Controlling Unsightly Summer Weeds

If the hot dry summer has allowed many unsightly broadleaf weeds and crabgrass to encroach into your lawn then now is a great time to apply post-emerge herbicides to remove them. The combination products containing two or more herbicides such as 2,4-D, mecoprop, dicamba, carfentrazone, fluroxypyr, etc. are very effective on most broadleaf weeds. It is important to select a product that is labeled for your specific turf species. While bermudagrass is tolerant to most all of these herbicides centipede and St. Augustine can be quite sensitive and require formulations made specifically for them so read the labels carefully before applying. The most recent class of lawn herbicides is the sulfonylureas. These are very active compounds having very favorable environmental impacts and require only grams of product per acre versus pounds of some of the older products. While they may be difficult to find in small homeowner packaging they offer excellent control of many broadleaf weeds and some selective grasses and sedges with good turf tolerance. Products such as metsulfuron (Manor, Blade MSM), chlorsulfuron (Corsair), halosulfuron (Manage, Sedgehammer), trifloxysulfuron (Monument) flazasulfuron (Katana), foramsulfuron (Revolver) and sulfosulfuron (Certainty) are included in this family of herbicides. Again it is very important to read the labels to see what they control, where they can be used and for which turf species they can be applied to. The old stand-by for crabgrass control in bermudagrass and zoysia lawns has been MSMA (monosodium-methyl-arsenate) which is no longer labeled for residential applications. Quinclorac (Drive, XLR8) may be an alternative while sethoxydim (Segment, Vantage) can be applied to centipede.

Published 08/06/12

Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. wwells@ext.msstate.edu