April Showers! Winter Recap, Few Issues, and Tenacity Research Update
This winter was a cold ride temperature-wise. Or was it? Here’s how the Illinois State Climatologist summed up our January to February in 2025.
January Brought Winter Weather of Yore: The preliminary statewide average January temperature was 22.3 degrees, 4.4 degrees below the 1991–2020 average and tied for the 34th coldest on record going back to 1895. February’s Roller Coaster Weather Wraps up Winter: The preliminary statewide average February temperature was 28.4 degrees, 2.7 degrees below the 1991–2020 average and the 52nd coldest on record going back to 1895.
We are seeing color in the landscape! This always precedes leafing out of certain shrubs and trees. Yellow is the bloom of boarder forsythia (Forsythia x intermedia), as well as the flowers of cornelian-cherry dogwood (Cornus mas). That our earliest blooms in the landscape are often yellow is an interesting fact a superintendent shared with me years ago. It turns out carotenoids (yellow pigments) are among the easiest for plants to synthesize compared to blue or red pigments. There are other advantages: Yellow flowers reflect UV light and are easy to see, and more attractive to a diverse group of pollinators in the early spring (flies, bees, butterflies, etc.).
And what about cool season turfgrass? Well, good ‘ole Poa annua or annual bluegrass is glowing bright green and its boat-shaped leaf tips have been growing since March. Poa doesn’t like to wait. Our other primary turf species in the upper Midwest are semi-dormant state or growing very slowly. Waiting out early spring is a good strategy to avoid freeze injury. This week’s scouting has revealed turf health and surface conditions are looking great. A limited amount of snow cover in the upper Midwest during winter 2024-25 helped suppress fungal diseases. Instead, abiotic injury of putting green surfaces (winter desiccation) was more problematic. In most cases, permanent damage does not result; just temporary thinning and a delay in greenup. The 2025 growing season is off to a good/wet start. Enjoy!
Weather
Growing Degree Day (GDD) Models
Weather models are perhaps the best way to predict for some of the first plant protectant applications used in turfgrass. For example Michigan State University offers a website that allows users to see multiple predictive models. GDD Tracker offers everything from crabgrass preemergence applications to Poa annua seedhead suppression (those applications are happening right now) to predicting diseases like dollar spot. But there are other ways to do this if access to local weather data isn’t available.
- BEST — Predictive models are produced by scientific research and vetted by peer-review publication process. Local or regional validation sometimes called ‘ground truthing’ can be an ongoing process.
- VERY GOOD — Plant phenology uses observations of plant development. For example, boarder forsythia flower stage is used for several early applications. Examples include, crabgrass preemergence, Poa annua seedhead suppression and annual bluegrass weevil adult activity.
- GOOD — Other options include using historical records of when pests first appear. Calendar-based record keeping becomes better over time.
Scouting for Biotic Issues— Pink Snow Mold or Microdochium Patch (the fungus Microdochium nivale)
In Chicago during January and February of 2025, a total of 11.9 inches of snow accumulated. This meant winter 2024-25 ranked in the bottom 10 of Chicago’s record book for snowfall. Only nine other winters had less snow. Scouting in early March of this year we found snow molds were largely absent. The required environmental conditions were lacking.
Recommendations
See pages 26–27 in Chemical Control of Turfgrass Diseases 2024.
Scouting for Abiotic Issues — Winter Desiccation of Putting Greens (caused by dry conditions)
Winter desiccation is an abiotic (not a disease) problem of turfgrass that can happen when little to no snowfall occurs during a winter. And that’s been the trend for Illinois (Figure 1). Turfgrass in sandier soils are more vulnerable for desiccation; sand-based putting greens are at a greater risk.
Scouting for Seed Germination — Monitoring a dormant seeding (Nov, 2024)
We seeded a boarder area using ‘RTF’ tall fescue in November, 2024. It was needed to fill in the edges of our bermudagrass and zoysiagrass variety trial on a sand-capped tee in Lemont. This week tall fescue seedlings were visible and had been growing for about a week. A good sign of spring.
