STUDIES ON PATHOGENIC VARIABILITY OF MYCOGONE PERNICIOSA CAUSING WET BUBBLE DISEASE OF AGARICUS BISPORUS AND ITS MANAGEMENT
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Date
2024-05-22
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UHF Nauni
Abstract
The present studies entitled “Studies on pathogenic variability of Mycogone perniciosa causing wet bubble disease of Agaricus bisporus and its management” were carried out during 2022 and 2023. Extensive surveys conducted revealed that the incidence of wet bubble disease in different districts of Himachal Pradesh ranged from 3.28 to 16.42 per cent. The disease was prevalent in all mushroom growing districts with intensity in the range of 19.33 to 42.0 per cent over years. The per cent yield loss caused by wet bubble disease on white button mushroom data was reported to be maximum (25.12%) at Baba Dera in district Una with all overall yield loss ranging from 5.83 to 25.12 per cent. The mycopathogen Mycogone perniciosa was found to be persistently linked with the wet bubble disease. The fungal pathogen exhibited typical and distinctive symptoms of wet bubble disease. In vitro studies were conducted to assess symptomatological, morphological, physiological and genetic variability among eighteen isolates collected from major mushroom cultivation areas. Different isolates of the pathogen were observed to exhibit varying symptoms e.g., appearance of cauliflower like fruiting bodies, scattered sclerodermoid mass with amber-coloured droplets thickened stipe and interior stipe browning. Symptoms such as gill infection, foul smell, and appearance of brown, amber-coloured droplets and thickened stipe were used to characterize these isolates into highly virulent, moderately virulent and less virulent categories. Isolates MP-4, MP-7, MP-3 and MP-15 were highly virulent, isolates MP-2 and MP-18 were less virulent while remaining twelve isolates were categorized as moderately virulent isolates. The isolates were observed to produce light brown to pale white coloured colonies, with texture ranging from uneven striate to even and fluffy and growth rate ranging from 17.00 to 51.00 mm per week. Bi-celled aleurospores were seen in all the isolates while eleven out of eighteen isolates were seen to produce single- celled conidia with size range of 5.7-22.5 × 1.5-6.4 μm. The dendrograms constructed by using similarity matrix on the basis of RAPD and ISSR primers revealed that isolates MP-13 and MP-15 showed highest similarity coefficient (0.89) while MP-4 and MP-10 showed minimum similarity coefficient (0.04). The results showed that temperature range of 22-25 ℃ and pH 7 was most suitable for optimum growth of the pathogen. The primary inoculum of the pathogen was observed in the contaminated casing soil with which it reaches the farms during the interval of button mushroom crop production. Spent mushroom compost and garden soil were found to contain propagules of the pathogen. Among bacterial isolates, B-1 (Bacillus subtilis strain MPS1), B-8 (Pseudomonas aeruginosa strain MPS2) and B-9 (Bacillus velezensis strain MPS3) exhibited effective mycelial inhibition of 75.11, 73.09 and 70.41 per cent, respectively of the pathogen fungus under in vitro conditions while, under in vivo conditions maximum yield (14.01 kg per 100 kg compost) and minimum per cent disease intensity (4.45 %) was seen in treatments with consortia of B-1+B-8+B-9. In-vitro evaluation of ZnO nanoparticles synthesized using bacterial atagonists against M. perniciosa revealed that maximum (79.49 per cent) mycelial inhibition was recorded in case of ZnO-NP2, followed by ZnO-NP3 (78.46 per cent) and ZnO-NP1(73.39 per cent) at 1000 ppm concentration. Under in vivo conditions, maximum yield (13.24 kg per 100 kg of compost) and minimum per cent disease intensity (4.75 %) was obtained in treatments with consortia NP-1+NP-2+NP-3.