Past and present research on winter desiccation

By Adam Thoms, Iowa State University

Current and future research projects should build on the findings of the past. That is the case in one WinterTurf study being conducted at Iowa State. One of the largest issues in the northern United States for turfgrass is winter desiccation (Figure 1). During winters with a lack of snow cover the turfgrass remains exposed to the atmosphere and wind will blow over the area causing a loss of water from leaf tissue. This is most common in late February to March after the snow has melted. Golf courses are prime locations for winter desiccation. Turfgrass species can be affected differently, with creeping bentgrass being more susceptible to winter desiccation than other turfgrass species. This creates a perfect situation for winter turf injury, and something that has created numerous research projects in the past. One of those previous projects was work by Nick Christians, recently retired professor at Iowa State who investigated topdressing to lessen the impact of winterkill.  

Between 1980 and 1984, Christians’ trial investigated topdressing after the last mowing in areas susceptible to winterkill (Christians et al., 1985). During this period the winters were very cold with variable amounts of snow cover. There was a thought around that time that using a darker material for topdressing would speed up spring recovery by capturing heat. He also investigated rates of nitrogen fertilizer in combination with those treatments. There were three rates of topdressing used: a non-topdressed control, 0.77 cubic yards per 1000 ft² of a sandy mixture, and 0.77 cubic yards per 1000 ft² of a soil mixture along with three rates of nitrogen: an unfertilized control, 0.5 lbs. of nitrogen per 1000 f² and 1 lbs. of nitrogen per 1000 ft². In three of the four years, the nitrogen treatments helped increase spring recovery; however, the lower rate of nitrogen was similar to the high rate of nitrogen for recovery. Like the nitrogen rate, both topdressing treatments improved spring recovery compared to not topdressing, and again the sand mixture worked as well as the soil mixture (Figure 2). These results indicate that the darker material did not improve turfgrass recovery, and there is no reason to apply soil, especially if you have a sand-based root zone. 

While that research was useful, today superintendents use additional practices to see if they can help prevent winterkill. These practices can vary from sand topdressing to the addition of covers (both permeable and impermeable) as well as various chemical applications to increase water holding ability or decrease the loss of water from the plant. In recent years, there has been a growing concern about how to prevent greens from drying out in the early winter. Recent weather patterns have had warmer than normal temperatures with less precipitation occurring after irrigation systems are winterized. This causes debate on whether superintendents should be applying various products to help prolong the moisture applied before winterization of the irrigation system. We currently have a study with creeping bentgrass pots in a growth chamber that is investigating how various treatments will help during the early winter (Figure 3). Treatments include sand topdressing, growth covers, applications of wetting agents, and anti-transpirant products to see if we can increase the amount of moisture for the plant during this period. Results should be presented in early 2025.

References

Christians, N. E., K.L. Diesburg, and J.L. Nus. 1985. Effects of Nitrogen Fertilization and Fall Topdressing on the Spring Recovery of Agrostis palustris Huds. (‘Penncross’ Creeping Bentgrass) Greens. In F. Lemair (ed.). Proc of the 5th Int. Turfgrass Res. Conf. July 1985. Avignon, France. pp 459-468.