Several Pest Management Issues to Think About if You are Saving Cover Crop Wheat or Barley for Grain Production

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu and Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

With the high prices of wheat and barley some cover crops may be kept for grain instead of plowing them under. As long as the stand is sufficient for economical yield the fields can be managed for grain production. There are several pest management issues that could be a problem if you have decided to do this. Loose smut is a systemic fungus disease that is transmitted in infected seed. Infected seed looks healthy and germinates as if it were not infected. When the seed germinates the fungus is activated and systemically grows within the young seedlings. The fungus remains in the plant over the winter and when growth resumes the fungus grows with the plants and eventually to the head where the fungus spores replace the wheat or barley kernel and other flower parts. The only window to control this disease, if the seed is contaminated, is with a seed treatment for loose smut at planting. If the cover crop seed was certified and/or treated with Baytan, Raxil, Vitavax, or Dividend at rates for loose smut control, the crop is protected. Currently there is no labeled foliar fungicide for wheat or barley that will control loose smut if the plants are infected. There is no way to tell if the crop is infected until heading, so if you planted untreated, saved seed or untreated seed from an unknown source there is a risk of loose smut at heading.

Since cover crops are often planted before production fields, Hessian fly could be a potential problem. Fields planted well before the “fly free” dates (New Castle County -Oct 3; Kent County – Oct 8 and Sussex County- Oct 10) could have been exposed for a longer time to egg laying by Hessian fly adults. Any eggs laid in the cover crop wheat hatched into maggots which fed on that wheat and then changed into pupae (called flax seeds) to survive the winter. When the Hessian fly adults emerge from the flaxseed this spring, they will seek a host upon which to lay their eggs. Since wheat is the principal host plant of the Hessian fly and they are not strong flyers, these fields may be susceptible to spring infestations. Please refer to the article “Management of Hessian Fly in the Spring” in WCU Volume 16, Issue 1 for sampling and possible control options.

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