Industry experts share tips on how to prepare for snow mold breakouts

As weather climates continue to change, superintendents must be ready for snow mold’s unpredictability. (Photo: Paul Koch)

As Paul Koch, Ph.D., associate professor in the Department of Plant Pathology at the University of Wisconsin–Madison, reflects on recent snow mold trends, he believes one especially stands out. More and more golf course superintendents are encountering ever-changing weather climates, which are decreasing snow mold control’s predictability.

Paul Koch, Ph.D.

“For example, more winter rainfall events lead to more rapid degradation of snow mold fungicides and reduced protection,” he explains. “Because of warmer temperatures, turf won’t be fully hardened prior to winter, either. In addition, turf will be highly susceptible going into snow cover, enabling snow mold to develop once conditions are conducive.”

To help avoid this trend — as much as superintendents can avoid fluctuating weather climates, that is — Koch advises them to not apply their snow mold fungicide as soon as a cold snap or light snowfall occurs for the first time this fall. He stresses that this is especially important if their course encounters such conditions well in advance of their typical fall applications.

“The earlier those products are applied, the more exposure to rainfall and snowmelt events they will have, and the likelihood for degradation will increase,” he emphasizes.

In preparation for the future, Koch thinks the influences of steadily changing weather climates will not only vary, but be unpredictable too, even if winters become warmer. In fact, he believes that much of the U.S. will continue to experience the snow mold that it previously has, at least in some way.

“Superintendents must identify the snow mold that they typically experience on their course today and develop a control program specifically for that snow mold,” Koch says. “For instance, if their course now has pink snow mold rather than gray or speckled snow mold, they should use products like fludioxonil and iprodione, which have stronger efficacy against pink snow mold than demethylation inhibitors (DMIs) do.”

Photo: Quali-Pro

Bret Corbett

Albaugh Specialty Products

Bret Corbett

Product Development Manager

Golf course superintendents can take several proactive steps to prepare their courses for potential snow mold outbreaks. Snow mold thrives under snow cover when the turf is not properly managed. To mitigate the risk, superintendents should apply fungicides in late fall before the first snowfall while combining contact and systemic fungicides for broader protection. Cultural practices — along with healthy turf maintenance — can also limit the disease outbreak. Superintendents should mow regularly until the grass stops growing and avoid heavy fertilization in late fall, as excessive nitrogen can promote lush growth that’s susceptible to snow mold.

They should start preparing for snow mold in late summer to early fall, too. By monitoring weather forecasts and understanding the local climate, they can time their fungicide applications and cultural practices effectively.

Rick Fletcher

Nufarm

Rick Fletcher

Technical Services Manager, Turf and Ornamentals

Snow mold is caused by cold weather fungi that primarily affect cool-season grasses in northern climates. Multiple pathogens cause these diseases, and each has climate conditions that favor its development, from cold and wet with no snow cover to frozen with prolonged snow cover. By knowing their area’s historical weather patterns and previous snow mold events, superintendents can plan a winter season prevention program. They should also research the pathogens that are prevalent in their area, to receive insights into the effective mode of action (MOA) combinations and product choices that are available.

An effective approach to a season-long snow mold treatment plan involves combining three to five plant location and MOA strategies. For example, historical G-VG performers for pink snow molds are thiophanate-methyl, iprodione, flutolanil, fludioxonil and strobilurins. For gray snow molds, chemistries like pentachloronitrobenzene (PCNB) and demethylation inhibitors (DMIs), such as tebuconazole or metconazole, can be used.

Photo: Nufarm

Bobby Kerr

Quali-Pro

Bobby Kerr, Ph.D.

Technical Services Manager

Superintendents can prepare for snow mold outbreaks by applying a fungicide or a program of fungicides in the fall (typically in October). However, this is dependent on location and yearly weather patterns. The closer to snowfall the applications can be made, the better. There are three main snow mold pathogens that superintendents need to know about: gray snow mold (Typhula incarnata), speckled snow mold (Typhula ishikariensis) and pink snow mold (Microdochium nivale).

With four active ingredients in its formulation, one type of fungicide, known as Enclave, will offer superintendents consistent snow mold protection. During the 2021-2022 winter season, a single, 8 fl. oz. per 1,000 sq. ft. application of Enclave, prior to snowfall, controlled all three pathogens in trials from Idaho, Michigan, Minnesota, New York, New Hampshire, Oregon, Utah
and Wisconsin.

Lisa Beirn, Ph.D.

Syngenta

Lisa Beirn, Ph.D.

Technical Services Manager, Northeast and Mid-Atlantic

It’s never too early to begin preparing a course for snow mold. Snow mold prevention involves several critical elements, though: properly identifying snow mold species, selecting a fungicide, understanding application timing and frequency and preparing for recovery efforts if needed.

For example, to select proper cultural and chemical control methods, superintendents must know whether their course is prone to pink, gray or both snow mold diseases. Fertility can impact the severity of Microdochium patch, so it is best to avoid urea or late-season potassium applications if Microdochium patch is a concern. Similarly, not all fungicides are effective against both species, so superintendents should select products that are labeled for the species that are present in their course.

It’s critical to properly time applications before the onset of permanent snow cover, typically at the end of October or early November, varying by geography. The addition of a pigment can improve turf’s overall quality and appearance, too.