The final droplets of the calendar year are exiting spray nozzles. So, what’s next?
It’s time to wait out the winter. Snow mold can be a destructive nuisance appearing at the wrong time. What happens beneath snow or rain in the winter months doesn’t emerge until the following spring. Impressing golfers at the start of a new season requires calculated fall application timing.
“Like with so many diseases that we battle in turf, make sure you are putting an application out before you start getting pressure,” says BASF senior technical specialist Kyle Miller. “Make sure that timing in late fall is preventive and your application goes out just before you are expecting any permanent snow cover. After that, there’s not a whole lot that you can do.”
A snow mold application marks the end of the spray season for turf teams in parts of the country where it gets wet and cold. Notice a certain word missing from the previous sentence? There’s a prominent type of snow mold that doesn’t require snow to become a problem on playing surfaces. Color can help a turf manager identify pink snow mold, also frequently referred to as Microdochium patch or Fusarium patch, which is caused by the pathogen Microdochium nivale. Symptoms are expressed as pink, white or tan patches.
“Pink snow mold can occur in a lot of different geographies, north to south” Miller says. “One of the things about pink snow mold is that you don’t have to have snow cover to get it. Disease symptoms may appear in the spring because you have this sporodochia on infected leaf blades. When you get sunlight on it, it shows up really pink.”
Miller adds that pink snow mold can occur as far south as Florida and can be an issue on both warm- and cool-season grasses. The disease also presents a concern along stretches of the West Coast from Southern California to upper Washington. Cool, but not in Miller’s words “super cold, and damp weather,” can make turf susceptible to pink snow mold. The disease can be developing under the feet of golfers enjoying winter rounds. “It does like wet conditions,” Miller says. “That’s why in the spring we can see it in a lot of the areas, even moving south, because we might have cool and wet weather.”
The other prominent type of snow mold is more associated with, well, winter. Caused by the pathogen Typhula incarnata, gray snow mold needs a minimum of 60 days of snow cover to develop, according to Miller. Color can also help a turf manager identify gray snow mold, because symptoms are expressed via gray and white patches. “The bottom line,” Miller says, “is if you have snow cover longer than two months, you’re going to have conditions favorable for gray snow mold. It needs to be continuous. We can’t have a 30-day window of snow cover and then another 40 days of snow cover later on in the winter. That wouldn’t be long enough to incubate that snow mold to express itself.” A third and more aggressive pathogen, Typhula ishikariensis, causes speckled snow mold, which requires 90 days of snow cover to develop, according to Miller.
Gray and speckled snow mold can become an issue in parts of the Upper Midwest, where prolonged snow cover creates ideal conditions for winter pursuits such as snowmobiling and cross-country skiing. The same conditions, though, might not be ideal for early and even mid-spring golf if proper snow mold control tactics aren’t deployed.
Cultural control practices are limited, Miller says, beyond developing a fertility program to ensure playing surfaces don’t enter winter overly lush. The more lush the turf, the more susceptible it becomes to snow mold pathogens.
Miller recommends superintendents begin thinking about snow mold applications and fungicide selection as early as mid-summer. Sure, that might seem early. But the shift from summer to winter can happen rapidly, especially considering the number of items on late summer and fall to-do lists.
“Make sure that your timing is such that you don’t get caught with snow coming down before you have your application on the ground,” Miller says. “Don’t wait too long, because if you’re spraying onto snow-covered turf, that fungicide is not going to get to the target.”
The purpose of a late-fall application is straightforward. “We’re trying to stop a very, very high amount of that inoculum so that we don’t see symptoms in the spring,” Miller says. In areas with severe pressure, Miller adds, two applications on high-value surfaces such as greens can provide added protection: a first application around 45 days before snow cover, followed by a second application 30 days later.
Options for reducing disease severity are abundant, with multiple chemical classes and active ingredients providing control. Researchers, manufacturers and turf managers have spent decades honing snow mold programs.
“We have been battling snow mold for a lot of years now and companies like BASF have put together recommendations on products, most applied in combinations or as pre-mixes, that are well proven with research throughout the snow mold belt,” Miller says. “There are a lot of products out there that are very good on snow mold, and they can give you a very nice, clean surface in the spring once snow cover is melted off.”
Miller calls Insignia® SC Intrinsic® brand fungicide (active ingredient: pyraclostrobin) and Trinity® fungicide (active ingredient: triticonazole) “foundational” snow mold products within the BASF portfolio. “Those two products, when tank mixed, are very effective on snow mold,” he says. “In the severe areas, we would like to add other products to help them along, but those are the two core BASF products that have shown excellent results on snow mold.”
When it comes to the final spray of the calendar year, turf teams only have one opportunity to make a clean first impression with golfers at the start of the new season.
“It’s important to understand when snow mold is going to be more severe, when it is going to be a little less severe, and understand some of the conditions that can occur during the winter months to predict what we can expect the following spring,” Miller says. “When we have a winter where we have a lot of warm weather and a lot of rainfall, we’re probably not going to have nearly as much pressure because it’s not under snow cover. However, fungicides may not last as long under warmer conditions, so we have one thing working for us and one thing working against us.
“Most importantly, it’s all about the timing and using products that have been proven in research trials. A lot of times the answer might not be one or two fungicides. It might be a combination of two, three or maybe four fungicides depending on where you are located and the level of pressure that you see in that particular region.” ?