Wet Again! Brown Patch, Dollar Spot, 1st Melting Out, TED Turf Education Day, Green Research

CDGATurfgrassProgram
6 min readAug 18, 2023

Thunderstorms would appear and then reappear. Large precipitation totals occurred on Monday and Thursday in northern Illinois. Comparatively, our situation this week is insignificant given conditions in other parts of the United States (storms in the Pacific Ocean played a major role in historic fires and loss of life). In the upper Midwest, a dry August period seems to have ended. Though summer isn’t over yet. August often means tired plants (wear) will definitely have a hard life. It helps to explain a few new aspects from lawns to fairways. The new foliar diseases we’ve begun to see — rusts and leaf spots — are, in part, due to compromised plant defenses. Any reduced root biomass means less stored energy (Plant Physiology 101).

Image 1. Thunderstorms returned to northern Illinois with significant accumulations of rain. Number 3 featuring creeping bentgrass varieties of Pure Select (approach) and PC2.0 (green), Bob Berry Sunshine Course, Lemont, IL. Settle Aug 17, 2023

In the landscape, most annual flowers are now peaking. Whether in the ground (landscape beds) or in a container (pots), massive amounts of blooms are now at hand. On golf courses, conditions continue to remain much better than expected. Our latest deluge of wet weather was met with dry soil conditions and thus well received. If this summer indeed ends on a wet note our undivided attention will be on roots. Here’s why. High traffic areas are vulnerable to wet, compact soils. This creates a greater incidence of root rots unless dealt with culturally (poking holes via aerification) and/or preventatively (fungicides are applied, then immediately watered in to depth of roots). Dense, healthy grass in August means one thing — roots!

Weather

Figure 1. Current air and soil temperatures. Nights have begun to feel increasingly cool. Bob Berry Sunshine Course, Lemont, IL
Image 1. Rain gauge reading a day after heavy rain, Bob Berry Sunshine Course, Lemont, IL. Singh, Aug 15, 2023
Figure 1. Heavy rains turn a dry August period upside down. Root health is now a focus. Data Source: WGN Weather Blog (Mon totals through 8:30 pm)

Brown Patch, Rhizoctonia solani

Update on research that uses a creeping bentgrass tee at North Shore Country Club in Glenview.

Quick Points

  1. Change. Summer conditions that were conducive (nights in the upper 60s and a leaf wetness duration of 10 hours or more) are now changing.
  2. Leaf Wetness. Ample leaf wetness continues to exist, 10 hours or more.
  3. Temperature. Cooler nights (easing away from 65-70 degrees) are now limiting brown patch development.
  4. Ajuvants. Testing SYNC® by Precision Laboratories (Kenosha, WI) for any additional ability to improve fungicide efficacy. Current data shown without final statistical analysis.
Figure 1. Research: Fungicide treatments versus brown patch disease in 4 ft x 6 ft treatment plots (mean of 4 replicates) on a creeping bentgrass practice tee. All rates listed are fluid ounces per 1,000 sq ft. North Shore Country Club, Glenview, IL.
Image 1. A single untreated 4 ft x 6 ft plot with brown patch negatively impacting the quality of a creeping bentgrass practice tee, North Shore Country Club, Glenview, IL. Singh, Aug 14, 2023

Dollar Spot, Clarireedia jacksonii

Update on research that uses a creeping bentgrass tee at North Shore Country Club in Glenview.

Quick Points

  1. Disease Progression. Conditions generally remain conducive for rapid dollar spot development in Chicago from August through September. Nighttime lows in the 50s ends dollar spot epidemics (October).
  2. Temperature. Favored by air temperatures ranging from 60–90 degrees (optimum 70–80 degrees).
  3. Ajuvants. Testing SYNC® by Precision Laboratories (Kenosha, WI) for any additional ability to improve fungicide efficacy. Current data shown without final statistical analysis.
Figure 1. Research: Fungicide treatments versus dollar spot disease in 4 ft x 6 ft treatment plots (mean of 4 replicates) on a creeping bentgrass practice tee. All rates listed are fluid ounces per 1,000 sq ft. North Shore Country Club, Glenview, IL.
Image 1. Dollar spot continues to progress in Chicago given conditions (humid) are currently ideal for its development. Here, a susceptible Kentucky bluegrass cultivar in the rough isn’t helped by slower growth characteristics caused by its location on a mound. Bob Berry Sunshine Course, Lemont, IL. Settle, Aug 17, 2023

First Report of Melting Out of Kentucky Bluegrass, Pyrenophora spp.

Note: New Latin name is used to describe a complex of leaf spot fungi (Drechslera refers to the asexual stage of Pyrenophora).

One more sign of fall you ask? Melting out of Kentucky bluegrass roughs has begun in Chicago. I scouted the usual areas on Sunshine Course in Lemont and found it for the first time this week. A problem on older Kentucky bluegrass varieties without genetic resistance. Newer Kentucky bluegrass cultivars have been selected for resistance to this disease.

Symptoms

Initially small flecks appear. They grow into spots that elongate parallel to a leaf blade axis. Over time more appear and coalesce. It can progress to a point of severe thinning. How “melting out” gets its name.

