Pre-emergent Control of Grassburs

Mario Villarino- CEA-Texas Agrilife Extension Service- Hopkins County

 

 Field sandbur (grassbur) is a summer annual grassy weed that can be found in home lawns, sports fields, parks and along roadsides. This weed is especially adapted to dry, sandy soils but can be found growing in other types of soils as well. The big problem with this weed is the sharp, spiny burs that are part of the inflorescence. These burs can be painful and are difficult to remove from clothing material. Field sandburs (grassburs) generally start germinating in late spring and will continue to germinate until late summer or early fall months. This weed will continue to grow until the first hard frost or freeze occurs in the fall. Field sandburs (grassburs) are generally not a problem in well maintained turfgrass areas. With proper fertilization, mowing and irrigation, you can produce a turf that is dense enough to prevent sandbur (grassbur)s from becoming a problem. However, if field sandburs (grassburs) do become a problem there are several effective herbicides that can be used to control this particular weed.

The most effective and efficient method of control is to use a pre-emergent herbicide.  To be effective, the pre-emergent herbicide need to be applied before weed seeds germinate -- generally when the soil temperature (NOT the air temperature) reaches 52 degrees F.  If a post-emergence herbicide is used, wait until the day time temperatures are about 75 degrees F. for the products to be most effective. To insure complete control of germinating grass burrs in heavily infested areas, extend the residual of the herbicide barrier in the soil and thus extend the length of control period by making applications of the pre-emergent herbicide EVERY 6 WEEKS through September. In areas with a light infestation of grass burrs, two applications that are 6 weeks apart and after the initial application should control seed germination. As always, the pre-emergent application needs to be watered in thoroughly. Not applying enough water after application of a pre-emergent herbicide is one of the main reason for failure to effectively obtain control of the annual grassy weeds such as sandburs (grassburs). Remember to always follow the herbicide instructions for application recommendations, doses and use precautions. Always use herbicides with grassbur control listed on the label (adapted from Controlling Field Sandbur (Grassbur) in Turfgrass by James A. McAfee, Ph.D.)