Identify and Control Weeds in Your Lawn

Weed Identification and Control for Northwest Florida Lawns

Hi, this is Skip with Father and Son Pest and Lawn Solutions. Today we're doing some weed identification. We're walking a large, empty lot and looking at different weeds you'll likely find in your own lawn, talking about what they are and how to control them.

Virginia Buttonweed

Virginia buttonweed is a very common and aggressive weed. This time of year it has small white flowers with four distinct petals, and its leaves often show a reddish or purplish tint, though sometimes an entire patch will be all purple, all green, or a mix of both.

This weed spreads through long runners extending out from a central stem, and it will smother out healthy grass if left untreated. It also reproduces through seed pods along the stem, in addition to spreading by runners.

Pulling Virginia buttonweed rarely removes the entire root system. The root tends to snap off, leaving enough behind for the plant to regrow. Because of this, spraying is far more effective than pulling. Celsius is the main product used to control it, and Quicksilver is another option, though Celsius is generally the better choice.

Dollarweed

Dollarweed is another very common weed and one most people recognize. It's actually an aquatic plant that loves moisture, so it often shows up in areas with a high water table, heavy irrigation, or standing water, though it can also survive in drier conditions.

Dollarweed spreads through underground runners rather than seeds, and it can choke out a healthy lawn if it gets out of control. It's also highly adaptable. It will grow at whatever height you mow your lawn, and if left unmowed, it will grow up through surrounding grass or even bushes, outcompeting the plants around it.

Fortunately, dollarweed is one of the easier weeds to control. Trimec works well at a low rate that won't harm the grass but will kill the dollarweed effectively.

Torpedograss

Torpedograss is a bluish-green grass that, like dollarweed, favors wet, marshy areas and spreads through underground runners. It will invade lawns and pop up through St. Augustine, centipede, zoysia, or whatever turf grass you have planted.

The only product that controls torpedograss is Quinclorac, sold under the brand name Drive by another manufacturer using the same active ingredient. Quinclorac can only be used on zoysia and Bermuda grass. It will kill St. Augustine and centipede, so if torpedograss is growing in either of those grasses, there's currently no treatment that won't also damage the lawn. Torpedograss can't be eradicated, only suppressed with regular Quinclorac treatments on the grass types it's safe to use on.

Spurge

Spurge is a small-leaf, low-growing, highly adaptive weed. It commonly shows up in lawns, planting beds, and cracks in driveways and sidewalks, essentially anywhere it can send down a root.

MSM, also sold under the brand name Rometsol, does a good job controlling spurge.

Dichondra

Dichondra looks similar to dollarweed at first glance, but its leaves are heart-shaped with a distinct indentation where the stem meets the leaf. Dollarweed leaves don't have that shape. Dichondra also grows in moist areas, like dollarweed, but is more challenging to control.

The same product, Trimec, works on dichondra, but it typically takes two to three treatments to control it, compared to one or two treatments for dollarweed.

Pensacola Bahia Grass

Pensacola bahia grass is a grassy weed identifiable by its crow's-foot-shaped seed head. It's more of a pasture grass and isn't commonly used as turf because of its sparse growing pattern, though it's often used on medians and roadsides for its drought tolerance and resistance to most diseases and insects.

Its seeds get carried by the wind into lawns, where the stems can grow a foot or more tall within just a few days of mowing. It grows in clumps and doesn't spread by runners. The same MSM or Rometsol product used on spurge will also suppress Pensacola bahia grass.

Florida Pusley

Florida pusley looks similar to Virginia buttonweed since both have small white flowers, but the two can be told apart. Virginia buttonweed flowers have four petals with slicker, more oblong leaves, while pusley flowers have five petals with broader, more velvety leaves.

Pusley is easier to control than Virginia buttonweed. Trimec works well on it. Like buttonweed, it spreads from a central point using runners, but unlike buttonweed, it doesn't produce seeds, making it less aggressive overall, though it still needs to be treated.

Chamberbitter

Chamberbitter resembles a miniature mimosa tree, with small oval leaves lining a central stem. Each stem can carry several seed pods, and a single plant can produce hundreds of seeds, which is what makes it spread so quickly. Mowing over the seeds actually helps distribute them further across the lawn.

Chamberbitter is also highly adaptable, staying low when mowed regularly but growing tall when competing with other plants for sunlight in unmowed areas.

Chamberbitter is a late germinator, typically not sprouting until around May. The most effective control combines pre-emergent and post-emergent products. Apply a pre-emergent herbicide in late March or early April, before soil temperatures warm enough for the previous year's seeds to germinate. For active chamberbitter already growing, Celsius is the only effective product, though it may take two to three applications. Since the germination season runs from May through October, a regular booster application of pre-emergent control every month or two helps keep it suppressed throughout the growing season.

Globe Sedge

Globe sedge is sometimes mistaken for sandspur, but the small balls on globe sedge are soft rather than prickly. Sedge is a distinct category of plant, not a grass, and one way to tell the difference is by rolling the stem between your fingers. Sedge stems are triangular, while grass stems are round.

Globe sedge grows in clumps with a central root system, and pulling it typically brings up a large clump of root. Sedgehammer is a product made specifically for controlling sedges, including globe sedge, though it won't work on other types of weeds.

Spreading Crabgrass

Crabgrass is best controlled with a pre-emergent herbicide applied in early spring, which eliminates most of it before it germinates. If crabgrass shows up later in the season, treatment options depend on your grass type.

For centipede lawns, Grass Getter controls crabgrass and other grassy weeds without harming the centipede, but it cannot be used on other grass types like zoysia or Bermuda, since it will kill them. For zoysia or Bermuda lawns, Quinclorac, the same product used for torpedograss, also helps control crabgrass.

There is currently no product available that controls crabgrass in St. Augustine lawns without also damaging the St. Augustine. A product that once did this was pulled from the market by the EPA for environmental reasons, and no replacement has been developed since.

Popcorn Tree Saplings

Technically a weed is just a plant growing where it isn't wanted, and that includes tree saplings like this one, a baby popcorn tree, also known as a Chinese tallow tree. These trees were brought to the area back in the 1600s and 1700s because they produced wax used in candle making.

Popcorn trees grow quickly and provide shade, but they've become highly invasive. This particular property once had hundreds of them, and the state of Florida has since outlawed nurseries from selling them. A mature popcorn tree can reach 20 to 40 feet and produces hundreds of seeds, leading to hundreds of new saplings nearby. The name comes from the white seeds that appear in the fall, which resemble popcorn.

No spraying is needed to control these saplings. As long as they're kept mowed down along with the lawn, they won't survive or grow past that height. They only become a problem in areas that aren't regularly mowed.