Wheat Curl Mite & Wheat Yield Losses
Wheat curl mite is one of the more difficult pests to manage in wheat. This is in part due to the limited options available for preventing populations from infesting a field and rapidly reproducing. Other pests can often be managed through the use of insecticides or miticides. However, due to the wheat curl mite’s small size and tendency to inhabit protected areas of the wheat plant, chemical management is often impractical.
Although very high mite populations may result in yield losses of as much as 10%, the main concern regarding this pest is its ability to vector Wheat streak mosaic virus (WSMV). Severe infestations of WSMV could result in 100% yield loss of affected fields when infection takes place in the fall. Wheat streak mosaic virus acquisition occurs when the young (nymph) wheat curl mite feeds on an infected host. Acquisition can take 10 to 30 minutes, but the virus will remain active within the mite for 7 to 9 days. Once ingested, WSMV will remain active while the mite develops, but will not pass from one generation to the next through developing eggs.
Steps Towards Managing Wheat Curl Mite
Due to the ineffectiveness of chemical management for the wheat curl mite, the best approach is to prevent the “green bridge” from occurring. The term green bridge refers to volunteer wheat or other grass hosts that may harbor populations of the wheat curl mite prior to the new wheat crop emerging.
Wheat curl mites are not able to fly, but their small size allows them to be transported by wind. If populations of the wheat curl mite have been building in alternative hosts, it is much more likely that they will occur in the new crop. Alternative hosts for the wheat curl mite include volunteer wheat, corn, foxtail, millet, sandbur, and several other grass weeds.
To reduce wheat curl mite habitat and populations:
- Use herbicides or tillage to remove living plant alternative host material in and around the target field at least two weeks prior to planting. The wheat curl mite can survive for approximately 8 hours during warm temperatures without a food source, which makes fast acting herbicides more favorable for use.
- Plant later in the season. Wheat curl mite population growth is reduced when temperatures are at or below 50° F. However, population growth is increased when temperatures are between 70-80° F.
- Rotate with broad leaf crops such as sunflower, field peas, canola etc. Although wheat curl mites can be blown by wind from other fields up to 2 miles away, planting into wheat or adjacent to previous wheat fields increases the risk for wheat curl mites to move into the new field.