Lawn Care Corner: Dealing with Mature Weeds - National Association of Landscape Professionals

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Lawn Care Corner: Dealing with Mature Weeds

Photo: FMC Professional Solutions

This late in the summer season if you’ve got lawn care clients complaining about weeds, you’re often dealing with mature versions that are more challenging to banish from the yard.

While they may take a little more effort to get rid of, not all hope is lost when it comes to managing mature weeds. Below are some of the likely mature weeds you may be dealing with in your area and how to control them.

Crabgrass

Like most other weeds, crabgrass is easier to control when it is young and small compared to multiple tillered crabgrass. Dr. Tina Bond, technical service manager with FMC Professional Solutions, says there aren’t any cultural practices that will impact mature crabgrass as the key is prevention.

Maintaining a healthy lawn can help reduce crabgrass germination and prevent it from spreading. Practices like mowing at the proper height, applying balanced nutrition, irrigating deeply and infrequently, and selecting turfgrasses that are vigorous can help win the battle against crabgrass.

“If you’re having challenges with mature crabgrass the best way to control it is to use a post-emergence herbicide, like Solitare WSL that has excellent post-emergence crabgrass control,” Bond says. “Sequential applications may be necessary.”

She says it’s best to apply herbicides at temperatures below 85 degrees F at this time of the year. Even post-emergence herbicides are best for controlling young, smaller crabgrass plants. Larger weeds are always harder to control, no matter the type of weed, so a second application may be necessary.

“Products containing, fenoxaprop and quinclorac are good choices for crabgrass control,” Bond says.

Goosegrass

Mature goosegrass is another weed that isn’t impacted by cultural practices. Aside from the normal cultural practices of maintaining a healthy lawn, reducing soil compaction can also reduce goosegrass as they tend to grow in compacted areas.

“Goosegrass is a challenging grass to control,” Bond says. “Goosegrass has developed resistance to dinitroaniline herbicides and metribuzin, so it is important to use sound rotational practices. Dismiss, Dismiss NXT and Dismiss South both will control goosegrass when applied to newly emerged weeds in the 1-4 leaf growth stage.”

Bond says to ensure maximum efficacy with these applications, make sure the soil is not dry prior to the application. Good soil moisture aids the uptake and efficacy of these herbicides.

Sedge

Depending on your location, different sedges like yellow nutsedge, kyllinga and purple nutsedge are thriving at this time of year. Bond says that Dismiss NXT is effective for controlling yellow nutsedge and kyllinga, while Dismiss South is a good option for purple nutsedge.

“When applied after shoot emergence, but prior to tuberization, more specifically when soil temperatures at a depth of 2” are > 65°F for 7 consecutive days, Dismiss NXT can reduce tuber viability in yellow nutsedge which means fewer plants in future years,” Bond says.

Summer Annuals and Perennial Broadleaf Weeds

Some of the problematic summer annuals you might be seeing include doveweed and spurge. While these should be dying down soon, summer annuals are using this time to start producing seeds.  

“Unfortunately, the seed set this year will survive to supply next year’s weed establishment,” Bond says. “If you can get out a preemergence herbicide for those seeds at the right timing that will greatly reduce the population next season.”

As for perennial broadleaf weeds like dollarweed and clover, Bond says they can be controlled with post-emergence herbicides as well. It’s important to identify the weeds correctly to select the proper herbicide for control.

Created in partnership with the experts at FMC True Champions

Jill Odom

Jill Odom is the content manager for NALP.

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