Dog Days of Summer! Humid Week, Volunteering, Dollar Spot, Summer Patch, UW Field Day and Research

It was a hot, humid, cloudy week. Yes, we are now experiencing the dog days of summer and the cicadas are singing. It was in the forecast and was expected. Extreme heat, daily highs at or above 90 degrees, didn’t exactly materialize for Chicago. Nevertheless, we were ready to react and that’s what your golf course superintendent and staff do for a living. All the planning, hard work and execution up to now pays big dividends in August — a time when peak golf course playing conditions exist. Simply said, if you are enjoying a summer of healthy turfgrass in the landscape, backyard or the living surface of a golf green it means one thing; It wasn’t chance, it was coordinated work. For example, creeping bentgrass at low heights of cut do not like certain things when it’s hot. Each year, one factor usually rises to the top as summer continues. We usually just point to a thin, compacted, off-color area and say a single syllable word. Wear. Excessive wear can happen in many ways via equipment (mowers), foot traffic (golfers), or tires (golf carts).

Image 1. Handwatering creeping bentgrass tees early in the morning means one thing. Preparations of day number two of competition are underway. Western Amateur, Exmoor Country Club, Highland Park, IL. Settle Aug, 3, 2022

But there is good news. In most instances turfgrass wear is an easy fix. Listen to your golf course superintendent and staff. In fact just this week, at Exmoor Country Club, I violated a traffic rule near a green. I listened, I learned, I made the correction and I never did that again. The creeping bentgrass approaches to the greens were all the better. In the early morning hours on the maintenance crew at the Western Amateur you quickly realize one fact. Everyone makes a difference when it comes to a golf course tournament. And that includes… turfgrass wear. Find out the correct way to ‘traffic’ the areas of a golf course. Then do it. I was also fortunate to realize volunteering makes a difference. Be aware of the needs around you and consider filling in a gap or two, or three. Most importantly, keep enjoying some of your time outdoors!

Weather Update (August’s First Week) by Shehbaz Singh, MS

North Chicago, Glenview. Over the last weekend temperatures were comfortable with highs ranging from 83 to 86°F. Nighttime low temperatures even dipped into the 50s. However, during the week, temperatures became hot again. As the week progressed, highs ranged from 82 to 92°F and lows ranged from 63 to 74°F. North Chicago suburbs experienced two days (Aug 2-3) when air temperatures were higher than 90 °F. It was humid too. The relative humidity during the week days it ranged from 78 to 83%. No heavy rainfall was experienced over the evaluated time period except isolated showers (trace amounts) on most days. Cumulative rainfall in the north Chicago suburbs was generally less than 0.5 inch.

Figures 1 and 2. Weather conditions during the first week of August at Bob Berry Sunshine Course, Lemont, IL.

South Chicago, Lemont. The air temperature was similar to the north suburbs. Tuesday to Thursday recorded relative humilities higher than 80%. Similar to the north suburbs, no heavy rainfall was experienced. Cumulative rainfall over the last seven days was 0.04 inches in Lemont.

Research on Dollar Spot, Clarireedia jacksonii

It has been a good year for dollar spot on creeping bentgrass greens. That’s just to say track dollar spot in research situations —an untreated check. It tells us we are experiencing a big difference between growing season 2021 and 2022. Overall, 2022 has been more consistent weather-wise. Consistent humid conditions have been experienced and that is more typical of a summer season in the upper Midwest.

Here’s some new research on how wetting agents can provide additional benefits beyond just improving water availability in sand-based root zones.

Materials and Methods. A study is being conducted on a Providence plus L-93 creeping bentgrass nursery green at North Shore Country Club in Glenview, Illinois.

  • A randomized complete block design with four replications is being used. Individual plot size is 4 by 6 feet.
  • Product application occurred via a CO2-powered back pack sprayer at 40 psi with flat fan nozzles. Applications were not watered in.
  • During high dollar spot disease pressure three dates of application occurred; Every 14 days on Jun 27, Jul 13 and Jul 25.
  • A low rate of Daconil Action at 2 fl oz/M (chlorothalonil) was used as a way to test if surfactant products can help produce suppression of dollar spot control. Note: Daconil Action is labeled for dollar spot at 4 fl oz/M.
  • Our threshold for acceptable visual quality is 6 (scale of 1–9, 6 or greater is acceptable). Our acceptable threshold for dollar spot in this study was infection center damage of 10% or less per plot.

DewCure by Mitchell Products. Surfactants of DewCure (blue line) and an experimental called Rhizo 6785 (yellow and purple lines) have provided a reduction in dollar spot pressure in 2022. Past CDGA research at North Shore Country Club (2010) on a L-93 creeping bentgrass fairway indicated DewCure could reduce the number of curative applications of Daconil Ultrex It was better than other biorational products which included Bacillus subtillis. In the end, DewCure was better than other biological treatments of which would require more Daconil Ultrex applications to maintain acceptable dollar spot control in a fairway situation (10% or less). For more on that previous research click here.

Rhizo 6785 by RhizoSolutions LLC. In 2022 we are testing newer wetting agent chemistries. One experimental chemistry, Rhizo 6785 has matched DewCure in reduction of leaf wetness and thus suppression of dollar spot. By August 1, all treatments have allowed us to provide a level of dollar spot suppression compared to untreated. Products that can reduce leaf wetness intensity and/or leaf wetness duration have utility for a golf course superintendent. You see, most of our common foliar fungal diseases of turfgrass require a minimum leaf wetness duration of 10 hours. Without leaf wetness the fungus cannot grow and infect. Check it out.

