Biological control of Fusarium wilt of tomato with hypovirulent binucleate Rhizoctonia in greenhouse conditions

Four isolates of hypovirulent binucleate Rhizoctonia (HBNR), G1, L2, W1, and W7 were used for control of Fusarium wilt of tomato (FWT) caused by Fusarium oxysporum f. sp. lycopersici (FOL). HBNR isolates could significantly reduce disease severity (foliar symptoms and discoloration inside the stem) among five experiments under single and double applications. Reduction of disease severity by HBNR isolates, however, differed depending on HBNR isolates and treatments. Of four isolates, isolate HBNR W7 could significantly and consistently reduce (P = 0.05) disease severity. Application of HBNR isolates significantly reduced (P = 0.01) the number of colonyforming units of FOL in stems and roots of tomato. Among the HBNR isolates, G1, W1, and W7 could significantly increase (P = 0.05) fresh weight of the plants (stems and leaves). These results indicate that isolates of HBNR have a greater potential as biocontrol agents against FWT. This is the first report of biocontrol of FWT by HBNR under greenhouse conditions.