By now, anyone who is not familiar with research out of Michigan State that quantifies the effects of reduced mowing frequency and increased lightweight rolling on bentgrass putting surfaces no doubt has had their head buried in a bunker.
With the number of annual bluegrass putting greens under management, it seemed odd to researchers at Oregon State that similar studies never had been performed on Poa. That's why the team of Brian McDonald, Tod Blankenship, CGCS, Rob Golembiewski, Ph.D. and Tom Cook set out to see if golf course superintendents managing annual bluegrass could benefit from a similar program, i.e., if they could roll more and mow less and still produce conditions similar to putting surfaces that were mowed daily.
In fact, the research team had three hypotheses in their study that was conducted in 2008-09: 1. that mowing four days per week and rolling daily could produce green speed within 6 inches of surfaces that were mowed daily; 2. using plant growth regulators could help increase green speeds as well as maintain them from morning to afternoon; 3. green speeds will increase more with use of a heavy roller vs. a lightweight roller.
They determined, McDonald said, that acceptable green speeds could be maintained with a program of mowing four days per week and rolling daily, a regimen that on bentgrass not only produced acceptable putting conditions, but improved turf quality as well. Plots in the Oregon State study, while indicating acceptable putting conditions with a rolling/mowing program, did not experience any turf damage due to rolling or increased turf quality, McDonald said.
Plots were maintained at 0.15 inches, admittedly not putting green height. Subsequent studies, the results of which have not yet been published, examined mowing and rolling programs at lower heights of cut, McDonald said.
"The 0.150 mowing height was a necessary compromised resulting from needing to start the trial so soon after the green was built," McDonald wrote via email. "Preferably, we would have chosen 0.125 inches or maybe even 0.115. In 2011 and 2012, we looked at three mowing heights 0.100, 0.125 and 0.150. We hope to get this published late this year, or early next year."
The researchers tested examined five programs mow daily, no rolling; mow daily, roll three days; mow daily, roll daily; mow four days, roll daily; alternate mow and roll daily with plant growth regulators and without and with a lightweight roller (845 pounds) and a heavy roller (1,140 pounds).
They were able to produce putting conditions within 6 inches of those produced by mowing daily with a program of mowing four days and rolling seven days. Use of Primo helped produce faster green speeds in the first year of the study, but was not significant in year two, McDonald said. Primo also did not help maintain green speeds into the afternoon.
Use of the heavier roller resulted in increased ball roll distance across all mowing programs alternating mowing and rolling daily in the first year of the study, but not the second, a differential the researchers attributed to unevenness in the newly constructed test green.
The greatest ball roll distance (11.2 feet) was achieved through a program of mowing and rolling daily, but the difference between that regime and mowing four days per week and rolling day, which produced a morning ball roll distance of 10.8 feet at a mowing height of 0.15 inches.
"The take-home message are: first you don't need to mow every day unless you are trying to achieve super-fast green speeds," McDonald wrote. "Secondly, if you are trying to achieve really fast green speeds, try to achieve it first with higher heights of cut and more (frequent) rolling."
Even on annual bluegrass.