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Title: Reduction of Rhizoctonia bare patch win wheat with barley rotations.

item Paulitz, Timothy
item JIRAVA, R

Submitted to: Washington State University College of Agriculture and Home Economics
Publication Type: Experiment Station
Publication Acceptance Date: 4/20/2007
Publication Date: 7/20/2007
Citation: .Schillinger, W.F., Paulitz, T.C., Jirava, R.P., Schafer, H.L., Schofstoll, S.E. 2007. Reduction of Rhizoctonia bare patch win wheat with barley rotations.. Washington State University College of Agriculture and Home Economics. XB1045E.

Interpretive Summary: Until now, rotation crops have not been shown to have any effect on Rhizoctonia bare patch, because of the wide host range of the pathogen, Rhizoctonia solani AG-8. However, after 6 years of continuous spring cereal production in a direct-seed experiment near Ritzville, we have observed that wheat following barley has less disease and greater yield than continuous wheat, even though barley is a host for this pathogen. The mechanisms behind this disease suppression are unknown.

Technical Abstract: Rhizoctonia bare patch caused by Rhizoctonia solani AG-8 is a major fungal root disease in no-till cropping systems. In an 8-year experiment comparing various dryland no-till cropping systems near Ritzville, Washington, Rhizoctonia bare patch first appeared in year 3 and continued through year 8. Crop rotation had no effect on bare patch during the first 5 years, but from years 6 to 8, both soft white and hard white classes of spring wheat grown in 2-year rotation with spring barley had an average of only 6.6% of the total land area with bare patches compared to 15% in continuous annually soft white wheat or hard white wheat (i.e. monoculture wheat). Although average grain yields for both soft white wheat and hard white wheat were greater (P<0.001) when grown in rotation with barley than in monoculture in years 6 to 8, monoculture hard white wheat was more severely affected by Rhizoctonia than soft white wheat. Soil water levels were higher in bare patches, indicating that the roots of health cereals did not grow into/underneath bare patch areas. This is the first documentation of suppression of Rhizoctonia bare patch diseases in low-disturbance no-till systems with rotation of cereal crops.