Control weeds, volunteer wheat after harvest
Controlling Volunteer Wheat
By far, the greatest risk for developing serious wheat streak is from volunteer wheat that results from hail during the three weeks prior to harvest. This volunteer allows for a continuous “green bridge” to carry mites and virus to the next wheat crop. Uncontrolled pre-harvest volunteer wheat virtually assures a serious infection of wheat streak in surrounding fields the following year!
The risk of developing wheat streak from volunteer wheat emerging after harvest is much lower than the risk from pre-harvest volunteer, but this risk will depend on the length of time between its emergence and when wheat emerges in the fall.
Breaking the Green Bridge
The most likely source of mites carrying wheat streak mosaic virus are the fields right next to a wheat field. Therefore, controlling volunteer wheat will reduce the risk of developing problems in adjacent fields. However, when large hailstorms result in widespread volunteer and a number of uncontrolled volunteer fields are present throughout a community, the risk of developing serious problems is increased for the entire community. A community-wide effort is necessary to control volunteer in those areas where widespread pre-harvest hail resulted in extensive volunteer.
The most effective way to manage this disease is to break the over-summering “green bridge,” and thus, avoid the buildup of mites and virus before winter wheat is planted in the fall. To be effective at breaking the green bridge, all volunteer plants must be completely dead. The goal must be to completely eliminate pre-harvest volunteer for two weeks between harvest and emergence of fall-seeded wheat.
Volunteer can be effectively controlled by tillage or chemical means. Weather conditions will influence the effectiveness of the method that is used. If conditions following harvest are warm and dry, shallow tillage can provide rapid and highly successful control of volunteer wheat. Tillage is less effective at providing adequate volunteer control when soils are wet or cool conditions exist.
When plants are growing well, glyphosate will provide excellent control of volunteer. If plants are stressed, glyphosate efficacy is reduced and growers should consider shallow tillage or a herbicide containing paraquat, for example Gramoxone Inteon.