Weed of the Month: Wild Oats
Author: Allison Kosto, MSU Broadwater County Extension Agent
Weed of the Month: Wild Oats
Allison Kosto
MSU Broadwater County Extension Agent
Although not a problem in lawns, gardens or even rangeland, wild oats are a major cropland weed across the United States.
Description & Habitat
Wild oats are native to Europe and Asia. They are now widespread across the world through a variety of dispersal methods including through cultivated crops, farm equipment and contaminated seed. In the United States, wild oats are most problematic in the northern prairie region in areas where there are a large amount of grain crops. They can be found in fields, roadsides and disturbed areas.
An annual plant (life cycle of one year), wild oats are closely related to cultivated oats. At the seedling stage, the two types are nearly impossible to tell apart although there are discreet differences under a magnifying lens. When the seedhead is present, it is easier to tell the difference. Cultivated oats have a narrower, more compact panicle which is the cluster of flowers that form the seeds. However, this difference can still be hard to see unless the two types are side-by-side.
Wild oats are primarily a concern in cropland where they reduce crop yield, increase production costs, increase harvest time, contaminate seed, host pests and disease, and decrease grain quality. Ten wild oat plants per square foot can reduce barley yield by 18 percent and wheat yield by 24 percent. Just one wild oat plant per square foot can reduce wheat and canola yield by 10 percent.
Another major issue with wild oats is herbicide resistance. The first documented case of herbicide resistance to wild oats occurred in 1990 to the herbicide Fargo. Since that time, wild oats have grown resistant to two other herbicide groups, and some populations even show multiple resistant types.
Management
Integrated weed management (IWM) is critical to control wild oats. IWM is the use of multiple weed control methods to manage weeds. Wild oats are a prime example of what happens if farmers become too reliant on herbicides.
The best strategy is to prevent wild oats from becoming established. Techniques to do this include using only clean certified seed, cleaning machinery between fields, planting perennial grasses along field borders, and destroying seedlings before they produce seed.
Tillage has control benefits when done correctly. Seeds will not survive well on the soil surface, but buried seeds can still emerge when buried 6 inches or more. In order for tillage to be an effective means of control, it must be done frequently to bring the buried seed back up to the surface. Delaying tilling after harvest can be helpful as well because it can result in some loss of wild oat seed on the soil surface. This followed by a shallow tillage (less than 2 inches) can cause a flush of the weed seeds to germinate and then die overwinter.
Crop rotation is critical to control wild oats by extending the time between cereal crops. Crop rotation allows growers to rotate to more effective grass herbicides. Perennial broadleaf crops such as alfalfa are especially effective in reducing wild oats.
Herbicides are still a tool in the toolbox but should not be relied upon fully. Herbicides should be rotated frequently. Tank mixing multiple herbicides can also be effective in bringing greater control and reducing the likelihood of resistant strains developing. Chemical options depend on the type of crop grown. Always read and follow the entire label when applying herbicide.
For assistance on weed identification and management, contact the MSU Extension Office in Broadwater County at 406-266-9242.
Article Images
Click on Image Thumbnail(s) to view fullsize image
PhotoCredit: Provided by County Extension Agent
Image 1 Caption: Wild Oats- Bugwood
Provided by County Extension Agent
