Ideal plant populations for wheat in Kentucky will be about 30 to 35 plants per square foot. However, populations as low as 18 plants per square foot can result in about 90 percent of yield potential. Each plant should have a minimum of three tillers (including main stem) at this point. There should be around 70 to 100 tillers (includes main stems) per square foot for maximum yield.
You can count plants per square foot to determine if populations are adequate. In 7.5-inch rows, a liner row of 19.2 inches equals one square foot. If rows are 7 inches, then a 20.6 linear inches equals one square foot.
The first application of nitrogen should have helped with tiller development. Taking stand counts as wheat starts some rapid growth should let you know just how much the early nitrogen application helped. Even if tiller counts are still low, total winter/spring nitrogen applications should not exceed 100 to 120 pounds of nitrogen per acre. For example, if 60 pounds of nitrogen was applied in late February/early March, then 40 to 60 additional pounds of nitrogen should be applied in the second timing. Excessive nitrogen will increase the chances for lodging.
Rapid growth of wheat the week of March 14, 2011 also means we could have rapid growth of some weeds. Evaluate fields for weeds and make appropriate decisions on herbicides. Some herbicides can cause more wheat damage if applied too close to a nitrogen application. Double-check and follow labels to avoid injury to the wheat.
Even though the wheat is a little behind at this point, there is still a good chance at getting excellent yields. At the prices locked in last fall and the current commodity prices, good wheat yields will be a great thing.
For more on evaluating wheat stands, or other topics on wheat production, contact your county extension office.
Chad Lee, Extension Agronomist, University of Kentucky