![Snow mold on grass](/images/librariesprovider2/images/research/2024/snowmold_web.jpg?sfvrsn=e359c63e_1/)
Here in the northern hemisphere, July represents the middle of summer. So why discuss snow and snow mold? Going back to 1970, snow mold control was the topic of the first refereed journal publication from Joseph (Joe) Vargas Jr., Ph.D.
Vargas (1942-2024) served on the faculty at Michigan State University (East Lansing) for 55 years. He earned a B.S. from the University of Rhode Island, an M.S. from Oklahoma State and a doctorate in plant pathology from the University of Minnesota. His
career focus was turf disease management, fungicide resistance and chemical, biological and genetic turf disease control. He gave presentations for superintendents throughout the U.S. and to greenkeepers in Europe, Asia, Australia, South America and
South Africa. Karl Danneberger, Ph.D., (Ohio State) and Brandon Horvath, Ph.D., (University of Tennessee) are two of his graduate students working in academia, and many others are working in the turfgrass industry.
Vargas received the GCSAA Distinguished Service Award in 1997 and the USGA Green Section Award in 2007 and in 2016 was inducted into the Michigan Golf Hall of Fame (the only turfgrass pathologist in any golf hall of fame). If there were a Mount Rushmore
honoring the early pioneers of turfgrass pathology, Vargas would be there along with Drs. Houston Couch (1924-2004), Noel Jackson (1931-2018) and J. Drew Smith (1922-2003).
Back to Vargas’ snow mold work from 1970. This research was published in Plant Disease Reporter, but today the scientific journal is called Plant Disease by the American Phytopathology Society. Back then, those journal articles had the look and
format produced by the classic typewriter. In those days, college students could earn extra money working in the typing pool. Yes, boys and girls, the professors would provide pages of hand-written manuscripts to be typed; if you made a “typo,”
you had to retype the entire page all over again.
Typhula blight (today this disease is called gray snow mold) was described as a severe problem on creeping bentgrass (Agrostis sp.) and annual bluegrass (Poa annua) in northern Michigan. In that geographic region, snow cover can persist, thus producing
environmental conditions favorable for the disease. In those days, mercury- and cadmium-containing fungicides provided satisfactory control of Typhula blight; however, as Vargas stated: “The need for an effective fungicide to replace them is
imperative for climatic regions subject to severe Typhula blight attacks.” Also, there was a desire back then to stop using heavy metal-based fungicides.
Vargas conducted replicated fungicide field trials on Penncross creeping bentgrass at a golf course in Harbor Springs, Mich. The site was mowed at 0.5-inch (13-millimeter) height-of-cut at three-day intervals. A field trial was conducted during the winters
of 1968-69 and 1969-70. Treatments were Calo-Clor (60% mercurous chloride + 30% mercuric chloride; wettable powder and granular formulations); chloroneb (1,4-dichloro-2, 5-dimethoxybenzene; 65% wettable powder and 10% granular formulations); and a
non-treated check. With both trials, fungicide treatments were applied once in November; plots were evaluated once in April. The treatments were applied from a John Bean Spartan Sprayer at 200 psi (1,379 kPa) — commonly used then, but basically
a sprayer that resembles a car tire air compressor!
Combining data from both trials, untreated turf plots had 86% to 93% plot area damaged with Typhula blight, and all fungicide treatments effectively controlled the disease. No turf injury was observed with any of the chloroneb treatments, but those mercury-based
products did cause turf discoloration and injury. Best disease control was observed with chloroneb WP at 9 ounces per 1,000 square feet (27.5 kilograms per hectare) or chloroneb granular at 2.5 to 3.75 pounds per 1,000 square feet (122 to 183 kilograms
per hectare).
This is an example of those early research reports that Vargas produced that provided valuable information to turf practitioners. Chloroneb fungicide was labeled for gray snow mold and Pythium blight diseases of turf for many years, but not effective
against pink snow mold or Microdochium patch. Consult with your local distributor to see if chloroneb is still available.
Thank you, Dr. Vargas, for your contributions to turfgrass science and for being a good friend and colleague to the turfgrass industry.
Source: Vargas, J.M., Jr., and J.B. Beard. 1970. Chloroneb, a new fungicide for the control of Typhula blight. Plant Disease Reporter 54(12):1075-1077.
Mike Fidanza, Ph.D., is a professor of plant and soil science in the Division of Science, Berks Campus, at Pennsylvania State University in Reading, Pa. He is a 22-year member of GCSAA.