Soils Pass Mid 50s! Few Issues, Waitea Patch, and Dollar Spot Research

CDGATurfgrassProgram
7 min readApr 19, 2024

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The third full week of April brought near ideal conditions for turfgrass growth on several days. The take home message here? Nothing better than cloud free days during spring in the upper Midwest. In a week, high temperatures crossed 80 degrees for the first time. Then there is less noticeable, but impactful, change. Soils have warmed past 55 degrees and continue to slowly gain heat. Few issues of greens were reported. The first maladies in March and April are behind us (snow molds, yellow patch). Kentucky bluegrass roughs and lawns are now green and growing — known for its dark green color, medium texture, and distinct boat shape leaf blade tip. Yes, Bob Berry Sunshine Course saw its first official mow of the rough.

Image 1. The first day of golf happened this week as Bob Berry Sunshine Course opened for play. Golfers enjoy hole one. On a windy day, a group from Revelation Golf putt balls onto a ‘Pure Distinction’ green from a ‘Crystal Bluelinks’ fairway/approach. Settle, Apr 16, 2024

And spring progresses. A foliar disease which causes bright yellow rings called Waitea patch appeared on Poa greens for the first time. In the landscape, about half the deciduous trees now have leaves. And the native oaks? Well they are just beginning to think about it — leafing out. Many more woody ornamentals were noticeable. If you looked up, redbud trees were suddenly in full bloom. The fragrant smell of Korean spice viburnum flowers was in the air. Actually, this spring has turned out to be more gradual than we first thought. And that’s okay. That’s normal. Next week is to see highs in the 60s with lows in the 40s. And if a gardener? Yes, there’s a frost advisory this weekend. So continue to enjoy a more “typical spring” outdoors. Just remember your jacket(s) and cover any sensitive vegetation.

Weather

Figure 1. Average soil temperatures at a 2" depth now near 60 degrees (2 inch depth). Certain preventative soil-based fungicide applications begin at 55 degrees. Bob Berry Sunshine Course, Lemont, IL
Figure 2. A more “typical spring” in Chicago is now being observed. Data provided by NOAA

Scouting for Broadleaf Weeds — Lesser Celandine, (Ficaria verna)

After speaking with a superintendent about broadleaf weeds we were seeing he mentioned one that is increasingly problematic in the Chicago forest preserves. It is called lesser celandine. Also known as fig buttercup. Anything that has a bright yellow bloom is noticeable. This one does and it will remind you of dandelion somewhat when you fist see it. However, it shares no other similarities. By June, lesser celandine simply disappears (a spring ephemeral perennial plant). It’s life strategy uses photosynthesis via early spring growth to then store carbohydrates into bellow ground tubers. Those belowground plant parts make it especially difficult to control unless a systemic herbicide is used. Removal by hand simply doesn’t work.

Lesser celandine is an invasive weed

  • Basal rosette of dark green, shiny leaves
  • Leaves are kidney or heart-shaped
  • Aggressive creeping/spreading growth habit
  • Well adapted to shade environments
  • Competitive advantage = early spring growth
  • Flowers elevated on single stalk with 8-12 yellow petals
  • Reproduces primarily vegetatively via prolific tubers and bulblets
Figure 1. Map of lesser celandine in the United States and Canada. Courtesy EDD MapS
Image 1. Lesser celandine is competing with a shaded fine fescue lawn in the early spring.Settlel, Apr 15, 2024
Image 2. Lesser celandine close up showing the yellow flowers with 8–12 petals. Settle, Apr 15,2024

Invasive Species Information

See Midwest Invasive Species Information Network or MISIN

University of Illinois Fact Sheet

Lesser Celandine Becoming a Major Problem in Parts of the State

Image 1. Dandelion is a common weed in turfgrass areas and easily competes with Kentucky bluegrass as it begins to green up in the spring, Bob Berry Sunshine Course, Lemont, IL. Settle, Apr 10, 2024

Scouting for Disease — Brown Ring Patch aka ‘Waitea Patch’ (Waitea circinata var. circinata

A ‘first report’ of Waitea patch occured this week. It is most problematic on Poa annua greens during spring in Chicago. This is a Rhizoctonia disease that was given the different name of Waitea by taxonomists. Historically, the CDGA Turfgrass Program has conducted an extensive amount research on Waitea patch.

