Table 1 Visual quality, shoot density and canopy smoothness ratings of 26 creeping bentgrass cultivars grown on a native soil research putting green at Purdue University, West Lafayette, Ind.

Several studies throughout the United States document the performance of the most recent generation of bentgrass that arrived on the scene in the 1990s. One study in central North Carolina evaluated 20 cultivars at two locations (Durham and Pinehurst) and reported that all cultivars tested provided appearance or quality equal or better than Penncross (Bruneau et al., 2001).

At the Pinehurst location on a restricted air movement putting green, the effects of mowing heights of 5/32-inch versus 1/8-inch and fungicide (whether to go with or without) were monitored closely.

The results showed that in the restricted air movement environment four cultivars — A-1, Crenshaw, G-6 and L-93 — were generally superior to Penncross, but varied slightly depending upon the specific management regime examined.

In this era of decreasing maintenance budgets and increasing labor and fuel costs, one area that might be prone to a reduction in spending would be the area of pesticides. Thus, a primary interest for many golf course managers has been cultivar disease resistance. Previous studies have shown significant differences among cultivars.

Quick Tip

In a Northern location in Wisconsin, Penncross, Penn G-2 and Penn A-4 were evaluated. In that study the cultivars ranked Penncross better than G-2 and A-4 for dollar spot resistance. The researchers suggested the higher shoot density of the G-2 and A-4 may have contributed to increased spread of the dollar spot fungus from leaf to leaf. In the North Carolina study, several cultivars had good dollar spot resistance including A-1, A-4, Cato, Dominant Blend, G-2, G-6, L-93, Penncross, Pennlinks, Providence and Mariner.

It was interesting to note that no cultivar had better dollar spot resistance than Penncross, which was more resistant than Backspin, Century, Crenshaw, Imperial and 18th Green. In addition, several cultivars were noted for good brown patch resistance at both mowing heights studied. These included Cato, L-93 and Providence.

Some may ask if it isn't broke, then why try and fix it? We have grasses like the Penn A and G series and other cultivars like L-93 with very good dollar spot resistance, so why change?

Even today, more than 15 years after its introduction, many respected golf course managers and agronomists still recommend A-4 or the A-1/A-4 blend for new putting greens and "gas and grass" renovations. Perhaps people are comfortable with it just because of its track record and the fact that these cultivars are proven performers at some of the most well-recognized golf courses. But that philosophy has never satisfied turfgrass scientists and breeders as we are constantly striving to improve conditions and provide practical solutions to modern management challenges.

How cultivars rate

Today there are even more choices in bentgrasses. Based on my experience and that of some other turfgrass scientists, many of these cultivars appear to have much narrower regions of adaptation. Some cultivars perform very well in certain regions while they are poor performers in other locations.

Additionally, there seems to be some reluctance to adopting the most recent generation of high shoot density bentgrasses due to a perceived increase in maintenance requirements. This has resulted in some breeders marketing their bentgrasses as the ones that provide "championship conditions without the championship maintenance needs" compared to "the forgiving bents."