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Wild Garlic Control in Turfgrasses

Tim R. Murphy and B. J. Johnson

The University of Georgia

College of Agricultural and Environmental Sciences

Wild garlic, often called wild onion, is commonly found in most turfgrasses throughout Georgia and the southeastern United States during the late fall through spring months. While wild garlic and wild onion are similar in appearance, wild onion can be distinguished from wild garlic by presence of a fibrous coat on the central bulb, no offset bulblets and leaves that arise near the base of a solid flowering stem. Wild garlic has a bulb with offset bulblets that are enclosed by a "papery" membrane. Wild garlic also has slender, hollow cylindrical leaves that occur on the flowering stem up to one-half the height of the plant. In Georgia, wild garlic is more common than wild onion. Since both species respond similarly to herbicides, it is not necessary to identify which species is present before selecting a herbicide for control.

Wild garlic is highly objectionable due to its rapid growth in cool-season turfgrasses after mowing, and clumpy appearance during the dormant period of warm-season turfgrasses. Additionally, the unpleasant odor of mowed wild garlic can linger over an entire neighborhood for several hours after mowing.

Wild garlic is tough to control. A single plant usually has several bulblets that will sprout and grow at different times. Not all bulblets sprout in the same year. Thus, it usually takes 2 to 3 years of postemergence herbicide use to control wild garlic on a particular site. Several herbicides are available to control wild garlic in turfgrasses. Probably the most commonly used herbicide is 2,4-D, or 2-way and 3-way herbicides that contain 2,4-D. Studies conducted in Georgia showed that timing and number of applications are more important with 2,4-D alone than with combinations of 2,4-D+MCPP+dicamba (Trimec Classic). Two applications of 2,4-D (Jan. 1 + Mar. 1) for two consecutive years were required to obtain 90% control. However, the timing of application was important for optimum control. The control ranged from 28% for Dec. 1 + Mar. 1 treatments and 60% for Dec. 1 + Jan. 15 treatments to 92% for Jan. 15 + Mar. 1 treatments. In contrast Trimec Classic applied as a single application for two consecutive years (Jan. 15 or Mar. 1) controlled 98% wild garlic. The control from similar applications on Dec 1 was not as good (74%). Neither 2,4-D nor Trimec Classic effectively controlled wild garlic during the first year of treatment. Two applications per each of two years were also required with dicamba (Vanquish) to control wild garlic. The control was 72% following the single application compared to 98% following multiple applications.

Most 2,4-D and 2,4-D containing products are available either as an amine or ester formulation. Due to vapor drift concerns, ester products are not recommended during the warm months of the year or during the spring "leaf-out" of deciduous trees and shrubs. However, ester formulations are generally more herbicidally-active during the cooler temperatures of the winter months. Additionally, relative to amine formulations, ester formulations are more quickly absorbed by weed foliage and are relatively resistant to removal by rain. Since vapor drift, or volatility, is not an issue during the cool winter months, ester formulations of 2,4-D and phenoxy-containing herbicides should be used for wild garlic control.

Roundup Pro at 16.0 fl. ozs./acre has good to excellent activity on wild garlic when applied twice during a single year. However, the control from Dec 1 + Mar 1 (75%) or from Jan 15 + Mar 1 (78%) was not as good when applied on Dec 1 + Jan 15 (94%). When Roundup is used for wild garlic control, the turfgrass must be completely dormant at time of treatment to prevent turfgrass injury. Roundup Pro is labeled for use only on dormant bermudagrass. The use of Roundup Pro on warm-season turfgrasses such as centipedegrass, zoysiagrass and St. Augustinegrass is not recommended.

Studies conducted at Mississippi State University showed that Image had good activity on wild garlic. However, the control (averaged over five rates and two years) was 75% when Image was applied from Nov. 27 to Dec. 3 compared to only 49% when applied Mar. 4. Image is labeled for use on bermudagrass, centipedegrass, and zoysiagrass and is not recommended for winter applications to St. Augustinegrass. For wild garlic control, Image should be applied to emerged wild garlic after the first killing frost and before spring transition. Mowing of wild garlic one to two weeks after treatment is recommended for improved appearance of the turfgrass area during the winter months. The newest option for emerged wild garlic control in bermudagrass, centipedegrass, St. Augustinegrass and zoysiagrass is Manor (metsulfuron). Manor applications may be made anytime during the late fall, winter and early spring months. Similar to Image, a nonionic surfactant at 0.25% v/v should be added to the Manor spray solution. Manor is not recommended for use on tall fescue.

Wild garlic can be effectively controlled in turfgrasses. However, patience and persistence is necessary. Herbicides used to control wild garlic kill this weed very slowly. Also, on severely infested sites, it will be necessary to apply herbicides for two or more years to obtain effective control.