Last Frost! Video #1, Few Issues, A New Disease?, and Tall Fescue Tenacity Research
Our last week of April finished colder than we would have liked. With lows in the mid-30s some frost returned in the morning hours. Yep, lawns and roughs again had that whitish look due to ice crystal formation. By the way, always stay off frost covered turfgrass unless you’d like your grass to have your shoe size displayed in shades of brown. On another note, more and more birds are now singing AND we have also begun to enjoy more color. You see, disease resistant flowering crabapples, Malus spp. broke the flower speed limit. Lilacs, Syringa vulgaris et al., followed suit. And further down, Chicago’s turf continues its finishing touches of spring green up. A yellow flowering spring nemesis is also more apparent. A tap-rooted wonder weed, dandelion, Taraxacum officinale, is showing its seedheads.
And on golf courses this week, they were making educational videos? Well at least one did. Sunshine Course saw the CDGA Green Committee and advisor Sheldon Solow in action. Key superintendents were interviewed on all aspects of a certain topic that we spend a major amount of time thinking about, talking about, as well as maintaining — sand bunkers. More on that will follow. A diagnostic mistake was made and instead of Waitea the other W word was said. Say what? Incubation of a sample provided the answer. Get ready for take off as the forecast for May is making us smile. The upper Midwest and its cool, wet “shoulder seasons” are the bane of many a golfer and superintendent. But then, like the flip of a switch it is over and it’s May. On your mark, get set, go — Mother Nature is about to switch to warm (80s).
Weather
Scouting for Broadleaf Weeds — Wild Violet (Viola sororia)
Every once in a while you see a lawn full of a certain broadleaf weed — the right plant in the wrong place — and you think “that might just work”.
I saw that this week and the weed was uniformly distributed and in full bloom in a shaded lawn. And it was attractive. The weed in question is wild violet. And if you thought there was one, you would be wrong. Life is always more complicated. For my education I turned to Dr. Aaron Patton at Purdue University — Go Boilermakers.
Many Wild Violets
“Collectively, turf managers refer to the Midwest species common blue violet (Viola sororia), wooly blue violet (Viola papilionacea), and confederate violet (Viola sororia f. priceana) all as wild violet. Additionally, yellow violet (Viola pubescens) is also found in Indiana.”
Wild Violet Identification
- Heart shaped leaves with a point — rounded teeth on margins
- Reproduce by short rhizomes and seed
- Rhizomes can be large or the size of your “pinky” finger
- Shady environments are preferred
- A difficult-to-control broadleaf perennial
How to Control Wild Violet?
- Culturally, wild violet can be decreased by more frequent mowing only; the influence of irrigation, drainage, and soil compaction is not known
- Herbicides are labeled (several)
Want a Wild Violet Lawn?
- Reduce nitrogen (don’t fertilize)
- Maintain shade (don’t prune trees)
Fact Sheet by Purdue University
Wild Violets by Aaron Patton
Scouting for Disease — A new Basidiomycete Disease Causing Yellow Rings (Waitea Patch look-a-like)
First Report of a basiomycete fungal disease causing yellow rings/patches on a Poa annua/creeping bentgrass green. This was misdiagnosed a week ago (by you know who) as Waitea patch. It was a look-a-like!
The type of fairy ring? This appears to be more of what we would call Type II (stimulated growth of interior patch inside ring), but it also has elements of Type I (the ring itself may progress from yellow to brown). Possibly this is caused by midday wilt stress.
Proper Diagnosis Can Take Time
However, after incubating a cup cutter sample over the weekend (96 hours) profuse surface mycelium developed in the band of the ring. It was examined. This is not a Rhizoctonia disease we know as Waitea circinata var circinata because the mycelium did not have characteristic right-angle branching.
Another Fairy Ring
Instead it turns out the fungal mycelium has clamp connections at its cell divides (septations). It means it falls into the group of fungi that we blame for causing fairy ring . Am I writing this on Frisky Fairy Ring Friday? Yes.
Current Information — UCONN Turf Pathology, @UConnTurfpath
Dr. John Inguagiato reported something recently in Connecticut that was a match to what we found in Chicago at about the same time. It’s something new and easy to misdiagnose.
- The Chicago timing was similar — cool, wet conditions (mid-April)
- The Chicago green was similar — a green having a large proportion of Poa annua
- The Chicago look was similar — yellow rings that could easily be misdiagnosed as Waitea Patch (aka brown ring patch)
- The Chicago fungal characteristics were similar — relatively large hyaline hyphae with easy-to-see clamp connections, sometimes twisting in a ropelike fashion
Recommendations
At this point recommendations are to treat as fairy ring. Best advice would be to stick with the plan/your fungicide program for 2024. Go ahead and apply your preventive fairy ring program which typically uses an initial DMI fungicide application followed by a second application 28 days later. The soil average soil temperature at a 2 inch depth was approximately 55 degrees when symptoms were noticed in Chicago. This matches up nicely with the standard first preventive fairy ring application timing.