Control

Best control starts at establishment. Use newer varieties of Kentucky bluegrass.

For more information see the National Turfgrass Evaluation Program website and look for a test site nearest your location. Please see below.

Image 1. A Kentucky bluegrass rough around creeping bentgrass with initial signs of leaf spot/melting out (darker green, older variety — far left), Bob Berry Sunshine Course, Lemont, IL. Settle, Aug 17, 2023
Image 2. Close up of thinning (tan to bronze leaf blades) of a Kentucky bluegrass rough caused by leaf spot/melting out, Bob Berry Sunshine Course, Lemont, IL. Settle, Aug 17, 2023
Image 3. Leaf spots beginning to coalesce on Kentucky bluegrass leaf blades, Bob Berry Sunshine Course, Lemont, IL. Settle, Aug 17, 2023

Reference

Compendium of Turfgrass Diseases — Fourth Edition. 2023. Tredway, Tomaso-Peterson, Kerns, and Clarke, editors

Illinois Landscape Contractors Association (ILCA) Turf Education Day (TED) Thu, Sep 21, 2023

See below and Click Here for more information and to register.

The Must-Attend Event for All Turf Care Professionals. Location: NIU Conference Center in Naperville, IL.

Green Research — August 15, 2023 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., Florida.

· 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 greens over time. A reduction in visual quality (July versus August) is due to incidence of localized dry spot and solid tine aerification (last week). Bob Berry Sunshine Course, Lemont, IL. Aug 15, 2023
Figure 2. Visual quality of front, middle, and back sections of each green at Lemont, IL. All greens saw acceptable visual quality (6.0 or greater). Bob Berry Sunshine Course, Lemont, IL. Aug 15, 2023
Figure 3. Normalized Difference Vegetation Index (NDVI) of front, middle, and back sections of each green at Lemont, IL. All greens saw acceptable quality. Bob Berry Sunshine Course, Lemont, IL. Aug 15, 2023
Figure 4. Firmness of front, middle, and back sections of each green at Lemont, IL. Surfaces were less firm than last month (temporary/likely due to aerification). Bob Berry Sunshine Course, Lemont, IL. Aug 15, 2023
Figure 5. Sheer strength of front, middle, and back sections of each green at Lemont, IL. Similar trends among sections were observed for shear strength compared to last month. Overall average in August (17.9 Nm) was lower than overall average in July (19.5 Nm). Bob Berry Sunshine Course, Lemont, IL. Aug 15, 2023
Figure 6. Soil moisture of front, middle, and back sections of each green at Lemont, IL. Bob Berry Sunshine Course, Lemont, IL. Aug 15, 2023
Figure 7. Monthly average root length of each green at Lemont, IL. The practice green is a variable depth sand root zone built in 2020 (Penn A1 plus A4 values shown for reference). Greens 1, 2, 3 are a USGA-spec root zone built in 2004 (OO7 values shown for reference). Bob Berry Sunshine Course, Lemont, IL.
Figure 8. Root length of front, middle, and back sections of each green at Lemont, IL. Bob Berry Sunshine Course, Lemont, IL. Aug 17, 2023
Figure 9. Ball roll of front, middle, and back sections of each green at Lemont, IL. Given aerification by solid tine, little decrease in ball roll was observed for most greens. Bob Berry Sunshine Course, Lemont, IL. Aug 17, 2023
Figure 10. Ring nematodes extracted from front, middle, and back sections of each green at Lemont, IL. Nematodes are just beginning to establish on a new variable depth root zone built in 2020. Other greens (1, 2, 3) are older, built in 2004 then renovated in 2020 having same USGA-spec root zone. Bob Berry Sunshine Course, Lemont, IL. Aug 17, 2023
Figure 11. Stubby root nematodes extracted from front, middle, and back sections of each green at Lemont, IL. Nematodes are just beginning to establish on a new variable depth root zone built in 2020. Other greens (1, 2, 3) are older, built in 2004 then renovated in 2020 having same USGA-spec root zone. Bob Berry Sunshine Course, Lemont, IL. Aug 17, 2023
Figure 12.Root knot nematodes extracted from front, middle, and back sections of each green at Lemont, IL. Nematodes are just beginning to establish on a new variable depth root zone built in 2020. Other greens (1, 2, 3) are older, built in 2004 then renovated in 2020 having same USGA-spec root zone. Bob Berry Sunshine Course, Lemont, IL. Aug 17, 2023

Final Photo

A zoysia lawn glows in northern Illinois. Zoysia japonica is cold tolerant and even looks good in Chicago, IL. Settle, Aug 16, 2023.Zoysia japonica (commonly known as Korean lawngrass, zoysiagrass or Japanese lawngrass). It is native to the coastal grasslands of southeast Asia and Indonesia. The United States first introduced Z. japonica in 1895.” See Wikipedia for more.

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CDGATurfgrassProgram

Written by Derek Settle, PhD & Shehbaz Singh, MS. Mission: Provide science-based turfgrass research and diagnostics to 400+ member golf courses/superintendents.