Control of bottom rot disease of lettuce ( Rhizoctonia solani ) using preparations of Trichoderma viride, T. harzianum or tolclofos‐methyl

Isolates of Trichoderma were tested for their ability to control Rhizoctonia solani in lettuce seedlings and mature plants in a glasshouse. The best isolate (T. viride IMI 298375) was tested for its ability to control bottom rot disease in mature lettuce plants grown in polythene tunnels. Control was achieved in several trials but there was little evidence for much improvement after repeated applications and control with Trichoderma was poorer than that obtained with a standard treatment with tolclofos‐methyl. Evidence was obtained to suggest however that enhanced growth of lettuce plants following treatment with Trichoderma can produce marketable yields of lettuce similar to those obtained with tolclofos‐methyl.