Fall! Education, ABW Again?!, 1st Grub Damage, Dollar Spot, Green Research

The most often said sentence of the week? “Fall is nice!” We are comfortably in a different season now. Here are some fall observations that golf course superintendents have taught over the years: 1) Day length is increasingly shorter, 2) A decreasing sun angle creates longer and longer shadows, 3) Cool night temperatures (50s) in the fall ends most disease/dollar spot, 4) Best time to seed/establish turfgrass is in the fall.

Image 1. As we begin fall (officially) the turfgrass et al. is looking good and the tree leaves are all still green! Glen Oak Country Club, Glen Ellyn, IL. Settle Sep 13, 2023

In the landscape, certain trees are increasingly jumping the gun. A single branch can be seen flagging early fall color. Some of the earliest fall color (yellow) is usually seen on honey locusts which are just about everywhere in Chicago. Lawns are increasingly with signs of fall which is, of course, core aerification followed by seed (the woes of 2023 = primarily thinning by drought). And superintendent and staff are increasingly communicating about “fall projects”. Fall also means we begin to attend education offerings from now until early spring. Finally, it was “Thank a Superintendent Day” on September 12. A global event! BIGGA (British), ASTMA (Australia), CGSA (Canadian), FEGGA (European), GCSAA (America) were all involved. Details from GCSAA, “began in 2017 to recognize those who are essential to golf’s success, has grown, so has the number of organizations”. #ThankASuper

Weather

Figure 1. Cooler fall temperatures are now in place, Bob Berry Sunshine Course, Lemont, IL.

Fall Turfgrass Education —SAVE THE DATE

1. Turf Education Day (TED) Thursday, September 21 (REGISTER NOW)

Keynote Presentations

• Bees, Pesticides & Politics: Challenges & Opportunities for Sustainable Urban Landscapes, Daniel Potter, PhD, University of Kentucky
• NEW! Technologies for Turfgrass Management: Current Trends and Future Applications, Chase Straw, PhD, Texas A&M University

2. CDGA Turfgrass Seminar Saturday, October 14 (SAVE THE DATE)

Round Table Discussion on Sand Bunker Technology & A Field Trip

• Superintendent Panel: Reed Anderson, Don Cross and Dan Tully
• Industry Expert: Doug Myslinski
• See Chicago’s Newest Bunkers: Cog Hill’s Dubsdred Course

3. 71st Midwest Turf Clinic Wednesday, December 6 (SAVE THE DATE)

Hosted by Midwest Golf Course Superintendents Association (MAGCS)

Keynote Presentation

• Everything You Wanted to Know About Annual Bluegrass Weevils, Ben McGraw, PhD, Penn State University

Annual Bluegrass Weevil (ABW) — Found at a 2nd location in Chicago

We documented a second location in Chicago this week with an infestation of annual bluegrass weevil. As before, we found that it only associated with annual bluegrass (Poa annua). The annual bluegrass was in decline and unable to handle wear.

The situation at this course were similar to the 1st course ABW was identified at in Chicago. Damage was limited to annual bluegrass at short mowing heights of 0.5 inch or less in green collars and annual bluegrass in tees. As before, greens were not affected (frequent daily mowing of greens likely interferes with ABW establishment and thus provides protection).

Golf Course Areas Where ABW Damage Observed

1. ABW x Traffic by equipment wear (green collars).
2. ABW x Injury by concentrated foot traffic and divots (tees).

Image 1. A golf green collar where annual bluegrass is wilting and then dying in small areas. The creeping bentgrass component remains healthy. Settle, Sep 13, 2023

Image 2. Damage by annual bluegrass weevil can be confused with both biotic and abiotic issues. Here the damage (yellowing)looks like a fungal disease of annual bluegrass known as anthracnose. Settle, Sep 13, 2023

Image 3. The easiest way to sample for annual bluegrass weevil larvae and pupae in the soil is by taking a cupcutter core and carefully pulling it apart. Settle, Sep 13, 2023

Image 4. A single pupae of annual bluegrass weevil is quickly found (the small cream color looking thing in my hand). Settle, Sep 13, 2023

The ABW Expert

In each case, during a course visit, I was able to reach out and contact Dr. Ben McGraw of Penn State University by phone and he then provided helpful advice. Dr. McGraw is the recognized expert when it comes to annual bluegrass weevil. His lab continues to study this new insect pest as it continues to spread to golf courses in the United States and Canada.

