Virginia buttonweed, Diodia virginiana, is one of the most difficult weeds to manage in home lawns throughout Louisiana. It is a deep-rooted perennial plant with a spreading growth habit. The elliptical shaped leaves are arranged opposite each other along stems. The most characteristic feature of this plant are the small white tubular flowers with four petals that appear in late summer through fall.
If left untouched Virginia buttonweed can eventually form a dense mat by late summer. Notice the white flowers with four petals. By the time they appear late in the season, the plants have matured and hardened off, making them difficult to remove. Photo by Dr. Ron Strahan.
Good example of Virginia buttonweed growing in bermudagrass. You can see the low growing, spreading growth habit as it spreads throughout the lawn. Photo by William Afton.
One of main reasons why Virginia buttonweed is so difficult to manage is because it can reproduce itself by seeds, roots, or stems. Regular mowing of the lawn has the potential to spread Virginia buttonweed around the yard because stem fragments can easily root and start new plants. Some homeowners often resort to hand pulling but this too can lead to the spread of root and stem pieces. The best approach to managing Virginia buttonweed in the home lawn is to take an integrated approach and combine several control methods together.
Cultural control methods are often overlooked but they can help with long-term control if the homeowner stays persistent. To reduce the competitive advantage of Virginia buttonweed take necessary steps that promote the growth of healthy turfgrass.
Supplement irrigation when rain is not providing enough water for the lawn. Provide deep and infrequent irrigation to encourage lawn growth. Allow the lawn to thoroughly dry out before reapplying. Excessive irrigation and water logged soils can predispose the lawn to a Virginia buttonweed infestation
Apply practices that reduce soil compaction. Compacted soils are a problem in South Louisiana due to the amount of rainfall we receive in a year. Normal human traffic can also lead to compacted soil areas. The simplest way to reduce soil compaction is by using a core-aerifying machine. The machine removes plugs of soil in an effort to break up the compacted layer and increase water infiltration. Warm season turfgrasses like centipedegrass, st augustinegrass, bermudagrass, and zoysiagrass can be aerified during the active growing season. To reduce soil compaction from the use of riding lawnmowers, mow in different patterns and avoid taking the same path every time.
Severe infestations may require the use of an herbicide to control and suppress Virginia buttonweed. Preemergent herbicides are gaining in popularity but they have little to no effect on Virginia buttonweed and therefore, are not recommended.
Virginia buttonweed is tolerant of most selective herbicides used for weed control in the home lawn, especially later in the season when plants have matured and hardened off. Spray programs should begin early in the season as the plants emerge from winter dormancy.
Four way herbicides (2,4-D + dicamba + mecoprop + carfentrazone) can be used during the months of April, May and June before the average high temperature exceeds 85°F. Some of the common trade names include Speed Zone Southern and Weed Free Zone.
If applications are needed later in the season, use the active ingredient metsulfuron. It can be found in MSM Turf. One of the most effective herbicides to control Virginia buttonweed is Celsius (iodosulfuron + thiencarbazone + dicamba). Both of these herbicides can be applied when temperatures exceed 85°F.
Remember to always read and follow label instructions before applying any pesticides.