Lawn burweed (Soliva sessilis Ruiz and Pavon) is a cool-season, annual broadleaf weed common throughout Louisiana. Its leaves closely resemble parsley but it can be distinguished by its sharp spines. It spreads through seed. Lawn burweed can grow in a wide range of soil types. It is typically found in areas with moist soil and thin turfgrass. It has a prostrate, low growth habit and can tolerate low mowing practices.
Lawn burweed can be distinguished by its leaves, which are bright green and narrowly divided or lobed, similar to parsley. Leaves are oppositely arranged on the stem and sparsely hairy. Once established, it branches out freely, prostrate across the ground. Lawn burweed produces very small, inconspicuous flowers in the leaf axil, which is where a leaf connects to a stem. Flowers mature into seeds with hard coverings and sharp spines or burs. For more information on lawn burweed identification and characterization, visit the USDA Plants Database at https://plants.usda.gov.
The best way to prevent or reduce weed encroachment is to maintain a healthy lawn through proper fertilization and soil pH and regular mowing. Properly maintaining a lawn through these cultural practices promotes dense and vigorous turfgrass, allowing it to better compete with weeds. Below are the recommended mowing heights and nitrogen fertility rates recommended per turfgrass species. In addition to these lawn care practices, manual removal of weeds may also be necessary.
In addition to cultural practices, herbicide applications may be required to achieve effective weed control. Simazine has good pre-emergence and early post-emergence activity on lawn burweed and can be part of an overall lawn burweed control strategy. Post-emergence herbicides will still most likely be necessary to achieve control. The most important factor for effectively controlling lawn burweed is to apply post-emergence herbicides in early winter prior to flowering and seed set. The plant becomes highly difficult to control once the burs are formed.
When applying any type of herbicide, you must follow the manufacturer's labeled directions. For more information regarding pesticides for turfgrass, please reference the Louisiana Suggested Chemical Weed Control Guide at the LSU AgCenter website www.lsuagcenter.com.