Image 1. Bright yellow rings of Waitea patch on a green with high proportions of Poa annua. Settle, Apr 18, 2024
Image 2. Waitea patch has bright yellow rings/patches which vary in size from inches to feet. Settle, Apr 18, 2023
Image 3. A close up of a yellow ring on a bentgrass/Poa green surface shows Poa annua reacting, while creeping bentgrass less so. Settle, Apr 18, 2024

Waitea Patch Quick Facts

  • On Poa greens (common), Waitea patch causes bright yellow rings which measure a few inches to 1 feet or more in diameter
  • Rings can merge together to develop a “honeycomb” or “scalloped” look
  • On creeping bentgrass greens (not as common), Waitea patch rings will appear orange-bronze
  • A majority of systemic fungicides provide good control of Waitea patch both preventatively and curatively
  • Thiophanate-methyl should be avoided with regard to Waitea patch; research has shown it can increase this disease

CDGA Research on Waitea — excerpt from a 2010 preventive fungicide study at Biltmore Country Club in N. Barrington, IL

“At this site in 2008, 2009 and 2010, Waitea symptoms first occurred on 22 May, 18 May, and 25 May respectively. In all years, Waitea disease developed into June, but symptoms were absent in months thereafter. During autumn, Waitea is infrequently reported on Chicago greens for unknown reasons. Untreated plots saw peak disease development on 25 May with 13% damage by Waitea, and by 9 Jun disease symptoms naturally ended. Compared to the untreated control, all treatments reduced both Waitea percent and number except Daconil Ultrex and Harmonizer-alone. The remainder of fungicides tested allowed only trace levels (2% or less) of Waitea on all dates rated…”

Preventive control of brown ring patch and Microdochium patch on a Chicago Poa annua golf green, 2010. Authors: Settle, Sibicky, Rincker

Curative control of brown ring patch on a Poa annua golf green in Chicago, 2009. Authors: Settle, Rincker

Fungicide programs on greens for disease control, 2023. by Shehbaz Singh, MS

This study was sponsored by Syngenta and was initiated as an early curative to address dollar spot of a golf green. In 2023, especially dry weather conditions in the spring delayed dollar spot development until summer. Therefore, first fungicide application was made only after dollar spot development began on July 31, 2023.

Image 1. A creeping bentgrass nursery green originally seeded with ‘L-93’ plus ‘SR1119’ (Poa annua currently represents 10–20%) saw a fungicide study by Syngenta. It was conducted on the upper end of nursery green where dollar spot tends to be most prevalent, North Shore Country Club, Glenview, IL. Singh, Sep 25, 2023

Objectives

  • Evaluate two fungicide programs for dollar spot control
  • Estimate turf quality visually (1–9 scale) and electronically by Normalized Difference Vegetation Index (NDVI)

Materials and Methods

The study was conducted using a randomized complete block design and used 3 treatments with 4 replications. Individual plot size was 4 ft x 6 ft.

Fungicides were sprayed using a CO2 backpack sprayer at 40 psi that used three nozzles with XR TEEJET 800VS and applied water equivalent to 2 gals per 100 sq ft. A total of 5 applications were made for each treatment (see table 1).

Table 1. A putting green fungicide study to control dollar spot using a green pigmented product called Appear II. The study began at first signs of dollar spot during peak summer heat and stress during late July of 2023.

