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Why is crabgrass difficult to control? And what can be done about it?

Crabgrass has a lot working in its favor. It grows all season long, it seeds prolifically and it’s a heat- and drought-tolerant plant. Plus, weather extremes break down the preemergent you’ve already applied to defend against this dreaded weed. It’s a problem for everyone.

Although crabgrass is an annual weed, it germinates and grows and produces new growth nearly all season. Unlike most annual weeds that die after seed maturation, crabgrass produces new growth and new seed heads week after week.

The continuous flowering of crabgrass results in each plant being capable of producing more than 150,000 seeds.

With this many seeds, it’s easy to understand why crabgrass is such a tough opponent.

Photo: Forest and Kim Starr, Starr Environmental, Bugwood.org

Photo: Forest and Kim Starr, Starr Environmental, Bugwood.org

To further complicate things, crabgrass is a C4 plant. C4 plants are extremely efficient in hot and sunny weather conditions. This enables crabgrass to grow more aggressively, especially in comparison to common cool-season C3 plants, through the summer months.

So, you’ve applied a preemergent treatment early in spring, but as spring changes to summer, weather extremes are inevitable. Shifts in weather can rapidly break down the protective herbicide barrier leaving you susceptible to escapes. These breaks allow crabgrass seed to germinate and break through the canopy.

Once crabgrass has germinated and grown to the mid-tiller stage, most herbicides struggle to knock it down. Standing up above the lawn surrounding it, unsightly crabgrass is bad for LCOs and their business.

Failure to control crabgrass at this critical point can lead to customer complaints, call-backs and cancellations—thereby increasing labor costs and decreasing revenue, as well as the chances of a tarnished business reputation.

So what’s an LCO to do?

1. Make sure crabgrass seeds do not spread.

Stopping the spread of seed will greatly reduce crabgrass outbreaks in the future. Prior to mowing, seek out problematic crabgrass areas and rake up the weed from its prostrate position. With the seed branches now standing up above the height of the lawn, you’ll be sure to mow off the seed head before it can produce any further seeds.

In lawns with heavy weed infestations, using a grass catcher should also be considered. This will ensure crabgrass and other weed seeds are not returned to the soil.

2. Replant bare spots.

A healthy lawn is a great defense against any type of weeds—including crabgrass. Exposed soil allows weed seeds to easily germinate and take root. Understand the turf species and preemergent herbicide plan for the lawn you are treating. From there, you will be able to pinpoint the next opportunity for successfully reseeding open areas in the lawn.

Once a healthy lawn is established, remember to not mow too low. Taller grass will make it more difficult for crabgrass seed to develop. A mowing height of 2 inches to 3 inches is suggested for many turfgrass varieties.

3. Use an effective post-emergent herbicide designed for crabgrass control.

Post-emergent herbicides, such as Quincept, will take out crabgrass without harming the surrounding desired grass. Quincept herbicide, exclusively from Nufarm, offers three powerful actives: 2,4-D, quinclorac and dicamba. It is ideal as a spring cleanup product or late season for weed escapes. Quincept is most efficacious on crabgrass before the second tiller then at five or more tillers. If a second application is needed for crabgrass in 2- to 4-tiller stages, allow 14 to 21 days between applications.

Go beyond crabgrass control

Quincept provides the post emergence performance and power needed to address more than 200 broadleaf and grassy weed problems. This includes the control of tough challenges such as foxtail, barnyardgrass and signalgrass. It works as a broadcast spray or spot application with no eye protection required. A single application works to control less mature, light weed populations. A second application may be required to control heavy, mature broadleaf weed infestations.

Make Quincept your summer weed solution

QuinceptQuincept is labeled for most managed cool-season and some warm-season turfgrasses, including residential and non-residential lawns and grounds. When it’s time for spring or late-season clean up, rely on Quincept.

Visit NufarmInsider.com to learn more.


This page was produced by North Coast Media’s content marketing staff in collaboration with Nufarm. NCM Content Marketing connects marketers to audiences and delivers industry trends, business tips and product information. The Landscape Management editorial staff did not create this content.

Header photo: Nufarm.