Spring Returns! Soils Warm, Broadleaf Weeds go KaBoom, and Moss Research

6 min readApr 12, 2024

With that first chilly week behind us, April feels more like April. Quickly signs of spring have appeared (soil temperatures have warmed). The downward trend reversed, and currently soils are nearing 50 degrees and superintendents took note. Threshold soil temperatures are used to time initial plant fungicide applications: 55 degrees (fairy ring and take-all patch) and 65 degrees (summer patch). Familiar flowers finally made their debut. Lawns saw yellow dandelion and purple henbit. As for ornamental trees, white to pink to yellow Magnolias (a favorite) have begun, whereas bradford pears (no longer favored) are currently in full white bloom.

Image 1. Aerification of greens remains a regular spring phenomena especially noticed by golfers . Simply made holes the antidote to compaction/poor rooting. Twin Orchard Country Club, Long Grove, IL. Settle, Apr 9, 2024

Another familiar site this week? Just drive by a golf course and you’ll likely see a variety of aerification methods “in play”. Used to achieve what some call “the holey grail”, the primitive act of punching holes in golf surfaces is simple yet important. Soil channels provide enhanced root growth — the easiest (and quickest) way to optimize turfgrass health. Meanwhile, spring 2024 continues with news. This week it was air temperature statistics. We continue beyond the norm and, since January 1, are averaging more than 5 degrees above normal. Chi-town is experiencing its 5th warmest year since 1871 (our February was the warmest ever in 153 years). Big story number 2: The Masters. After thunderstorms delayed play on day 1, two Americans were on top early — DeChambeau and Scheffler. Spring has returned!


Figure 1. April Warms: Average soil temperatures at a 2" depth are now past 50 degrees (2 inch depth). Certain preventative soil-based fungicide applications begin at 55 degrees. Bob Berry Sunshine Course, Lemont, IL
Figure 2. Good news on drought as we begin this growing season. Drought conditions across the contiguous United States as of March 26, 2024. Extreme (red) and exceptional (dark red) drought was present in relatively small parts of the Southwest and central Great Plains. Map by NOAA

Scouting for Broadleaf Weeds — Dandelions, Taraxacum officinale

One of the first weeds you’ll notice in the spring is dandelion. We saw it begin in spades this week and happened as soil temperatures crossed 50 degrees this week. If desired, dandelion is relatively easy to control with current broadleaf herbicides.

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

Dandelion Fact Sheet — Purdue University

For more on dandelion and control options Dr. Aaron Patton has more.

Scouting for Disease — Microdochium Patch or Pink Snow Mold (Microdochium nivale)

In a week little disease activity was observed overall. Cool, wet conditions continued the development of certain fungi. In one case a superintendent scouted Microdochium patch developing on a creeping bentgrass green.

Image 1. Symptoms of Microdochium patch are distinct and can look like a target. Also known as pink snow mold. Cool, wet conditions has given this disease ideal conditions for development. It doesn’t need snow cover to occur, just extended periods of leaf wetness. Courtesy Chicago GCS, Apr 2, 2024

New Root Zones Problematic (Yellow Patch, Rhizoctonia cerealis)

Yellow patch (R. cerealis) was confirmed once again this week at a course visit. As before the disease was associated with a new golf green. The common thread of all the Chicago yellow patch (Rhizoctonia cerealis) outbreaks in 2024 this spring continues to be two fold: wet, cool conditions plus new USGA-spec greens with a new root zones. Older, established greens are not nearly as affected. All this suggests natural antagonistic soil microbes are part of the explanation. If missing (the microbes/the good guys and girls) yellow patch can be problematic. Outbreaks have been independent of creeping bentgrass variety used. More research is needed.

Image 2. Yellow patch (R. cerealis) on a new creeping bentgrass green (Pure Distinction + Pure Select + Penn A1) looks different compared to Microdochium patch (see image 1). Notice a majority of the damage is localized to the outer “smoke ring” and this is typical of Rhizoctonia diseases of turf. Settle, Apr 9, 2024

Moss Control in Greens with Newer Granular Products, 2023. by Shehbaz Singh, MS

In 2023, a moss control study sponsored by The Andersons was conducted on a L-93 plus Providence creeping bentgrass nursery green at North Shore Country Club, Glenview, IL. The results will be discussed below.