New Illinois Golf Course Pest = Summer 2023

For Illinois this is a new pest which had not been previously reported. It’s first report occurred at a golf course in Chicago one month ago (August, 2023). The good news is that lawns will not be negatively impacted. Annual bluegrass weevil prefers short mown annual bluegrass as its host. That puts it squarely on the shoulders of golf course superintendents to deal with.

Table 1. Newest reported locations of annual bluegrass weevil at golf courses in the United States and Canada. Courtesy Dr. Ben McGraw, Penn State Univ

Image 2. Most current map of annual bluegrass weevil impacting golf courses in the United States and Canada. Color Key: Red to orange colors are oldest reports (1957 = first report in New York) and blue colors are most recent (2023 = Illinois)). Courtesy Dr. Ben McGraw, Penn State University

Annual Bluegrass Weevil Symptoms are Easily Confused

1. ABW symptoms can be confused with foliar disease — anthracnose of annual bluegrass.
2. ABW symptoms can be confused with root disease — summer patch of annual bluegrass.
3. ABW symptoms can be confused with equipment wear — excessive wear of green collars we typically associated with turning of green mowers.
4. ABW symptoms can be confused with foot traffic — excessive wear of green collars by foot traffic concentrated in the on/off areas of greens.
5. ABW symptoms can be confused with localized dry spot —midday wilt caused by excessive root feeding by dense populations of ABW larvae (white grubs).
6. ABW symptoms can be confused with physiological decline — turfgrass decline during periods of excessive heat (90+ degree highs).

Upcoming Education on ABW

Save the Date December 6, 2023. Dr. Ben McGraw will be the keynote speaker this year in Chicago at the Midwest Association of Golf Course Superintendent’s annual education event Turf Clinic and Annual Meeting. Held each year at Medinah Country Club.

More Information on ABW

Annual Bluegrass Weevil

Report of Grub Damage in Chicago

A good Super Scout out there reported fall’s first animal damage on a fairway. The animals are usually not scene because it occurs during the night. Nocturnal animals are blamed and usually thought to be skunks and raccoons. The damage is digging. A natural consequence of three things: 1) They forage in turfgrass for food. 2) Annual white grubs are a favorite food. 3) Skips can happen in the insecticide application we use to prevent annual white grubs (beetle larvae).

Image 1. Animal damage of a creeping bentgrass fairway due to searching for annual white grubs. Courtesy Chicago GCS, Sep 13, 2023

More information on Annual White Grubs

Managing White Grubs in Turfgrass Dr. Douglas S. Richmond, Purdue University

Dollar Spot, Clarireedia jacksonii

Dollar spot development always peaks in the fall. Why? Conditions are perfect for its development for one. Also, it also has something to do with epidemiology and the growth curve of diseases isn’t linear. The curve shape is more of a logarithmic curve. That’s a steep incline and that is not good.

One fact you’ll learn when dealing with peak dollar spot pressure is that a strict calendar-based timing is problematic. A 28 day interval on a preventive fungicide program isn’t going to work in situations with older creeping bentgrass varieties. That’s a fact. That would be in the fall. In Illinois, our highest dollar spot pressure on greens, tees, and fairways begins about mid-August/September. On fairways, fungicide spray intervals may need to be decreased to 21 days or (in cases of peak pressure) even 14 days.

Image 1. Peak dollar spot pressure on a L93 creeping bentgrass plus Poa annua fairway surface. A PBI Gordon fungicide study with 4 ft x 6 ft plots arranged in a randomized complete block design with 4 replicates. North Shore Country Club, Glenview, IL. Settle, Sep 11, 2023

Figure 1. Dollar spot development during 2023 in an L93 creeping bentgrass fairway. A period of severe drought occurred from May to June and this delayed natural disease development by 1–2 months. It wasn’t until early August that dollar spot disease progressed. Both Daconil Action (Syngenta) and Kabuto (PBI Gordon) were applied every 14 days beginning June 12 (rates listed are oz per 1000 sq ft). North Shore Country Club, Glenview, IL

Besides dry weather delaying the onset of dollar spot we now have newer varieties that have been selected for dollar spot resistance. It’s “baked in” with genetics. These newer varieties are able to delay dollar spot development when looked at in research trials. It means that they are now different from some of the models that are designed to predict dollar spot. In other words, newer creeping bentgrass varieties are allowing reduced inputs with regard to fungicides.

