Crop Scene Investigation - 40 Solved: Getting to the root of Jereme's failing soybeans

Thursday, January 3, 2013

When Ontario agriculture ministry field crop plant pathologist Albert Tenuta looked closely at the roots of Jereme's soybeans, he found soybean cyst nematodes (SCN).

These microscopic roundworms feed on the roots of soybeans, retarding root growth, starving the plant of nutrients and disrupting water uptake. Typically, this results in stunted plants with yellow or bronze foliage.

The cysts can mimic many common problems such as potassium and nitrogen deficiencies, iron deficiency chlorosis, herbicide injury, soil compaction, drought stress and other soybean diseases, explains Tenuta. Yield losses can range from 15 to 30 per cent for susceptible varieties.

When Tenuta asked Jereme what soybean variety he planted, he immediately recognized that the glyphosate-tolerant variety was not SCN-resistant. He also made a conscious note that Jereme's farm was located in an area with a history of heavy SCN pressure – near the Kent and Essex County border.

Another compounding factor was Jereme's practice of planting soybeans continuously in the field. When Tenuta later toured some of the farmer's other soybean fields, he noticed visual evidence indicating SCN in these fields as well.

Tenuta adds that there are effective measures to help reduce the impact of SCN. In Jereme's case, SCN has had minimal impact since he restored an effective rotation and switched to SCN-resistant soybean varieties. Congratulations to Raube Beuerman, Dublin, for his correct answer. BF