Root Diseases of Wheat and Barley During the Transition from Conventional Tillage to Direct Seeding.

The use of direct seeding (no-till) in place of tillage can reduce soil erosion and improve water infiltration. However, despite these improvements in soil quality, growers in the Pacific Northwest are reluctant to adopt direct seeding, partially because of fears of increased root diseases caused by Gaeumannomyces graminis var. tritici, Rhizoctonia spp., and Pythium spp. To examine the effect of the transition from conventional tillage to direct seeding, field plots were established at two locations. One site had been managed with direct seeding for 12 years, and the second had been conventionally tilled. Over 4 years, a portion of each plot was tilled or direct seeded, and planted to wheat or barley. Plants in the tilled plots had consistently more crown roots than plants in direct-seeded plots. Rhizoctonia root rot and yield did not differ between tillage types during the first 2 years of the study. However, in the third and fourth years of the transition to direct seeding, a higher incidence of Rhizoctonia root rot, increased hyphal activity of R. solani, and reduced yields were observed in direct-seeded plots. Populations of R. oryzae and Pythium spp., and incidence of take-all were the same for both management practices.