Jarrod O. Miller, Extension Agronomist, firstname.lastname@example.org
If you ended up with a range in planting dates for your small grains this year, it is a good time to scout your fields to see what spring may look like. So far in December we have had 10 days with temperatures below freezing in Georgetown, with the lowest temperature at 22°F. November was warmer on average (48°F), but also saw 10 days below freezing. In Newark our low was 20°F, with at least one day never getting above freezing. This is compared to last year, where we saw 80° temperatures in November.
Winter wheat can tolerate temperatures far below freezing if planting conditions were right, so a 20° temperature is more of a problem in October or April. However, if you planted too late or too shallow, a deep freeze can kill your small grains. Getting out in the field now can reveal damage from the past few weeks, and let you get a hold on emergence, tillering and if your crowns are protected in the soil.
Some fields planted in the right window may still be showing signs of damage from cooler fall temperatures, but should recover in the spring. This includes the purple leaves we’ve seen on rye and wheat in Georgetown, and reported to Phillip Sylvester in our Kent County Extension Office. These purple colors can be related to wet, cold soil and phosphorus availability to small grains, similar to what you may see in spring planted corn. Michigan State Extension has an excellent explanation of these conditions (http://msue.anr.msu.edu/news/purple_leaves_on_wheat_explained), from which your wheat should pull out just fine this spring.
Rye with purple tips at the Carvel Research and Education Center
Leaf damage due to freezes or wind burn may also be present, and is prominent in our malting barley trials at Carvel. As long as the crown is protected below ground, this is just cosmetic and new leaves will emerge in the spring.
Barley with freeze damage.
While wet soils are causing P issues, they may also insulate your fields from freezing temperatures. Soils often stay warmer than air temperatures in the winter, especially when there is ample sunlight or a mulching (residue) layer on the surface. Moist soils also change temperature slower than dry soils, buffering your crowns against the cold.
Still, every year and field is different. If you want to know whether your small grains should have been planted earlier, deeper, or with a shot of nitrogen, you should monitor these fields going forward and take good notes for next year.
This article was also posted on the Delaware Agronomy Blog (http://sites.udel.edu/jarrod/2017/12/14/cold-weather-and-small-grains/).