Katie Jennings, Department of Horticultural Science, North Carolina State University
A Practical Approach for Growers
Weed control remains one of the most labor-intensive and costly challenges in strawberry production. Without proper management, troublesome weeds like yellow nutsedge, henbit, common and mouse-ear chickweed, Carolina geranium, curly dock, hairy vetch, and other winter and even summer annuals like pigweed species can quickly become a problem in row middles and in the strawberry planting holes and ultimately reduce yield.
In plasticulture systems, effective weed management hinges on integrating multiple strategies including chemical, mechanical, and cultural to maintain productivity and reduce crop loss. Strawberry growers routinely use a combination of fumigation, herbicides, hand weeding, and cover crops in the row middles (between plastic-mulched beds). Complementary cultural practices, such as planting healthy, disease-free transplants and rotating fields, can help reduce weed populations over time. However, many growers commonly use the same fields for strawberry production due to their proximity to roadside markets. While convenient, this limits the ability to rotate crops, a strategy that could otherwise help reduce weed populations and break pest and disease cycles. Starting with healthy, vigorous strawberry plants is essential, as they are better able to tolerate herbicide applications, and a strong crop canopy helps suppress weed germination and growth in the planting hole and contributes to more effective overall weed management throughout the season. Managing weeds in field margins is also important, to reduce the weed seedbank.
Hand weeding is an effective tool, especially for removing weed escapes. However, labor costs are significant. Strategic use of herbicides and cultural controls can reduce the need for hand labor. Annual ryegrass in the row middles can suppress weed growth between plastic covered beds. However, quick establishment is critical. Otherwise, weeds may outcompete the ryegrass.
Each herbicide used in strawberry production has specific limitations, including restrictions on timing and application method. Crop safety often depends on whether the herbicide is applied preplant or postemergence, and observing preharvest intervals is critical to ensure crop safety. Read the label before buying a product to ensure that it is appropriate for your situation.
For preemergence weed control, some products with EPTC (Eptam 7E, Epitome), napropamide (Devrinol 2-XT, Devrinol 50DF-XT), flumioxazin (Chateau SW, others), oxyfluorfen (Goal 2XL, others), and sulfentrazone (Spartan 4F, others) can be applied to the pre-formed bed prior to laying plastic. If EPTC is used for preemergence control of yellow and purple nutsedge in the beds, it must be applied at least 45 days prior to planting strawberry plants. Sulfentrazone has greater activity on yellow nutsedge than purple nutsedge and will also control other troublesome weeds in strawberry including henbit, common, and mouse-ear chickweed, and Carolina geranium. Flumioxazin controls many problematic weeds in the bed including henbit, common and mouse-ear chickweed, wild radish, shepherd’s purse, cutleaf evening primrose, and corn spurry.
Postemergence (POST) over-the-top options for broadleaf weed control in the strawberry bed after transplanting is limited to clopyralid (Stinger) which requires a state-specific 24(c) (special local need) registration. It controls two very troublesome and competitive weeds, vetch and curly dock. Requirements for Stinger use vary by state, so review the 24(c) label for your state, as applicable. Not all southeastern states have one.
Some products containing acifluorfen (Ultra Blazer, others), carfentrazone (Aim EC, others), glyphosate, and paraquat are registered for POST application in strawberry row middles. These herbicides must be applied with care to avoid contact with strawberry foliage. To minimize the risk of crop injury, most require the use of hooded or shielded sprayers to prevent drift onto the plants or fruit. Product selection and application timing are crucial to avoid crop injury and maximize effectiveness. For postemergence grass control in strawberry beds or row middles, clethodim (Select, others) or sethoxydim (Poast) can be safely applied over the top of strawberry plants without causing crop injury. In summary, no single tactic will deliver season-long weed control. Instead, growers should tailor programs using preplant fumigation, well-timed herbicide applications, properly managed annual ryegrass in the row middles, strategic hand weeding, crop rotation when possible, and good field hygiene.