product and process for combating the ill of fiede cice afio bolosi cereals

摘要

1486262 Combating take-all disease in cereals INSTITUT NATIONAL DE LA RECHERCHE AGRONOMIQUE 17 Sept 1974 [27 Sept 1973] 40427/74 Heading ASE [Also in Divisions A2 and C6] The cryptogamic "take-all" disease of cereals (wheat, barley, rice) produced by the fungus Ophiobolus graminis is countered by application of abnormal homogeneous strains of Ophiobolus graminis to the seed or soil. These are obtained by cultivating the fungus on an agar medium, which fungus is taken from cereals growing in an intensive rotationcropping field in the years following the maximum intensity of the disease, at which time the cereals show only very slight signs of attack, and selectively cultivating strains which exhibit a uniform growth pattern when viewed under light, as distinct from the normal strains which give concentric growth zones. The cells of the abnormal strain may be inoculated into the soil in the form of a culture on a finely divided supporting medium e.g. cereal grains which have been rendered incapable of germinating, straw, flour or cereal waste. Seeds may be protected from infection by providing them with an adhesive coating of methyl cellulose or polyvinyl pyrrolidone and then bringing the coated seeds into contact with the cells of the abnormal strain, living or dead. The protective effect of the abnormal strain on the growth of a wheat seed is illustrated by a test wherein the soil in box 11. Fig. 4. is inoculated with the abnormal strain at level 16 and a highly virulent strain at level 15 (c.f. boxes 12 and 10). In a further test, grains of barley which had been colonised by growth of the abnormal strain thereon, were exposed to infection by highly virulent strains inoculated into the soil at increasing depths, as shown in Fig. 3.