Nematode fears move to corn
Soybean cyst nematodes are old news in Indiana. Now corn nematodes are making noise. There are also opportunities to treat for corn nematodes now that we didn’t have before.
• Test to determine if corn nematodes are present.
• Votivo sold with a higher rate of Poncho will control nematodes.
• Replicated strips are needed to pick up possible differences.
The Indiana Certified Crops Advisers panelists advise you on how to get the best use of corn with nematode protection, plus how to know whether the product is really helping yields or not.
Question: I agreed to buy 40 bags of seed corn treated with something that’s supposed to control nematodes. I don’t even know if I have a nematode problem. Is there some way I can test to see if it really helps? If I plant one field with it across the road from one without it, will that tell me what I need to know?
Greg Kneubuhler, G & K Concepts, Harlan: Nematodes may become a hidden pest because without testing, you can’t determine level of infestation. They can’t be seen without lab equipment. Now is a good time to begin planning for potential nematode issues. If you farm sandy soils, your potential may be higher. However, nematodes have been found across the entire state. The best time to sample is four to six weeks after planting. A few weeks ahead of or after the window doesn’t make a big difference.
Planting of a field opposite the other will not be an effective way to discern the need for nematode protection.
Jesse Grogan, LG Seeds, Lafayette: Yes, there is a way to test the nematode product. Fill the planter so that you can harvest side-by-side strips across the field. One strip should be with the nematode product, next to untreated corn strips. Nematodes are not equally distributed, but are clustered throughout the field.
Repeated strips are likely to pick up patterns. That will give you multiple comparisons to make a decision about a nematode product’s effectiveness. Planting a whole field as a block across the road won’t give you good information. Soil and root tissue samples can be collected from several strips in mid-June and sent to a lab for nematode analysis to confirm nematode infestation.
Darrell Shemwell, Posey County Co-op, Poseyville: Testing for nematodes is fairly simple. If there are areas in a field where you have seen symptoms, such as uneven stands or stunted plants in your corn, dig up two to four plants and leave the soil and roots intact. These samples should be taken during the middle of the growing season to determine if the nematode populations are at densities high enough to cause significant damage. You should also collect plant and soil samples of healthy plants to compare to stunted plants, and send them to an authorized lab.
Many seed companies are selling hybrids that are treated with a higher rate of Poncho and Votivo to control nematodes in cornfields. I suggest planting side-by-side in fields where nematodes are thought to be a problem. These plots should be replicated if possible across the field by using the same hybrid of corn, the untreated seed and the Votivo-treated seed. Be sure to weigh plots at harvest to determine yield differences.
This article published in the April, 2011 edition of INDIANA PRAIRIE FARMER.