A few times in the past month, I wrote about the herbicide we use in the rough, know as Tenacity, that selectively removes Creeping Bentgrass (CBG) from the desirable Kentucky Bluegrass (KBG) and Tall Fescue (TF) roughs. This product, which we used off and on for the last 8 years or so, turns the CBG bleach white after about 2 weeks. To be effective, we have to treat the rough 3 times, with 2 weeks between each treatment. Interestingly, the chemical is only effective when used in early autumn. Applications of the same rate in April or May, for example, are ineffective.
Many of our roughs have a substantial amount of CBG is them, which makes them a poor candidate for this treatment. When the percentage of the CBG population exceeds 20%, this treatment would be far to aggressive and unacceptable because much of the rough would be eliminated. However, on #1, this treatment is perfect. Last winter, we replaced all of the sod in the rough on the hole. With rough that is brand new, annual treatments of Tenacity will prolong the life of the sod, maintaining good definition between rough and fairways. If you look at the rough on #1, you can see spots of white grass that are actually tiny clumps of CBG that are being affected by the herbicide. If these tiny clumps of CBG went untreated, they would triple in size every year until a majority of the rough is CBG. This is why the effective life expectancy of new sod is about 4 years before it has a blotchy appearance in our area. CBG will always have a competitive advantage over TF and KBG simply because of the mild climate with excess rainfall. But in the case of #1, the spots are small enough that when the CBG dies, the voids will be filled by the growth of the surrounding desirable species of grass. There shouldn't be a need to re-sod any large areas because of widespread Bentgrass death.
Going forward, my goal is to make more of an effort to use our sod budget in larger area, like re-sod an entire hole as opposed to smaller areas like a green surround here and a tee complex there. This allows us to focus on these herbicide treatments on a larger scale. This winter, we will likely be spending considerable time replacing rough on #10 and #11.