Tenacity Herbicide for Selective Removal of Creeping Bentgrass from ‘HD Sport 2.0’ Kentucky Bluegrass by Shehbaz Singh, MS
A herbicide study sponsored by Syngenta is being conducted on tees A, B, and C at Bob Berry Sunshine Course in Lemont, IL. Tee A has ‘HD Sports 2.0’ Kentucky bluegrass, Tee B has ‘HGT’ Kentucky bluegrass and Tee C has ‘RTF’ tall fescue. Results from Tee A or ‘HD Sports 2.0’ Kentucky bluegrass are discussed below.
2023 Study
Initiated in August 2023, this study was conducted on the upper south side of Tee A. To promote the regrowth of Kentucky bluegrass, liquid urea was applied six times at a rate of 0.25 lbs N/1000 sq ft bi-weekly following the second application date on Sep 12, 19, 26, and Oct 3, 10, 17.
2024 Repeat Study
To validate and confirm the findings from the 2023 study, a repeat study was initiated on the lower south side of Tee A in September 2024. To promote the regrowth of Kentucky bluegrass, liquid urea was applied six times at a rate of 0.15 lbs N/1000 sq ft bi-weekly following the second application date on Sep 17, Oct 1, 15, 29, and Nov 12, and 26, 2024. A similar collaborative trial was also conducted by Dr. Aaron Patton at Purdue University in West Lafayette, IN.
Tee A Background
Tee A was originally established with ‘Penncross’ creeping bentgrass (2003-4). In 2020, the tees were renovated and converted to Kentucky bluegrass through a two-step process: 1) Application of the non-selective herbicide glyphosate to eliminate the creeping bentgrass. 2) Removal of dead turf using a sod cutter. Despite this effort, a 2022 evaluation revealed that up to 80% of the Kentucky bluegrass turf had been re-contaminated with creeping bentgrass. Within three years of renovation, the original creeping bentgrass was aggressively displacing the Kentucky bluegrass
Objectives
- Evaluate Tenacity for selective removal of creeping bentgrass
- Evaluate the regrowth of Kentucky bluegrass
Material & Methods
The 2023 study and 2024 repeat study were conducted using a randomized complete block design with 4 replications. Three treatments were used. Individual plots were large and measured 5 ft x 10 ft. Treatments were applied using a CO2 backpack sprayer operated at 40 psi; three nozzles with XR TEEJET 800VS. Applied in water equivalent to 2 gallons per 100 sq ft. A total of 2 or 3 applications were made. Tenacity was mixed with a non-ionic surfactant (NIS) at the rate of 0.25% by volume.
Data
- Visual Quality (1–9 scale, with 6 = minimum acceptable and 9 = best)
- Normalized Difference Vegetation Index (NDVI) using GreenSeeker/Trimble HCS-100
- Creeping Bentgrass and Kentucky Bluegrass (% per plot)
- Transitional Brown Turfgrass (% per plot)
- Phytotoxicity (% per plot)
2023 Study Results
- Study Start: Contamination by creeping bentgrass was 78.8%.
- 6 Months: Significant reduction in bentgrass by tenacity. Two applications 14 days had 5% bentgrass contamination, while three applications 14 days apart had 1.75% bentgrass contamination.
- 1 Year: Regrowth of creeping bentgrass was observed in tenacity-applied plots. Two applications had 13.75% and three applications had 4.5% bentgrass regrowth.
- 1 1/2 Year: Regrowth of creeping bentgrass in two Tenacity applications was significantly increased to 25% while it was just 2.5% for three applications treatment.
2024 Repeat Study Results
- Study Start: Creeping bentgrass contamination was 74.1%
- 2 Months: Creeping bentgrass contamination was significantly reduced to 40% for both two apps. and three apps. tenacity treatments.
- 6 Months: Creeping bentgrass contamination was significantly reduced to 1.25% for three apps. treatments, while 17.5% creeping bentgrass contamination was observed for two apps. treatments
Final Photo
