Windy! LDS, Fairy Ring, Pythium Root Rot, and Fairway Research

Windy & Warm! A combination of wind and warmth suddenly brought us closer to summer — the look and feel. It also represented the first real test of healthy roots. Most would pass the test with not flying colors, but a ‘flying color’ given the goal is to remain green. Scouting this week revealed our first glimpse of situations where midday hand watering of golf greens IS REQUIRED. In some cases healthy roots were lacking — not too surprising given overly wet conditions have predominated up to now in spring 2024. In other cases, a lack of healthy soil conditions were apparent — our first episodes of severe localized dry spot and fairy ring were experienced in greens. Water hoses were off the storage racks and “putting out hot spots” as needed.

Image 1. A creeping bentgrass/Poa annua putting green a warm (90s) and windy day in Chicago has purplish patches which are most commonly associated with midday wilt stress. Settle, May 21, 2024

In the landscape this week, one flower was hard to miss. Peony or Paeonia officinalis is a longstanding favorite that is always in peak bloom about Memorial Day. Meanwhile, those periodical cicadas did begin to emerge with greatest numbers are expected in green spaces where development has remained curtailed. Such urban areas with largely undisturbed soils are represented by our forest preserves, parks, cemeteries and golf courses to name a few. And for those who would like to learn more about modern golf course construction see May’s CDGATV video which contains our first educational topic simply called Sandstorm. Listen and see how the Bob Berry Sunshine Course takes a deep dive into the topic of bunkers. After you watch that important Sandstorm video, enjoy your holiday weekend!

Weather

Figure 1. Soil temperatures cross 70 degrees and puts us into summer-like conditions. Bob Berry Sunshine Course, Lemont, IL

Figure 2. Do not panic, but the latest Climate Prediction Center 90 day forecast (Jun, Jul, Aug) now indicates a warmer than normal summer for just about every state = includes Illinois. The last very hot summer for Chicago (40+ days with highs over 90 degrees) was 2012. Map courtesy NOAA

Scouting for Disease — Fairy Ring, type 1 (multiple basidiomycete fungi species)

Our first report of an aggressive type 1 fairy ring negatively impacting a green came earlier than expected. You do not want type 1. For the fairy ring connoisseurs: Type 1 = dead rings, type 2 = green rings, and type 3 = rings of mushrooms or puff ball fungal fruiting structures. The weather shift to windy and warm this week created a significant dry down which was the primary contributing factor.

Is Fairy Ring Pathogenic?

Fairy ring (multiple basidiomycete fungi) are not directly pathogenic to turfgrass. Instead these fungi consume organic matter produced by turfgrass. Species of turfgrass that spread via stolons (creeping bentgrass) or rhizomes (Kentucky bluegrass) are most likely to have a proliferation of organic matter in the form of thatch.

Thatch

Low levels and no more of thatch is a major goal of turfgrass managers. One reason is that thatch/organic matter increases the likelihood of fairy ring and associated localized dry spot or LDS. And although not directly pathogenic these fairy ring fungi can significantly damage turfgrass (especially in sandy soils).

Image 1. Signs of a fairy ring fungus causing an issue includes shapes of circles, arcs and scalloped edges. Underneath the damaged turf, fungal mycelium is responsible for hydrophobic conditions that impair normal water infiltration. Settle, May 21, 2024

Image 2. A research project is initiated for BASF to assess newer fungicides in their curative ability to control fairy ring. Ten treatments are arranged in a randomized complete block design with four replications. Settle, May 21, 2024

Control

Type 1 fairy ring can be particularly troublesome on sand based greens where conditions of hydrophobic soil are common.

• Fertilization via nitrogen or iron can be used to mask symptoms — most useful if type 2 (green rings)
• Aerification methods are used to create channels to break through hydrophobic soils — from pitch forks to solid tine aerification machines
• Products called soil surfactants are used to help rewet soils — a plethora of products exist, use those which have been researched on greens
• Fungicides are useful, but require reapplication on at least a 28 day basis for prevention — newer DMIs are considered the best options in the spring for broad-spectrum suppression of fairy ring

Fungicide Recommendations for Fairy Ring

Click link & see pages 17–18. Chemical Control of Turfgrass Diseases 2020

Scouting for Disease — Pythium Root Rot (multiple Pythium species)

Root rots are a problem that can be unnerving. They lurk beneath the ground in otherwise healthy stands of turfgrass — out of site and out of mind. Conditions that are cloudy and wet will allow root rots to progress without symptoms — our preceding two months. A weather shift to windy and warm can quickly result in damaging symptoms by root rots — this week! A primary contributing factor can be an upper organic layer which does not dry out — the one I measured in a new green with Pythium root rot symptoms was about 1 inch. Young bentgrass greens normally have an organic layer that must be monitored = regular aerification is the solution.

Pythium as a group are not true fungi and instead are oomycetes. Oomycetes are more closely related to brown algae. This means specific “Pythium specialist” fungicides are required. Thus, proper identification is required. Aboveground symptoms alone are not adequate as root rots such as Pythium will have many look-a-likes.

