A creeping menace

Golf course superintendents in the Transition Zone and parts of the South face a unique set of problems when it comes to growing turf. The summer heat makes it difficult to grow cool-season grasses, while many times the warm-season grasses will not make it through some of the cold winters we occasionally experience.

Nowhere is this more evident than around greens. Because bentgrass is weakened during the summer months, it is susceptible to encroachment from the heat-loving bermudagrass that surrounds the greens. Superintendents spend a great deal of time and effort combating this problem but, unfortunately, no simple solution exists.

The problem of encroaching bermudagrass is becoming more widespread as bentgrass greens become more common in the South. Newer bentgrass varieties are more heat-tolerant than older types, and many courses are converting to bentgrass greens. The majority of golf courses in Georgia, where I work, already are growing bentgrass greens. Even courses in Florida now are using bentgrass greens a great deal.

In my experience, three options for controlling bermudagrass encroachment are practical.

  1. Install a plastic barrier around the greens

    I'm aware of one Florida company (Greens Encroachment Inc., North Palm Beach, Fla.) that has developed a method of installing the barrier with minimal surface disruption. Once the barrier is in place, you use a special edger to trim and remove the bermudagrass. This system costs about $2,500 per green for the barrier. A few clubs in Georgia have this system in place and from what I gather, they seem to be happy with the results.

  2. Use less-aggressive grasses around greens

    This seems like a sensible solution, and many superintendents have tried it, using bentgrass, ryegrass or zoysiagrass. However, success with this method has been modest for various reasons, depending on the turfgrass species. Bentgrass does not seem to perform well at the higher height of cut, and ryegrass really struggles with the heat in the summer. Zoysiagrass seems to work best, but I've found that it's a constant battle to keep bermudagrass out of the zoysiagrass. So it doesn't actually solve the problem, it just takes it away from the green. You still have to deal with bermudagrass invading the weaker grass.

  3. Apply a herbicide

    Chemical control can be obtained with Tupersan (siduron) herbicide. Southern courses often use Tupersan to convert old bermudagrass greens to a newer bentgrass variety by using this chemical. Similarly, we have had good success with Tupersan at Peachtree to help control encroaching bermudagrass.

We apply Tupersan six times a year at 1 pound per 1,000 square feet. We make our first application in late March with subsequent applications in April, May, June, September and October. The reason for the fall applications is to weaken the bermudagrass as it goes into dormancy.

Our industry sees the introduction of many great new products every year. I'm optimistic that a simple, inexpensive technology will eventually be introduced to address the problem of bermudagrass encroachment. Until then, the options I've discussed here — while not perfect — offer some hope of managing the bermudagrass problem.

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