Wheat Curl Mite, Aceria tosichella.
Wheat curl mite on leaf.
Close-up of wheat curl mite (SEM).
The wheat curl mite is widely distributed in North America. These tiny Eriophyid mites are important vectors of wheat streak mosaic virus (WSMV) which is one of the most destructive wheat diseases in western Kansas. They are also vectors of the High Plains Virus, a disease of wheat and corn in the Great Plains, and Triticum Mosaic Virus (TrMV). Combined infections of WSMV and TrMV can be especially damaging in wheat.
Adult and immature wheat curl mites are tiny, white, cigar-shaped organisms with four legs near the head. They are nearly invisible to the naked eye and fit between the veins of the wheat leaves. Eggs are placed in rows along leaf veins. The mites reproduce most rapidly at 75° to 85°F. Reproduction stops at temperatures near freezing, but the mites can survive for several months at near freezing temperatures and for several days at 0°F. Under good conditions, a generation can be completed in 10 days. Most mites are found on the terminal leaves and move to each new leaf as it emerges. Heavy mite populations can cause the leaf margins to role or curl inward hence the name. As the wheat plant dries down, the wheat curl mites congregate on the flag leaves and even the glumes of the head where they are picked up by wind currents and carried to their over -summering grass hosts including volunteer wheat, corn and a few other grasses. As summer hosts start to dry down the reverse process occurs and mites are carried by winds to newly emerged winter wheat. Hail during the heading period can lead to high oversummering populations by knocking heads containing wheat curl mites to the ground and starting early volunteer. This early volunteer can then be immediately infested with wheat curl mites.
Destruction of volunteer wheat at least 2 weeks prior to planting winter wheat in the fall is the most effective management practice for this mite and the disease that it vectors. Avoiding early planting can also reduce wheat curl mite numbers and the length of time that they have to transmit wheat streak. Varietal selection can also be an important way to reduce the impact of wheat streak. Producers in areas where wheat streak is common should avoid varieties that are highly susceptible to WSMV. The KSU cultivar RonL is a white wheat that carries a high level of resistance to WSMV provided it is not exposed to extremely high temperatures in vegetative growth stages. Thus, RonL should be planted mid-season to ensure its resistance is not compromised by high temperatures that may occur in either early fall or late spring. Additional information on varietal susceptibility to wheat streak is available in KSRE publication MF-991: Wheat Variety Disease and Insect Ratings. To date, control of wheat curl mites with foliar miticides has not been shown to be an effective practice.
P. E. Sloderbeck, J.P. Michaud, and Robert J. Whitworth -- May 2008
Page last updated 10/30/2013 by J.P. Michaud.