Data Collected

  • Dollar Spot (% per plot)
  • Visual Quality (1–9 scale, with 6 = minimum acceptable and 9 = best)
  • Normalized Difference Vegetation Index (NDVI) (GreenSeeker/Trimble HCS-100)
  • Localized dry spot (% per plot)
  • Yellow tuft (% per plot)

Dollar Spot

2023 Data. Average dollar spot in experimental plots was 5.4% at the start of the study. By study end (Oct 6, 2023) dollar spot had peaked with 57.5% plot damage in untreated plots. Both programs effectively controlled dollar spot (Fig 1.).

2024 Data. By spring (Apr 15, 2024) residual dollar spot injury was still evident and plots were rated. Natural recovery had occurred during a relatively mild winter and spring. Nevertheless, untreated plots remained significantly damaged by residual dollar spot infection centers. (Fig 2.)

Figure 1. Dollar spot disease development of untreated, fungicide program 1 and fungicide program 2 in 2023. North Shore CC, Glenview, IL
Figure 2. Residual dollar spot injury when evaluated the following year on Apr 15, 2024. North Shore CC, Glenview, IL

Visual Quality

2023 Data. At study start, visual quality of all treatments was lower than a minimum acceptable turf quality of 6.0. By study end (Oct 6, 2023), visual quality for both programs was 7.5 whereas untreated, badly damaged by dollar spot, remained unacceptable. The addition of Appear II in both programs enhanced the green color of creeping bentgrass turf (Fig 1.).

2024 Data. Nine months after the study had started residual dollar spot damage was still present and negatively impacting visual quality of untreated plots. However, the visual quality for both programs was acceptable (Program 1 was 6.5 and Program 2 was 6.0) (Fig. 2).

Figure 3. Visual quality of untreated, fungicide program 1 and fungicide program 2 in 2023. North Shore CC, Glenview, IL
Image 2. 2023 Data: Untreated (left), Program 1 (middle), and Program 2 (right), North Shore Country Club, Glenview, IL. Singh, Sep 25, 2023
Figure 4. Visual quality as affected by residual dollar spot injury when evaluated the following year on Apr 15, 2024. North Shore CC, Glenview, IL
Image 3. 2024 Data: Untreated (left), Program 1 (middle), and Program 2 (right), North Shore Country Club, Glenview, IL. Singh, Apr 15, 2024

Normalized Difference Vegetation Index

2023 Data. At study start an average NDVI of 0.69 was recorded for all treatments. At the end of the study (Oct 6, 2023), NDVI of untreated was significantly lower than fungicide program treatments (Fig. 5).

2024 Data. Nine months after the study had started residual dollar spot damage was still present and negatively impacting NDVI of untreated plots with a reading of 0.46. The NDVI for both programs was greater concurant with greater turfgrass density. NDVI readings of both Programs 1 and 2 was 0.55 and 0.59 respectively (Fig. 6).

Figure 5. NDVI of untreated, fungicide program 1 and fungicide program 2 in 2023. North Shore CC, Glenview, IL
Figure 6. Visual quality as affected by residual dollar spot injury when evaluated the following year on Apr 15, 2024. North Shore CC, Glenview, IL
Figure 7. Localized dry spot (LDS) of untreated, fungicide program 1 and fungicide program 2 in 2023. LDS was not present in the study when it was rated again on Apr 15, 2024. North Shore CC, Glenview, IL
Korean spice viburnum is known for its fragrant scent, Midwest Golf House, Lemont, IL. Settle, Apr 16, 2024 “Viburnum carlesii, the arrowwood or Korean spice viburnum, is a species of flowering plant in the family Adoxaceae (formerly Caprifoliaceae), native to Korea and Japan (Tsushima Island). Round clusters of red buds open to strongly scented, pale pink flowers in late spring. These are followed in late summer by oval red fruits ripening to black in autumn.” for more see Wikipedia

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CDGATurfgrassProgram
CDGATurfgrassProgram

Written by CDGATurfgrassProgram

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

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