By Ernie Flint, Agronomy MSU Extension
Photo Credit – Pawan Kumar, University of Georgia
You might say that reality is stranger than fiction when it comes to these tiny insidious worms that infest our fields and damage crops, gardens, lawns, and turfgrasses. I can’t think of a good reason why they are even here, but I expect some ecologist could set me straight on that.
I am interested in these tiny unseen worms, mainly because they do a lot of damage and are overlooked by most people. Like earthworms, they don’t have legs, but they do have one serious appendage. It’s called a proboscis, with which they can sting, inject and draw solutions from other organisms, including plants and animals.
Just about every crop has its nematode challenges. The Reniform nematode attacks a wide range of crops including cotton, soybeans and many horticultural crops. Levels of this nematode in the soil can reach extremely high levels. Hosts for this nematode are generally broadleaf plants, but they are not very active in the grasses, including corn and grain sorghum as well as the cool season grains.
The Southern root knot nematode can utilize an even wider range of crops than Reniform, since it can live on both broadleaf plants and grasses. The only non-host crop we have is the peanut. This is one reason peanuts have become more popular as a rotation crop in recent years. The peanut does have its own nematode however – the Peanut root knot nematode. So far, we have not had to deal with this pest in Mississippi, and we don’t want to bring it here by accident on farm equipment and other things that come from infested areas.
Another nematode species is the Soybean Cyst nematode which has, in the past, caused tremendous damage to soybeans in Mississippi. Several years ago, this nematode was essentially wiped out by a fungal infection, but recently it has begun to reenter our area. The best way to deal with it is by crop rotation and planting resistant varieties of soybeans. But this nematode has the ability to mutate and overcome resistance.
Nematodes are tricky since they can mimic the appearance of other problems. The symptoms of nematode activity are often misdiagnosed for soil fertility, drought, and disease symptoms. The damage they do to roots can create entry points for diseases that might otherwise be tolerated by crops.
A problem we have with overwintering of nematodes is that many of our winter weeds such as henbit, chickweed, deadnettle, the cress species, and others are hosts. This is one of the main reasons we encourage the planting of cover crops which are much less susceptible to nematodes and that offer several other benefits as well.
There are new methods for dealing with these pests that will be coming soon. This idea will be new to most of us, but from what I have seen, it works well. Like most people who are aware of the importance of this issue, I am ready to see something that is economical and not dangerous to the environment or to those of us who deal with it.