There are a number of tradeoffs for the advantages any one wild oat herbicide might offer. Early wild oat control can result in better yields because the weed has less time to compete with the crop. However, when a herbicide treatment is applied early, odds are greater that a late flush of wild oats will require a second herbicide application, or that some wild oats might escape treatment. Uncontrolled wild oats can reduce yields, and will produce seed that contribute to next year's wild oat problem. In general, under heavy wild oat pressure (over 15 plants/square foot) research has shown that a herbicide treatment should be applied as soon as possible to prevent high yield losses.

Foxtail Control: Making the decision on whether to control foxtail (green, giant and yellow) in small grains is not always easy. Research has shown that infestations of foxtail often do not decrease wheat and barley yields, however; heavy foxtail infestations can cause harvest problems (especially when straight combining) and can cause dockage when the grain is delivered to the elevator.

There are some situations when the cost of a herbicide treatment for foxtail control is not justified. These situations would include:

1. When foxtail infestations are light - Less that 20 plants/ft2.
    
2. When the foxtail emerges after the crop is in the 3 to 4-leaf stage. This is especially true for barley. Once the small grain is in the 3 to 4-leaf stage, it can usually out compete foxtail, there by making a herbicide treatment unnecessary. However, if the foxtail population is heavy (30 plants/ft2 or more) control may be needed.

Moisture stress is another factor that complicates this situation. Weeds will generally cause greater yield losses under drought conditions, therefore foxtail control would be more important in droughty fields.

Making the decision on whether to apply a herbicide for foxtail control is more complicated when the foxtail is emerging with or shortly after the small grain; as is the case in many fields this year. Some of the options to consider for foxtail control are:

• If the foxtail infestation is heavy, and is emerging with the small grain, consider harrowing or rotary hoeing as soon as possible. See the University of Minnesota Weed Science Web Site (http://appliedweeds.coafes.umn.edu/) for results of recent research on non-chemical control of foxtail in small grains.
   
• If a harrow or rotary hoe is not an option, then consider a herbicide. If wild oats are also in the field, the herbicides of choice are Puma – spring wheat and barley or Discover and Everest – spring wheat only, and Achieve - barley only. If the foxtail infestation is light to moderate, then it may be possible to wait and see if the crop will be able to out compete foxtail.
   
• If foxtail is still a problem by the time the small grain is in the 4 to 5-leaf stage, then one of the approval grass herbicides can be used for control. The number of herbicides labeled for grass control in wheat and barley is quickly decreasing. Several herbicides, including Tiller, Dakota, Cheyenne, Far-Go and Avenge are not longer being manufactured. There will be very limited supplies of these herbicides available for the 2004-growing season.

The postemergence grass herbicides available for use in 2004, application timing, grass weeds controlled, and labeled crop are summarized in the table on the following page.

link to further discussions on individual herbicides

Bev Durgan, Extension Weed Specialist