February 21, 2017
Assessing Your Winter Wheat Stand
Winter wheat is beginning to come out of dormancy, and the biggest concern on many growers’ minds is winter survival. Between growers who planted too early, resulting in too much growth too quickly, to those who planted later and were met with little to no precipitation, there are a lot of fields across all wheat growing states that may have stand issues. How do growers make the decision on whether to replant or power through the season? Following are four steps to help growers assess stand and make mid-season decisions for winter wheat.
1. Test for Winterkill
To test for winterkill damage, growers can dig up a few plants and bring them inside to warm up. Growers should place the plants in a bucket or tub and apply 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.
Another way to determine if plants are healthy is to remove some sample crowns from the field, place them in a closed plastic bag and leave them in a warm room. If the crown has a brownish or dry appearance, then growers should be concerned. Crown tissue that is severely damaged will quickly turn brown, while healthy tissue remains white.
2. Determine Plant Population
Growers can determine their plant population by doing stand counts. To complete a stand count, growers should observe three feet of a row in various locations throughout their field. To find a stand count, growers should count the number of plants in the three-foot length and find the average of the different counts. They should then 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 in the range of 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. Evaluate Number of Tillers
Stand issues can be overcome if heads per unit are higher than average because a thinner stand that has a lot of tillers per area can still compensate. Tillers are the ancillary stems that branch out from the main stem. Some varieties will not tiller profusely so it is wise to understand how much different lines can compensate.
To determine the number of tillers, growers can repeat the same process they use to determine plant population, this time counting both the tillers and the main stems. As a rule of thumb, more than 60 tillers per square foot is necessary for a viable crop.
4. Make a Decision
Once growers have observed the three conditions above, they will need to decide their next steps.
If winterkill damage is in an isolated area or is a relatively small percentage of the field, it’s recommended that growers let the spring play out.
If winterkill is uniformly 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 for maximum effectiveness. When plants suffer from winterkill, it leaves open area for increased weed pressure. Growers should consider making an additional herbicide application to control early-emerging summer weeds like kochia, Russian thistle and pigweed.
If large areas are affected it may be more lucrative to abandon the crop and replant with a spring wheat or another crop. Before making this decision, growers should talk to their agronomists to get their advice. Agronomists can help growers understand any herbicide carryover that may damage a replanted crop. Prior to removing a crop, growers should contact their crop insurance company to determine options as well.