UW Soybean Plant Health

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Soybean Aphid
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  Brown stem rot (BSR) is a major disease of soybeans in Wisconsin and in the Midwest. Incidence of brown stem rot has greatly increased over the past few years and the disease is found in all soybean-producing areas of Wisconsin. The increase in brown stem rot seen in recent years has been attributed to an expansion of soybean acres and shorter rotations.

While some soybean diseases are related to stressful growing conditions, brown stem rot is most severe when conditions are optimal for soybean growth. BSR is frequently associated with fields that do not respond to management practices and have difficulty achieving yields of 50 bushels/acre. 

Brown stem rot is caused by the fungus Phialophora gregata which lives in soil and soybean residue. The pathogen infects through the roots and invades the vascular system of soybean plants. The infection eventually impedes the movement of water and mineral nutrients needed for growth. 

Yield losses to BSR of 10-30% are common. BSR may reduce both seed number and seed size. Severely diseased plants may also lodge more easily than noninfected plants. Yield loss is greatest in cultivars with a longer relative maturity and if both foliar symptoms and stem symptoms are present. 

Brown stem rot will have a greater negative effect on yield if temperatures are cool (64-75F) in early August, followed by hot, dry weather during late pod-fill.copy
 


Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: University of Wisconsin-Madison, Departments of Agronomy, Entomology, and Plant Pathology at  www.plantpath.wisc.edu/soyhealth.

Last update 3/07