BIOLOGICAL-CONTROL - MICROBIAL VERSUS CHEMICAL FUNGICIDE ON GROWTH OFRICE INFECTED WITH FUSARIUM-MONILIFORME

Fusarium moniliforme produces giberellin, a phytotoxin with hormonal e ffect which causes ''bakanae'' disease in rice, characterized by uncon trolled growth eventual weakness and death of the plant In order to as ses the effectiveness of disease control, a comparative study was done between metabolites produced by soil isolated bacteria (with proved i n vitro activity against F. moniliforme) and four chemical fungicides: benomyl, triflumizole, perfurazoate and prochloraz. Rice seeds, conta minated with 14 isolates of giberellin producing F. moniliforme, were treated with concentrated microbial supernatant extract or chemical fu ngicide. Seedlings were transferred to a container with 50 g of soil, and incubated at 25 degrees C. Continuous analysis of growth and vigou r was carried out for 3 weeks nd showed that all five microbial extrac ts efficiently inhibited the development of typical overgrowth symptom . Microbial extracts had a better response than chemical fungicides. C onsidering the risk of environmental contamination by chemical agrotox ic agents, the present study contributes with an additional possibilit y of microbial metabolite application in fungal disease control, with the advantage of avoiding undesirable chemical residues in ecosystem.