Reduction of Rhizoctonia root rot of direct-drilled wheat by short-term chemical fallow

Abstract

This study has demonstrated that volunteer pasture, comprising mainly barley grass and ryegrass, which grows over several weeks between autumn rains and seeding, promotes damage to roots of direct-drilled wheat caused by Rhizoctonia solani. A chemical fallow, in which the volunteer pasture was sprayed 3-6 weeks before seeding, greatly reduced the root damage (based on visual ratings) caused by R. solani on direct-drilled wheat in the field and in a controlled- environment experiment in which field conditions were simulated. In the field experiment, grain yields of direct-drilled wheat following pasture in plots treated with herbicides was 2.2 t/ha compared with 1.2 t/ha in untreated plots. The application of herbicides did not affect the yields of wheat sown following cultivation.