Image 1. Signs of midday wilt stress associated with Pythium root dysfunction in a 1 year old ‘Pure Distinction’ putting green. Settle, May 23, 2024

Image 2. Close up of signs of midday wilt stress associated with Pythium dysfunction in a 1 year old Pure Distinction putting green. Settle, May 23, 2024

Image 3. An individual plant of creeping bentgrass suffering wilt stress with a youngest leaf blade remaining green and older leaves brown/senescing. This is a classic sign of wilting and the possibility of a root rot. Settle, May 23, 2024

Image 4. Pythium oospores found throughout shallow creeping bentgrass roots. This is what you are looking for when the host is a brand new creeping bentgrass green with a 1 inch layer of organic matter. Settle, May 23, 2024

Control

Pythium root rots are a chronic disease of creeping bentgrass greens. We do fully understand how susceptible the newest varieties actually are to Pythium root rots. More research is needed.

• Monitor the normally occurring organic layer in the upper root zone and do not allow it to exceed 1 inch in depth — Aerification methods are used to remove organic matter & sand topdressing is used to dilute organic matter
• Products called soil surfactants help reduce intensity of midday wilt stress of which Pythium root rot can be a contributing factor
• Pythium fungicides are not an elective but a requirement if growing creeping bentgrass. See 1, 2, 3 below
• 1) Use systemic products like phosphites or phosphonates on a regular basis during the summer season (Jun to Sep)
• 2) Use Pythium specialist fungicides during high pressure periods = wet conditions (cloudy and wet) followed by dry conditions (warm and windy)
• 3) The two newest Pythium fungicides have been well received by the turfgrass industry = Segway and Serrata

New Fungicide Recommendations for Pythium Root Rot

What fungicides control Pythium root rot on creeping bentgrass the best? by Jim Kerns et al. Golfdom, July 27, 2023

Newer Products are Best to Control Pythium in Turf

Newer Pythium products have allowed for greater efficacy as well as improved ability to rotate among FRAC groupings (reduces risk of fungicide resistance).

Table 1. Treatment information for three NC-State studies on ‘Dominant Plus’ creeping bentgrass versus Pythium root rot disesae. Modified from Golfdom

Shear strength relationship to below-ground measurements of golf fairways. by Shehbaz Singh, MS

Shear strength is generally referred to as the rotational traction force required to break the turf. Shear strength testing is commonly done for the sports field to better understand player-surface interaction. In the game of golf, surface strength has been used to estimate the ball mark severity on greens. USGA agronomists have begun to measure surface strength to develop a better understanding of its role in putting green performance. However, shear strengths’ relationship to other turf growth and playability characteristics largely remain unknown.

In 2023, a study was conducted to understand the shear strength relationship with above-ground and below-ground measurements of fairways at the Bob Berry Sunshine Course, Lemont, IL.

Objectives

• Evaluate the relationship of turfgrass shear strength versus turfgrass health measures both above and belowground.
• Evaluate shear strength as a predictor of turfgrass health prior to or during stress.

Description of Fairways

There are a total of four creeping bentgrass fairways which includes one apron near the large practice green at the Bob Berry Sunshine Course. During the 2020 renovation, creeping bentgrass turf on Fairway 1, 2, and 3 were killed and reseeded with different newer creeping bentgrass varieties. Also, the apron near the large putting green had artificial turf which was removed and similarly seeded with newer creeping bentgrass. Fairways were renovated in 2020 by Wadsworth Golf Construction Co.

Table 1. Fairways and description at Bob Berry Sunshine Course, Lemont, IL.

Image 1. Aerial view of putting greens at Bob Berry Sunshine Course, Lemont, IL.

Fairway Evaluation Methodology

• Each fairway was divided into front (approach), middle, and back sections.

• One point was marked each in front, middle, and back section of fairway in a straight line.

• Four data samples were collected around each point.

• Fairways were evaluated on exact points each month from April to October 2023.

Image 2. Evaluation Methodology: Aerial view of fairway 2 using SpecConnect software, Spectrum Technologies, Inc., Bob Berry Sunshine Course, Lemont, IL.

Data

• Turfgrass Quality — 1–9 scale, with 6 acceptable and 9 best
• Normalized Difference Vegetation Index (NDVI) — Greenskeeper/Trimble HCS-100
• Soil Moisture (%) — 1.5-inch depth TDR 350, Spectrum Technologies Inc.
• Shear Strength (Nm) — Shear-strength tester, Turf-Tec International
• Surface Hardness — TruFirm meter, Spectrum Technologies Inc.
• Root Length (inch) — Maximum root length using a standard 0.5-inch diameter soil core
• Organic Matter Accumulation (inch) — Maximum OM accumulation using 0.5-inch diameter soil sampler
• Nematode Population Density (per 100 cc soil) — Plant parasitic nematodes were extracted using a modified sucrose flotation technique. Soil samples were same cores used for root length measurement

Below-ground Measurement Data

Shear Strength: Trends showed lower shear strength values for all fairways during the spring months (Apr, May). This corresponds to slow growth of creeping bentgrass during the spring season in the Chicago area. Higher shear strength values were observed for all fairways during the summer months (Jun, Jul) when bentgrass is growing at its full potential. Shear strength values decreased during the early fall months (Aug, Sep).

