By Andi Anderson
Late summer and early fall provide excellent opportunities for farmers to control weeds in perennial forage fields. During this period, cool-season forage crops grow more slowly, making it easier to identify and manage troublesome weeds before the next growing season.
Several perennial weeds have continued to create challenges in forage fields, including hemp dogbane, milkweed, and Canada thistle. These weeds are difficult to manage because their extensive root systems allow them to regrow even after their aboveground growth is removed. Effective fall management can reduce the amount of energy stored in the roots, helping limit weed growth in the following year.
Frequent mowing remains an important tool for controlling dense weed patches. When combined with properly timed systemic herbicide applications, mowing can significantly weaken perennial weeds and improve long-term control. For maximum effectiveness, herbicides should be applied when weeds are actively growing and have recovered to a height of about 6 to 12 inches after cutting.
Several herbicide options are available for grass forage stands. Products containing dicamba and triclopyr are commonly used for controlling hemp dogbane and Canada thistle. Glyphosate is often considered one of the most effective options for milkweed management. Canada thistle can also respond well to treatments that include clopyralid or combinations of 2,4-D and dicamba, especially when applied in the fall while plants are moving nutrients into their root systems.
For alfalfa fields, weed management options are more limited, particularly in mixed alfalfa-grass stands. Metribuzin is one commonly used product, although it may provide only moderate control of certain perennial weeds. In pure alfalfa stands, dormant-season herbicides such as pronamide, hexazinone, and terbacil can help control weeds including quackgrass, thistles, and sedges. However, application timing and crop age are important factors that should always be considered before treatment.
Fall is also a good time to manage biennial and winter annual weeds. Poison hemlock, which reaches the rosette stage during late fall, can be controlled more effectively before it becomes established. Crestleaf groundsel is another weed that responds well to timely fall treatments in many forage systems.
Before selecting any herbicide, producers should carefully scout their fields to identify the weed species present. Reading product labels, following application guidelines, and understanding restrictions related to hay use and crop rotation are essential steps for successful weed management.
By combining field monitoring, mowing, and timely herbicide applications, farmers can reduce weed pressure, protect forage quality, and improve the long-term productivity of their hayfields and pastures.
Photo Credit: gettyimages-zoomtravels
Categories: Ohio, Crops