Will your winter wheat crop survive the brutal cold?
According to Romulo Lollato, Kansas State University Extension wheat and forage specialist, there are several factors that come into play when determining if this year’s wheat crop will endure Mother Nature’s wrath. The most important factors from the crop’s perspective are proper cold hardening and root system development, and the overall crop condition in terms of damage from pests. Other factors include air temperature, soil temperature at the crown level, snow cover and soil moisture content.
The current condition of the Kansas wheat crop varies, depending on region of the state and planting date.
Some early-planted fields saw rainfall events in mid-September, which resulted in good stand establishment and plant development. However, as much as 36% of the Kansas wheat crop emerged as late as November. These locations included wheat planted after corn in western Kansas, or after soybeans in central Kansas.
Lollato says the emergence rate was lower due to a lack of precipitation. A large portion of the wheat-growing region saw just 4 inches of rainfall in the last six months. Therefore, these fields had limited development of tillers and root, due to a combination of late emergence, and cool and dry weather conditions. “Fields in this condition will be more exposed to potential consequences of the cold temperatures,” he concludes in a recent K-State Agronomy eUpdate.
Assess the damage
Agronomists at Westbred offer seven tips for determining and dealing with winterkill damage in wheat.
1. Look for color. To test for winterkill damage, growers should dig up a few plants and bring them inside to warm up. Place the plants in a bucket or tub, and add water. If the plants quickly green up, it’s likely not winterkill, just plant tissue burn and dehydration. If the plant does not respond, it may have suffered winterkill.
Growers can also remove some sample crowns, place them in a closed plastic bag and leave them in a warm room. Damaged tissue will turn brown, while healthy tissue remains white.
2. Get counting. Do stand counts in the field. Count the number of plants in the 3-foot length at various locations. Find the average of the different counts. Multiply that number by four, then divide by the row width, in inches, to determine the number of plants per square foot.
Ideally, this number should be between 23 to 30 plants per square foot. However, anything from 15 to 22 plants per square foot can potentially bounce back to reach maximum yield potential.
3. Track tillers. Growers can make up for thinner stands with more tillers per area. To determine the number of tillers, growers can repeat Step 2 — but this time, count both the tillers and the main stems. It takes more than 60 tillers per square foot to produce a viable wheat crop.
4. Let it grow. If winterkill damage is in an isolated area or a small percentage of the field, growers may want to let the crop grow out.
5. Add nitrogen. If winterkill is uniform across the field, growers may need to spray nitrogen in the spring to stimulate tillering. This application should occur as soon as the plant breaks dormancy.
6. Watch for weeds. Winterkill leaves open area for increased weed pressure. Consider an additional herbicide application to control early-emerging summer weeds like kochia, Russian thistle and pigweed.
7. Abandon the crop. When winterkill affects large areas, it may be time to abandon the wheat crop and replant with another crop. However, it is a good idea to check with a local agronomist to understand herbicide carryover that may damage a replanted crop. Also, before tilling up the wheat crop, contact a crop insurance agent for options.
K-State Extension and Westbred contributed to this article.