2009-02-04 / Fields & Yields

In the Furrow

Winter Grain Mites
By Peyton Sapp County Extension Agent

Last year in February 2008, I was helping farmers in my previous county deal with an infestation of winter grain mites in small grains (wheat, oats, etc.) and pastures over-seeded with ryeg rass. Bobby Smith, Morgan County Extension Agent, says these mites are back this year in that area and causing trouble even earlier. The mites have been causing havoc in that area and pose an immediate threat to small grain and forage crops that have struggled to grow due to the lack of rain in early fall. I have not seen them here, yet.

The adult winter grain mites are small (1 mm) bugs that are dark brown to almost black with red legs. Small grains, including wheat, barley, and oats, are susceptible along with grasses, especially bluegrass, bentgrass, ryegrass, and fescue. The mite also infests and damages legumes, vegetables, ornamental flowers and various weeds.

Winter grain mites are active during cooler periods of the year (mid-fall to late spring) with peak populations in winter months. Infestations usually occur in January or February and appear to be more common in fields that have been previously treated with sludge or manure. Heavily infested fields appear grayish or silvery, a result of the removal of plant chlorophyll by mite feeding. When high infestations occur and feed on the leaves of plants for several days, the tips of the leaves exhibit a scorched appearance and then turn brown, and the entire plant may die. The mites do not cause the yellowing of leaves characteristic of spider mite infestations. Many infected plants do not die, but are stunted and produce little forage or grain. Damage on young plants is more severe than on older more established plants. Damage also may be greater in plants stressed by nutrient deficiencies or drought conditions.

Foliar applications of pyrethroids such as Warrior on small grains or Mustang Max on grasses are the best chemical controls available for winter grain mites. Be sure and follow the rate and usage restrictions on all chemical labels. Maybe the reason I have not seen winter grain mites in our area is that good cropping practices, like crop rotations, are also helpful in controlling them.

If you would like more information or think you might have a problem with winter grain mites, please contact the Burke County Extension Office at 706-554-2119.

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