- Maxtima by BASF has been tested for this new disease and works well personal communication with John Inguagiato
- Avoid older DMI fungicides that tend to have more growth regulation as you may unintentionally halt needed turfgrass growth and recovery
- Hand water dry areas of affected greens to avoid midday wilt stress — do not want yellow rings progressing to brown rings
- Consider a wetting agent application if history of LDS is known and/or if spring weather conditions are overly dry
Tenacity Herbicide for Selective Removal of Creeping Bentgrass from Tall Fescue by Shehbaz Singh, MS
In 2023, a herbicide study sponsored by Syngenta was conducted on tees A, B and C at Bob Berry Sunshine Course in Lemont, IL. Results from tee C which is ‘RTF’ tall fescue will be discussed below.
Tee C Background
Tee C was originally grassed to ‘Penncross’ creeping bentgrass (2004–2020). In 2020 the Wadsworth Golf Construction Company provided a extensive renovation of Bob Berry Sunshine Course. Creeping bentgrass was killed using glyphosate. The dead bentgrass surface was cut by a sod cutter and then removed. Tee C was reseeded with ‘RTF’ tall fescue. However, a 2022 evaluation of all tee surfaces at the course revealed up to 40% contamination of creeping bentgrass. Within 3 years of renovation, creeping bentgrass had found its way back and was aggressively contaminating the tall fescue tee surface.
Objectives:
- Evaluate selective creeping bentgrass removal
- Evaluate tall fescue regrowth
- Evaluate turf quality both visually (1–9 scale) and electronically by Normalized Difference Vegetation Index (NDVI)
- Evaluate 2 versus 3 applications
- Evaluate any phytotoxicity
Material & Methods
The study was conducted using a randomized complete block design.
- A total of 3 treatments
- A total of 4 replications
- Individual plot size = 5 ft x 10 ft
Treatment Description
Treatments were sprayed using CO2 backpack sprayer operated at 40 psi; three nozzles with XR TEEJET 800VS. Applied in water equivalent to 2 gal 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.
To promote regrowth of tall fescue, liquid urea was applied six times at a rate of 0.25 lbs N/1000 sq ft and began following the second application date on Sep 12, 19, 26, and Oct 3, 10, 17 in 2023.
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 (% per plot)
- Tall Fescue (% per plot)
- Brown Turfgrass (% per plot)
- Phytotoxicity (% per plot)
Creeping Bentgrass Contamination
At study start, the average contamination by creeping bentgrass in experimental plots was 38.6%. Three months later, bentgrass had been significantly reduced by Tenacity. For example, two applications 14 days apart had resulted in 2.8% creeping bentgrass and three applications 14 days apart had resulted in 6.3% creeping bentgrass.
After 6 months, creeping bentgrass in tee C was reduced to 3.7% and 5% for 2 and 3 apps respectively. Again, they were no different. The untreated plots remained unchanged with creeping bentgrass contamination levels still at 35%.
Tall Fescue Re-growth
At study start, the average amount of tall fescue in experimental plots was 64.3%. Three months later, tall fescue had significantly increased following Tenacity’s removal of creeping bentgrass. For example, two applications 14 days apart had resulted in 87.5% tall fescue and three applications 14 days apart had resulted in 85.0% tall fescue.
After 6 months, tall fescue in tee C had increased to 87.5% and 85.0% for 2 and 3 apps respectively. The untreated plots remained with good levels of tall fescue (71.8%).
Visual Turf Quality
Average turf quality of 5.8 was recorded at study start for all treatment plots. Following the tenacity first application, the visual quality of treated plots fell due to selective removal and browning of creeping bentgrass in patches.A significant increase in tall fescue population and supplemental nitrogen fertilization helped treated plots attain acceptable visual turf quality.
After 8 months (Apr 22, 2024), the visual quality for treated as well as for untreated remained 6.0 or greater (data not shown).
Normalized Difference Vegetation Index (NDVI)
Average NDVI of 0.660 was recorded at study start for all treatment plots. Following the tenacity first application, the NDVI of treated plots fell due to selective removal and browning of creeping bentgrass in patches. At 3 months, Tenacity treatments regained NDVI given tall fescue regrowth and nitrogen fertilization had occurred.
After 8 months (Apr 22, 2024), the NDVI for all treatments was higher than 0.78 (data not shown).
Final Photo
