Mottled Greens

Lighter patches of poa mixed with bentgrass

It is widely know that bentgrass is an exceptional putting surface and preferred around the world. Conditions are very smooth and putting is true. Our greens at Pinehurst consist of a mixture of various strains of poa annua and many varieties of bentgrasses. When they were originally seeded with bentgrass, the maintenance standards were to keep speeds in the 6-7 range on the stimpmeter. As the game grew, so did the desire for faster speeds. Older bent varieties were unable to handle lower mowing heights and would succumb to disease pressure. In turn, managers would fertilize and water them more to handle the increasing stress. This allows invasive poa plants to creep into the surfaces as they love low mowing heights, more fertilizer and water.
Poa seed heads prove that shade from trees
provide negative effects to the surface
Another factor for increasing poa populations on greens are the negative effects that trees can have on a putting surface. Trees shade much needed sunlight and also steal water and nutrients, which leads to even more water and fertilizer to be applied.
Maxwell Green predominantly poa
These greens were also built with native soils which means they don't drain exceptionally well. In 2007 a drainage system was installed and has proven to be very effective, but the poa had already dominated the surfaces by then. A vicious cycle is created with poa, because more water and fertilizer leads to fungal activity which then requires fungicides. Poa also produces pesky seedheads each spring. These require more maintenance with vertical mowing and grooming to keep them at bay. This added maintenance continues to stress any bentgrass left in the surface which just keeps giving the poa an advantage.
Pfluger Green with much more bentgrass
Over the past two seasons we have turned to growth regulators on the putting surfaces that suppress the poa activity and give bentgrass a competitive edge. We also use moisture sensors to monitor irrigation cycles and tissue samples to monitor fertilizer applications. This is a long road to go down but we are seeing progress each season. It will take years to undo what has been done. Chemical companies continue to improve formulations to assist with this battle.


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