Hot! 90s for Highs, 1st Summer Patch, Cyst Nematode, and Fairway Research
Hot! A hot week was forecasted and arrived on schedule. For this part of the country it means highs reaching 90+. This second heat wave of July heat came at the same time of our first reports of a summer root rot known as summer patch of bluegrass. It’s the usual belowground suspect (Magnaporthe) and a key turfgrass species that is vulnerable (Poa). All that is needed are wet conditions and regular (intense) thunderstorms. That continues to be our July theme. Overall, we have been spared from July’s 2023 temperature extremes. Many parts of the United States have seen earth-scorching hot temperatures. Phoenix, Arizona is one example. There, they are dealing with an ongoing streak of 110+ highs (30 days).
In the Illinois landscape, things continue to shine even though it’s late July. That’s right, regular rains and normal temperatures have kept things green. Nevertheless, hot summer periods, like this one, will test drainage and irrigation. When soils are warm, overly wet conditions can quickly cause negative root effects. That’s why handheld moisture meters are extensively used to help determine if midday water inputs are needed on greens — critical in summer. When hot, every skilled superintendent and staff must correctly balance many parts to be successful and not lose grass. Three key components will always include: turfgrass science, golf course design and the weather. In the end, we are without complete control.* *The weather!?!
1st Report — Summer Patch of Kentucky Bluegrass
Summer patch is a historically significant disease in turfgrass because prior to its discovery diseases of turf were just aboveground. This root disease was discovered in 1984. Prior to that it was confused with Fusarium blight (a foliar disease).
Today, the actual hosts has expanded from just Kentucky bluegrass to also encompass Festuca spp. Today, summer patch has also been associated with creeping bentgrass golf greens in hot, stressful places like the transition zone (the southernmost adaptation for its growth).
See Penn State Fact Sheet by Peter Landschoot. Turfgrass Diseases: Summer patch (Causal fungus: Magnaporthiopsis poae)
Compendium of Turfgrass Diseases, fourth edition. 2023. Tredway, Tomaso-Peterson, Kerns and Clarke, editors. APS Press. 100–103.
Landschoot, P. J., and Jackson, N. 1989. Magnaporthe poae sp. nov., a hyphopodiate fungus with a Phialophora anamorph from grass roots in the United States. Mycol. Res. 93:59–62.
Cyst Nematode and Creeping Bentgrass Greens
Cyst nematode, Heterodera, is a root-feeding plant parasite occasionally found in creeping bentgrass greens in the Chicago area. This endoparasitic nematode spends the majority of its life cycle inside roots. Cyst nematode is similar to root knot nematode in its feeding behavior. Because of this aspect, it has greater potential to cause physical root damage (reduced biomass) and/or reduced function (reduced ability to provide needed water and nutrients).
Like other root-related issues the symptoms are typically small patches that are off-color (bentgrass will look bronze and Poa will look yellow). Also the patches suffer midday wilt (patches are collapsed looking). Such symptoms can be confused with many other causes from abiotic (localized dry spot) to biotic (fungal root rots). Good water management helps to limit further damage caused by root loss on greens and the patches will usually subside on their own when cooler conditions return.
Historically, cyst nematodes were first diagnosed negatively impacting creeping bentgrass golf greens in about 2005 at two locations in Illinois (Chicago and central Illinois) by Dr. Randy Kane. A survey conducted over the past few years will help us determine the frequency of cyst nematodes in golf greens in Illinois. Is cyst nematode more common in golf greens than we previously thought?
Fairway Research — July 26, 2023 by Shehbaz Singh, MS
As part of our monthly evaluations of fairway, greens, and tees at Bob Berry Sunshine Course in Lemont, fairways were evaluated again. Investigations evaluate playability, agronomic characteristics and quality. There are total of four creeping bentgrass fairways with different varieties*. *Fairways were renovated in 2020 by Wadsworth Golf Construction Co.
Fairway 1: Crystal Bluelinks, 17,377 sq ft
Fairway 2: OO7, 10,254 sq ft
Fairway 3: Pure Select, 8,089 sq ft
Apron: Pure Eclipse, 2,000 sq ft
Evaluation Procedure. On each fairway, three points were selected in a systematic way using a straight center line in front (approach), middle, and back. Four data readings or samples were collected around each of the three marked points. Six sets of data were collected (see below).
· Visual Quality (1–9 scale with 9 best and 6 = minimum acceptable)
- Normalized Difference Vegetation Index (NDVI) was measured using GreenSeeker by Trimble.
- Soil Moisture was measured using TDR350 by Spectrum Technologies, Illinois.
- Surface Firmness was measured using Field Scout TruFirm by Spectrum Technologies, Illinois.
- Shear Strength was measured using Shear Tester by Turf-Tech International, Florida.
- Weeds (%) was visually estimated around each point in about area of a 5 ft radius circle.
- Localized Dry Spot (%) was visually estimated around each point in about area of 5 feet radius circle.
- Root Length was measured taking the average of four 0.5-inch diameter soil core samples (maximum root length)
- Thatch Layer (cm) was measured taking the average of four 0.5-inch diameter soil core.
- Root-Feeding Nematodes were extracted by lite sucrose centrifugation using 100g soil (upper 2-inches of four soil cores). Four samples or data readings were collected around the point for each parameter.