It is about time to prepare for the spring root diseases, take-all patch and fairy ring. Fairy ring has been reported to be caused by over 60 different Basidiomycete fungi with the most prominent hailing from the Lycoperdaceae family. Take-all patch is caused by the pathogen Gaeumannomyces graminis. Since the pathogens that cause these diseases infect the roots of turfgrass (or the rhizosphere in the case of fairy ring), damage will not be evident until drought and heat stress occur. Reduced or compromised root systems caused by fungal infection will not be able to absorb adequate water and nutrients and in turn are unable to withstand the rigors of drought and heat stress. The use of proper cultural practices, such as: maintaining low thatch levels, proper fertility (avoiding excessive nitrogen), relieving soil compaction, avoiding overwatering in the spring and providing proper drainage may not be enough to reduce infection by these springtime pathogens. Therefore if any of the aforementioned pathogens have caused significant problems in previous years, well-timed preventative fungicide applications are crucial towards to avoid disease symptoms later in the season.
Preventative applications have been shown to be the most effective means for managing both pathogens. However, a past history of these diseases is a prerequisite for making preventative applications. Curative applications will provide some level of control (but it is rarely satisfactory). Recent research presented by Dr. Lane Tredway of North Carolina State University at the New England Regional Turfgrass Conference indicated that fairy ring applications should be initiated when the 5-day average soil temperature reaches 55° F. According to soil temperature maps, New England soils should be within that range now or in the near future. Conveniently, this also coincides with the proper time for preventative take-all applications. It is important to remember that any fungicide applications should be made due to a past history of problems with these diseases.
According to "Chemical Control of Turfgrass Diseases 2011", a publication from Dr. Paul Vincelli of the University of Kentucky, most demethylation inhibitor (DMI-FRAC #3) and strobilurin (QoI-FRAC #11) fungicides are effective in managing fairy ring and take-all. A second application is recommended in approximately 2-4 weeks after the first application for both diseases. Tank mixes with DMI and QoI active ingredients would be a good choice for the second application. The second application should be made based on weather conditions, if it is still cool, delay making a second application until 3-4 weeks after the initial. Moving the fungicide active ingredient down into the root zone by increasing the spray water volume or by applying post-application irrigation is critical, since you are attempting to protect roots from fungal infection. Therefore, fungicide applications should be made at a rate of 5 gallons of water per 1000 square feet or watered in with ¼ inch of water right after the application if made at a lower water volume such as 1 or 2 gallons per 1000 square feet.
To decide if a preventative application is the necessary course of action for you, first determine if fairy ring or take all has been present on your golf course in the past, or take this year to make an assessment of these pathogens on your course. If you see symptoms but are uncertain of the pathogen, take a sample and send it to the UMass Extension Plant Diagnostic Lab to get an official diagnosis.
Submitted by: Dr. Geunhwa Jung