Pythium-induced damping-of disease is a major disease limiting cucumber and tomato production in diferent parts of the world. The current study investigated the efciency of Talaromyces variabilis and its bioactive metabolites in suppressing Pythium-induced damping-of of cucumbers and tomatoes. T. variabilis inhibited the in vitro growth of P. aphanidermatum in solid and liquid media. In addition, abnormalities in P. aphanidermatum hyphae were observed as a result of T. variabilis. Extracts from T. variabilis induced cellular leakage and suppressed oospore production of P. aphanidermatum. Biochemical analyses of T. variabilis metabolites showed that T. variabilis produces glucanase, cellulase and siderophores, suggesting the contribution of these metabolites in the inhibition of P. aphandermatum growth and in hyphal abnormalities. Treating cucumber seeds with spore and mycelial suspension of T. variabilis isolates led to a signifcant improvement in the seedling survival of P. aphanidermatum-inoculated seedlings from 18 to 52% (improvement by 34%) for isolate 48P and from 30–66% (improvement by 36%) for isolate 28R. Similarly, treating tomato seeds with spore and mycelial suspension of T. variabilis isolates led to a signifcant improvement in the seedling survival of P. aphanidermatum-inoculated seedlings from 7 to 36% (improvement by 29%) for isolate 28R and from 20 to 64% (improvement by 44%) for isolate 48P. Diferences in the percent improvement in seedling survival between experiments may be related to diference in the efcacy of the two diferent isolates or their interaction with the hosts and pathogen. The use of T. variabilis in the biocontrol of Pythiuminduced diseases may ofer alternatives to the currently used chemical control.

Pythium-induced damping-of disease is a major disease limiting cucumber and tomato production in diferent parts of the world. The current study investigated the efciency of Talaromyces variabilis and its bioactive metabolites in suppressing Pythium-induced damping-of of cucumbers and tomatoes. T. va...