Hold On To Those Roots

The season is progressing nicely to date and I believe most managers are happy with the state of their turf as the beginning of summer approaches. The rooting I have observed in putting greens has generally been good in well-managed soil- and sand-based greens. But then again that is what we expect to see in late May with optimal soil temperatures and no extraneous events. It is critical to create optimal conditions for root development in spring, and equally important to do whatever possible to maintain that root mass as long into summer as possible. This can be very challenging, and at times impossible, with annual bluegrass greens.

The decline of root systems in greens usually begins at some point in June, after annual bluegrass has completed seeding, soil temperatures begin to climb, and maintenance intensity increases. A gradual transition to the summer heat allows the annual bluegrass some opportunity to reestablish its energy reserves and continue to produce new roots or at least retain the roots it has. A fast blast of heat in late May and early June often spells trouble for annual bluegrass and a long summer for managers. There are other factors that will impact rooting at this critical time of the season. Here are few to consider:

• Keep the height of cut as high as possible for as long as possible. Maintain regular light topdressing, use a rolling program, and utilize growth regulators to provide pace and smoothness while maximizing leaf tissue for sun absorption. Golfers and managers need to realize there are limits to when and how hard the turf can “pushed.” Know and respect your limits.
• Research has shown that shaded turf will not be able to produce the same level of energy and as a result its root mass will be 50-60 percent less than turf growing in full sun.
• Water management is critical. Strongly consider adding a moisture meter to your tool chest if you do not already have one. There is no better means to monitor soil moisture and gain understanding as to how your greens dry down and the turf reacts to different levels of soil moisture. The meters can help you determine when, where and how much water is required.
• Less invasive forms of cultivation can be beneficial for retaining roots longer into summer. The use of needle tines, small diameter star tines, and water injection can help to maintain gas exchange in the root zone and create more favorable growing conditions. However, all of these practices are disruptive to the roots to some degree so it is best to use them when weather conditions are favorable. Do not force the issue if your turf is already very weakly rooted.
• Be on the lookout for root pathogens that can slowly impact roots. Certain species of Pythium can infect roots and cause a significant amount of decline. Often the symptoms are not readily apparent until the summer heat arrives and at that point it is too late. Summer patch treatments are underway at many golf courses. Work with a pathologist to monitor for spring and early summer root pathogens, especially if annual bluegrass is the predominant species.
• Parasitic nematodes are becoming more frequent pests of annual bluegrass and creeping bentgrass on putting greens in New England. Parasitic nematodes by themselves will not kill putting green turf. But the high populations already being reported are causing damage and place an additional level of stress on root systems. Now is the time to sample your greens if you suspect a potential problem. Stunt, lance and root knot nematodes are the usual suspects. A composite sample taken from across the green is preferred but a cup cutter sample collected from a weakened area will also work. Unfortunately, there are few effective control options available to managers in New England. Those golf courses that are supporting high populations of nematodes need to take an even more conservative maintenance approach with an emphasis on producing more roots that can sustain the turf under the higher nematode feeding pressures.
• Creeping bentgrass is the grass of choice for golf courses in the northeastern part of the country. The plant’s ability to produce deeper and more vigorous roots makes it the most desirable species. Any means to encourage the establishment and spread of bentgrass will make life in the summer and winter months much easier for golfers and turf managers in New England.

Enjoy the final few days of spring. I think most will fondly remember the spring of 2012 as being kind and producing good growing conditions. Now we can only hope for a smooth transition into summer. We hope to see many of you in our travels and wish you all deep and vigorous rooting in the summer ahead. 

Northeast Region Green Section - Dave Oatis, Director doatis@usga.org; Adam Moeller, Agronomist amoeller@usga.org Jim Skorulski, Senior Agronomist jskorulski@usga.org.