David M. Kopec, Extension Turfgrass Specialist
Late spring and early summer are often the best growing times for creeping bentgrass. They are now a long ways a way from very cold night time temperatures, and the winter purple is long gone. They have recovered from any spring aerification, and respond immediately to fertilizer and top-dressing treatments. You are satisfied with root growth, as evidenced by deep healthy roots noticed when changing cups or direct probe sampling, and you have finished your spring Preventative maintenance on the irrigation system.
Yet, one hat afternoon, you start to see hot turf appear before your eyes, and much to your surprise. There are a couple of causes for this.
In the spring, when the days get hot, and the nights are still cool, the bentgrass in the desert gets waxy. The leaves and stems become shiny, similar to the sheen on perennial ryegrass. Only on bentgrass, its over the entire plant. I can't say exactly why this happens, but I have witnessed it over and over again. Perhaps the plants are getting ready for the hot summer. The build up of wax on the leaf is an adaptation to protect the leaf in hot weather. The trouble is, that all this wax in a dense turf canopy....repels water. Thus, the water you apply through irrigation does not get into the ground. You will find sand that is very dry in patches rom this. This is very different from localized dry spot. The "waxy" patches are spaced randomly in the green, as so it does not look like an irrigation spray pattern problem.
CURE: Wetting agents are necessary. This makes it easier for the water to penetrate the waxy turf. You should see a response in 1-2 days after an application. More often than not, you will need to be on a re-application program, every 12-24 days, according to the label.
If you can, also aerify the greens with either 1/4 inch solid tines, or with the water injector aerators (hydroject). The solid tine holes are gone in 36 hours, when the greens are growing good. If growth is to rapid, then groom as needed, to thin the canopy as well. Don't go over board though.
The application of the wetting agent should not be a substitute for your sand top-dressing program either.
This wax build-up usually goes away as soon as higher night temperatures occur, and the bent starts to revert to its normal "leaf looking" characters. And by this time, growth has slowed a lot. So don't go overboard on a late verticutting, trying to get rid of a waxy condition, since high temperatures are right around the corner. Maintain iron applications for greenhouse in June, rather than counting on nitrogen, exclusively.
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.