|Cochran, A - PURDUE UNIVERSITY BOTANY|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2000
Publication Date: N/A
Technical Abstract: No-till soybean production is thought to favor Phytophthora root rot (PR). Root infections by Phytophthora sojae can be controlled by using soybeans with Rps genes, but our surveys suggest 60% of the cultivars available in the Midwest do not have Rps resistance. To determine the effects of no-till on PR, population dynamics of P. sojae, and soybean yield, we compared susceptible (rps) and resistant (Rps1-k) soybeans in moldboard plow vs. no-till systems in a soybean-corn rotation and in continuous soybean cropping. Disease symptoms and yield losses (>10bu/a) were observed primarily with the susceptible cultivar and were consistently high in the no-till system. More isolates of P. sojae were recovered from no-till soil samples (19x) compared to tilled soil samples in the soybean-corn rotation. Continuous soybean cropping supported high levels of P. sojae in both tillage systems, but yields were reduced most in no-till plots. Use of Rps1-k soybeans appeared to minimize inoculum potential, particularly in soybean-corn rotations. These data verify increased risk of PR loss with reduced tillage and emphasize the need for soybean cultivars with Rps genes.