AUBURN, Ala.—Gardeners say ‘April showers bring May flowers.’ While these showers may bring flowers for gardeners, it can cause problems for corn producers. In corn fields, wet weather in April is a recipe for nematode problems—specifically cotton root knot and stubby root nematodes. The root knot nematode is a pest that affects both cotton and corn.
Dr. Austin Hagan, an Alabama Cooperative Extension System plant pathologist, said the cooler April weather was conducive to the growth and support of the nematode population.
Nematodes Not Widely Recognized as Yield-Reducing Pests
Nematodes are not widely recognized as a yield-reducing pest of corn. However, producers are more concerned and familiar with nematodes and their control in other summer cash crops such as cotton and peanuts.
“In a multi-year rotation study at the Plant Breeding Unit a decade ago, yield losses in corn of up to 30 percent were attributed to the cotton root knot nematode,” Hagan, who is also a professor in the Auburn University Department of Entomology and Plant Pathology, said. “The study shows yield declines of 4 to 11 percent correlate with every 100 cotton root knot juveniles in a fall nematode soil assay.”
However, the impact of stubby root nematode on corn yield is still unknown.
Stunting from stubby root nematode can be dramatic, but also localized in corn. Producers may see patchy, stunted areas in corn, easily confused with fertility and pH issues.
Nematodes are roundworms from the phylum Nematoda. There are many kinds of nematodes residing in the soil. While an important part of the ecosystem, nematodes can have a major impact on establishing plant stands and may also stunt seedling growth.
“Because of the cooler weather last month, cotton root knot and stubby root nematodes significantly slowed corn seedling growth across the southern half of the state,” Hagan said.
Regional agents throughout the state have been fielding questions and helping producers make decisions about nematode treatment.
Wiregrass Regional Extension Agent, Brandon Dillard, said he suggested producers put out a nematicide as they were planting corn.
“This spring’s planting conditions were similar to conditions during the spring in 2016,” Dillard said. “That year, growers experienced issues with nematodes in corn. We suggested applying nematicides in hopes that farmers would be able to prevent major crop damage.”
Unfortunately, there is little producers can do at this point. Producers can aim to optimize fertility and supplemental irrigation to minimize stress and encourage root growth. Fertilization and irrigation will help offset feeding injury to the root system.
“There are no post-plant nematicides labeled for use in corn,” Hagan said. “Ongoing research projects at several Alabama Agricultural Experiment Station research units are addressing this issue.”