Mutual Effects in Vitro of Micro-Organisms Isolated from Tree Seedlings, Nursery Soil, and Forests

Selected isolates of actinomycetes and fungi imperfecti isolated from tree seedlings, nursery soils, and basidiomycetes isolated from fruiting bodies were paired on cornmeal agar, and the mutual effects recorded. In the majority of 1205 different combinations, antagonism was present, but in many there were no mutual effects. Stimulation took place very seldom. The most common effect was the inhibition of growth for a distance of 0 to 20 mm. Very often the growth of the colony was inhibited on contact or soon thereafter. Lysis was observed in several cases. Although antagonism or sensitivity to antagonism was typical of many isolates, it was lacking in certain combinations of each isolate. Isolates of the following genera were among those usually exhibiting strong antagonism: Armillaria , Bacterium , Cylindrocarpon , Gliocladium , Penicillium , Russula , Streptomyces , Suillus , and Trichoderma . Many species of Fusarium , Gliocladium and Streptomyces were the most insensitive isolates and several basidiomycete and phycomycete species the most sensitive ones.