Hello Spring! Mild Winter, Little Snow, Few Issues, and Bentgrass Variety Research
March 2024 was a bit of a teaser as far as a spring goes. It just means we were being told (and it felt like) it was going to be a warm one early on. And then it wasn’t. And that was good. March is a difficult month for growers as freezing injury will occur if things green up too early — Poa is our main victim. And so March is pretty much the killing month for the Poa annua portions of greens. Poa is willing to risk it all = begin growth in March. But, thanks to Mother Nature, Poa annua stayed safe during this particular real life superintendent and staff episode (early spring 2024). Nevertheless, March didn’t disappoint and we experienced a little bit of everything weather-wise. After a rapid warm up early, a late midwestern snowstorm more or less coincided with spring’s start one week ago.
A majority of cool season turfgrass, not fooled, continues to remain in a semi-dormant state and is growing very slowly if at all. Regular scouting has now begun, and I can report things are looking quite good. Mild weather conditions this “off season” (also known as Dec, Jan and Feb) were a bonus for plant health and more. In most cases, superintendents and staff are way ahead of schedule on construction projects and the usual spring preparations. And so are we. For example, a periodical cicada with the latin genera name of Magicicada is scheduled to appear as things green up in late April/early May. Facts on that entomological phenomena can be found in April’s Chicago District Golfer Turfgrass column. The 2024 growing season will see a magical start?
Weather
Growing Degree Day (GDD) Models for Herbicides
We use weather models as a way to predict when our first turfgrass applications. We are using scientific research only after they have been vetted by the peer-review publication process. Other options include using a simple calendar method which is static year to year OR another dynamic way to do it is called plant phenology — boarder Forsythia flower is the one indicator that is most commonly used for crabgrass preemergence and/or Poa annua seedhead suppression.
Click here to see what the GDD model is currently predicting for the Bob Berry Sunshine Course in Lemont, Illinois. BIG differences between years 2023 and 2024 given this base 32 window occurs from 250–500 degree days.
- On March 27, 2023 GDD 32 = 254. It meant the threshold to make applications had just been met (250 is the start).
- On March 27, 2024 the GDD 32 = 478. It means the window to make optimal timed applications is ending (500 is the end).
Timing Crabgrass Preemergent Applications in the Spring
Excellent Communication by Kevin Frank, PhD, Michigan State Univ
“Summer annual grasses such as crabgrass require proper soil temperature and moisture to germinate and establish. Eighty percent of germination will occur when soil temperatures at the 0–2 inch depth are consistently between 60 and 70 F. For preemergence herbicides to be effective, they need to be applied before the soils reach this optimum temperature range. At the Hancock Turfgrass Research Center on Michigan State University’s campus, soil temperature at a 2-inch depth exceeded 50 F for the first time this year on March 13, 2024. This corresponded almost perfectly with the GDDTracker, which indicated East Lansing, Michigan, was in the optimum application window for preemgence herbicide applications on March 12.”
Read Entire Article
Scouting Reveals… Snow Mold Injury (not much)
Snow molds? A typical spring will generally see an amount of snow mold injury. It is most commonly found in areas which remain shaded and are wet (low areas surrounded by trees). But with a snow deficit this winter the associated snow molds are largely absent. Two out of our three months (Dec and Feb) did not see much snow at all which meant instead of the usual 30 inch average snowfall we saw something like 10 inches?!? That was good news for a new creeping bentgrass variety trial established in Lemont last fall. It continues to remain without fungicide applications and is virtually blemish-free (only traces of snow mold were present in Feb).
Scouting Reveals… Divots by Golfers (a lot)
Divots in March?!?
Instead of snow molds, it turns out unrepaired divots are more impactful early in the growing season. Such voids can have a negative effect on playability. Additionally, these open areas are an invitation for annual bluegrass establishment because, as mentioned previously, it is among the earliest to begin growth in the spring (see image 3).
New Divot Research
A 2022–23 CDGA study looked at how to repair divot injury across three seasons — spring, summer or fall.
