STUDIES ON FOOT AND ROOT ROT OF WHEAT: II. CULTURAL RELATIONSHIPS ON SOLID MEDIA OF CERTAIN MICRO-ORGANISMS IN ASSOCIATION WITH Ophiobolus graminis SACC.

Abstract

The antagonistic and compatible growth relationships of 66 cultures of bacteria and fungi, most of which were from the soil, towards O. graminis on potato dextrose agar and Molisch's salt peptone agar, were compared with the effect of each on the virulence of this pathogene on wheat seedlings in open soil culture.Of the 21 cultures which controlled the virulence of O. graminis in the soil, only 15 of these were antagonistic on potato dextrose agar, while of the 45 cultures which gave intermediate or no control, 17 were compatible and 28 were decidedly antagonistic. From data secured indirectly, the antagonism or compatibility of the micro-organisms toward O. graminis, observed on potato dextrose agar, did not seem to depend on active alkali or acid more than on other metabolic products. The study apparently demonstrates that the growth reaction of various micro-organisms and O. graminis, associated on the two solid media used, is not a reliable indication that the same micro-organism will or will not suppress the virulence of this pathogene on wheat in soil in open pot culture.