Annual bluegrass.

The grass we want to grow on greens, tees and fairways is creeping bentgrass. We have a very nice stand of bent on all of our playing surfaces. However, annual bluegrass (poa annua) has crept its way into all of the stands of grass that we manage. Last year we started a spray program on fairways which will reduce, but not eliminate, the amount of poa in our fairways. There are a few reasons we want to reduce poa in fairways; it is a weaker grass that doesn't withstand stress very well, be it from heat, drought or wear, it reduces consistency of the playing surface due to seed head formation in the spring and it has some pretty serious disease and pest pressure issues.
In the early spring we spray a growth regulator called Embark to reduce seed head formation and to help the health of the plant. This may seem counter intuitive, after all why would we want to help the plant that we are trying to get rid of? Well, we like our jobs and if we didn't do this the course would look and play very badly. Also, grass that goes to seed puts all its energy into that process and is in turn a much weaker plant heading into the summer, which is a recipe for dying grass (again, we like working at Barrington). As we move into the summer months we are switching to a different growth regulator called paclobutrazol which has a stronger effect on the poa than the bentgrass. This will allow the bentgrass to out compete and in turn crowd out the poa.
Last year when we sprayed there was a slight yellowing on the fairways as a result of the paclobutrazol (Discussed here). This is normal and we expect to see a bit this year and in order to minimize that we started at a very low rate and timed the application to coincide with our fairway fertilization. Ideally, you'll never notice. Now, this yellowing eventually goes away as the plants become accustomed to the growth regulator and soon return to their normal color. As this happens, the bentgrass will continue to increase in fairways and so too will consistency, both in appearance and play-ability.
Now, one of the biggest reasons we want to reduce poa is because of the pests that go after it. One of them is a disease called anthracnose which will kill poa very quickly and has the best name of all the turf diseases. However, what I want to talk about today are annual bluegrass weevils. I've mentioned how the weevils are a new arrival to the area in previous posts and this year we have some damage in fairways and tees. Through the use of paclobutrazol we will reduce the amount of poa available we also reduce the potential damage that can be inflicted on our course. We do have some good products to control the weevils, but if we can pair that with a reduction in their food source, it will make those products that much more effective.

Weevil damage.

Weevil larvae. This is what we want to eliminate because they are the ones that actually kill the plant. The adults lay eggs in the leaves of the plant and then larvae then eat their way down the plant, through the crown, and into the thatch layer. The products we spray are ingested when the larvae eats the plant.

Ian