Syngenta offers recommendations to minimize losses from winterkill damage in wheat

The historic drought last year coupled with limited snow cover in early 2013 has raised concerns about the possibility of winterkill and poor wheat stands this spring. Syngenta recommends wheatgrowers scout fields for signs of winterkill over the coming weeks and assess stands to identify potential damage.
 
“Drought is one stress that will be compounded with another stress – for example, the low temperatures. Drought and limited snow cover typically increase the possibility of winterkill in wheat,” said Joel Ransom, extension agronomist at North Dakota State University. “The greater potential for damage from winterkill this year will depend on the amount of snow cover we receive yet this winter, along with how our weather shapes up as spring approaches.”
 
During the winter, growers typically rely on snow to insulate their wheat and shield crowns from low temperatures, according to Ransom.
 
“Four inches of snow is an amazing insulator; where the surrounding temperature may be minus 40 degrees Fahrenheit, crown temperatures with four inches of snow cover never go below 20 degrees Fahrenheit,” said Jochum Wiersma, extension agronomist at University of Minnesota. “This year we went into winter dry and have had relatively little snow. With limited snow cover and the fluctuation between mild to very cold temperatures, the chances for winterkill increase.”
 
Identifying winterkill injury in wheat
 
Wheat growers are encouraged to identify winterkill damage and to then employ appropriate follow-up actions. Experts note that it is often difficult to distinguish between the damage from winterkill and damage from other potential problems, including snow mold, barley yellow dwarf virus, salt damage, frost injury or even Pythium.
 
Pythium, for example, will not kill plants outright, but rather colonize roots and cause uneven crop growth throughout the field. Winterkill, on the other hand, tends to encompass and destroy larger, more general areas of the field and impacts plants that are left unprotected by snow cover. Jill Herold, agronomic service representative for Syngenta based in Montana, explained that properly identifying issues in the field can mean the difference between having a successful crop and not having one at all.
 
“The impact of improperly identifying winterkill versus disease or insect damage will be reflected in a grower’s ROI and the management decisions he or she needs to make very soon,” Herold explained.
 
Evaluating the degree of winterkill injury in wheat
 
To manage the effects of winterkill, growers must evaluate the degree of winterkill injury in their wheat and adjust next steps accordingly. Symptoms to observe include: plants with one or more dead leaves; patches of dead plants in the field; tiller development without accompanying root system growth; and wilting, yellow and dying of some leaves after spring green-up. Growers are urged to wait until plants break dormancy and fields begin to green up before finalizing any replanting decisions.
 
This year, the drought contributed to small, less winter-hardy seedlings, leading to less established stands that will be more vulnerable to winterkill this spring. Before taking extreme action this spring, such as destroying any remaining winter wheat crop and replanting, Syngenta suggests growers take careful steps to evaluate their wheat stands this spring to see if the crop will be worthwhile to take to harvest.
 
“If you are curious to see whether seedlings are still viable, simply dig up the crowns, wash them off, cut off the dead top growth, place it on a moistened paper towel and place everything in a plastic bag to prevent drying out. Then just wait for them to break dormancy at room temperature,” Wiersma explained. “If they’ll grow leaves again within just a few days, the crowns are still viable.”
 
For assessing stands a good rule of thumb is if a grower’s stand is less than 75 percent, he may want to reseed, suggests Don Drader, agronomic service representative for Syngenta in Washington.   He urges growers to consider the cost of spraying out the existing crop, new seed and potential yield reduction from winter wheat going into spring wheat before making the decision to reseed.
 
Act early to minimize damage from winterkill; considerations for 2013
 
It’s important for growers to begin early with best management practices to protect their wheat against the effects of winterkill. Before planting in the fall, agronomists suggest choosing winter-hardy wheat seed varieties and selecting a good quality seed treatment program to ensure healthy, strong plants.
 
“Strong, healthy plants are more likely to survive versus stressed plants from disease and insects,” Drader said. “Selecting varieties with strong winter hardiness traits and using a seed treatment program will help protect plants from as many adverse effects as possible.”
 
Herold adds, “Seed treatments act as a barrier between the seed and the environmental elements while also protecting the seeds against the risk of damage from early-season diseases and insects. Additionally, seed treatments can hold up against cold temperatures, offering seeds more protection.”
 
Vibrance™ brand fungicide seed treatments work to strengthen the plant by boosting RootingPower and providing protection against damaging diseases. According to Drader, growers who used Vibrance brand seed treatments for 2012 winter wheat planting saw very good stand strength in fields with high Rhizoctonia pressure, keeping wheat healthy throughout the cold months.
 
In addition to variety selection and seed treatments, growers can also employ other cultural practices to help increase wheat yields. Using a no-till or reduced tillage production system can be beneficial as standing stubble helps catch snow and insulate the crop, ensuring protection from low temperatures.
 
As winter wheat breaks dormancy, scouting and stand assessments will be crucial in helping growers determine whether or not winterkill damage will impact their winter wheat yields. Be sure to contact your Syngenta representative or local extension office for further guidance on properly identifying and managing potential winterkill damage and taking the necessary steps to grow more wheat.