Actinomycetes as Biological Control Agents for Calves' Brains Fungus, Diehiomyces microsporus, in Mushroom Culture.

Abstract

[[abstract]]Of 384 bacterial and 426 actinomycete samples obtained from compost and casing soil, 70 bacteria and 227 actinomycetes inhibited D. microsporus on agar media. In further tests in paired cultures in compost in culture tubes the actinomycete isolate A-1759 was effective under sterile and nonsterile conditions while A-1518 was effective only in sterile compost. Isolates A-1708 and A-1713 were not effective when tested in nonsterile compost, although they both displayed a wide inhibitory zone against D. microsporus on agar. None of these isolates was inhibitory to mushroom. The bacterial isolates B-1303 and B-1304 were inhibitory to mushroom in sterile compost. The actinomycete A-1403 was parasitic to mycelium of D. microsporus on slide cultures. In tests in mushroom houses inoculation of compost with A-1403 before peak heating protected the mushrooms from a challenging inoculation with D. microsporus but was less effective when introduced at casing time. Isolate A-1759 was ineffective when inoculated to either compost or casing soil. Isolate A-1403 appeared to be closely related to Streptomyces circulatus and A-1759 to Micromonospora parva