was 81.96% (salicylic acid) and
54.64% (jasmonic acid) at same concentration. The integrated managements of dry bubble disease
caused by V. fungicola during the cultivation of A. bisporus in cropping period of 2016 and 2017
showed that all the treatments individually as well in combinations affected all yield parameters at all
stages of growth of A. bisporus. However, the integrated disease management reported when treatments
combination (bacterial isolate BII, neem seed kernel extract and salicylic acid) were applied at both
spawning and casing time resulted in maximizing yield (24.75%) and minimizing disease incidence
(4.31%) in cropping duration of 37 days.
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