By Todd Mathews
Golf Course Superintendent
Plant Growth Regulators (PGR's) are being used on the course to improve summer turf conditions. PGR's have been around for several years and their use is becoming more widespread on golf courses. PGR's slow the growth rate of plants but research has shown that many side benefits are occurring with their use. We have used PGR's on our greens for years to combat poa annua and to suppress seed head production. An added benefit of PGR use on greens is the slower rate of turf growth. When the growth rate is slowed, the greens putt smoother and faster. PGR's also produce a more dense, compact turf which is ideal for golf shots

Last year we experimented with PGR's on other areas of our course such as the collars, tees, and some areas surrounding our greens. We saw very promising results and decided to go farther in 2006 with the use of PGR's. When the extreme heat of July and August of 2005 damaged much of our turf, the areas where we had applied PGR's were in better condition. Research has shown that PGR's toughen or pre-stress turf which conditions it for the heat.

PGR's are being used by some courses to remove unwanted poa annua from turf. Poa annua is affected by PGR's more than any other turf. Poa annua will turn yellow when PGR's are applied. If a high rate is applied, the poa annua may even die. There is an abundance of poa annua at our course and we are seeing significant yellowing from our initial PGR application. The yellowing will last for a couple of weeks and then we should see the return of good, green color. The shock to the turf from the PGR is normal and it is what provides the pre-stress conditioning. It is like the old saying "that which does not kill us makes us stronger."

In May, we applied a PGR to our tees, collars, fairways, and green surrounds. The tees and collars seem to be coping with the PGR shock the best, probably because they were treated last year. The green surrounds have been knocked for a loop but by mid June they will be looking better and hopefully they will be pre-stressed and ready for the summer heat. The poa annua in our fairways is experiencing some yellowing which makes it easy to see just how much poa annua we have to contend with.

We continue search for anything that will help us to provide better summer playing conditions. We have rotated and experimented with different fungicide combinations, used PGR's for pre-stress conditioning, and are planning to experiment with bermuda grass. Growing healthy turf through July and August in Cumberland County is difficult because we are stuck between 2 growing zones, or what we call a transition zone. The summers can be too warm for some plants and the winters can be too cool for others. We will keep fighting and keep experimenting until we find a solution to the problem of summer turf decline.