The Ohio State University

Home TurfNotes With fall rapidly approaching, many golf course superintendents are in the process of heavily topdressing and coring to reduce soil organic matter and thatch. Fall topdressing is normally done at a rate to bury or cover the turf. After the sand dries, which may take hours, the material is brushed or dragged into or off of the turf. Under high temperatures and a sunny sky the canopy temperatures rise significantly.

We conducted a series of studies to look at the impact of fall topdressing on canopy temperatures during the day. In this report the study is briefly described and portion of the data are provided.

The study was conducted at the OTF Research and Education Center, Columbus on a 'Penncross' creeping bentgrass turf mowed at 0.125 inch height of cut. Sand topdressing (100%) was applied with a topdressing unit on August 22, 2006 at approximately 10 am. The top photograph provides you with an idea of the topdressing rate. On an hourly basis, some of the plots were brushed (middle picture) and canopy temperatures recorded. Plots that received no sand topdressing were recorded during the same period, as the topdressed plots, and those with the sand brushed in.

The ambient air temperature for that day reached a high of 90 F, under sunny skies (The photos were taken on a day when the study was conducted under cloudy conditions). The turf was irrigated prior to the study to field capacity.

Results: Where the sand remained on the turf it was approximately 20 degrees warmer than the plots that had not received sand topdressing regardless of the time of day. When sand was brushed in or removed from the plots, the temperature decreased by more than 60% usually in the order of 13 degrees Fahrenheit (Figure 1., bottom photograph). The brushed in plots remained approximately 7 degrees Fahrenheit warmer than the untreated plots. As time passed, the brushed plots equilibrated close to the untreated canopy temperatures. In the plots where the sand remained on the turf for more than 2 to 3 hours, noticeable wilting occurred when the sand was removed compared to the untreated plots.

Conclusion: Under sunny hot conditions, do not allow the sand to remain on the turf for extended periods during the day. Rapid canopy temperatures occur that contribute to increase wilting when it would normally not be observed. Following the topdressing process of brushing or dragging, irrigate immediately.

Posted by Aneta Studzinska, Jill Taylor & Karl Danneberger