Poor emergence or damping off of young soybean plants can be a sign of a seedling disease or root rot problem, especially following cool, wet weather as experienced in much of the soybean growing part of Western Canada this spring.
As Holly Derksen, plant pathologist with Manitoba Agriculture, explains in this Soybean School West episode, there are four main pathogens responsible for root rot and seedling disease in soybeans on the prairies: Phytophthora, Pythium, Rhizoctonia, and Fusarium. (continued below)
Seed treatments will generally offer two to three weeks of protection, she notes, but some early-planted soybeans may have been slow to emerge and susceptible to these pathogens.
Phytophthora — the most common soybean root rot culprit in the region — will tend to appear later in the growing season, after soybean plants have been stressed. A longer crop rotation will help reduce phytophthora levels in a field, Derksen points out fusarium, rhyzoctonia and pythium unfortunately enjoy a wide spectrum of hosts, so rotation is a less effective management option.
While there’s little that can be done now to address a root rot problem, properly identifying the pathogen can help prevent problems in future years, whether that means using a seed treatment, waiting for warmer soil temperatures before planting or choosing a resistant variety.