Security blanket

by John Reitman

Covering the putting surfaces each offseason has been a part of the management plan at Rockrimmon Country Club in Stamford, Conn., for many years, but the needs that prompted their use have changed over time.

Initially, Tony Girardi began using turf covers almost 20 years ago to create a greenhouse effect on putting surfaces adversely affected by shade. The extra warmth provided by the covers – as much as 15 degrees above the ambient outdoor temperature – served as an incubator of sorts, helping to promote turf growth in the thinning greens, he said.

Since then, a tree-management plan embraced by members means Girardi no longer faces those challenges associated with excessive tree cover, including thinning turf due to shade and lack of circulation. Today, the greens get all the sunlight and air movement they need, eliminating the need for turf covers to promote growth.

Now, rather than cover just his most troublesome greens from mid-November through mid-April, he covers all 18 greens, plus the practice green from the middle of December through mid-March to protect the greens from desiccation.

“The thought process here has shifted from using covers to grow grass to protecting the turf in winter,” said Girardi.

At North Oaks Golf Club outside Minneapolis, Jack MacKenzie also has been using turf covers for several years.

Until several years ago, MacKenzie had been using covers in the spring only to give the turf a boost before the start of the golf season. But that all changed in 2005 when what MacKenzie called “significant winter injury” occurred on 16 greens.

It’s not that North Oaks never experienced significant winter injury in the past. What had changed, MacKenzie said, was the golfers’ expectation level.

“Until then, a little winter damage was not a big deal,” MacKenzie said. “Now, they want the course to be perfect from when the snow melts until when we cover it up.”

Unrealistic though those expectations might be, MacKenzie strives to do his best since losing turf to winter damage in 2005.

He began protecting the greens from winter freeze-thaw-freeze conditions by covering the six most at-risk greens with permeable wood-fiber mats. Noting the advertised life expectancy of three years, MacKenzie bought replacement covers in 2008, but was pleasantly surprised that fall to learn the original covers remained in excellent shape. Rather than replace the original covers, he found himself with enough covers for 12 greens. That cycle repeated itself in 2010 when he bought three more and instead of replacing what appeared to be covers in perfectly good condition, MacKenzie use the six new ones to complete cover of all 18 greens. Another set of covers bought this year finally supplanted those bought in 2005, which he has custom cut to begin covering troublesome tee complexes.

The difference, MacKenzie says, is night and day compared with pre-2005 conditions.

Still, there is more than one school of thought regarding the covering of putting greens. Some use them simply to protect against winter injury, and those who use them to simulate the effects of a greenhouse and promote growth. Still there are others who believe using covers is like fooling with Mother Nature in that they don’t allow the cool-season grass to sufficiently harden off for the long winter season ahead, and possibly opening the turf to disease pressures later that it is unable to counteract.

Brian Horgan, Ph.D., of the University of Minnesota, said that in a survey of superintendents about the use of greens blankets, only 15-20 percent of those polled covered their putting surfaces.

Although those on both sides of the question of whether to cover greens or not are steadfast in their opinions on the matter, little scientific research has been conducted on the subject, Horgan said. And that is mostly because even in areas such as Minnesota that experience severe winters, it is impossible to ensure an outdoor research facility would be exposed to the conditions needed to conduct successful field trials.

MacKenzie’s years of experience using turf covers are just as valuable as any research studies he could read.

The greens at North Oaks emerged from last winter in near-perfect condition while putting surfaces at other Minneapolis-area courses, including some that use covers, fared worse. The difference, he believes, is due in part to microclimate conditions.

“In a 10-year period, I think these will provide good protection two of 10 years,” he said. “There will be one year they won’t do a lot, and the other seven years we’ll get adequate snow cover that it wouldn’t have mattered whether we used them or not.”

More important than research on whether covers work or not and why, according to Horgan is adequately preparing the subsurface for the winter depending on what conditions persisted throughout the playing season.

“We’ve had a tough summer in Minnesota. How do you put greens to sleep in a drought,” Horgan said. “You have to prepare your soils first for those drought conditions. You have to do things to protect the crown of that plant.”

Adequate preparation of the putting surfaces also includes making fertilizer and snow mold applications before putting the course to bed for the winter.

Girardi applies 0.75 pounds of organic fertilizer in October, while MacKenzie applies an average of 0.08 pounds of nitrogen once per week throughout the playing season. Both highlighted the importance of making a snow mold application before the turf goes into dormancy. Ensuring the latter often is a challenge.

“We had two weather prognosticators say the window for that was closed last weekend, while another one said the cold was going to snap and that it going to warm up again,” MacKenzie said. “The weather is always a crapshoot.”

Selecting the right type of turf cover depends on the needs of that particular property, Horgan said. Impermeable covers are designed to help protect against crown hydration, while permeable blankets are engineered to help create a greenhouse effect and promoting growth in established turf.

There also is a financial cost associated with using turf covers.

MacKenzie uses 15-18 blankets per green at North Oaks. Enough blankets to cover all 18 greens cost him about $15,000. Girardi says the covers he uses at Rockrimmon run anywhere from $1,400 to $2,000 per green.

“It’s been very successful here,” Girardi said. “The members have been so impressed that they kept increasing allocation for using greens covers.”

Like MacKenzie, Girardi also custom cuts old covers for use on tees.

While the cost associated with covering greens might be a roadblock to some considering the advertised lifecycle, storing covers properly can help them last longer.

MacKenzie, who has become a poster boy for extending the lifecycle of covers, dries his wood-fiber blankets thoroughly and stores them outdoors under a double layer of black tarps. He also inserts clothes dryer fabric softener sheets to repel any rodents that might think about burrowing or nesting in them. Likewise, the black tarp attracts enough heat in the summer – even in Minnesota – that nothing can live, grow or thrive inside them, including wood pathogens he said could result in thinning turfgrass.

“That’s almost like an autoclave,” Horgan. He added that while the covers can carry wood-borne pathogens, no research suggest that they are carriers of the pathogen that causes snow mold.

"I know some people don't like them, but I like them," MacKenzie said. "There is a cost involved, and they are a lot of work to put out, but I sleep better at night knowing I'm using them."