Farmers have been wide open the last several weeks harvesting cotton and peanuts. With commodity prices in the state they have been in the past few seasons, our rotations have shortened, dramatically in some cases. This has led to an increase pressure from disease, nutrient deficiencies, and higher nematode populations.
Nematodes are microscopic unsegmented roundworms, and not all are harmful, but there are several species in our area that parasitize our crops. Each species is crop specific, so crop rotation is the best way to prevent populations in each field from reaching levels that economically damaging to your crops. While we do have pesticides that are labeled for some of our crops, they may not be economically feasible in every case, especially in dry land fields that will not make high enough yields to pay for the nematicide. Therefore crop rotation is the easiest way to manage nematodes, but even it is not bullet proof because nematodes may feed on weeds and continue to increase their populations.
Nematode damage is typically in patterns throughout a field, and not uniform to a specific row. Circular spots of stunted plants are a good indication that nematodes are feeding on plant roots and stressing those plants. Interveinal chlorosis of plant leaves are also a good indication that plants are being fed on by nematodes. However, the best time to verify this is to take samples in the fall and send them to the lab to positively identify what nematodes you have, and what crops they affect. Attached below is a very good publication from UGA that lists which nematodes feed on what crops, lists how to sample, and what numbers of nematodes start to show damage for each crop species.
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