A Break! Recovery, Wear Injury, Fairy Ring, Lance Nematodes and a Mini Field Day
A break! The forecast called for a hot day (90+) with an afternoon thunderstorm which would drop temperatures (70s) and that’s exactly what happened on Wednesday afternoon, July 16. It means a week of needed recovery for cool season turf can happen. A hot summer came at us hard. A heat wave the July 4th weekend. And what did we learn? 1) You need a full month of optimal temperatures (60–75 degrees) in June to grow roots —oddly cool spring temperatures did not allow for normal creeping bentgrass development. 2) It is trying when you have older push-up putting greens with limited drainage and thus greater shifts in root biomass — it’s like managing freshly laid sod. 3) It’s always a challenge when you have restricted air movement — tree pruning important. All of the above creates less resilient golf greens for what happens next — peak play in summer.
Etiolation (abnormal bentgrass growth) became the word of the day, then the week, then half of July. Diagnostic visits shot up and it turned out a majority were not disease-related. The “root” of the cause was most always physiological decline of creeping bentgrass. The basics of growing grass were “in play”. During all of it, there was one aspect that went our way — it did not flood. Two historically challenging summers in Chicago were 2010 and 2011 because both saw flooding on the same day (July 23) during peak heat. But it isn’t all about turfgrass as our friend Dave Ward reminded us this week. We reviewed a native out-of-play area as well as a new fine fescue area this week in Lemont. During this review purplecone flower (Echinacea purpurea) and a short prairie grass called side oats gramma (Bouteloua curtipendula) were most impressive. Summer isn’t over, there will be a round two, possibly even a round three. Until then, enjoy this break just like bentgrass. A cool summer period arrived just in time.
Weather
Scouting for Abiotic Disorders — Wear Injury
July has been a tough month as far as wear injury of cool season turfgrass goes. Whenever turfgrass is under a significant amount stress — either too hot, too dry, or too wet — it’s better to do nothing.
Lawns — For example, not a good time to mow the lawn. Also, certain species such as fine fescue have less wear tolerance and so genetic characteristics are also a consideration.
Putting Greens — We are seeing injury associated with clean up laps as per usual. However injury by traffic by any means during especially hot periods is probable and will happen instantly when turf is under stress. Recovery can take weeks (14 to 30 days ). What happens in July will be in place until sometime in August or even September.
Examples of Traffic Injury
- Midsummer hot and dry: +90 high temperature plus wilting turf
2. Midsummer hot and wet: +90 high temperature plus saturated soil
3. Midsummer repeat mowing in the same direction: Most often on edges or “clean up laps” of turfgrass surfaces. Sometimes it cannot be helped.
4. Foot traffic: Most often on putting greens, but can occur in all turfgrass surfaces when conditions are stressful.
5. Read and respect signage: Most often it is done to help maintain plant health during especially stressful conditions.
Cultural Solutions — Putting green example
Patterns of injury are a common occurrence in mowing patterns on putting greens. Areas most impacted are most often associated with tight turns — certain greens that fall victim each year. The simple fix is actively changing the way we do things immediately.
- Equipment adjustment (raise mowing heights, use solid rollers)
- Reduce frequency of mowing (daily is problematic during especially hot conditions)
- Monitor clipping yield (cool season turfgrass isn’t growing much at all when especially hot)
- Use rolling instead of mowing (but watch it, even rollers can be injurious if not operated correctly; avoid rapid starts and stops)
- Clean up laps are always trouble (depends on design, but do not be naive = expect increasing injury as summer progresses in certain putting greens)
Helpful Resources
Managing Traffic on the practice putting green. Zac Nicoludis, agronomist, USGA, Jun 15, 2018.
“Standing in the same spot to repeatedly hit putts can result in substantial damage in the shape of two footprints. If there is a need to repeatedly putt from the same location, it is recommended to stand on a towel. However, this only provides so much protection. Periodically rotating one’s stance is always the best course of action.”
The risks of mowing green grass during summer drought. Turbeville, University of Minnesota, May 30, 2023.
“Mowing the lawn removes parts of the plant causing mechanical damage and leaf senescence. This process removes the plant’s growing apical meristem, causing secondary shoots to grow. When you mow a lawn, you stimulate plant growth, but in drought and heat stress it becomes counterproductive.
