A biennial weed named for its flowers' lacy appearance, Queen Anne's lace (Daucus carota var. carota) appears in lawns as a low rosette of leaves in its first year. It produces tall flowering stalks the following year. Certain kinds of herbicides provide effective control of Queen Anne's lace without harming grass, and improved lawn maintenance helps prevent the weed from flowering and returning. Hardy in U.S. Department of Agriculture plant hardiness zones 3 through 9, Queen Anne's lace is also called bird's nest and wild carrot.
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Herbicides for Broadleaved Weeds
When properly applied, herbicides formulated to kill broadleaved weeds control Queen Anne's lace but not all kinds of grass. Herbicides containing 2,4-D or triclopyr control that biennial, broadleaved weed, according to the USDA Forest Service website. A product that contains 2,4-D, mecoprop -- abbreviated MCPP -- and/or dicamba is a popular choice for general broadleaf weed control, according to the website Turfgrass Science by Purdue Extension and University of Illinois Extension. Herbicides for broadleaved weeds also can harm desirable plants, including shrubs, however, and so they must be applied with care. Young grass is also vulnerable to those herbicides. Don't apply them to turfgrass seedlings until after the third mowing, and wait four to six weeks before applying herbicides to newly sodded areas. Applying the herbicides when the temperature is higher than 85 degrees Fahrenheit increases the risk of them damaging grass.
Applying an herbicide to control Queen Anne's lace is most effective in fall. Queen Anne's lace produces a deep taproot in its first year, and the flowers that appear the following year produce 1,000 to 40,000 seeds per plant. Controlling the first-year plants is important to help prevent the weed from spreading, and careful lawn preparation increases the chances of successful control. Stop mowing your lawn three days before applying an herbicide, and irrigate the grass thoroughly 24 hours before the application if the soil is dry. Apply enough water to moisten the soil to the depth of the grass roots.
Caution when applying a broadleaved herbicide to Queen Anne's lace helps protect yourself, other plants and the environment. Put on a long-sleeved shirt, long pants, socks, closed-toe shoes, gloves and safety goggles, and apply a ready-to-use product that is 7.59 percent 2,4-D, 1.83 percent mecoprop-p and 0.84 percent dicamba on a dry, windless day. Because some broadleaf herbicides aren't suitable for all kinds of grasses, checking the label of the herbicide you use to determine the product's safety for your lawn's grass and using a different product if necessary is essential. Apply the product at a rate of 4 fluid ounces per 1,000 square feet, or according to its manufacturer's instructions. Don't apply the product near open water, drains, sewers or gutters. Wait three days before mowing your lawn.
Regular herbicide treatments and proper lawn maintenance help prevent Queen Anne's lace from returning. Broadleaf weed seeds can remain in soil longer than 30 years, and applying an herbicide annually for several years may be necessary. Mowing your lawn when it grows 3 to 3 1/2 inches tall, removing one-third of the leaf blades' height each time, also will help provide control. Water your lawn when it shows signs of drought stress, such as a bluish-gray hue or footprints remaining in the turf. Apply water until the soil is moist to the depth of the grass roots. Fertilizers also help prevent Queen Anne's lace by encouraging a dense lawn. Apply 2 to 4 pounds of nitrogen per 1,000 square feet of lawn per year in two applications: one in early fall and one in late fall.