County Extension Agent on combatting Winter Grain Mites
They are back! Last year in February 2008 we had an infestation of winter grain mites in small grains (wheat, oats, etc.) and pastures over-seeded with ryegrass. They are back this year and causing trouble even earlier! These little critters have been causing havoc in our 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.
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. The two main damages are reduced forage yield and reduced grain yield in the spring and summer.
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. Winter grain mites are another reason the good cropping practices, like crop rotations, are useful in weed and insect controls.
For more information on this and other current local issues, contact your local County Cooperative Extension office at 1800ASKUGA1.
Printed in the January 8, 2008 edition.