The effect of crop rotation with wheat and oats on the incidence of Fusarium crown rot of wheat

Abstract

Crown rot is a serious disease of wheat in the central and western parts of the Orange Free State. The disease, caused mainly by Fusarium graminearum Group 1, is difficult to control and crop rotation has been suggested as a control measure. The effect of an oats-wheat crop rotation system on various crown rot parameters was compared with a wheat-wheat monoculture system (a five-month fallow period between crops) over a period of three years. Two wheat cultivars, differing in susceptibility to the disease, were incorporated in the rotation experiments. From soil dilution plates, significant differences were observed in soil populations of Fusarium spp., but these differences were not consistent for each season. Except for 1989, when the wheat monoculture system yielded more plants with severe crown necrosis than the oats-wheat cropping system, no significant differences were observed between cropping systems for crown rot severity or the number of white heads observed. In contrast to the above, highly significant yield differences were observed. Higher yields were obtained in the oats-wheat cropping system than in the wheat monoculture system. Molen produced higher yields than Scheepers 69. No evidence could be found to show that oats stimulates sporulation of F. graminearum Group 1.