July's Weed of the Month is wild carrot (Daucus carota), also known as Queen Anne's lace. It is native to Europe and Asia and was introduced to North America as a vegetable crop. Since its introduction, wild carrot has naturalized and is found in every state, including a large part of Minnesota.
Wild carrot is a biennial that grows as a rosette in its first year and flowers in its second year. The stem is hairy, and the leaves are alternate, feathery, and lacy. The flowers are tiny, white, and occur in 2-4 inch clusters. When the seedhead dries, it will curl up and fall off, scattering seeds. The plant develops long taproots that smell like edible carrots.
Wild carrot is found in a variety of habitats, including pastures, old fields, prairies, and ditches. It spreads by seed which is distributed by human activities, wind and animals. The seed has hooked spines that attach to clothing and animal fur. It quickly outcompetes other species and is a threat to native habitats; however, healthy native grasses and forbs can suppress wild carrot over time.
Wild carrot looks very similar to a very toxic plant called poison hemlock. However, poison hemlock reaches heights of eight feet, and stems are hairless and have purple spots. The sap of wild carrot may also cause a rash; protective gloves, long sleeves, and long pants should be worn when working around this plant.
Wild carrot is a Restricted Noxious Weed in Minnesota. Although landowners are ultimately not required to control or eradicate Restricted Noxious Weeds on their properties, they are encouraged to manage wild carrot appropriately to prevent future spread of this species and degradation of native habitats. Several management options are available for wild carrot. For all options, infestation sites will need to be monitored and treated repeatedly until the seedbanks are depleted.
• Do not plant wild carrot or collect its seed.
• Small infestations can be controlled manually by digging and removing the tap roots.
• Mowing can be effective to prevent the plants from going to seed. Mowing should be done while the plant is flowering but before it goes to seed to prevent spreading seed to new areas. Do not mow wild carrot stands that are producing seeds. Mowing equipment will distribute seeds to new areas and make existing infestations expand and become denser.
• Large infestations can be controlled with foliar herbicide applications.