Main content area

Effects in vitro of nine fungicides on growth of entomopathogenic fungi

Majchrowicz, I., Poprawski, T.J.
Biocontrol science and technology 1993 v.3 no.3 pp. 321-336
biological control agents, entomopathogenic fungi, toxicity, adverse effects
The effects of nine fungicides were evaluated in vitro on the entomopathogenic fungi Beauveria bassiana, Conidiobolus coronatus, C. thromboides, Metarhizium anisopliac, Paecilomyces farinosus, P. fumosoroseus, Scopulariopsis brevicaulis and Verticillium lecanii. The susceptibility of the fungi to the fungicides varied. The dithiocarbamate derivations zineb + copper oxychloride, and mancozeb completely inhibited germination of C. coronatus, C. thromboides, B. bassiana, P. farinosus, M. anisopliae and V. lecanii. The fungicides triadimefon, copper oxychloride, metalaxyl, sulfur, sulfur + nitrothal-isopropyl and hymexazol exhibited various effects on the fungi. Usually, fungistasis was more pronounced at 15 degrees C than at 25 degrees C and the inhibitory effects were in direct proportion to the dosage of active ingredient (recommended field rate, 10 fold higher and 10-fold lower). In a few combinations, fungi partially overcame or even recovered from the initial inhibition of growth which might have resulted from delayed germination. In other cases, inhibition of growth occurred only after a delay and its intensity increased with time. Stimulation of fungal growth when it occurred was rarely permanent. Generally, adverse effects were much greater against the entomophthoraleans C. coronatus and C. thromboides than against the Hyphomycetes. Extrapolation of the results to practice and to the field situation is difficult. Nevertheless, the data presented give an idea of possible side-effects in nature.