Shear strength numbers for fairways were relatively higher than the greens on all rating dates. This corresponds to more stolon growth in fairways due to higher mowing height than putting green.

Trends show Apron ‘Pure Eclipse’ with higher shear strength values on most rating dates. It could be a varietal effect or due to more growth in the apron area since it is closer to green and receives optimum soil moisture all year long. Number 2 fairway ‘007’ had a lower shear strength number on most rating dates in 2023.

Figure 1. Shear strength of creeping bentgrass fairways from Apr 2023 to Sep 2023, Bob Berry Sunshine Course, Lemont, IL.

Soil Moisture: Trends showed greatest soil moisture was associated with fairway 3 in a majority of months sampled. Least soil moisture was associated with fairway 2 in May. This corresponded to a period of drought in the spring which began in May and peaked in June.

Figure 2. Soil moisture of creeping bentgrass fairways from Apr 2023 to Sep 2023, Bob Berry Sunshine Course, Lemont, IL.

Root Length: Trends showed lower root length for number 2 fairway ‘007’ for most rated months in 2023. It could be an attribute of poor drainage due to a lack of a below-ground drainage system in fairway 2. Number 3 fairway ‘Pure Select’ had good root length all year long possibly due to the small area comparatively and below ground drainage system. Root length numbers for all fairways were higher for the sample taken from the front section where soil moisture is usually higher than the middle and back sections.

Figure 3. Maximum root length of creeping bentgrass fairways from Apr 2023 to Sep 2023, Bob Berry Sunshine Course, Lemont, IL.

Organic Matter Accumulation: Organic matter accumulation depth for fairways ranged from 0.63 to 1.4 in. Organic matter accumulation for bentgrass green increased from the summer months to the fall months. Organic matter accumulation for fairways was higher compared to greens.

Figure 4. Organic Matter Accumulation of creeping bentgrass fairways from Apr 2023 to Sep 2023, Bob Berry Sunshine Course, Lemont, IL.

Figure 5. Total plant parasitic nematodes extracted from creeping bentgrass fairways from Apr 2023 to Sep 2023, Bob Berry Sunshine Course, Lemont, IL.

Total Plant Parasitic Nematode Populations: Root-knot (Meloidogyne), Stunt (Tylenchorhynchus), Ring (Mesocriconema), Spiral (Helicotylenchus), and Lesion (Pratylenchus) nematodes were detected in fairways. Overall, a higher number of ring and spiral nematode populations were observed for all fairways. A smaller number of root-knot and stunt nematodes were observed. However, lesion nematodes were only found for the ‘Crystal Bluelinks’ fairway.

Compared to other fairways, number 2 fairway ‘007’ had a lower number of nematodes on most rating dates in 2023. This likely was influenced by lower plant health measures of ‘007’ versus other cultivars (reduced maximum root length and lower shear strength).

Figure 5. Root knot nematodes extracted from creeping bentgrass fairways from Apr 2023 to Sep 2023, Bob Berry Sunshine Course, Lemont, IL

Root-knot Nematode Populations: Root-knot (Meloidogyne) is the most problematic nematode of those found. It was most consistently found in fairway 1 ‘Crystal Bluelinks’. In other fairways, root knot may still be establishing and below our detection threshold.

Correlation Analysis Fairways 1, 2, 3 and Apron Correlations ranked from highest to lowest

• Soil Moisture: A moderate positive correlation between shear strength and soil moisture was observed with ‘r’ value of 0.45.
• Root Length: A weak positive correlation between shear strength and root length was observed with ‘r’ value of 0.35.
• Organic Matter: A weak positive correlation between shear strength and organic matter accumulation was observed with ‘r’ value of 0.28.
• Root-Knot Nematodes: A weak positive correlation between shear strength and root-knot nematodes was observed with ‘r’ value of 0.35.
• Total Nematodes: A weak negative correlation between shear strength and total nematodes was observed with ‘r’ value of -0.25.

Table 2. Correlation analysis of below-ground measurements with shear strength. Using the average data of each measurement over the 2023 season (Apr-Sep). The number value stands for the coefficient of correlation ‘r’ which ranges from -1 to 1. ‘r2’ stands for the coefficient of determination which ranges from 0 to 1.

Final Image

Peony is associated with Memorial Day. Often used as a flower at gravesites. Evanston, IL. Settle, May 24, 2024

“Paeonia officinalis, the common peony, or garden peony, is a species of flowering plant in the family Paeoniaceae, native to mainly mountainous areas of Southern Europe and introduced in Central and Western Europe and North America. Paeonia officinalis was first used for medicinal purposes, then grown as an ornamental. Many selections are now used in horticulture, though the typical species is uncommon. Paeonia officinalis is still found wild in Europe.” For more see Paeonia officinalis here.