Winter update: seedheads, crabgrass, and fun facts in the Midwest

Managing annual bluegrass seedheads

Let’s lead off with annual bluegrass, or Poa annua, (or maybe Poe Anna if you watch golf commentary). Winter isn’t over yet. Meteorological spring begins March 1st, astronomical spring begins March 20th. However, Poa began February 21st. This is when we started fielding questions about Poa seedhead suppression. On golf course putting greens, seedheads are not desirable. We do not harvest the seed to grow future stands, we prevent the seedhead emergence to maintain better turfgrass quality.

Poa seedheads begin to emerge at the onset of warmer weather. Luckily, researchers have begun tracking the timing of seedhead emergence and correlated it with environmental conditions. An example is the calculation of growing degree days (GDD). Michigan State University has a freely available GDD tracker ( that provides turf managers easy access to this information. Currently (as of February 24th), much of Illinois is in the early application window for Poa seedhead control. The timing for control is well ahead of pace set in 2016.

Growing degree days by February 24th in 2017 compared to 2016

Calendar based spray applications may not be desirable in 2017. Other researchers have also indicated the need to combine GDD models with onsite scouting to better time your spray applications. Dr. Matt Elmore, Turf Weed Scientist at Rutgers University, has recently commented on this subject and has provided high resolution images to assist in scouting.

Control recommendations may vary across Illinois. Central IL and further south may have already sprayed or will be spraying in the near future. Northward, in Chicagoland, the timing of Poa seedhead control may be further delayed due to the onset of more seasonable weather. Regardless of which region you are located in, scouting is very important during this unusual winter! An important consideration is whether or not to include Primo in combination with Proxy for the first spray application. Primo applied this early may yield undesirable discoloration to putting green turf if frost/freezes are expected.

Crabgrass prevention

Preemergence crabgrass control should also be on the back of your minds. I have yet to hear or see confirmation that crabgrass has germinated in any region of the state. The first areas to check for crabgrass germination are on bare soil areas with south facing slopes. Many turfgrass managers also use GDD’s and phenological indicators, such as forsythia blooms, to help target crabgrass preemergence applications. Please note that forsythia looks similar to other flowering plants such as winter jasmine (which blooms much earlier) so make sure the forsythia is indeed forsythia.

Forsythia is a phenological indicator plant for crabgrass germination and contains 4 leaflets. Winter Jasmine has 5–6.

Quick note on snow mold

As a turfgrass pathologist, I would be remiss if I did not mention pink snow mold. So far, I have heard few reports of active pink snow mold in Chicago southward. I have seen older patches that carried over from the fall. Putting greens that have been mowed or covered with tarps are at the greatest risk of pink snow mold. Research by Dr. Paul Koch (Turfgrass Pathologist at University of Wisconsin) indicates that applications of fungicides made in the fall are long gone. It may be appropriate to consider a fungicide application on putting green surfaces. Relatively inexpensive chemistries are available to provide some protection to the turf (i.e. Chlorothalonil, Iprodione, or Tebuconazole among others). If possible, leave a check plot to see if the applications were worthwhile! Early season dollar spot control will be included in the next report.

Symptoms of pink snow mold that likely occurred last fall.

Warm temperatures, winter play, and fun facts

Record warmth has swept across the Midwest for the better part of two weeks. Some golf course superintendents have mowed greens in February for the first time.

Other golfing facilities have seen increased revenue from February tee times. So how warm has it been? Chicago and Rockford has set daily temperature records for four consecutive days from 2/17 through 2/20.

Winter play on putting green surfaces that have yet to resume active growth is a warranted concern. Here are some excellent resources for those interested.

University of Nebraska:

United States Golf Association:

— — — — — — — -

Twitter: CDGATurfgrassProgram


Phone: 630–685–2307


Show your support

Clapping shows how much you appreciated CDGATurfgrassProgram’s story.