Broadleaf Weed Control in Lawns

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10 May

Broadleaf Weed Control in Lawns

Professional Landscape Management has always used Integrated Pest Management (IPM) when approaching a broadleaf weed problem. Studies by Purdue University and the University of Illinois indicate pesticides along with proper cultural practices can manage the problems: “Dandelions and other broadleaf weeds are among the most troublesome turf pest problems in lawns. Even though these weeds are fairly easy to control, complete eradication is not possible or practical, and a few weeds are acceptable.

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 mowing too short, no or improperly timed fertilization, and over or under-watering. Weeds can also infest areas killed by disease or insects.

Where Do Broadleaf Weeds Come From?

  • The seeds of broadleaf weeds occur naturally in all soils, and can persist for 30 or more years.
  • Most broadleaf weeds are prolific seed producers. Many produce thousands of seeds per plant, and these seeds can disperse into your lawn from miles away.

Herbicidal Control Measures

The most common herbicide choice is a general purpose mixture comprised of two or three of the following individual herbicides or active ingredients: 2,4-D; MCPP (mecoprop); and dicamba. Multiple active ingredients will control a wider spectrum of broadleaf weeds, than a single active ingredient.

The best time to apply a general-purpose broadleaf herbicide is mid-September to early November. The fall is the best time to control perennial broadleaf weeds such as dandelion, plantain, and clover. Going into winter these weeds are storing energy reserves in stems and roots. Thus the herbicide will enter the plant and travel to these plant parts 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.

Cultural Practices

  • Mow at 3.0 to 3.5 inches.
  • Mow frequently so as not removing more than 1/3 of the leaf blade at a single mowing. This may mean mowing twice weekly in spring and every other week in summer.
  • Irrigate deeply and infrequently. Water to wet the soil to the depth of rooting and then do not water again until you see the first sign of drought stress.
  • Fertilize to create a dense lawn by applying 2 to 4 pounds of nitrogen per 1000 ft2 per year. Some weeds such as clover are indicators of nitrogen deficient lawns.”

***** This year, Professional Landscape Management has added another dimension to its broadleaf weed control arsenal – a product that prevents some broadleaf weed seed from germination for up to three months. This means that the dandelion seeds you see in late spring won't become the dandelion flower you see in fall. *****