Last updated 2/23/98
Control of Broadleaf
Weeds in Homelawns
Zac Reicher and Clark Throssell
Dandelions and other broadleaf weeds are listed among the most troublesome turf pest problems in lawns. Even though these weeds are fairly easy to control, it is important to understand that you need not eliminate all weeds from your lawn, and a few weeds are acceptable. It is not economically or environmentally practical to eliminate all weeds from your lawn. The best way to minimize weeds in your lawn is through good cultural practices. On the other hand, the best way to encourage weeds in your lawn is by using poor management techniques such as low mowing, no or improperly timed fertilization, and over-watering. Weeds can also infest areas killed by disease or insects.
Where Do Broadleaf Weeds Come From?
Cultural Control Measures
Herbicidal Control Measures
The best herbicide choice is a general-purpose mixture made of two or three of the following components: 2,4-D; MCPP (mecoprop); and dicamba (Banvel). Products with more than one herbicide component will control a wider spectrum of broadleaf weeds. Read and follow all directions on the herbicide label.
The best time to apply a general-purpose broadleaf herbicide is mid-September to mid-October. The fall represents the best time to control perennial broadleaf weeds such as dandelion, plantain, and clover. These weeds are storing energy reserves for the winter in their roots. Thus the herbicide will enter the plant and travel to the roots with the food reserves, thereby giving a complete kill of the weed. The second best time is in the late spring or early summer period after the weeds have flowered. If applying in the late spring, be extremely cautious with these herbicides near ornamentals, trees, flowers, and vegetable gardens because these plants can be damaged by these herbicides through direct application, drift, and/or volatilization. This is one of the reasons why we prefer to apply these herbicides in the fall.
Summer Annual Weed Control
Summer annual weeds (spurge, knotweed, purslane, etc.) are very difficult to control for a number of reasons. Depending on the species, summer annual weeds germinate at different times during the summer and mature in a very short period of time. Thus, a single application of herbicide might only control a single species of weeds because other species haven't germinated yet or have grown too large to be controlled. Plus, summer weeds have a thick, waxy layer on their leaves to prevent water loss which also limits the herbicide from penetrating the leaf. Consider the following strategies for controlling summer annual weeds.
Weeds like creeping Charlie (ground ivy), thistles, and wild violets are difficult to control because they spread by underground stems or root stocks. Herbicides often control or burn back the top growth, but generally will not translocate to give a complete kill. Plus, these weeds often get started in the shade or other areas where the desirable grass is compromised. The non-pesticidal approaches are necessary to help minimize these weeds. Broadleaf herbicides containing 2,4-D, MCPP, and dicamba should be used. A herbicide containing triclopyr and chlopyralid is very effective on these weeds, but this product is currently available only to professionals. Either consider hiring a professional to control these difficult weeds, or learn to coexist with these weeds and not spend time and money trying to control them.
It is impossible to get 100% weed control in your lawn. By combining cultural methods and an application of broadleaf herbicide in the fall, you should be able to minimize the number of broadleaf weeds in your lawn.
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