Photo: William M. Brown Jr., Bugwood.orgWhile some diseases like fairy ring remain fairly constant in their symptoms, causal pathogens and disease cycles, the strategies superintendents use to battle them are fortunately evolving. Dr. Lane Tredway, associate professor of plant pathology at NC State University, provides some perspective on practical approaches to dealing with fairy ring.
Has fairy ring always been a nuisance?
“Before we started researching it, fairy ring was one of the more common complaints I had from golf course superintendents. Looking at it, there really weren’t any sort of specific recommendations on how to manage or prevent the disease. As a result, superintendents were shooting in the dark and many were missing.”
Does fairy ring make it in the Top 10 list of annual disease problems?
“Fairy ring is absolutely in the Top 10 Disease list, -- maybe even in the top five in many areas of the country.”
If fairy ring feeds on organic matter in the soil, is it a problem with USGA greens?
“In the Southeast, we experience the greatest problems with fairy ring on USGA putting greens. These sandy soils are very prone to turning hydrophobic, which is one of the ways that fairy ring can cause damage to turf.”
Is there a time of year when fairy ring is more prevalent?
“In the past, most people were making the mistake of attempting to control or treat the disease on a curative basis. The problem was in the mode of infection of the pathogen, since it doesn’t necessarily infect the actual turf.
“The fairy ring fungus grows on the thatch and organic matter in the soil, and in doing so changes the physical and/or chemical properties of the soil. This, in turn, leads to a change in the growth, appearance, or health of the turf plant.
“The problem with attempting to ‘cure’ the disease is that once the symptoms appear, the soil has already been compromised. Unfortunately, a fungicide application at this point won’t return the soil back to normal.” Tredway went on to explain that he teamed up with Lee Miller, an assistant professor with the division of plant sciences at the University of Missouri, to study the preventative use of the DMI class of fungicides and found several products, including Tourney -- a member of this class, have been very effective for these preventative applications.
When asked about their findings, Miller explains superintendents have to be careful with their application strategy. DMI fungicides are plant growth regulators in themselves, so it’s not a good idea to mix other PGR’s in the tank. Miller also explained that many superintendents, in their curative attempts to control fairy ring, used wetting agents in the tank to help move the fungicide into the thatch/mat layer since hydrophobic conditions existed. BUT, as a preventative application, wetting agents are not necessary, as the fungicide should be watered in with 1/4 to 1/8 inch of water and wetting agents may move the product past the target area.
Remember, the hydrophobic condition doesn’t exist yet in the preventative mode.
For more information on Miller’s research, please click this link: http://turfpath.missouri.edu/reports