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How to identify and prevent crabgrass and goosegrass

February 17, 2022 -  By
Crabgrass can be easily identified thanks to its light color, pointed leaves and twisted vernation membrane ligule. (Photo: Quali-Pro)

Crabgrass can be easily identified thanks to its light color, pointed leaves and twisted vernation membrane ligule. (Photo: Quali-Pro)

When grassy weeds take root, it’s a tall order to rid a lawn of them. That’s why it’s important to implement a
preventive plan this spring for weeds like crabgrass and goosegrass.

Avoid turf takeovers

These two summer annual weeds can develop a dense canopy and outcompete the desired turfgrasses, says Eric Reasor, Ph.D., southeast research scientist at PBI-Gordon.

Eric Reasor

Eric Reasor

“Dense weed canopies shade turfgrass plants to the point where they cannot properly grow and tiller,” he says. “Moreover, weeds do not tolerate foot traffic and use as well as turfgrasses, leading to bare and unsafe areas.”

These grassy weeds will compete with the turf for light, nutrients, water and space during the warmer months, says Dean Mosdell, Ph.D., technical manager at Syngenta. They also set seeds to spread next year.

“At the first frost, these plants will die, leaving voids in your lawn for increased weed invasion,” says Mosdell.

Ian Rodriguez, Quali-Pro

Ian Rodriguez, Quali-Pro

The No. 1 prevention against crabgrass and goosegrass is having a healthy turf base, so lawn care operators (LCOs) should ensure they don’t have bare spots or other areas that would be more susceptible to weeds, says Ian Rodriguez, Ph.D., technical services manager at Quali-Pro.

“Try to avoid going into the winter months with weak areas in the turf,” Rodriguez says. “You want it to transition out of dormancy as fast as it can.”

To prevent crabgrass and goosegrass from leaving their mark, LCOs need to ensure they follow the best practices for identifying and treating these weeds.

Properly identify weeds

Crabgrass and goosegrass are often confused with each other. However, it’s important operators properly identify them because most herbicide control options for goosegrass are different than for crabgrass.

Both annual weeds typically germinate in the spring, grow in the summer and set seed in the fall. Crabgrass germinates when soil temperatures are 55 degrees F for several consecutive days, and goosegrass germinates when soil temperatures approach 60 degrees F.

Crabgrass tends to have a lighter green color than goosegrass and the surrounding turf. It has rolled vernation, membrane ligule and pointed leaves.

Goosegrass leaves have more rounded leaf tips, flattened stems and a white-colored plant base, Reasor says. Goosegrass is also more common in high-traffic areas with soil compaction, like along curves, driveways or sidewalks.

How to treat

With few postemergent options for these weeds, applying a preemergent herbicide is the best course of action for crabgrass and goosegrass.

Operators should apply a preemergent herbicide prior to germination. Application timings depend on their location and soil temperatures, ranging from late January in the South to early April in northern states, Mosdell says.

For the most efficient treatment plan, operators should plan to treat these weeds a year in advance, Reasor says. That aids in an LCO’s ability to do timely herbicide applications, plan for herbicide mode of action rotation and use early order programs. Also, the preemergent program should involve split applications.

“Make initial applications prior to germination and then a secondary application two months later,” Reasor says. “A third application may be beneficial if goosegrass is a persistent issue.”

Waiting too late to put out pre-emergents or not applying them at all are the biggest mistakes Rodriguez sees operators making with these prolific seed producers.

“If you skip it, you’re going to have way more problems throughout the season with weed control than if you had done at least one preemergent application,” Rodriguez says.

While preemergent herbicides are highly effective, post-emergents such as fenoxaprop, fluazifop, pinoxaden and quinclorac, can be used to control escapes during early growth stages, but the best approach is a well-rounded one.

“It is vital to properly manage turfgrass through cultural practices, scout for weeds and use post-emergent herbicides to maximize herbicide efficacy and manage against herbicide resistance,” Reasor says

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