Impact of Fungicides on the Growth and Distribution of Soil Mycoflora in Agriculture Fields at Narasannapeta

Pesticides have different undesired effects on soil diversity and functioning affecting microorganisms by reducing their numbers, biochemical activity, diversity and changing the microbial community structure. Eleven fungal species like Aspergillus flavus, A. niger, A. oryzaae, Curvularia lunata, Fusarium oxysporum, F. solani, Penicillium aurentiogriseum, P. chrysogenum, P. frequentans, Rhizopus stolonifer and Trichoderma harzianum were selected for the study. Three commercial fungicides i. e, Carbendazim, Copper Oxy Chloride and Mancozeb were used to study their effects on soil fungi. The study was conducted to determine the effects of fungicides application on soil fungal populations, at different application rates ranging from litre, 1litre and with the control soil samples having no fungicide injection. A total of 282 colonies of 11 species were isolated from the control plates examined in 3 different crops (Rice, Black-Gram and Ground-Nut) of Narasannapeta Mandal, in Srikakulam District.163 and 88 colonies only were isolated from the soils treated with and 1 Lt Carbandazim, 159 and 79 colonies from soils treated with and 1 Lt COC and 138 and 55 colonies from soils treated with and 1 Lt of Mancozeb, thus confirming Mancozeb as the most destructive. The results reveal that fungicide applications caused drastic reduction in microbial population present in the soils when compared with the control. Death of the micro-organisms deducts the decomposition of dead leaf material into its organic and inorganic constituents leading to reduction in the incorporation of organic matter into the soil structure thereby affecting the soil fertility.