(Near) Perfect Conditions! Turfgrass Quality Peaks, Pythium Root Rot, and Green Research

5 min readJul 21, 2023

Perfect! Saying that can get you in trouble, but in a week it really was true. We saw some of our best days of turfgrass growth. For cool season turf, it meant the weather had finally cooperated. What does that look like? The days were not too hot (80s for highs), the nights were not too cool (60s for lows) and frequent, severe thunderstorms were absent (a relief). Likewise, our field research projects saw turfgrass with highest quality to date. For example, a creeping bentgrass fairway fungicide study had Shehbaz calling ratings of: 9, 9, 9, 8, 9, 8 (1–9 scale, 9 = best). I said, “Are you kidding me?”.

**Image 1.** Regionally (upper Midwest), turfgrass quality is seeing peak quality. Proof comes from Purdue’s 2023 Turfgrass Field Day where Kentucky bluegrass never looked so good, West Lafayette, IN. Settle, Jul 18, 2023

This Illinois-week it felt less like July and more like June. In the landscape, Kentucky bluegrass lawns are healthy. No drought stress. No disease. Just the usual dog patch or two (Canis lupus familiaris). In the landscape it is increasingly obvious the perennial flowers are having a good year too. Things like purple coneflower (Echinacea) are 2–4 ft tall and the Rudbeckia isn’t too far behind. We continue to enjoy a relatively cool summer for the upper Midwest. I said it last week and I’ll say it again, get outdoors. Perfect!

Weather

**Figure 1.** Optimal temperatures for cool season turfgrass growth. Bob Berry Sunshine Course, Lemont, IL

**Figure 2.** During July dry conditions improved in Illinois, but a majority of the state still remains behind on annual rainfall. Year to date preciptation (percent of normal) for Illinois. Illiniois. Illinois State Climatologist

**Figure 3.** The extended forecast for August looks similar to what was experienced in July. That’s good news for the upper Midwest, but not so good for many other states were above normal temperatures are predicted. NOAA Monthly & Seasonal Color Outlook Maps

Turfgrass Quality Peaks

**Figure 1. Optimum Quality:** An L-93 creeping bentgrass fairway study sees its best visual quality in July. In June, localized dry spot (LDS) was the primary factor that reduced visual quality below acceptable levels (6.0) in all treatments. Only trace levels of dollar spot exist at this time (no disease yet). North Shore Country Club, Glenview, IL

**Image 1. Optimum Quality:** Shehbaz Singh measures reflectance of turfgrass to determine Normalized Difference Vegetation Index (NDVI) in 4 sq ft treatment plots. This is the electronic version of visual quality. Pythium root rot fungicide study in a Penn A1/A4 creeping bentgrass green, Hinsdale Golf Club, Clarendon Hills, IL. Settle, Jul 20, 2023

**Image 2. Rapid Growth:** During ideal weather conditions, turfgrass growth is usually also rapid. A Kentucky bluegrass rough around a 777 creeping bentgrass practice puttting green. Bob Berry Sunshine Course, Lemont, IL. Settle, Jul 21, 2023

Pythium Root Rot of Creeping Bentgrass

We had expected some trouble after last weeks tremendous rain and we began to see some of that this week. Root rots are a risk after heavy rains anywhere poor drainage exists. Other site related factors are important when it comes to root rots. Those should be documented so that changes can be made in the future. Here are some of the factors in this case:

Rapid — damage on green occured surprisingly fast
Older — push up construction with poor drainage
Small — prone to greater stress due to foot traffic and compaction
Height of Cut — a greater level of plant stress occurs on greens
Shallow Rooted — has a history of root rot
Shaded — near a fence line with trees
Pythium Fungicide Application — must water in immediately after application (needed when targeting a root rot)

Fungicide Recommendations for Pythium Root Rot

For most current fungicide recommendations see link. NC State TurfFiles

**Image 1.** Patchy symptoms on a bentgrass/Poa annua golf green that occurred rapidly during a relatively dry week (followed a very wet week of 4 inches of total rainfall). Settle, Jul 21, 2023

**Image 2.** Foot traffic was too much for wilted turf and the footprint caused it to collapse. Settle, Jul 20, 2023

**Image 3.** No signs of foliar fungal mycelium and the overall effect was collapsed turfgrass leaf blades with a bronze color. Settle, Jul 21, 2023

Green Research — July 19, 2023 by Shehbaz Singh, MS

This is our fourth monthly investigation at the Bob Berry Sunshine Course in Lemont. Investigations continue to evaluate each green for quality, agronomic, and playability characteristics.

Three greens and one practice green

Greens 1, 2 and 3 are around 5,300 sq ft each. The practice green is about 7,811 sq ft. As a part of renovation project in 2020, the grass on greens 1, 2 and 3 was killed. The uppermost mat layer was removed and then reseeded to newer creeping bentgrass varieties. The practice green was completely reconstructed as a variable depth green and then reseeded with two varieties that split it in half. All work was conducted by Wadsworth Golf Construction Co.

Green 1. Pure Distinction
Green 2. OO7
Green 3. PC 2.0
Practice Green. Penn A1 plus Penn A4 (half of green) & 777 (half of green)

Evaluation procedure. On each green, three points were selected in a systematic way (straight center line in front, middle, and back). Three data readings or samples were collected around each of the three marked points. Five sets of data were collected (see below).