Skip to main content

Cause There Ain’t No Cure for the Summertime Yellows

Turf stresses causing summertime yellows

In 1958 Eddie Cochran recorded the song “Summertime Blues”, which has been covered by numerous musicians over the last several decades. “Back in the day” I personally became acquainted with this song from the version recorded by The Who. Whenever I hear the catchy refrain, “Sometimes I wonder what I’m a gonna do… cause there ain’t no cure for the summertime blues…” it takes me back to those stress-free summers long ago…

[Tweet “Before you get too crazy or aggressive with any management practice, PLEASE think twice!”]

Regardless of the artist, this refrain has relevance for a lot of the unhealthy turf symptoms I have witnessed this summer, which has many turf managers singing their own version of the Summertime blues. With the onset and persistence of the first real summer in the last 3-4 years there are not only cool-season turf managers experiencing “The Blues” but their turf is experiencing a case of the “Summertime Yellows” with yellow symptoms being reported. I can almost hear the turf singing a version of the “Summertime Yellows”.  So what exactly might be causing these cases of the late-summer yellows? The short answer is LOTS of things “might” be causing summertime yellows, but it depends on individual circumstances. Factors causing yellow turf include:

  • General environmental stress (excessive heat exposure, anaerobic soils, scald and various combinations of all of these)
  • Various turf disease pathogens like those that cause etiolated tiller syndrome (a.k.a. ETS)/Acidovorax/bacterial wilt
  • Compromised cool-season root systems
  • Various nutrient deficiencies
  • Summer induced iron chlorosis (KBG and bent)
  • Mechanical damage
  • “Wet”-wilt
  • Senectopathic disorders
  • And more!!! (e.g. nematodes, etc.)

Etiolation

Lets dive into a few of the causes for the summertime yellows (in bold above). For our first case of the yellows, let’s start with ETS, also referred to as “etiolated tiller syndrome” or what some are calling bacterial wilt. My colleague here at Purdue, Dr. Rick Latin, published a really nice article a few years ago in the GCSAA magazine discussing Acidovorax in depth. The bottom line from my perspective on this is, “It’s complicated”. Yellowing or chlorosis of leaf tissue is the only consistent symptom from field reports. Sometimes there will be reports of gangly, “etiolated” shoots which contain yellow to white leaf tissue. Sometimes depending upon prevailing environmental conditions these shoots will transition to death, sometimes not. Sometimes this unnatural looking tissue will wilt and syringing helps alleviate the condition. Often in diagnostic laboratories there will be bacterial streaming and many samples exhibit signs and symptoms of other disease problems. Like I said, “It’s complicated” and the best medicine here appears to minimize turf stress as much as possible, apply plant protectants and wait it out.

Lawn Thinning

Lawn turf with thinning turf density and some yellow leaf tissue. Additional KBG lawn turf with good density but yellow, etiolated leaf tissue

Lawn Yellowing

Lawn turf with thinning turf density and some yellow leaf tissue. Additional KBG lawn turf with good density but yellow, etiolated leaf tissue

Nutrient Deficiency

A second yellow that many might experience this time of year is nutrient related and referred to as “summer induced iron chlorosis”. This yellow turf is most common in the Midwest (naturally higher pH soils like > 7.5) on Kentucky bluegrass and creeping bentgrass turf and the chlorosis lasts for about 2-4 weeks. It is usually observed during late Aug. through early September appearing in small dispersed patches across the turf. The turf team at Iowa State studied this problem with graduate student David DeVetter’s thesis project. They concluded that high soil temperatures and a dysfunctional root system in alkaline soils were two of the main factors affecting this yellow. Applying iron containing products helped but with the onset of cooler soil temperatures the yellow tissue also disappeared.

Putting green turf yellowing

Putting green turf with yellow shoots.

Traffic Stress

A third “yellow” is often self-induced by many turf managers in the form of mechanical damage. In this situation the turf abrasion occurs due to aggressive mowing, cultivation, rolling or traffic. Last month my research group observed a very strong yellowing response related to mechanical damage in one of our putting green research trials where we were simulating golfer foot traffic. As the study was winding down we really “hammered” (a nod to Dr. Kaminski’s favorite term related to the induction of turf injury) the plots with multiple passes to separate our treatments. Initially the turf simply appeared bruised and matted down. About 5 days later, however, there were localized chlorotic or yellow patches with localized areas containing etiolated leaf tissue. Again this yellow is stress induced and totally preventable in many circumstances.

