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OSU Extension

College of Food, Agricultural, and Environmental Sciences

September 24, 2019 - 8:01am --

Between prevented plant acres and some of the acres already harvested for corn silage, there are opportunities this year to get a winter wheat crop planted within the optimum recommended planting period, as one important factor to maximize yield potential and achieve a high yield.  The Ohio Agronomy Guide says the best time for planting winter wheat is a 10-day period starting the day after the Hessian fly-safe date.  That date for Wayne County is September 26.  Long-term field research results indicate that planting 20 days after the fly-safe date typically results in a 10% yield reduction and by 28 days after the fly-safe date, a 23% yield reduction is expected. 

Andy Michel, Pierce Paul and Laura Lindsey, OSU Extension specialists provide the following comments regarding why that fly-safe planting date is correlated to good winter wheat production:

“Adults of the Hessian fly lay eggs in emerging wheat. These eggs then hatch into small larvae that feed before spending the winter surrounded by a protective case known as a flaxseed.  The early autumn feeding will stress the young wheat plant right before the winter, resulting in stunted and wilted plants.  Very little egg laying occurs after the fly free date, which helps to limit infestation. Wheat varieties with resistance against the Hessian are available, in addition to seed treatments, which can help limit damage.

Two main aphids infest wheat in Ohio: the English grain aphid and the bird cherry-oat aphid.  These aphids rarely cause economic injury on wheat from feeding. However, they can transmit several viruses that can severely impact wheat including Barley Yellow Dwarf virus.  These aphids do not only feed on wheat, but several other grasses that serve as natural sources of viruses.  If wheat is planted too early, and emerges before the aphids overwinter or stop feeding, they can be early transmitters of viruses.  Although seed treatments could help kill the aphids, they may survive long enough to transmit the virus to the plant.  Any transmission in the autumn would likely serve as a local source in the following spring.

Although not directly related to the Hessian Fly, planting after the fly free date also helps to reduce the early establishment of leaf diseases like Stagonospora leaf blotch and powdery mildew. Planting date is indirectly linked to spore production by fungi that cause these diseases and infection of young plants. The earlier you plant, the more spores are available, and the more suitable (warmer) conditions are for infection. Fall infections often leads to more damage and greater yield loss in the spring, especially of susceptible varieties are planted and not protected with a fungicide at Feeks 8 (flag leaf emergence). As conditions become cooler after the fly free date, pathogens that cause leaf diseases become last active, and as such, are less likely to infect plants.”

            While the fly-safe date and timing of planting after that date have a significant impact on yield potential, another factor to consider is crop rotation.  A number of prevent plant acres had small grains planted with intended use as a forage crop to be harvested after September 1.  If these acres go back into a fall-planted winter wheat crop, then there are additional disease management considerations.  Pierce Paul, OSU Extension specialist, says that he never recommends planting a small grain crop after another small grain crop or even after another grass crop like corn, because that is a situation that increases the risk of head scab and take-all disease. The best practice is to follow winter wheat after a soybean harvest that allows planting within the 10-day after the fly-safe date period.  This is not a likely scenario for most Wayne County acres this year given late planting dates.  For those growers that find themselves in a situation where winter wheat will have to follow a small grain or corn crop, Pierce Paul advises the following management practices:

  • Select and plant the most resistant variety that you can find.  Check the Ohio Wheat Performance Trials report (, and select a variety with resistance to as many diseases as possible.  Give priority to head scab, Stagonospora, and powdery mildew resistance.
  • If conditions become favorable for disease development in the spring, resistance alone will not control head scab. Plan to apply a fungicide if it becomes wet and humid during flowering.
  • If you cannot rotate away from a small grain crop, the next best option to reduce spore build-up in the field is tillage.  Most of the common leaf and head diseases in Ohio and even some root diseases survive in crop residue. Tillage will bury residue, leaving fewer spores available to infect the newly planted crop. Tillage will also speed-up residue decomposition.

For more information about winter wheat management, contact the Wayne County Extension office at 330-264-8722.



Rory Lewandowski is an OSU Extension Agriculture & Natural Resources Educator and may be reached at 330-264-8722.

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