How to prevent winter desiccation in creeping bentgrass

By |  September 20, 2016 0 Comments

Bill Kreuser, Ph.D., is a turfgrass scientist at the University of Nebraska-Lincoln. One focus of his research is understanding and preventing winter injury of creeping bentgrass. You can reach Bill at wkreuser2@unl.edu and on Twitter @UNLTurf for more information.

Q: Describe a “typical” winter in Nebraska.

Like most locations, there is no such thing as a “typical” Nebraska winter. In general, the change from a mild fall to a harsh winter usually happens over a day or two. Winter is characterized by periods of windy, bitterly cold, dry weather alternating with periods of windy, warm, in the 50s F, and dry weather.

Q: What have you learned in your research to prevent winter desiccation injury?

All of our research has been on creeping bentgrass (Agrostis stolonifera) greens and fairways. We learned that crown moisture content is directly linked to cold hardiness. Crown moisture of 50 percent to 60 percent is ideal, with 55 percent to 60 percent the sweet spot. Above 60 percent crown moisture and the plants become more susceptible to death from crown hydration when the cells in the crown take up water during a warm period followed by a cold snap.

When crown moisture falls below 50 percent the plants become more susceptible to dying due to cold temperature, but with the catch that the plants die at a warmer temperature. To prevent turf loss due to winter desiccation, superintendents should be focused on preserving crown moisture.

Q: How do superintendents preserve crown moisture?

The most successful way to preserve crown moisture is to use what we term a physical approach, which is a permeable cover, an impermeable cover or a thick layer of sand topdressing. All of them worked well in our research. One word of caution is to remove the impermeable cover before it gets too hot in spring, or the turf can be damaged under the cover.

Chemical approaches we tested were mineral oil, green pigments, wetting agents and anti-transpirants, none of which were effective in preserving crown moisture and preventing winter injury during Nebraska’s harsh winters.

Q: What about watering, especially during the winter?

Superintendents should water into late October and early November to maintain crown moisture in the 55-60 percent range so the turf goes into winter healthy and properly hydrated. In some cases, superintendents blow out their irrigation system too early in fall and the turf suffers from a lack of water. The tradeoff is blowing out too late, and the heads may freeze due to an early winter storm.

Watering during winter helps maintain crown moisture and is a helpful strategy to prevent turf loss from winter desiccation. The volume of irrigation water needed to maintain crown moisture in winter is relatively small and should be in the range of 0.1 inch. For a frame of reference, roughly 60 gallons of water per 1,000 sq. ft. is equal to 0.1 inch of water.

How frequently to water greens in winter is part of the art of greenkeeping. We have not been able to develop any reliable prediction models to help determine if water is needed.

It is possible to overwater in the winter, which can lead to turf loss from crown hydration. Keep in mind your goal is to provide a small amount of water to wet the canopy so the cells in crown stay properly hydrated. You are not watering for the root system.

Q: Anything else you would like to add?

During our research to understand crown moisture content in winter, a great deal of turf was lost. We used the dead turf to learn about turf recovery methods following winterkill. From the turf recovery research, we learned that clear or white covers helped speed up recovery. There was a considerable amount of recovery from the surviving creeping bentgrass plants, but it took a long time, until mid-July and without traffic stress, so seeding is essential following turf loss due to winter desiccation. Nitrogen applied at 0.1 lbs. nitrogen per 1,000 sq. ft. per week was ample fertilizer to promote recovery.

Post a Comment