Winter is just beginning, but warmer temperatures and game day will be here before we know it. As you plan for the upcoming season, there are a handful of weeds and one insect you should pay special attention to.

Four Problematic Weeds

There are hundreds of different weeds that can appear on your sports fields, but four of the most important ones to control are annual bluegrass (Poa annua), roughstalk bluegrass (Poa trivialis), creeping bentgrass, and goosegrass. These grassy weeds are known for being difficult to control, causing playability issues, and negatively affecting aesthetics.

Annual Bluegrass (Poa annua)

Annual bluegrass is an incredibly adaptable grass that is often found on moist, compacted fields. It produces seeds rapidly and can tolerate incredibly low mowing heights, allowing it to expand quickly and outcompete desirable turfgrass.

Applying a selective pre-emergent herbicide like Kade 4L, which contains prodiamine (40.8%), will prevent Poa annua seedlings from germinating. Dimension 2EW, which contains dithiopyr (24%), will also provide effective control. Be sure to check the label of whatever product you choose to ensure it’s compatible with your field’s turf type.

In terms of post-emergent control, there are no selective products that can be used on cool-season fields. A product like Revolver (2.34% foramsulfuron) will control annual bluegrass on warm-season fields, however.

Roughstalk Bluegrass (Poa trivialis)

Commonly abbreviated as “Poa triv,” roughstalk bluegrass is a light-colored perennial weed that spreads via seeds and stolons. It prefers moist, shady areas but can survive under the sun if there’s enough moisture in the soil.

On warm-season fields, Specticle FLO (7.4% indaziflam) will prevent Poa trivialis seedlings from germinating. On zoysiagrass and bermudagrass, Negate 37WG (20% metsulfuron-methyl, 16.67% rimsulfuron) will provide post-emergent control. 

If you’re planning on overseeding next year, be sure to choose high-quality seed. Poa trivialis seeds are often present in low-quality seed, and these seeds are often the cause of infestations. Be sure to clean your equipment after encountering Poa trivialis to avoid spreading it.

Creeping Bentgrass

Creeping bentgrass is a perennial weed that spreads via stolons and forms a dense mat that can outcompete your turf. It is commonly found on fields constructed from HGT Kentucky bluegrass sod due to seed contamination. Because bentgrass seeds are extremely small, they can inadvertently mix with bluegrass seeds during sod production.

The best way to control creeping bentgrass on Kentucky bluegrass is with mesotrione. While commonly found in granular starter fertilizers, Armortech Trione provides mesotrione (40%) in liquid form. Armortech Trione is the only product you’ll need to use since it provides both pre- and post-emergent control of creeping bentgrass. Weeds absorb mesotrione through the roots, so Armortech Trione must be watered in to be effective.

Goosegrass

Goosegrass is an annual weed that germinates once soil temperatures reach 60°F at four inches. Like many weeds, goosegrass thrives in compacted areas and areas with no shade. It will also compete with your turf for nutrients and water.

While some sports turf managers choose to mow over weeds, goosegrass is arguably the worst weed to use that strategy on. Each goosegrass plant can have up to 20 stems and carry 50,000 seeds, so mowing over it is like pouring gasoline on a fire. 

Apply a selective pre-emergent herbicide like Dimension 2EW, Kade 4L, or StriCore (46.88% pethoxamid) to prevent goosegrass from germinating on cool- and warm-season turf. Ronstar FLO (34.1% oxadiazon) is a great option for sensitive warm-season turf.

Once goosegrass has appeared, a selective post-emergent herbicide like Armortech Trione or Dismiss (39.6% sulfentrazone) will effectively control it on cool- and warm-season fields.

Annual Bluegrass Weevil

This may sound surprising since annual bluegrass weevils are most commonly found on golf courses, but our customers in Ohio and Pennsylvania have found this well-known (and hated) insect on their sports fields within the last few years. 

Annual bluegrass weevils (ABW) target these fields because they have Poa annua in them. The larvae will feed on the stem before moving to the crown, which can kill the turf. Since ABWs have varied lifecycles, you can have larvae feeding on the stems while adult weevils eat through the crowns.

Damage caused by ABW appears similar to root diseases like dollar spot. To determine if you’re dealing with ABW, peel back the edges of the damaged turf and try to visually locate adult ABW under the surface. Your ATS rep can provide additional scouting guidance if you need it.

Preventative control is the best way to combat ABWs. Preventative options include Durentis (47.85% chlorantraniliprole) and Tetrino (4.07% tetraniliprole). For curative control, MatchPoint (36% spinosad) is a standout option. Arena 0.25G (0.25% clothianidin) is a granular product that provides both preventative and curative control.

When using herbicides and insecticides, be sure to rotate chemistries to prevent resistance. For more spring-season preparation tips and product recommendations, reach out to your ATS rep. If you’re new to ATS, you can find a rep here.