Pest Alert №5 — Fairy Ring
Its’s Frisky Fairy Ring Friday! Well, at least that’s become a popular thing on Twitter hasn’t it? (for those with fairy rings in the myriad of turfgrass environs) Which brings me to the point of this alert. We have begun to see more and more fairy ring activity in Chicago. This is not unexpected. Its a fungus. It likes it hot.
Conditions. Generally, we expect fairy ring activity on golf greens when soil temperatures are at their peak (Jul-Aug). That is right now. Also, fluctuating soil moisture conditions of wet then dry are known to stimulate fairy ring activity. That is 2021. Think about this 2021 growing season in Chicago. We began record dry, then were very wet, and now we are dry again. We wanted a nice easy Chicago growing season. Never going to happen. Our heads are spinning as usual. That is me.
Summer heat. Midsummer is when we typically see our most aggressive fairy ring in golf greens. Summer always matters more. Why? Because in summer a combination of factors can MORE quickly lead to dead zones behind the expanding rings. That is the type of fairy ring you do not want to meet. We call dead rings type 1 and they are the worst. Type 2 the other ones that glow a darker green. Type 3 are the mushrooms and puff balls only. Type 6? All of the above and I made that up.
Causal agent. Multiple basidiomycete fungi are capable of causing rings on greens. The exact number we generally are given in our books is large, like hundreds, but the reality is only a handful are responsible in greens most of the time. Some good work on this by Lee Miller et al. Look it up.
Fungicide Prevention. Preventive fungicide programs timed in the spring when soil temperatures are rising is how we currently address most fairy ring that can negatively impact golf greens. And it has worked out pretty well. Fairy ring was once a big problem on greens. This is no longer the case.
However, we still can see situations of break through in midsummer. Some curative applications are going out about right now. And the good news is that we have a lot more fungicide options to control fairy ring than we had ten years ago. Yes, that’s right a single class of fungicides, SDHIs, has grown tremendously for use in turf. Also we are seeing newer DMIs enter the scene. DMIs have historically provided very good suppression of fairy ring for extended periods. FYI the newest ones hitting superintendent’s shelves are much better (less PGR effects).
Wetting Agents. This alert would not be complete without mentioning wetting agents. How good are wetting agents? In certain curative situations wetting agents can deliver symptom reduction comparable to the best fungicides we use for fairy ring. In a recent study I conducted in Atlanta, GA it turned out that spring wetting agent applications were better than spring fungicide applications when addressing residual fairy ring damage in a zoysiagrass fairway. We don’t exactly know why. Mike Fidanza has theories.
Take Home Message. You need to use both fungicides and wetting agent chemistries if you want the most efficacious curative control of fairy ring in golf greens.