Original Articles

Biological control of Rhizoctonia solani by two Trichoderma species isolated from South African composted soil

Published in: South African Journal of Plant and Soil
Volume 21, issue 3, 2004, pages: 139–144
DOI: 10.1080/02571862.2004.10635039
Author(s): K.S. Yobo, Republic of South Africa, M.D. Laing, Republic of South Africa, C.H. Hunter, Republic of South Africa, M.J. Morris, Republic of South Africa

Abstract

Strains of two Trichoderma species isolated from composted soil were evaluated for biological control of Rhizoctonia solani. Macroscopic observations of in vitro bioassays revealed that the Trichoderma isolates overgrew the pathogen completely and that a brownish discolouration occurred at the initial point of interaction. Ultrastructural studies demonstrated that the Trichoderma isolates coiled around the R. solani hyphae and subsequently caused cell wall lysis. Application of Trichoderma formulations to cucumber seeds in the greenhouse significantly increased the percentage germination, survival and overall dry weight biomass of seedlings compared to a diseased control. Chitinase activity was detected on agar plates supplemented with colloidal chitin. The mycoparasitism of the two Trichoderma isolates indicates that there may be a reservoir of Trichoderma isolates which may be used as biological control agents for local South African soil conditions.

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