EFFICACY OF THE MICROBIAL CONTROL AGENT TRICHODERMA ASPERELLUM STRAIN T34 AMENDED TO DIFFERENT GROWTH MEDIA AGAINST SOIL AND PLANT LEAF PATHOGENS

Suppressive composts are a viable alternative to fungicides for biologically controlling diseases of plants grown in pots. However, not all composts suppress plant diseases, and the range of pathogens affected and level of suppression vary. Moreover, the formulation of composts is sometimes necessary in order to improve their physical and chemical characteristics and this can lead to a reduction in their suppressive capacity. In this study, the efficacy of the biological control agent Trichoderma asperellum, strain T34 (amended to the different growth media) is evaluated against different soil and plant foliar diseases. Amendment of T34 to conducive peat or perlite significantly reduced Fusarium wilt severity in carnation and tomato. In addition, the application of T34 to a formulated compost made of vegetable and animal market waste, sewage sludge and yard waste restored its natural suppressiveness against Fusarium wilt in tomato. Amendment of T34 to aged suppressive olive marc compost and spent mushroom compost improved their natural suppression capacity against Rhizoctonia solani incidence in cucumber. However, T34 did not improve the high level of suppression of aged cork compost or grape marc. Moreover, T34 amended to hydroponics significantly reduced disease caused by Pseudomonas syringae pv. lachrymans in cucumber and, in Arabidopsis plants grown in sand-potting mixture, it reduced the disease caused by P. syringae pv. tomato, Plectosphaerella cucumerina and Hyaloperonospora parasitica by the induction of systemic resistance.