Elad, Y., Department of Plant Pathology and Microbiology, Faculty of Agriculture, The Hebrew University, P.O. Box 12, Rehovot, Israel
Chet, I., Department of Plant Pathology and Microbiology, Faculty of Agriculture, The Hebrew University, P.O. Box 12, Rehovot, Israel
Henis, Y., Department of Plant Pathology and Microbiology, Faculty of Agriculture, The Hebrew University, P.O. Box 12, Rehovot, Israel

Trichoderma harzianum preparations was used in two successive field experiments in commercial strawberry nurseries and fruiting fields. Disease severity of Rhizoctonia solani in daughter plants was reduced by 18-46 % in the treated nursery plots. Infestation of nursery soil with the pathogen, as tested by planting beans in soil samples was reduced by the Trichoderma treatment by up to 92% as compared to the untreated control. A rapid decline of the disease was observed in soil from T. harzianum treated plots, successively planted with bean seedlings. More isolates of Trichoderma sp. antagonistic to R. solani, were found in the infested field as compared to the non infested one. Trichoderma harzianum treated plants, transferred to the commercial field gave a 21-37% increase in early yield of strawberries. A combined treatment in the nursery and in the fruiting field resulted in a 20% yield increase as compared to control plots. © 1981 Martinus Nijhoff/Dr W. Junk Publishers.