Check out: Down and Dirty

The suggestion here is avoid or back away from excessive grooming, sand topdressing or cultivation during severe summer conditions. I will have to consult with my fellow Down and Dirty writers and perhaps @iTweetTurf to come up with something catchy to describe this yellow. At the moment I’m thinking or borrowing from some French-Italian words to create something along the lines of “Le Jaune musciad stunad patch” (which roughly translates to… yellow, mushy, moron patch). I’m still open to other suggestions but since its preventable, a synonym for knucklehead appears appropriate.

Turf yellowing from traffic stress

1. Putting green turf on left with localized yellow patches some containing etiolated tissue due to substantial induced mechanical damage from simulated foot traffic.

Senectopathic Disorders

For our fourth and final yellow…“Got senectopathic disorders?” One of my former instructors and pioneer in turf pathology, the late Dr. Houston Couch, coined the term “senectopathic disorders” in his 3rd edition of his book, Diseases of Turfgrass. These are described as a “biotically incited disease that can only develop after plant tissue is in advanced senescence.” First let’s break down the word senectopathic. Senescence: the growth phase in a plant or plant part (as a leaf) from full maturity to death and Pathos: the Greek word, which means “suffering,” “experience,” or “emotion”, Merriam Webster’s dictionary defines pathos as a quality that causes people to feel sympathy and sadness. This sympathy part of the definition of senectopathic seems appropriate as some turf managers have been sharing some photos of really sad looking cool-season turf.

Read Also: Soil Microorganisms, Phytobiomes, and Spring Break for Soil Nerds

Senectopathic disorders include a wide range of signs and symptoms and Dr. Couch even lumped basal rot anthracnose in this category. Pathologists have argued over this classification but the bottom line is these kinds of symptoms are manifested on turf tissue that lacks vigor (caused by advanced age of leaves, various stresses, etc.) and is simply too weak to outcompete the potentially damaging organisms. Perhaps ETS is really just a senectopathic disorder as well? I’ll let my pathology colleagues arm-wrestle over this one…but a lack of vigor seems to be a primary contributing factor.

So what does it all mean?!?

I suppose a modified refrain from Eddie Cochran is in order… “Sometimes I wonder what I’m a gonna do… cause there ain’t no cure for the summertime yellows…” Sadly, this is true and there is no easy “cure” for these turf yellows during summer. The only thing that a turf manager really can do is minimize stressful conditions and wait for mother nature’s cure which is some nice cooler autumn weather.

With this in mind, choose your management strategies wisely, paying particular attention to correcting poorly drained soils, providing balanced nutrition and also limiting the potential for mechanical damage when turf is heavily trafficked or a cultivation or grooming event has occurred.

Finally, as I mentioned in my previous post about Hot, Wet, Stinky Soils before you get too crazy or aggressive with any management practice, PLEASE think twice! For example, moderately heavy sand topdressing applied to weakened annual bluegrass on a 95 degree day, just because it was on your maintenance calendar you outlined this spring is probably not a good idea. There is nothing worse than causing severe mechanical damage to summer stressed turf that you know later that you could have prevented. #FacePalm !, or for our more seasoned readers, the Homer Simpson “Doh!”.

Lastly, a thought for you and the turf plants… remember to “Hold on and breathe!”, oxygen and air movement are important to turf vigor, do what you can to facilitate this, and as my colleague Dr. Fidanza says… #HitIt !!! We continue to look forward to seeing your “FriskyFairyRingFriday posts! Wishing you all the best for the rest of this turf season.

Footnote

Here is some useless trivia to impress your friends and family: “Summertime Blues” by Eddie Cochran is included on the soundtrack for the essential must have movie for all turf managers, Caddyshack. It is also is ranked #73 in Rolling Stone magazine’s 500 Greatest Songs of all-time!

Be sure to follow them on Twitter