Lawn Burweed

Nothing designates spring’s arrival like walking barefoot on a lawn of lush, green grass. This pleasant experience can often turn into a painful, sticky situation with the presence of lawn burweed. Other names for this weed are spurweed and stickerweed. Lawn burweed (Soliva sessilis) is a winter annual that germinates throughout thin turf in the fall months as temperatures cool. It remains small and inconspicuous during the cold winter months. However, as temperatures warm in the early spring, lawn burweed initiates a period of rapid growth and begins to form spine-tipped burs in the leaf axils. The seed is contained within the hooked bur.

Description

Lawn burweed is a low-growing, freely branched winter annual. It has opposite, sparsely hairy leaves that are twice divided into narrow segments or lobes.

Leaves are approximately ½- to 1½-inches long and ¼- to ½-inch wide. It has small (¼ inch or less in width), inconspicuous flowers in the spring. It attains an overall diameter of 6 inches and a height of 3 to 4 inches. The most prominent identifying characteristic of lawn burweed is its spine-tipped burs, often hard to see but easily felt.

Lawn burweed (Soliva sessilis) growth habit.
Joseph M. DiTomaso, University of California – Davis, Bugwood.org

Lawn burweed (Soliva sessilis) leaves and fruiting head.
Joseph M. DiTomaso, University of California – Davis, Bugwood.org

Cultural Control

Maintain a healthy, dense lawn by fertilizing and liming according to soil test results and mowing at the proper height and frequency for the specific turfgrass in the lawn. Healthy lawn grasses can outcompete burweed for light, water, and nutrients and reduce the level of infestation. For more information on growing healthy turfgrass, see HGIC 1201, Fertilizing Lawns; HGIC 1205, Mowing Lawns; and HGIC 1207, Watering Lawns.

Chemical Control

Post-emergence Control: The key factor to effectively controlling lawn burweed is to apply a post-emergence herbicide during the winter months of December, January, and February. The weed is smaller and easier to control during this time of year and has not yet developed the spine-tipped burs. Control is not impossible in March, April, and May, but the spines have already formed by this time and will remain after the weed dies. Because lawn burweed is a winter annual, it will begin to die in late spring as air temperatures reach 90 °F. Once the weed has reached a more mature state, multiple herbicide applications may be necessary, which increases the potential for turfgrass injury. Dead or alive, lawn burweed poses a painful problem. The only solution to this is early identification and control.

Table 1. Turf Tolerance to Post-emergence Herbicides for Lawn Burweed Control.

A three-way herbicide may be used on bermudagrass, zoysiagrass, centipedegrass, St. Augustinegrass, and tall fescue. The active ingredients of a three-way herbicide typically include the following three broadleaf weed killers: 2,4-D, dicamba, and mecoprop (MCPP). Products that contain a higher percentage of dicamba and mecoprop will more effectively control lawn burweed. 2,4-D controls this weed less well.

Herbicides containing 2,4-D should be applied at a reduced rate on St. Augustinegrass and centipedegrass to prevent damage to these lawns. If a second application is needed, apply the herbicide in spot treatments. Repeated applications of a three-way herbicide should be spaced according to label directions. Read the label for the rate to use on each turfgrass species. See Table 2 for examples of brands and products for use on residential lawns.

In addition to three-way herbicides, there are several other herbicides that can be used for lawn burweed control in home lawns. Atrazine may be used for weed control in centipedegrass and St. Augustinegrass. Atrazine applied in November will have post-emergence activity against newly sprouted lawn burweed seedlings and also will have pre-emergence activity against those that have not yet germinated during the fall. Do not apply atrazine to lawns in areas with a high water table. Do not apply atrazine herbicides within two times the width of the drip line of desirable hardwood trees and shrubs. See Table 2 for examples of brands and products for use on residential lawns.

The herbicide mix of thiencarbazone, iodosulfuron, and dicamba, as found in Celsius WG Herbicide, is selective to control many broadleaf weeds and several grass weeds in all four of the common warm-season grasses. It cannot be used in fescue lawns but can be used to remove fescue from warm-season lawns. Apply when lawn burweed is actively growing and again 2 to 4 weeks later. Adding a non-ionic surfactant, such as Southern Ag Surfactant for Herbicides or Hi-Yield Spreader Sticker Non-Ionic Surfactant, will increase control. Celsius WG Herbicide is safe to apply during spring green-up of warm season grasses.

Metsulfuron, such as in Quali-Pro MSM Turf Herbicide, gives very good control of lawn burweed in bermudagrass, centipedegrass, St. Augustinegrass, and zoysiagrass lawns. Quali-Pro Fahrenheit Herbicide also contains metsulfuron along with dicamba. For these two professional products, a non-ionic surfactant, such as Southern Ag Surfactant for Herbicides, Hi-Yield Spreader Stickers non-ionic surfactant, or Bonide Turbo Spreader Sticker, is required at 2 teaspoons per gallon of spray mix for best control. A non-ionic surfactant will help the herbicide adhere to the leaves for increased penetration.

Do not apply metsulfuron to lawn if over-seeded with annual ryegrass or over-seed for 8 weeks after application. Metsulfuron may cause temporary yellowing of turfgrass. Do not apply metsulfuron to turfgrass under heat and drought stress. Do not plant woody ornamentals in treated areas for one year after the application of metsulfuron. Do not apply metsulfuron herbicides within two times the width of the drip line of desirable hardwood trees and shrubs. Do not apply metsulfuron herbicides when high temperatures are above 85 °F.

CAUTION: Most post-emergence herbicides should not be applied during spring transition (green-up of lawn) or when air temperatures exceed 90 ºF as this may cause severe damage to the turfgrass. A newly seeded lawn should be mowed a minimum of three times before applying an herbicide.

Note: Read and follow all label instructions when using herbicides. Repeat applications 10 to 14 days apart may be required for acceptable control by post-emergence herbicides. Do not mow within 48 hours after the application of most herbicides. Most post-emergence herbicides need to dry on the leaf surface before irrigation or rainfall occurs.

Pre-emergence Control: Isoxaben is a pre-emergence herbicide for control of lawn burweed, as well as many winter broadleaf weeds in bermudagrass, centipedegrass, St. Augustinegrass, zoysiagrass, and tall fescue. Apply isoxaben in late September to early October before the winter weeds germinate. A repeat application may be needed 8 weeks later if there is a heavy infestation of weeds. Do not reseed or overseed within 60 days of last application, and do not apply to newly seeded lawns until the lawn has been mowed three times. Granular pre-emergence herbicides must be activated by ½ inch of rainfall or irrigation as soon as possible after application. See Table 2 for examples of brands and products for use on residential lawns.

Table 2. Herbicides to Control Lawn Burweed in Residential Turfgrass.

Pesticides are updated annually. Last updates were done on 8/21 by Joey Williamson.

Originally published 06/09