Should you expect nematode pressure?

Published on: 15:48PM May 18, 2010
David Long
In the South, a recent acreage shift away from cotton has increased corn and soybean acres. In some areas, crop rotation helps manage nematode populations, but when rotational crops also host these microscopic, thread-like worms, this strategy doesn’t help. Because cotton, corn and soybeans are all host crops to several of the same nematode species, growers who have historically battled nematode damage in their cotton fields can expect to see yield loss due to nematodes in their corn and soybean crops, too.

Soybean nematodes live in all soil environments, but damage is often more apparent in lighter, sandier soils, or under stress conditions. While symptoms vary and are not always visible, growers will notice a loss in yield. Symptoms can include premature yellowing and wilting, root galls, chlorosis of the leaves, stunting of roots and shoot, poor pod set and reduced feeder roots. Nematodes also cause significant damage to crops by facilitating fungal infections that can lead to extensive root decay.

Photo: Dead, stunted, and chlorotic plants caused by root-knot nematode. Source: Clemson University

To clearly identify below-ground symptoms, roots should be dug and closely examined. Below- and above-ground symptoms are not always distinct enough to use as a sole basis for diagnosis, so it is best to collect soil and root samples for a laboratory analysis.

Do you know if you have nematodes in your fields?