Posts Tagged ‘freeze injury’

Another Risk of Frost on the Small Grain Crop

Thursday, April 26th, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Although the various forecasting sites differ in what morning will be the coldest over the weekend and into early next week, several suggest the possibility that frost pockets will develop in the Mid-Atlantic region with the greatest risk for the northern areas of the region. The winter wheat crop is beginning to reach heading and will be at one of its most susceptible stages for frost injury. It’s hoped we won’t have freezing temperatures which can completely destroy the seedhead turning it into a watersoaked mass that will not recover (See Photos 1 and 2).

Photo 1. Freeze damage to winter wheat in northern Delaware causing tiller injury, seedhead death, and leading to infection with many secondary pathogens. (Photo taken two weeks after a severe frost.)

Photo 2. Emerging flag leaf following severe frost injury.

Although there’s nothing producers can do to effectively prevent frost damage on their small grains, they should scout their fields to assess the amount of damage a few days to a week or so after the injury occurs. This should help with their marketing plans.

When the frost injures the pollen containing anthers, the seedhead will emerge normally but you may be able to detect white awns or white florets or heads that may remind you of wheat scab (Photo 3). In his “Wheat Disease Update” in this issue of WCU, our Plant Pathologist, Bob Mulrooney, comments on the possibility of scab in wheat this year and indicates that even in irrigated fields the chance is rather low due to the extremely dry spring weather. Therefore if you see heads that remind you of scab, the more likely explanation will be frost or freeze injury. Unfortunately, the impact of this type of injury on yield is severe. A number of good publications are available on the internet showing photos of injury symptoms and discussing yield implications. In particular, the University of Kentucky and Dr. Lloyd Murdock has had a lot of experience with this problem.

Photo 3. White, water soaked florets from frost/freeze damaged wheat in 2012