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, these pre emergents need to be applied before weed seeds germinate — generally when the soil temperature (NOT the air temperature) reaches 52 degrees F, and then watered in thoroughly. This usually occurs March 1-15 in the central Texas area.Preemergence herbicides include Surflan (oryzalin), Pendulum (pendimethalin) or Barricade (prodiamine). A second preemergence application 60 days after the first will be beneficial.
There are very few post emergent treatments available for field sandbur (grassbur) control since MSMA and DSMA are no longer available to homeowners. Imazaquin (Image®70 DG herbicide) is one of those products available to homeowners and can be applied when sandbur is actively growing following spring green up, through the summer months and into fall. Results may vary based on the plant size and density.
A dense stand of healthy grass provides the best weed control. Because most weeds are “opportunists” that invade weakened lawns, the fight against weeds starts with good management. All cultural practices such as mowing, fertilizing and watering should be done in a manner and time that will favor the grass rather than the weeds. Height of mowing influences competition against weeds such as crabgrass – the higher the cut, the lower the infestation. Frequent light sprinkling encourages shallow-rooted weeds and seed germination. Less frequent “deep-soak” watering that maintains a dry surface layer provides the grass with a competitive advantage.
For more information about controlling sandburs or other lawn and garden questions, contact the Texas A&M AgriLife Extension Service at (979) 865-2072, or click the Ask the Agent tab.
Prepared by Philip Shackelford, PhD
County Extension Agent for Agriculture & Natural Resources
Texas A&M AgriLife Extension Service of Austin County
The information given herein is for educational purposes only. References to commercial products or trade names are made with the understanding that no discrimination is intended and no endorsement by Texas A&M AgriLife Extension Service personnel is implied.