Fall is the Best Time to Control Dandelions and Perennial Weeds
By Ron Honig
Mid-October to early November is a great time to treat perennial broadleaf weeds such as dandelion and field bindweed. With shorter days and cooler temperatures, these perennial weeds are moving nutrients from their foliage down to their root systems. A fall herbicide application applied to the foliage will move a dose of herbicide down to the roots as well and improve chances of satisfactory weed control.
For many perennial broadleaf plants, including dandelion, a fall application of the herbicide 2,4-D in amine or ester form will provide good to excellent control. The best response may be seen when using the herbicide products which are a combination of three or more active ingredients such as Trimec Classic or one of the Weed-B-Gon or Spectracide brand products. These products usually include the active ingredients 2,4-D and dicamba, plus additional herbicides such as quinclorac or mecoprop (MCPP).
Dandelion is a perennial plant and will survive the winter and green up again in the spring. New dandelion plants often sprout and emerge in late summer and thus are vulnerable to a fall herbicide application.
University tests show a fall herbicide treatment on dandelions often yields over 90 percent control the following spring verses only 50 percent or less control from a single treatment performed in the spring or summer.
Field bindweed is a perennial vine with whiteish-pink flowers and arrowhead-shaped leaves. Bindweed produces an extensive root system that once established, can be difficult to decrease. Kansas State University research shows fall herbicide applications containing the chemicals dicamba and quinclorac provide the best control of field bindweed and the best chance of weakening and reducing the root system.
Chemical premixes containing dicamba and quinclorac are readily available at your garden supply store. To find these products you must read the portion of the label indicating the active ingredients in the product and not just the product’s brand name.
Henbit is a winter annual and sprouts in the fall up until sustained cold temperatures stop its emergence. When temperatures warm again, henbit then continues to emerge in late winter to mid-spring. In fertile lawns, henbit can grow a foot high or more with bright purple flowers. Unlike dandelion and bindweed, henbit will eventually die back when hot weather arrives.
Once henbit begins to grow in the spring and produce flowers, it becomes significantly harder to control with herbicides. Fall and early spring herbicide treatments with one of the combination products will provide the best control.
The recommended use rates provided on the herbicide product labels are normally sufficient to provide excellent control when applied in the fall. For best results, choose a day when the temperature is at least 50 degrees F during the daytime.
The one weed we see so much of in late-summer and fall is prostrate spurge. It is that circular, low growing weed that seems to grow out of every sidewalk crack and when its stems are broken, produces a white, milky sap. The good news is prostrate spurge is a summer annual and will freeze in the coming weeks. Thus, it will not require any herbicide treatments.
