Brown wheat mites like cold weather
February 23, 2010
They like cold weather! Can you believe it? They are certainly nothing like me. The critter I am speaking of is the winter grain mite.
I have said it enough this winter that most of you know that I am a warm weather person. I’m not saying I love it when it gets up to 100 degrees, however I will take 100 over 20 degrees nearly every time. That’s especially true if there is any wind involved. Now like most of you I prefer 70 degree weather, but we don’t get a lot of that. Some can tolerate the heat better, some the cold better. Although I have lived in Kansas all my life and like the variation in seasons, I have been a wimp when it comes to the cold ever since I got minor frostbite as a kid when I went hunting one time. If you like the cold, you fit in with these winter mites.
We have been getting reports of high winter grain mite populations recently. It’s been cold enough without snow cover this winter that most of the wheat went dormant brown more than usual. Typically, we don’t worry too much about these mites until the wheat starts greening up.
This mite has been an occasional concern, particularly in the south central area in recent years, but it might occur about anywhere. This is a cool weather pest, active during the fall and spring. Since it lays over-summering eggs on plant residues, it is more common where wheat follows wheat and perhaps where there is minimum disturbance of plant residues such as in no-till.
The bright reddish-orange legs provide a quick clue in identification of this small brown mite. Mites tend to hide at the base of plants during the day and feed at night causing an off-color, silvery-gray appearance of leaf tissue. They take the chlorophyll out of the leaf tips which give that silvery look from a distance. Except in extreme cases, fall damage often appears to be temporary since that by the following spring; it is sometimes hard to distinguish from treated and non-treated fields.
Fields with loose, sandy or loamy soils are more at risk than those with hard, clay soils. Significant infestations are more common in central Kansas. Because fall populations develop from eggs laid the previous spring, problems are worse in continuous wheat. Crop rotation is helpful in reducing problems, although field borders may be affected when mites migrate from wild grasses. Control may be necessary if large portions of a field show symptoms and mites appear abundant in relation to the amount of plant growth.
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You might start checking fields now to get a heads up before green-up. They are easier to find on cloudy days or when it is only half light in early morning or evening. You may have to pull several scattered plants and put them in bags and them someplace warm for counting – 50-100 plants are worth treating. However, when soil moisture is good and the wheat is not under stress, it can outgrow mite damage. Also, as long as the wheat is dormant, they shouldn’t cause much damage.
These mites are primarily a small grains pest, but they can sometimes be a problem in lawns that have cool season grasses such as fescue, bluegrass or on bentgrass golf greens. So, be on watch there as well.