(Photo courtesy Nick Christians, Iowa State)
Protect against desiccation and freeze injury
Dry and windy conditions in areas such as Western Iowa, Nebraska and farther west toward the Rocky Mountains can lead to desiccation, says Dr. Nick Christians, professor of turfgrass management in Iowa State University’s Department of Horticulture.
Laying down covers and performing light topdressing are two methods superintendents can use to protect their turf against desiccation, Christians says. Budget is a major determining factor regarding which route to pursue. Covers are a better practice than topdressing, but they are more expensive.
Winter watering is also a major practice in drier areas, Christians says. “It’s so dry that you’ll lose the grass if you don’t get some water on it,” he says. “That’s true in Colorado and Wyoming and Western Nebraska and places like that. You’ve got to put some water on them in the wintertime or you’ll lose them.”
Desiccation is less of an issue in areas around Ohio than it is out West, says Dr. Karl Danneberger, professor in Ohio State University’s Department of Horticulture and Crop Science. But some superintendents might want to topdress fairly heavy late in the season for another reason: freeze injury. Unlike topdressing for desiccation, topdressing for freeze injury is not directly related to budget concerns. While Poa annua is susceptible to both desiccation and freeze, bentgrass is more effected by desiccation than freeze injury, Danneberger says. The answer to the question of whether to topdress would be largely determined by what a specific superintendents’ topdressing program looks like for the rest of the year, says Bob Vavrek, director of the USGA Green Section’s Central Region.
In certain regions, such as the central part of Iowa where Christians conducts research, turf can suffer from desiccation one year and from snow mold another. Last winter was wet there, and this year is shaping up to have similar results – conditions Christian says are good for superintendents. “If they go into the fall in good, wet conditions, that is a better guarantee they’re going to get through,” he says. “If they go when it’s really dry, going into winter, then they’ve got to more carefully prepare for desiccation.”
If superintendents expect dry conditions and choose to fight desiccation by applying covers, Christians says, they should apply a fungicide in the event that the cover increases the turf’s susceptibility to snow mold.
Apply fungicides for snow mold
In Michigan and Wisconsin and northern parts of New York and Ohio, snow mold treatments become the most important uses of fungicides on golf courses, Danneberger says. “I’ve known guys to miss it,” he says. “They’ve lucked out. Sometimes the snow will disappear and they’ll get a chance to go out and spray. But that’s real critical.”
Many superintendents around the Great Lakes treat fairways for the disease. To the south, in areas such as Columbus, where Ohio State is located, superintendents more often limit applications to greens and tees, Danneberger says. In those areas, pink snow mold can grow without snow cover.
“Nearly all of the country can experience pink snow mold, and for the Pacific Northwest and much of the North pink snow mold can be observed beginning in October,” says Dr. Paul Koch, assistant professor of plant pathology at the University of Wisconsin-Madison. Throughout the rest of the country, pink snow mold more often develops between December and February. Gray or speckled snow mold can begin growing in October, but it is not usually visible until the spring.
In general, superintendents should not treat for snow mold before the first frost, but they should treat before snow cover if they are in an area where disease pressure is high, Koch says. “The snow mold fungi begin to germinate and grow when soil temps reach about 50 degrees Fahrenheit, so an application three to four weeks prior to your final application can act to reduce snow mold inoculum at an early stage,” he says.
Many combinations of fungicides can provide quality control and fit different budgets, says Koch, who advises that superintendents speak with representatives.
Although fungicide application dates and rates are highly region- and weather-specific, there is one general truth, Vavrek says. “Pretty much every state would at least probably treat greens, tees, for snow mold,” he says.
Maintain soil fertility
As with any other time of year, superintendents will benefit through the winter by balancing their soil fertility ahead of time, says Dr. Aaron J. Patton, associate professor of agronomy at Purdue University. Patton recommends applying nitrogen in the fall. Standard application rates are approximately a half-pound per thousand square feet for short-cut turf and three-quarters-of-a-pound to a pound for rough.
Depending on the time of year and the region, superintendents might apply fertilizers in granular form, Vavrek says. Conversely, some superintendents might not put down a late fall application at all.
The dates between fall fertilization and dormant fertilization vary from region to region, Vavrek says. “You’re going to see a big difference in a state like Illinois,” he says. “The days they’re going to recommend in Evansville or let’s say, Carbondale, Illinois, are going to be different than Chicago.”
In areas that consistently have snow mold, such as Northern Minnesota, Northern Wisconsin, the Northeast and at high altitudes in the Rocky Mountains, superintendents should be particularly careful not to overfertilize, Christians says.
Researchers in Ohio State University’s Department of Horticulture and Crop Science generally support late-season nitrogen fertilization, Danneberger says. They have seen enhanced root growth and greening in the spring. “If you get on really sandy mediums and things like that, they may say it leaches,” he says. “But as a general rule, I like late-season fertilization.”
If a course’s soil needs potassium, a pound per thousand square feet is a good amount, Patton says. “That’s kind of known as a winterizer-type element, but most research with potassium shows that if your soil tests don’t indicate you need potassium, there’s really not a benefit to those late fall potassium applications,” he says. “So I just would encourage superintendents to apply potassium based on what the soil tests say they need.”