Evaluating Wheat for Winter Injury

• Winter wheat stand evaluation should focus on both plant population and plant health.
• Winter dormancy breaks at or above a soil temperature of 39° F; therefore, evaluations should start after about 10 to 14 days of warm weather.¹
• Evaluate the stand, the average number of plants/ft², stand uniformity, and number of tillers.

Determining Stand Count

In order to obtain an accurate stand count, be sure to allow plants enough time to green up and resume growth after breaking winter dormancy. Using a yard stick, count the number of plants along a 3 foot distance and repeat this procedure in several locations throughout the field.² Average those counts to determine the average number of plants/3 foot of row. Multiply that number by 4 and divide by the row width (in inches) to determine the number of plants/ft². 

For example, in a 7-inch row spacing, if the average number of plants is 44 per 3 foot of row length the calculation would be:

44 average number of plants x 4 / 7 inches = 25.1 plants/ft²

Optimum plant stands for maximizing yield potential are in the range of 23 to 30 plus plants/ft². Plant stands of roughly 15 to 22 plants/ft2 can return yields close to full yield potential when conditions are ideal. If the number of plants/ft² is determined to be 15 or above, tillering can help compensate for poor stands. For those fields with tillers, 15 tillers/ft² are needed for a viable crop.

Evaluating Plant Health

Assessment of plant health should be done by digging several plants and observing the roots for a healthy appearance. Healthy roots should be white and without any dark or soft spots, while healthy dissected crowns should be white to light green. Under circumstances where the majority of plants appear to be unhealthy, crop destruction may be warranted.

Management

If plant stand counts are below 5 to 10 plants/ft², destroying the wheat stand and planting another crop may be justifiable. Crop options for replanting may be corn, soybean, or sorghum, but always consult with your seed and herbicide consultant to understand any herbicide carryover concerns that may damage the replanted crop.

Seed cost, fuel, crop protection inputs (herbicides, insecticides, fungicides), cost to destroy, and projected wheat yield (if kept) compared to a new crop potential yield and return should be considered if replanting to a new crop. Prior to destroying a wheat crop, the crop insurance company should be contacted to determine options if needed and review your insurance policy.

Summary

• Evaluation of wheat stands is important for quick management decisions.
• Plants with a healthy crown can develop new growth early in the season.
• White, healthy roots without dark soft spots and white to light green internal crown tissues are indications of a healthy wheat plant.
• Removing the wheat stand and planting another crop may be justified if the plant stand counts are below 5 to 10 plants/ft².

Sources:

¹Lindsey, L., Lentz, E., and Paul, P. 2014. Evaluating winter wheat stand. C.O.R.N. Newsletter. The Ohio State University. http://corn.osu.edu

²Rankin, M. Evaluating and managing winter wheat stands in the spring. University of Wisconsin. www.uwex.edu Ransom, J. 2009. Evaluating winter wheat stands. Northwest Research & Outreach Center. University of Minnesota. www.nwroc.umn.edu

Web sources verified 05/01/2017. 150326133845