We are using two different chemicals this year. We are using Ronstar in some of our weaker turf areas and on tee boxes because it is safer on these areas and will allow the turf to fill in throughout the growing months while still providing excellent weed control. The second chemical we are using everywhere else is Specticle. This is a newer chemistry that is one of the best preemmerges on the market. Since we had more weeds than usual last year, we spent a little more money this year and beefed up our program.
Another thing we are doing is adding a Glyphosate (active ingredient in Round Up) product in with our chemical. This is going to clean up any weeds that have germinated over the winter due to the extremely wet weather we have had. Since it has been so cold, the Bermuda grass is completely dormant and this will not harm it.
We feel this will provide us with a relatively weed free golf course for the summer. 