Image 2. A new creeping bentgrass variety trial (19 cultivars total) is being established. It has 19 cultivars arranged in a randomized complete block design with 4 replications. We are investigating improved dollar spot resistance now available in the newest varieties, Bob Berry Sunshine Course, Lemont, IL. Settle, Sep 14, 2023

More Information via a USGA Green Section Record

Dollar Spot Control — Predictive Models, Threshold-Based Applications, or Calendar-Based Applications? Addison Barden, July 5, 2019

Green Research — September by Shehbaz Singh, MS

As a part of monthly evaluation of greens, fairways, and tees at Bob Berry Sunshine Course, all greens were evaluated last week.

Background

All are creeping bentgrass. Greens 1, 2 and 3 are around 5,300 sq ft each. The practice green is about 7,811 sq ft. As a part of renovation project, the grass on green 1 to 3 was killed, uppermost mat layer was scrapped off and then were reseeded to newer creeping bentgrass varieties. The practice green was completely reconstructed as a variable depth green and then reseeded (see above). All work was conducted by Wadsworth Golf Construction Co.

Green 1. Pure Distinction

Green 2. OO7

Green 3. PC 2.0

Practice Green. Penn A1 plus Penn A4 (half of green) & 777 (half of green)

Evaluation procedure. On each green, three points were selected in a systematic way (straight center line in front, middle, and back). Three data readings or samples were collected around each of the three marked points. Five sets (five greens) of data were collected.

• Visual Quality (1–9 scale with 9 best and 6 = minimum acceptable)
• Normalized Difference Vegetation Index (NDVI) using GreenSeeker by Trimble
• Soil Moisture using TDR350 by Spectrum Technologies
• Surface Firmness using Field Scout TruFirm by Spectrum Technologies
• Shear Strength using Shear Strength Tester by Turf-tech International Inc.
• Root Length was measured taking the average of four 0.5-inch diameter soil core samples (maximum root length)
• Root-Feeding Nematodes were extracted by lite sucrose extraction with centrifugation using 100g soil (upper 2-inches of four soil cores). Four samples were collected around the point for each green area.
• Ball roll was measured using USGA stimpmeter for front, middle, and back section of each green.

Figure 1. Visual quality of front, middle, and back areas of greens at Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 2. Visual quality of greens over time with localized dry spot causing a majority of negative effects all year. Quality trended the same from August to September, except for Green 2 (OO7) which showed a slight decline in ratings (values of OO7 shown as reference), Bob Berry Sunshine Course, Lemont, IL.

Figure 3. Normalized Difference Vegetation Index of front, middle, and back areas of greens. NDVI for most greens remained the same from August to September, except for Green 2 (007) which showed a slight decline in ratings. Visual quality data showed similar trends. at Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 4. Surface firmness of front, middle, and back areas of greens. Average surface firmness of all greens in August was 0.46 in while in September was 0.49 in. A lower surface firmness number signifies firmer areas, Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 5. Shear strength of front, middle, and back areas of greens. Average shear strength (Nm) of all greens during August was 17.9 Nm while in September it was 17.5 Nm. A slight decrease in shear strength was observed. Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 6. Soil moisture of front, middle, and back areas of greens. Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 7. Maximum root length of front, middle, and back areas of greens. Trends for root length have remained same for greens during the year and the practice green (Penn A1/A4 and 777) saw greater roots than the other three greens (USGA built in 2003). The practice green is a newer green (variable depth built in 2020) and likely explains the better rooting observed. Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 8. Thatch accumulation of front, middle, and back areas of greens. Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 9. Ball roll (green speed) measurements of front, middle, and back areas of greens. Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 10. Ring nematode population densities in front, middle, and back areas of greens. Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 11. Stubby root nematode population densities in front, middle, and back areas of greens. Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Figure 12. Root knot nematode population densities in front, middle, and back areas of greens. Bob Berry Sunshine Course, Lemont, IL. Sep 13, 2023

Final Photo

A super duper pumpkin find occured this week at Glen Oak Country Club in Glen Ellyn, IL. Settle, Sep 13, 2023 “A pumpkin is a vernacular term for mature winter squash of species and varieties in the genus Cucurbita that has culinary and cultural significance but no agreed upon botanical or scientific meaning. The term pumpkin is sometimes used interchangeably with “squash” or “winter squash”, and is commonly used for cultivars of Cucurbita argyrosperma, Cucurbita ficifolia, Cucurbita maxima, Cucurbita moschata, and Cucurbita pepo.” More on Pumpkin from Wikipedia