Figures 1–3. Development of dollar spot and its effect on visual quality and a electronic measure of quality called normalized difference vegetation index (NDVI). North Shore Country Club, Glenview, IL

Summer Patch, Magnaporthe Poae

Summer patch can be an aggravating problem in summer. Hence the name. A chronic root rot closely associated with all bluegrass or Poa turfgrass species. This continues to one of our biggest problems on golf courses in the Chicago District. Diseases of roots are very difficult to diagnose with accuracy unless a trained plant pathologist is in the picture (aka there are many look-alikes).

Image 1. Summer patch of a bluegrass golf course fairway can be difficult to diagnose because the symptoms are easily confused with other issues both biotic and abiotic. Settle, Jul 25, 2022
Image 2. Close up of summer patch disease. A chronic root rot of all bluegrass species. Settle, Jul 25, 2022

Fairway Research at Bob Berry Sunshine Course by Shehbaz Singh, MS

At Bob Berry Sunshine Course in Lemont, there are a total of three creeping bentgrass fairways.

  • Fairway 1. Crystal Bluelinks
  • Fairway 2. OO7
  • Fairway 3. Pure Select

This week, we investigated fairways using turfgrass quality (1–9 scale, with 9 best and 6 acceptable), NDVI using a handheld GreenSeeker (Trimble Inc.), a surface hardness measurement using TruFirm (Spectrum Technologies) and soil moisture and surface temperature using TDR350 (Spectrum Tech.).

Additionally, we prepared a GPS map of all fairways for surface hardness and soil moisture. In order to do systematic investigation, VQ, NDVI, and firmness data was collected in three parallel lines (a total 12 data points with four points within each line) for the front, middle, and back sections of each fairway. The TDR350 data was collected first around the periphery of each fairway at 10 ft intervals and then in parallel lines with approximately 15 ft between lines to cover the whole fairway.

Visual Quality and NDVI. There were trends of visual quality and NDVI differences within each fairway among the front, middle, and back sections.

  • Crystal Bluelinks creeping bentgrass. Crystal Bluelinks saw good/acceptable visual quality in fairway number 1. Average visual quality in the front, middle and back areas sampled was 7.6, 7.0 and 6.4 respectively.
  • OO7 creeping bentgrass. OO7 saw good/acceptable visual quality in fairway number 2. Average visual quality in the front, middle and back areas sampled was 7.1, 7.2 and 7.4 respectively.
  • Pure Select creeping bentgrass. Pure Select saw good/acceptable visual quality in fairway number 3. Average visual quality in the front, middle and back areas sampled was 7.7, 7.5 and 6.6 respectively.
Figures 1 and 2. Trends within each fairway was most apparent in back areas (the back fairway area is near the approach of each green) where higher soil moisture caused by compaction and wear tends to occur. Note: Most apparent in fairways 1 and 3 (both have drainage swales) but not in fairway 2 (this fairway does not).

Surface Firmness. Trends were also observed for surface firmness data within the three fairways. A higher number for surface firmness means it is less firm. The back sections of fairways or approaches have a firmer surface compared to the front and middle sections. Compaction via equipment/mower wear in this part of the fairway is likely a factor.

Figure 3. Trends between each fairway showed fairway 1 and fairway 2 were firmer than fairway 3. This was likely a function of fairway design than it was the creeping bentgrass variety. For example, fairway 3 has a low center area with a drain is located in the middle.

Disclaimer. This was a one time data collection in a non-replicated situation. More data is needed (across a whole golfing season) to fully understand data differences among the creeping bentgrass varieties at Bob Berry Sunshine Course in Lemont, Illinois.

University of Wisconsin’s Field Day and the National Turfgrass Evaluation Program (NTEP) by Shehbaz Singh, MS

University of Wisconsin. On Tuesday, August 2, while at the University of Wisconsin’s turfgrass field day near Madison we noticed many NTEP turfgrass variety trials again. The better visual quality of newer creeping bentgrass cultivars is obvious. In the current 2020 NTEP Bentgrass Fairway Test, experimental varieties such as PPG-APMTV1 and PVF-PV-2 have much improved color and density compared to the older standard Penncross.

More Suitable for Golf. Continuous turfgrass breeding efforts over the years have greatly improved creeping bentgrass varieties. Each is now more suitable for the game of golf’s aesthetic and playability standards. Let’s not forget creeping bentgrass now has improved genetic resistance to dollar spot disease. This aspect alone allows for reduced inputs. Now that’s an improvement that translates into better environmental stewardship as well as cost savings for the game of golf.

Image 1. The 2020 NTEP Bentgrass Fairway Test at the O.J. Noer Turfgrass Facility Research and Education Center in Verona, WI. Settle, Aug 2, 2022

Final Photo

Dr. Doug Soldat discusses newer creeping bentgrass varieties for golf greens at University of Wisconsin’s annual turfgrass field day. Settle, Aug 2, 2022



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Dedicated researchers and turf pathologists working for golf course superintendents in the Chicago area.