Why are my soybeans yellow? Part 2

Soybeans throughout the county just don’t look good right now.  Development has been slowed and many fields have areas (sometimes large areas) with a light green or yellowish tint to the beans.  What is causing this yellowing? One possibility is:

Soybean Cyst Nematode

The soybean cyst nematode (SCN) remains the most devastating and yield-limiting soybean pathogen in Ohio and North America. SCN can cause over 30% yield reduction with no visible symptoms, therefore, early detection of this pathogen relies on testing your fields to know your SCN numbers!

Symptoms of SCN injury include presence of patches of yellow and stunted soybeans, with more pronounced symptoms in plants under stress and in sandy soils. Infected plants have poorly developed fibrous roots and with fewer Rhizobium nodules. Early in the growing season (6 weeks after planting), close examination of the roots may also reveal small, white to yellow spheres (bodies of female nematodes) attached to the root surface. These females are not much bigger than grains of coarse sugar, and should not be confused with the much larger Rhizobium nodules.

Spring is a good time to sample for SCN. A soil test in spring will reveal if SCN is present and if so, at what levels. If you are planning to participate in an on-farm trial that requires soil sampling, a subsample can be used for SCN testing. Additionally, if you planted corn, a soil sample from that field will reveal if you have SCN but most importantly, how much SCN. Knowing your SCN numbers will help you determine the best management strategy.    

With funding from the Ohio Soybean Council and promoting the mission of The SCN Coalition, we will process up to TWO soil samples, per grower, to be tested for SCN, free of charge.

Download and complete this Soil Sample Submission Form and mail your samples to:

OSU Soybean Pathology and Nematology Lab 

Attn: Horacio Lopez-Nicora, Ph.D.

110 Kottman Hall

2021 Coffey Rd.

Columbus, Ohio 43210



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