Submitted to: Canadian Journal of Plant Pathology
Publication Type: Review article
Publication Acceptance Date: 9/20/2002
Publication Date: 12/20/2002
Citation: PAULITZ, T.C., SMILEY, R.L., COOK, R.J. INSIGHTS INTO THE PREVALENCE AND MANAGEMENT OF SOILBORNE CEREAL PATHOGENS UNDER DIRECT SEEDING IN THE PACIFIC NORTHWEST, U.S.A.. CANADIAN JOURNAL OF PLANT PATHOLOGY. 24(4) 416-428. 2002. Interpretive Summary: This review article looks at the latest developments in the management of soilborne pathogens of cereals in the Pacific Northwest, primarily from the research labs of the authors. Under direct-seeding or no-till, the dynamics and prevalence of diseases change because of the lack of tillage and slower breakdown of crop residue. However, direct-seeding offers many environmental benefits, including reducing soil erosion and reduced fuel and labor inputs. This review specifically covers take-all, Rhizoctonia bare patch and root rot, Pythium seedling and root rot, and Fusarium foot rot.
Technical Abstract: Direct seeding or no-till leaves the soil undisturbed, except where the seed is planted and the soil fertilized. It offers several advantages in small-grain cereal production, including reduction in labor and other operating costs, reduction of soil erosion, and improvement of soil quality. However, only about 10% of small grains in the U.S.A. and 6% of the small grains in the Pacific Northwest (PNW) region of the U.S.A. are currently direct seeded. Root diseases are major constraints to adoption of direct seeding; they increase because of lack of tillage, increased crop residue left on the surface, and typically cooler and wetter soil conditions in the spring. This review covers some recent research on the four most important root diseases of cereals in the PNW and their causal agents. These diseases are rhizoctonia root rot and bare patch (Rhizoctonia solani AG-8, R. oryzae), pythium damping-off and root rot (Pythium spp.), take-all (Gaeumannomyces tritici var. tritici), and fusarium foot rot (Fusarium pseudograminearum and F. culmorum). We discuss how these diseases are affected by direct seeding and the impact of management strategies, including crop rotation, residue management, control of inoculum from volunteers and weeds, fertilizer placement, genetic tolerance, biological control, development of natural suppressiveness, and prediction of risk through DNA-based detection methods.