Very Wet! Dollar Spot, Brown Patch, Crabgrass, and Creeping Bentgrass Variety Research
We’ve remained as wet as it gets! Following the remnants of hurricane Beryl a week ago we really needed to dry out, but our saturated soils didn’t get any better. The rain continued. In a week we saw a little bit of everything weatherwise. Peak summer heat (90s) ended with unseasonably cool temperatures — “It feels like Florida!” became “It feels like fall!”. During that dramatic temperature shift, severe weather capable of producing tornadoes ‘kept us on our toes’, or ‘kept us in our basements’. A significant amount of tree damage would occur in Chicago’s south suburbs as well as in Indiana. In total it was a CliffsNotes of what summer 2024 has been like since the beginning. Consistently inconsistent sums it up.
In the landscape, if you are a gardener, it has been relatively easy in 2024. Or has it? If it has been easy, lighter soils and good drainage exist on your property. Or maybe you have an alternative solution like raised beds in place. If not, your plants likely suffered physiological decline (oxygen and gas exchange is required for normal root respiration) or a root disease or two (we have endured a plethora of fungal root rots). The same is true on golf courses. Whether beneath highly trafficked putting greens, low lying fairway areas, or everyone’s favorite hazard (sand bunkers), drainage is not an elective, it’s a requirement. Part of the secret of maintaining optimal playing conditions always resides below ground in the myriad maze of drain tiles which are strategically positioned to take away excess water. Rain or shine, the game of golf is resilient.
Weather
Scouting for Disease — Dollar Spot (Clarireedia jacksonii)
Consistent rainfall has meant foliar fungal diseases (as well as root rots) have been very problematic so far in the upper Midwest during summer 2024. Conditions for dollar spot have been ideal given warm nights combined with extended periods of leaf wetness.
Many fungicides are labeled for dollar spot and typically offer preventive control from 14–28 days. However, under high disease pressure (right now) application intervals are shortened to prevent disease breakthrough. For example, a long 28 day interval cannot provide suppression of dollar spot in fairway areas.
One exception is for golf courses who are using a newer creeping bentgrass varieties with improved genetic resistance. In those cases, fungicide inputs are less likely to see breakthrough during periods of peak dollar spot development.
Solutions for Dollar Spot
See newest 2024 recommendations in PPA-1: Chemical Control of Turfgrass Diseases 2024 (uky.edu).
Scouting for Disease — Brown Patch (Rhizoctonia solani)
Brown patch continues to be problematic. We conducted fungicide research for Corteva with a field day held this week. Corteva’s newest fungicide was launched at the Golf Industry Show in 2023. It is called Floxcor and the name reflects its active ingredient fluoxistrobin (a QoI or strobilurin fungicide). A few points of what we learned are below.
- Floxcor is capable of long lasting systemic control of brown patch without any negative growth regulation.
- Floxcor also provides a level of dollar spot suppression (source: CDGA creeping bentgrass research conducted in 2024 at North Shore Country Club in Glenview, IL).
- Both are important considerations when controlling a midsummer cool season turfgrass disease like brown patch.
Solutions for Brown Patch
See newest 2024 recommendations in PPA-1: Chemical Control of Turfgrass Diseases 2024 (uky.edu).
Creeping Bentgrass Varieties for Dollar Spot Resistance & Reduced Inputs by Shehbaz Singh, MS
A creeping bentgrass variety trial has been established at Bob Berry Sunshine Course in Lemont. The site is a USGA specification rootzone which was previously used for two creeping bentgrass 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 collaboration of a majority of Midwestern turfgrass researchers.
The current trial has a total of 20 creeping bentgrass varieties in a randomized complete block design with four replications.
Objectives
- Evaluate establishment rate
- Evaluate dollar spot susceptibility
- Evaluate other desirable characteristics such as spring green up
Materials & Methods
- Each plot (4 ft x 8 ft) was hand-seeded on Aug 28, 2023 at a rate of 1 lb per 1000 sq ft*
- *Landmark Seed Company ‘Match Play’ and ‘Spectrum’ bentgrasses were seeded on April 30, 2024
- Slow-release fertilizer was mixed with seed (Forever Green natural, 4–3–0)
- Grow in during the saw minimal inputs; 0.15 lbs N per 1000 sq ft as liquid urea in 2003 (Oct 4, Oct 10, and Oct 19).
- Slow-release fertilizer (Forever Green natural, 4–3–0) 0.5 lbs N per 1000 sq ft per month was applied in 2024 (Apr 16, May 21, and Jun 20).
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)
Update on dollar spot disease
Beginning in July, dollar spot development has begun during a period of high disease pressure. However, no statistical difference among 20 creeping bentgrass varieties currently exists. The average dollar spot incidence is less than 6% for all creeping bentgrass varieties. ‘Flagstick’ and ‘Puregreen’ were the only two entries with a tendency of more dollar spot (about 5%). A majority of the creeping bentgrass varieties saw trace levels of dollar spot (1% or less) and this includes ‘Centennial’, ‘Macdonald’, ‘Oakley’, ‘007XL’, ‘Mackenzie’, ‘Pure Distinction’, PST-0DSF, PST-0MRN, and PST-0R20.
Environmental Benefits of Reduced Inputs
All varieties are about 11 months in age except the newly added varieties of Spectrum and Match Play. No fungicide application has ever been made. Since this variety trial is to investigate the environmental benefits of dollar spot resistance, only minimal fungicide applications are planned. A curative application of Daconil Action (chorothalonil) fungicide will be made for each creeping bentgrass entry as needed. A 10% dollar spot threshold will be used (dollar spot will not be allowed to progress above 10% plot damage).
Expected Results
The total number of curative fungicide applications will be calculated at the end of each season. We expect to find reduced inputs with these newer creeping bentgrass varieties which were selected for superior genetic traits such as dollar spot resistance.
Visual Turf Quality and Normalized Difference Vegetation Index (NDVI)
No statistical differences were observed among creeping bentgrass entries for either visual quality or NDVI on July 16, 2024. At this time at fairway height, most do not have acceptable visual turf quality (6.0 or greater). However, six varieties currently have acceptable visual quality and those include ‘777’, ‘Centennial’, ‘007XL’, ‘Piper’, ‘PST-0MRN’ and ‘PST-0R20’.
Final Image
“Allium is a genus of monocotyledonous flowering plants with hundreds of species, including the cultivated onion, garlic, scallion, shallot, leek, and chives. The generic name Allium is the Latin word for garlic, and the type species for the genus is Allium sativum which means “cultivated garlic”. For more see Allium — Wikipedia.