Delaying lawn mowing during periods of heat and drought stress should reduce the risk of damage, even when the grass appears to be green and healthy.”
Scouting for Disease — Fairy Ring (various Basidiomycetes)
During the hottest periods of summer we can see severe damage by fairy ring. This has become a well-studied aspect of turfgrass maladies (Fidanza and Settle, 2007). Our worst type, type 1, causes dead rings or arcs of turfgrass that can measure inches or several feet in diameter. The basidiomycete fungi utilize turfgrass thatch (cellulose, hemicellulose and lignin) as a food source. Most thatch occurs in the upper 1–2 inches of a putting green soil profile.
Today, we used preventive fungicide programs designed to anticipate and prevent fairy ring growth. Each program uses a variation of 2 to 4 applications that are applied 21-28 days apart. Cooler areas of the country typically require 2 applications (upper Midwest) whereas warmer climates may require 4 or more (Florida) to prevent fairy ring development.
- The best class of fungicides for fairy ring prevention is DMI.
- Newer DMIs are preferred because they will have less impact on plant growth — especially important when cool temperatures are naturally slowing growth of creeping bentgrass (spring 2025 = case in point).
- Fungicides must be watered-in immediately following application to the depth of the mycelium— waiting later in the day or evening to water-in may mean that a fungicide targeting fairy ring may not work at all.
- Preventive fairy ring programs begin in the spring at soil temperatures (5 day average of 55–60 degrees at a 2 inch depth) based on research conducted by Lee Miller et al. at North Carolina State University.
Cultural and Chemical Recommendations for Fairy Ring
See page 18 in Chemical Control of Turfgrass Diseases 2024
Lance Nematodes (Hoplolaimus galeatus and other Hoplolaimus species)
Our first injury by nematodes occurred within the week. It’s not easy to figure out. Symptoms caused by nematode root feeding can be confused with a long list of problems — both biotic and abiotic. The best way to determine is by good sampling. For example, use a paired approach within each creeping bentgrass green. It means two samples are collected for comparison: 1) healthy area = check and 2) suspected nematode damage area).
Lance nematodes are relatively large (the largest most greens in the upper midwest will ever see). Lance are commonly found along with several other species which enjoy sites with light, sandy soils (a putting green root zone will do just fine). Other root-feeding nematode species include; cyst, root knot, stunt, stubby root, ring and spiral. The three problematic nematodes (ones we focus on) are cyst, root knot and lance. These three species can all feed as endoparasites (inside the root) which means they tend to cause more root dysfunction and root loss overall. It also can mean they are difficult to control!
Currently a good solution for lance nematodes is lacking, but new research indicates we may have an ability for suppression in the near future. In the meantime, lance nematodes will remain a problem for golf course superintendents where they exist. However, actual damage is usually subtle in cool season turfgrass. For example, both creeping bentgrass and Poa annua are naturally adapted (and tolerant) of midsummer root loss.
The best way to address situations (insert lance nematode here) where chemical control measures are lacking
- Cultural practices that promote root growth — aerification is king
- Soil moisture management — prevents turfgrass loss on greens
- Judicious midday hand watering — compensate for short roots
- Regular wetting agent applications — helpful to avoid midday wilt stress
- Foliar fertility to address nutrient deficiency — yellowing/chlorosis
Further Reading — a good tutorial on lance nematodes
Managing lance nematodes in warm-season turfgrass. Crow, University of Florida, Oct, 2021.
Education & Communication by CDGA’s Green Committee
They’re Here to Help! by Dwight Erskine
“It’s late May, and your turf doesn’t look like it had a favorable winter. It’s June and some of your fairways have that “cop circle” patches. It’s only mid-summer, but your greens already look like its late August. A look at several of your strategic 80-year old oaks is giving you bad vibes. What about that native area that your super has been nursing and it just looks like a big field of weeds?
Who you gonna call?”
Final Photo
“The Illinois Golf Hall of Fame Class of 2025 includes: Dan Dinelli — One of the nation’s leading turfgrass experts, Dinelli has been superintendent at North Shore Country Club for 36 years and a national voice in Phytobiome research, soil health, and sustainable agronomy. A third-generation superintendent, his career has been defined by innovation, stewardship, and leadership in golf course management.” for more information click here
