Some factors affecting occurrence of Fusarium Culmorum in the soil

Abstract

During a survey of soil fungi in plots of perennial rye-grass, Fusarium culmorum (W. G. Sm.) Sacc. was regularly isolated over a period of 21 months. Frequency of isolation was significantly greater from plots which had been limed and from those receiving nitrogen; there was, however, no evidence of an interaction between lime and nitrogen. There was also a significant seasonal variation in frequency of isolation. This could not be related simply to either soil moisture or temperature considered independently, but there was evidence of interaction in that low frequencies were associated with either (a) low temperature ( 7°) and low moisture; higher frequencies, on the other hand, were associated with high temperature coupled with high moisture. Frequency of recovery of the fungus from soil samples incubated in the laboratory for 28 days, under a wide range of temperature and moisture conditions, followed closely that found in the field. The inhibitory effect of high temperature at low moisture levels was not observed in sterilized soil, and it has been concluded that under these conditions microbial antagonism plays a significant role in determining the activity of F. culmorum. It has been found that, in sterilized soil at low moisture levels, Trichoderma viride suppresses growth of F. culmorum at temperatures above 10°, whereas at lower temperatures F. culmorum suppresses T. viride.