The idea. The sponsors of the study were golfers — our very own CDGA Green Committee. We found that seed is must when repairing a divot. Seed is an integral component of a divot mixes especially during the shoulder seasons of spring and fall.
Fall is problematic. In particular, fall divot injury stood out because divot mixes without seed (or unrepaired divots) were found to take several months to heal. In our case, without seed fall divots did not heal until the following summer in a creeping bentgrass tee or a Kentucky bluegrass tee.
Fact Sheets. Click here New Methods for Speedy Divot Repair
New Creeping Bentgrass Variety for Dollar Spot Resistance by Shehbaz Singh, MS
A creeping bentgrass variety trial has been established at Bob Berry Sunshine Course in Lemont. The variety trial site is a USGA specification rootzone which was previously used for two creeping bentgrass green variety trials. The first was a 2004–09 National Turfgrass Evaluation Program (NTEP) and the second was a 2009–2012 North Central Region study (NCERA 192) which is a collaborative of a majority of Midwestern turfgrass researchers. This current trial has a total of 18 creeping bentgrass varieties in a randomized complete block design with four replications.
Objectives
- Evaluate the establishment rate
- Evaluate the dollar spot susceptibility of each
- Evaluate other desirable characteristics such as spring green up
Materials & Methods
- Each plot (4ft x 8 ft) was hand-seeded on Aug 28, 2023 at a rate of 1 lb per 1000 sq ft
- Slow-release fertilizer mixed with seed (Forever Green natural, 4–3–0)
- Grow in saw minimal inputs; 0.15 lbs N per 1000 sq ft as liquid urea on each date of Oct 4, 10, 19, 2023
Data Collection– Every two weeks
- Visual Quality (1–9 scale, with 6 = minimum acceptable and 9 = best)
- Normalized Difference Vegetation Index (NDVI) using GreenSeeker/Trimble HCS-100
- Visual Turf Cover (% per plot)
- Visual Dollar Spot (% and number of spots per plot)
- Discoloration of Dormant Turf (% per plot) during winter months
- Spring Greenup (1–9 scale, with 6 = minimum acceptable and 9 = best)
Establishment Rate
Creeping bentgrass varieties saw varied establishment rates. Entries such as Barracuda, Centennial, Oakley, 007, OO7XL, Piranha, PST-0DSF, PST-0R20, PST-RODS, and Pure Eclipse had turfgrass cover ranging from 35- 40% just after three weeks from seeding when rated in September. Most reached 50% turfgrass cover after 5 weeks of establishment on Oct 2, 2023. However, cultivars such as Mackenzie, Macdonald, and PST-0MRN lagged behind at 36.5%, 46.25%, and 47.5% respective turfgrass cover. Instead, it took 7 weeks for these cultivars to reach 50% turfgrass cover.
Dormant Color
As air temperature drops during the winter period, creeping bentgrass enters a dormancy period. Its green color can change to a bronze color which may then progress to a straw color. Green color retention differences are known to exist during winter. In our trial, no significant differences were observed among any of the entries. However, trends were observed. The checks ‘Macdonald’ had less than 25% and ‘Pure Distinction’ had 28.7% discoloration from Dec 12, 2023 to Mar 15, 2024. Most entries in this trial had dormant discoloration ranging from 25 to 35 % on both ratings dates.
Spring Greenup
As air temperatures rise during the spring season, creeping bentgrass will regain its green color. However, the speed at which this happens varies among creeping bentgrass cultivars. In our study, no significant differences were observed among cultivars given spring greenup ratings were taken on Mar 26, 2024. The check ‘Mackenzie’ had a spring green rating of 3.5, a lower tendency versus other entries.
Pink Snow Mold (Microdochium nivale)
Incidence of pink snow mold was observed in just a few plots. Single pinkish to white patches 4-5 inches in diameter were associated with creeping bentgrass varieties Pure Distinction, Pure Eclipse, and PS-RODS. This outbreak saw only trace amounts of disease. Data could not be collected among all the replicates as is required for statistical analysis.
Final Photo
