Drying (trying)! Saturated Soils, Summer Patch, Fairy Ring, and Dollar Spot Research
The forecast had promised we would dry. And we did. It was a pleasure to experience a drop in humidity for a day or two. A lessening of water puddles happened in the lowest areas of every creeping bentgrass fairway. However, as quickly as it came, it left — humid air with cloud cover returned. In a week, severe thunderstorms would lash Chicago’s north suburbs and one course recorded ~6 inches of precipitation in 8 days. Without a doubt golf course fairways have been hardest hit in 2024. Our native soils are both strong (among the most fertile), and weak (drainage can be problematic). “Illinois is known for its “black dirt” with Drummer silty clay loam being the most common. The Drummer soil series consists of very deep, poorly drained soils that formed in 40 to 60 inches of loess or other silty material and in the underlying stratified, loamy glacial outwash; under native prairie vegetation.” USDA Natural Resources Conservation Service
In the landscape, a major disease of lawns has begun. Known as summer patch, it is the most common fungal root rot of bluegrass (Poa). The best two solutions are non-chemical: 1) Utilize higher heights of cut (low mowing heights increase plant stress) and, 2) conduct annual aerification events (compacted soils choke normal root growth). Believe it or not, aerification is already a hot topic for some Chicagoland golf courses given newer summer timings for aerification (mid-August) being implemented. Late summer aerification captures rapid creeping bentgrass growth and is also a good strategy to kick-start root recovery early. If you look it up, “Better through Golf” is the mission of the Chicago District Golf Association. “Better through Roots” is without a doubt the unofficial mission of every golf course superintendent.
Weather
Scouting for Disease — Summer Patch (Magnaporthiopsis poae)
Summer patch is a root, crown and stem disease of annual bluegrass, Kentucky bluegrass and fine fescue. It develops under periods of plant stress during periods of hot weather. Our first outbreaks of summer patch weren’t unexpected. They occurred in a week that followed a rapid dry down. Roots were already infected. Frequent rainfall had likely masked the development of symptoms.
Solutions for Summer Patch
Cultural Practices are Key
- Relieve compaction with core aerification in the spring and fall
- Maintain soil pH between 5.5–6.0
- Ammonium-based fertilizers appear to reduce symptoms, while nitrate forms increase severity. Urea forms seem to have a neutral affect.
Excellent Penn State Fact Sheet
Turfgrass Diseases: Summer patch (Causal fungus: Magnaporthiopsis poae) by Peter Landschoot, PhD
Fungicides
See newest 2024 recommendations in PPA-1: Chemical Control of Turfgrass Diseases 2024 (uky.edu).
Scouting for Disease — Fairy Ring (multiple basidiomycete fungi)
Wet followed by dry conditions are often associated with fairy ring. Fairy ring can be especially damaging in golf putting greens. Dr. Mike Fidanza has spent a majority of his career working on this particular turfgrass “disease”. In the article Fairy Ring 101, he describes in detail what happens in turfgrass systems. Here are some bullet points:
- Fairy ring indirectly causes turf damage by disrupting the environment below the surface.
- Type-I fairy ring symptoms are the most severe and are associated with necrotic or dead turf.
- Development of hydrophobicity or soil water repellency in the rootzone is one factor.
- Another factor is the accumulation of ammonium to levels toxic to plant roots.
Solutions for Fairy Ring
Control of fairy ring relies heavily on cultural practices like wetting agents. Newer DMI fungicides are also of interest because they can offer broad suppression of fairy ring fungi with minimal turfgrass growth regulation. See newest 2024 recommendations in PPA-1: Chemical Control of Turfgrass Diseases 2024 (uky.edu).
Evaluate spoon-feeding fertility to improve plant health and its ability to reduce fungicide inputs in a creeping bentgrass green by Shehbaz Singh, MS
An Aquatrols fertility trial is being conducted to evaluate its influence on dollar spot disease development in a creeping bentgrass nursery green. The objective was to determine if fertility products can maintain acceptable dollar spot control with reduced fungicide inputs. The study is being conducted at North Shore Country Club in Glenview, IL.
Material and Methods
The small plot study has 10 treatments in a randomized complete block design with 4 replications. Each individual plot size is 4 ft by 6 ft. Data shown reflects two (28 day) or three (14 day) applications on June 11, June 24, and July 8.
Objectives
- Determine if fertility products can maintain acceptable dollar spot control with reduced fungicide inputs
- Evaluate turf quality
- Evaluate any phytotoxicity
Measurements
- Visual Quality (1–9 scale, with 6 = minimum acceptable and 9 = best)
- Normalized Difference Vegetation Index (NDVI) using GreenSeeker/Trimble HCS-100
- Dollar Spot (% per plot)
- Silvery Thread Moss (% per plot)
- Color/Phytotoxicity (1–9 scale)
Dollar Spot Disease
Dollar spot disease incidence was minimal during June given cool temperatures were experienced. During July rapid development of dollar spot occurred. For example, on July 1, dollar spot in untreated plots was ~10%, but reached 35% two weeks later on July 15.
Daconil Action at 14-day Interval
Dollar spot in treatments of fertility products + Daconil Action 4 oz (full rate) remained acceptable (less than 10%). Under increased dollar spot disease pressure (Jul 8-22), the half rate of Daconil Ultrex was no longer able to maintain acceptable disease control regardless of additional fertility (Fig. 1).
Visual quality agreed with disease ratings and the half rate of Daconil Ultrex was unable to maintain acceptable visual quality regardless of additional fertility (Fig. 2).
Daconil Action at 28-day Interval
The full rate of Daconil Ultrex was unable to maintain acceptable disease control regardless of additional fertility beyond 14 days (Fig. 3).
However, of all treatments, CarbN + Fusion was different and the only treatment able to provide acceptable visual quality on 1 Jul and 8 Jul when dollar spot disease pressure was moderate (Fig. 4).
Final Image
“Hydrangea paniculata, or panicled hydrangea, is a species of flowering plant in the family Hydrangeaceae native to southern and eastern China, Korea, Japan and Russia (Sakhalin). It is a deciduous shrub or small tree, 3.3-16.4 ft tall by 8 ft broad, growing in sparse forests or thickets in valleys or on mountain slopes. In late summer it bears large conical panicles of creamy white fertile flowers, together with pinkish-white sterile florets. Florets may open pale green, grading to white with age, thus creating a pleasing “two-tone” effect.” For more see Hydrangea paniculata — Wikipedia.
