Air May 5, 2004

Thank you Gary, and good morning everyone.

The rain late last week was certainly welcome news, but the topic of discussion this week is, of course, the frost on Monday morning. Needless to say, at 8 a.m. on Monday morning, my phone was ringing and everyone wanted to know was if their was damage to the wheat.

Okay, the short answer - yes, there was damage. How much and how severe we won't know until later this week at the earliest. Let's hit the details. Wheat that is headed or flowering can be damaged by two hours of 30 degree or lower readings. Obviously the longer and the lower the temperature the more the damage will be. Wheat that is in the boot stage is slightly more cold tolerant, we generally say that damage starts after two hours of 28 degree readings or lower. Less injury, but still some, can be expected from exposure to those temperatures for less time. More injury can be expected from higher temperatures for a longer time. Monday morning temperatures at the Manhattan airport were at 32 degrees from 3 a.m. To 7 a.m. With a dip down to 31 at 6 a.m. That long at 32 degrees probably caused a little damage. We see some frost damage every year. In severe freeze damage you can walk into a field as little as six hours after warm up and smell the damage. I don't think we had that hard of a freeze. In other cases the damage is so subtle that part of the head or flowers are damaged and the only thing you know is that all of a sudden at harvest time you have empty heads. We are probably more in this range. One of the more common symptoms is burnt leaf tips - that damage should be showing up by now. If you saw frost on your wheat field, you probably had some damage. It is still early enough that undamaged tillers may make up all or some of that. We simply won't know for some time. By tomorrow or Friday I can probably start to detect the more obvious damage by looking at the wheat heads and flowers with a hand lens. If you have insurance, I would make sure that your carrier is notified that you may have frost damage. In severe damage cases we can harvest the wheat for hay. Hopefully we don't have that much damage, but for now, all we can do is play a waiting game!

This is Chuck Otte, Geary County Extension Agent, with Ag Outlook 2004.

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