Doveweed: identify it, treat it, keep it out

Doveweed is a very convincing impostor. UF/IFAS notes that it looks like grass and has a leaf width similar to St. Augustinegrass and centipedegrass, so it often goes unnoticed until it has spread. So where do you start? With color. Is the patch a brighter, glossier green than your turf ever turns? LSU AgCenter names that bright green as the feature that separates doveweed from these grasses.

Next, pull up one runner and look along it. Doveweed leaves are thick, shiny, and rubbery, and they grow from creeping stems that root at the nodes, per UF/IFAS. LSU adds that those stems are sometimes light pink to red. In summer, look for small flowers with three purple, sometimes blue, petals on short stalks near the nodes. If the color, the rubbery leaves, and the rooting stems all fit, you have doveweed.

Then check where the patch sits. LSU calls doveweed an indicator of poor drainage, and UF/IFAS says infestations favor wet areas. A patch in the low corner of the yard or beside a leaking sprinkler is pointing at the reason it moved in.

Timing is the first reason. UF/IFAS says doveweed seed starts germinating late in spring, when soil temperatures reach 65 to 70°F. A pre-emergent applied in February or March for crabgrass may be fading by then, so doveweed slips through a barrier that worked fine for everything else. LSU notes that it is usually established in lawns by late summer.

Mowing is the second. The stems root at every node, so a mower that cuts and scatters stem pieces spreads the weed even before it sets seed, per UF/IFAS. Mowing too short and too often makes it worse: UF/IFAS explains that doveweed leaves start growing flat to avoid the blade, shading the turf until doveweed displaces it.

Wet soil is the third. Drainage problems and overwatering favor doveweed and weaken the turf at the same time, which UF/IFAS describes as the perfect conditions for doveweed to take over. Growth slows once temperatures fall below 70°F, and that is usually when it drops seed for next year.

Prevention does most of the work. UF/IFAS calls a strong pre-emergent program the best control, timed to be active right before doveweed emerges in late spring. LSU AgCenter names indaziflam and dimethenamid as effective pre-emergents applied by late spring, and lists both as safe on St. Augustine, centipede, zoysia, and bermuda. If you already put down crabgrass preventer early, this is a second, later application, following the label for timing and rate.

For plants already up, the right product depends on your grass, per LSU's table:

• Atrazine: listed for St. Augustine, centipede, and zoysia. UF/IFAS says it gives both pre-emergent and post-emergent control and works best right before doveweed emerges, and that it significantly harms bermudagrass.
• Thiencarbazone, iodosulfuron, and dicamba (Celsius): listed for all four warm-season grasses. UF/IFAS says it gives good post-emergent control but works slowly, with symptoms taking 2 to 3 weeks to appear.
• Sulfentrazone plus metsulfuron: listed for all four.
• Sulfentrazone with 2,4-D, mecoprop, and dicamba: listed for zoysia and bermuda only. UF/IFAS notes that St. Augustinegrass is partially susceptible to 2,4-D and dicamba, and that some labels warn against use on Floratam.

Expect to repeat. LSU says multiple applications are usually needed, 2 to 4 weeks apart according to the label. Light to moderate nitrogen with or right after a treatment helps the turf recover and shade out survivors, per UF/IFAS. If a small area has been completely overrun, UF/IFAS suggests a directed glyphosate application followed by resodding as the faster fix.

Then change the conditions. Fix drainage, cut back watering, and raise the mower to the height your grass needs. UF/IFAS recommends leaving at least 3.5 to 4 inches on Floratam, Raleigh, and Palmetto St. Augustine. Because seed survives in the soil for several years, UF/IFAS plans doveweed management over two or three years rather than one season.