Common in the cold

Unfortunately, there is usually no getting away from it: the late fall and winter months can bring issues for lawn care operators and landscapers. Unless we are fortunate that weather conditions are not conducive to such problems, you will need to be proactive or be prepared to read the tea leaves and attack problems when they occur.

Snow and spring.

Jeff Kolbe, business consultant/manager of technical education for Spring Green Lawn Care, said the Northeast and Midwest could well see pink and gray snow mold this winter, while in the Transition Zone, spring dead spot may be a problem. And in the Pacific Northwest, snow mold could also prove to be an issue.

Spring dead spot is a fungal disease that attacks bermudagrass lawns and results from infection by one or more species of ophiosphaerella. Gray snow mold is caused by typhula incarnata and related species. And pink snow mold can destroy grass at the roots and crowns. Because it can survive without being noticed during the summer months, the disease can cause long-term harm to a lawn.

“Snow molds develop under snow cover during the winter months and can affect all cool season turf varieties and is common during years of heavy snowfall,” Kolbe says. “Long periods of snow cover are conducive to the development of the disease in the turf. As the snow melts and exposes the turf in late winter and early spring, the symptoms of snow mold will begin to show.”

Kolbe says snow mold will appear as pink, white or tan patches of dead and matted grass. Patches will range from two to 10 inches in diameter. “A white cobweb in appearance, mycelium can often be observed on the edges of the patches close to the edge of the melting snow,” Kolbe says. “If these areas are not addressed, these areas may not recover.”

Spring dead spot, says Kolbe, “appears as circular patches from six inches to several feet in diameter that remain dormant as the grass greens up in the spring.” These patches eventually die and can leave bare soil in the lawn. Spring dead spot will reoccur in the same spot each year and increase in size by several inches each year.

Prevention and treatment.

Okay, what can landscapers do to be proactive in preventing these issues? “For snow molds, mowing the turf slightly lower for the last cutting of the year can help in minimizing the problem,” Kolbe says. “A preventative fungicide treatment can also be effective for highly maintained turf. This application should be made prior to the first snowfall for the season.”

Kolbe says spring dead spot can also be controlled with a preventative application of fungicide. Applications are most effective when soil temperatures are between 60 and 80 degrees. This will allow the fungicide into the root zone where this disease does the most damage.

And, all is not lost if the diseases do show up in your lawns; they can be quickly and efficiently treated. “If snow mold does develop in the turf,” Kolbe says, “the first recommendation to help the grass to recover is to rake out the dead material to allow air to reach the crown of the plant. In many cases, the turf will then recover on its own.” But, in severe cases the areas may need to be renovated by reseeding the affected area.

According to Kolbe, spring dead spot patches in Bermudagrass recovers by the spread of the grass from the outside of the damaged area to the inside. This recovery process can be very slow, sometimes taking an entire growing season for the affected area of grass to fill back in. Proper fertilization will add in the recovery process.

John Steiner, regional manager for NaturaLawn of America, pointed to several common lawn diseases that can occur during the fall and winter months. “Some of the most common include rust, necrotic ring spot and snow mold,” Steiner says.

While rust will occur in most areas of the country, necrotic ring spot is most prevalent in the mountain areas of the U.S., he adds. “As for warm season turf diseases, these tend to be much more problematic due to the slower growth period of the turf from fall to spring. Two most common warm season diseases include take-all patch and large patch,” Steiner says.

Rust is a fungal disease that occurs on turf grasses when their growth is slowed. Necrotic ring spot is a disease that infects cool-season grasses, primarily Kentucky bluegrass. Take-all patch can occur on all species of bentgrass in temperate climates and large patch is a common disease of warm-season turfgrasses.

Steiner says rust will show orange-looking lesions on the outer area of the grass blade. “Also, if a homeowner were to walk through the lawn, they may notice their shoes have an orange-ish tint. Necrotic ring spot will first appear on Kentucky bluegrass as dark red blades forming circular patches. The pathogen infects the root systems in the spring and fall, and in summer, the plants will begin to wilt.”

Snow mold (pink and gray) begin their development in the fall, according to Steiner, and may become active in air temperatures from 60 degrees down to freezing. Pink snow mold will show irregular pinkish patches in absence of snow. Gray snow mold occurs on snow covered lawns with frequent variation in high and low temperature. Due to the warmer temperatures, snowmelts and can cause fungal development on the turf.

“Take-all patch starts out with irregular rings of grass with reddish leaves. They eventually will turn brown as the grass dies,” Steiner says. “These patches can be small, one to two centimeters or as large as three to four feet.”

Reasons and timing. The above-mentioned diseases tend to attack turf during late fall and winter “because the causal agents tend to be more active at cooler temperatures and when moisture is more frequent and in greater amount,” Steiner says. “In the case of root rot in warm-season lawns, one of the main causes seems to be the amount of moisture coming from hurricanes over the past several years. These rains set up this disease for the fall time period.”

In addition, warmer air temperatures tend to hang on in the winter in the South, creating a “plumb environment” for disease to thrive, says Steiner. Homeowners may contribute to disease activity by how they care for their lawn culturally. Poor mowing practices may have a great impact on the development of turf disease. With the weather tending to be warmer in the South, there is still a need for watering as well, another factor in turf diseases.

As mentioned, environmental conditions need to be favorable for diseases to be active. “This would include temperature, plenty of moisture and the pathogen to be present,” Steiner says. “If the weather patterns leading up to the time period and outbreak of disease are consistent with what is needed for disease activity, then once the environmental conditions are favorable, turf diseases become more active.”

Naturally, each winter season is different. “It would be advisable to look at not only current weather conditions but to also look back as far as 90 days prior to disease onset,” Steiner says. “Weather conditions going into this winter will have an impact on which types of disease may be active as well as their severity.”

Steiner says the best solution for turf disease is to maintain healthy turf. “Proper moisture, adequate nutrients and good cultural practices go a long way in preventing turf disease,” he says. “In addition, introducing varieties of turfgrass resistant to the specific disease pathogen helps to prevent disease activity.”

If there is turf disease activity, it’s best to look at what the cause is, not just the disease itself. If you are able to identify why the disease is occurring, it is easier to formulate a solution.

The author is a freelance writer based in Connecticut.