As populations of herbicide resistant weeds continue to grow, sound management practices are more critical than ever to keep these weeds under control. Fall herbicide applications are good tool for controlling existing weeds after harvest, which will provide a weed free field in early spring the following year.
According to Mark Loux, OSU Weed Specialist, “Even where the herbicides lack residual, the fall treatment seems to enable more effective control of marestail the following season. In some cases, it’s probable that you don’t even know how much the fall treatment helps out, but our research shows that more often than not it does.”
University research also suggests that most fall applied herbicides provide minimal residual control in the spring and that the greatest benefit from residual herbicides is gained from a spring application. The timing of fall herbicide applications is important to ensure control of existing weeds.
“In our research, herbicides seem to be effective for control of winter annuals and biennials well into December. The rate of plant death can slow considerably, but this is not a problem since weeds just have to die by early spring. Control of perennials typically declines in late November or early December though, depending upon weather,” writes Loux.
University experts have published several excellent articles on this subject that go into great detail, all of which are available online. Below are some effective fall herbicide treatments recommended by Ohio State University research. Keep in mind; it is important to make application decisions based on the weeds present and the crop to be planted the following spring.
Any Crop Next Spring:
-Glyphosate + 2,4-D
Soybeans next spring:
Canopy EX or DF + 2,4-D
Glyphosate + 2,4-D
Metribuzin + 2,4-D (excluding dandelions)
Corn next spring:
Basis + 2,4-D
Glyphosate + 2,4-D
Simazine + 2,4-D (except dandelion)