Image 1. Nursery green had creeping bentgrass ‘L-93’ plus ‘SR1119’ and Poa annua (two species estimated at 80–90% bent and 10–20% Poa). The study was conducted on the lower end of nursery green where moss infestation was most prevalent. North Shore Country Club, Glenview, IL. Singh, Oct 20, 2023


  • Evaluate moss control
  • Evaluate turf quality visually
  • Evaluate turf quality electronically
  • Evaluate occurance of phytotoxicity
  • Document incidence of disease

Materials and Methods

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


  • Visual Quality (1–9 scale, with 6 = minimum acceptable and 9 = best)
  • Normalized Difference Vegetation Index (NDVI) using GreenSeeker/Trimble HCS-100
  • Phytotoxicity (%)
  • Disease (%)


The study was initiated on Jun 10, 2023. Granular products were carefully hand-spreaded over experimental plots to provide optimum distribution. Quicksilver herbicide was sprayed in water equivalent to 2 gal per 100 sq ft using a CO2 backpack sprayer at 40 psi with a hand-held three nozzle boom (XR TEEJET 800VS). A total of 8 applications were made for each treatment. Except for Quicksilver, all treatments were watered in immediately after application.

Table 1. Treatments used for a moss study on a nursery green at North Shore Country Club in 2023.


At study start, the average moss infestation in all plots was 39.2%. By fall, 4.5 months later, moss was significantly reduced by all treatments versus untreated. Quicksilver and Fiesta provided best control with 5% and 1.3% moss remaining respectively. Castaway reduced moss levels to 21.7%

After 9 months, moss was reduced to 0% for both Quicksilver and Fiesta. Castaway reduced moss levels to 8.7% with greatest activity in the fall.

Figure 1. Moss Infestation (%) on a creeping bentgrass nursery green. A total of 8 applications occurred every 14 days from Jun 10 to Oct 13 in 2023. Fisher’s LSD (p<0.05). North Shore Country Club, Glenview, IL

Visual Quality

At study start, average visual turf quality in all plots was 4.5, lower than the minimum acceptable turf quality of 6.0. By fall, 4.5 months later and after completing 8 applications, the visual quality was better than untreated (2.7) for all treatments with Quicksilver at 5.5 and Castaway at 4.2. In contrast, the visual turf quality for Fiesta was acceptable at 7.0.

After 9 months, visual quality results remained quite similar to what was observed at 4.5 months: Quicksilver at 5.0, Castaway at 5.7, and untreated at 3.7. For Fiesta, visual turf quality remained 7.0. Fiesta consistently maintained a brighter green color due to a fertility effect (Fe and N).

Figure 2. Visual Quality (1–9, 6 acceptable) on a creeping bentgrass nursery green. A total of 8 applications occurred every 14 days from Jun 10 to Oct 13 in 2023. Fisher’s LSD (p<0.05). North Shore Country Club, Glenview, IL

Normalized Difference Vegetation Index

An average NDVI of 0.77 was recorded across all plots at study start. At 4.5 months, the NDVI for untreated was 0.68, Quicksilver was 0.67, Castaway was 0.74, and Fiesta was 0.77.

After 9 months, the NDVI for untreated was 0.55, for Quicksilver was 0.54, Castaway was 0.64, and Fiesta was 0.68. Quicksilver looked less green than other treatments after 8 applications and this caused lower NDVI ratings.

Figure 3. Normalized Difference Vegetation Index (NDVI) on a creeping bentgrass nursery green. A total of 8 applications occurred every 14 days from Jun 10 to Oct 13 in 2023. Fisher’s LSD (p<0.05). North Shore Country Club, Glenview, IL
Image 2. Shehbaz Singh takes photos of treatments in a moss study prior to initial treatments. North Shore Country Club, Glenview, IL. Jun 10, 2023.
Image 3. Photos of treatments at 4.5 months [A] Untreated, [B] Quicksilver, [C] Castaway, and [D] Fiesta at North Shore Country Club, Glenview, IL. Singh, Oct 20, 2023
Image 4. Photos of treatments at 9 months [A] Untreated, [B] Quicksilver, [C] Castaway, and [D] Fiesta at North Shore Country Club, Glenview, IL. Singh, Apr 8, 2024

Final Photo

PJM Rhododendron is a favorite. Purple to pink bloom begins in the spring, Evanston, IL. Settle, Apr 11, 2024. “Both species and hybrid rhododendrons (including azaleas) are used extensively as ornamental plants in landscaping in many parts of the world, including both temperate and subtemperate regions. Rhododendrons are often valued in landscaping for their structure, size, flowers, and the fact that many of them are evergreen. Azaleas are frequently used around foundations and occasionally as hedges, and many larger-leafed rhododendrons lend themselves well to more informal plantings and woodland gardens, or as specimen plants.” Wikipedia has more




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