Submitted to: American Society of Agronomy Meetings
Publication Type: Other
Publication Acceptance Date: 8/20/2003
Publication Date: 11/20/2003
Citation: PAULITZ, T.C., SCHILLINGER, W.F., COOK, R.J.2003. GREENHOUSE STUDIES OF RHIZOCTONIA BARE PATCH DISEASE IN SOIL CORES FOR DIRECT-SEEDED FIELDS. (CD-ROM).AMERICAN SOCIETY OF AGRONOMY ANNUAL MEETING, 2-6 NOV., DENVER, CO. ASA, CSSA, AND SSSA ABSTRACTS.
Technical Abstract: Rhizoctonia bare patch, caused by the soilborne fungus Rhizoctonia solani AG-8, can be a problem in direct-seeded small grains in rainfed areas of the inland Pacific Northwest, USA. Plants within patches are extremely stunted. The purpose of this work was to 1) compare Rhizoctonia populations at different positions within the patch and at different soil depths and 2) to see if patches would be maintained in the R. solani-infested cores over successive plantings in the greenhouse. Eight patches were sampled at two locations near Ritzville and Starbuck, WA. Soil cores (15 x 25 cm) were removed from the four positions within each patch- center, inside edge of the patch boundary, outside edge, and outside (healthy plants). Cores were planted with five crops of spring barley (Hordeum vulgare L.) over an 11-month period in a greenhouse at 16°C. Relative activity of R. solani AG-8 was monitored with a toothpick baiting technique. At the first planting, activity of R. solani was higher in the center and inside edge, but after the second planting, there were no differences among the patch positions. Based on plant height, patches were maintained in only 6 out of 16 sets of cores. R. solani activity was similar at all soil depths from 2-20 cm. These results indicate that a natural suppression may develop with monocropping of a susceptible crop, and may explain why patches disappear over time in a field.