A lot of the lawns we get called to look at in June were not damaged by bugs or fungus. They were damaged by the fix. Somebody sprayed a weed killer on a hot day, or used a product labeled for Bermuda on a centipede yard, and a week later the lawn looked worse than the weeds did. Herbicide injury is common in Jefferson County because the grasses we grow are sensitive, and it is worth knowing what it looks like.
What herbicide damage looks like
The clue is pattern. Disease and insects follow moisture and shade. Herbicide damage follows the applicator:
- Stripes or streaks that match spreader or boom width, with overlaps darker than the rest.
- Damage that stops at a hard line where the spraying stopped, such as the neighbor's property line.
- Circles around individual weeds where a spot spray hit the grass too.
- Worse near the driveway or a hard edge where the applicator turned around and doubled up.
- Uniform yellowing across the whole lawn a few days after an application, with no patches, no rings and no thinning first.
Symptoms by type: growth-regulator herbicides like 2,4-D and dicamba cause twisted, curled or cupped blades and stems, sometimes strap-like new growth. Atrazine and similar products cause yellowing between the veins and from the leaf tip down. Non-selectives like glyphosate cause a general yellowing that turns brown over a week or two, usually in a splash or drift pattern. Our guide to diagnosing drought, disease or insects covers the look-alikes.
The usual causes around here
The wrong product for the grass
Centipede and St. Augustine tolerate fewer herbicides than Bermuda and Zoysia, and many products sold for "southern lawns" are labeled for the latter two only. The small print on the back lists the grasses. If yours is not there, it is not safe. Our post on herbicides that are safe on centipede goes through it.
The right product at the wrong rate
Products that are labeled for centipede often carry a lower rate for it. Using the Bermuda rate on centipede is one of the most common injuries we see.
Heat
Most lawn herbicide labels restrict application above 85°F or when the lawn is drought-stressed. That rules out most afternoons from May to September. A product that is safe in April can burn a lawn in July.
Drift and volatilization
Some formulations turn to vapor in heat and move. Damage from a neighbor's spraying, or from a bed treatment drifting onto turf, follows the wind direction and is worse downwind.
Weed-and-feed in the wrong season
Combination products apply herbicide and nitrogen together, and on centipede that is often the wrong dose of both. See why weed-and-feed fails on centipede.
What recovers and what does not
Growth-regulator injury, the curled and twisted growth, almost always recovers. The grass grows out of it in two to four weeks of active growth, and the next mowing removes the damaged leaf. Yellowing from atrazine-type products also usually recovers if the rate was not extreme; give it a month. Glyphosate damage is permanent where it was direct: the plant is dead and the spot needs to be re-plugged or re-sodded. Splash and drift damage from glyphosate often kills only the leaf it touched and the stolons regrow.
Centipede is the slowest to recover from anything, because it grows slowly. A bad centipede injury in June may not fill in until the following spring.
What to do
- Stop applying anything. No fertilizer, no more herbicide, no "rescue" products.
- Water normally. Deep and infrequent. If the injury was from a soil-active product, a couple of extra deep waterings can help move it below the root zone on sand. Do not flood clay.
- Raise the mowing height and keep the blade sharp. Do not scalp off damaged leaf; let it be replaced.
- Wait four weeks before deciding what is dead.
- Then repair. Plug or sod the dead spots in late spring or summer.
Preventing it next time
Read the label for the grass, the rate and the temperature limit. Spray in the morning on a day under 85°F with no wind. Calibrate the sprayer or spreader on the driveway before you go on the lawn. Spot-treat rather than blanket-treating when the weeds are scattered. And accept that a few weeds are less damage than an injured lawn.
FAQ
Can herbicide damage come from the lawn service?
It can. Ask what was applied, at what rate, and on what date. A good operator keeps records and will tell you.
My neighbor sprayed and my lawn is yellow along the fence. What now?
Photograph it, note the date and the wind, and ask them what they used. Most drift injury on turf recovers.
Will fertilizer speed recovery?
No. Injured turf cannot use it, and on centipede it adds a second stress. Wait until the lawn is growing again.
Do you do weed control on centipede?
Yes, with products and timing chosen for the grass. It is part of the plans we build.
If a weed treatment has left your lawn worse than the weeds, get in touch and we'll tell you what it is and whether it comes back. We work lawns throughout Jefferson County, from Monticello out to Aucilla.