Each year in the early spring, when it is warm enough to walk outside on the lawn bare foot, the county agent gets several calls from homeowners on how to control that sticker weed. By then it is too late.
Lawn Burweed, (Soliva pterosperma) also known as spurweed or sticker weed, is a low growing cool season annual. The leaves are opposite, sparsely hairy and twice divided into narrow segments or lobes. Flowers are small and inconspicuous. Fruits are clustered in leaf axils having sharp spines that can cause injury to humans.
Spurweed reproduces by seed. Each year, if spurweed is given the proper environment, these seeds will germinate sometimes in November through January. Normally, germination and growth take place in areas where your permanent warm season grass has declined. To prevent growth of weeds in the lawn, homeowners may first begin by implementing sound cultural practices. For instance, soil sampling and fertilizing accordingly, ensuring proper mowing heights, making sure you have sharp blades on the lawn mower, along with proper irrigation practices.
The best defense against weeds in a home lawn is to have a dense, healthy turf canopy. Be certain to remove no more than one third of the height of the turf in a single mowing. Removing excess turf tends to leave holes in the canopy that weeds will often invade. Follow a recommended fertility regimen for your specific turf species. Fertilize only when the grass is actively growing. Over fertilization also can cause detrimental effects to the turf and leave voids in which weeds can establish.
If spurweed has made a significant establishment in your lawn, then in addition to the cultural practices previously listed, herbicides are used as supplemental aids in controlling weeds. Atrazine/simazine will control many broadleaf weeds and some grass weeds. This should be the first line of defense for controlling most weeds in St. Augustine grass and centipede grass (mid-late winter). Atrazine/simazine also works well on spurweed in dormant bermudagrass in late winter. Remember that control is reduced as weeds mature.
Problems can occur with atrazine/simazine application in summer on St. Augustine grass. These problems include increased grey leaf spot disease, chinch bug occurrence, and an associated degree of phytotoxicity (leaf burn). If atrazine is applied during the summer, use only the one-half normal rate to prevent these problems. However, remember you want to start spurweed (sticker weed) control now, before it makes its seed head and while you're warm season grass is dormant.
Always read and follow all pesticide label directions. THE LABEL IS THE LAW. Use no more or no less of the product than the label recommends, and heed all safety precautions. Government regulations, testing and evaluation requirements ensure lawn care products present no unreasonable health risks to users, their families, or their neighbors. As long as pesticides and fertilizers are used correctly, they will not harm the environment or you.
For more information regarding this or any other horticultural topic, please feel free to contact Rafash Brew
, Regional Horticultural Specialist, with the LSU AgCenter at 318-368-9935