Poa or Bent?

Let's start at the beginning. In 2010 the US open was at Pebble Beach. The USGA decided to use the venue to start a conversation about water. They did this by shutting it off at this iconic seaside course. The result was an off-color HD camera defying event that had everyone talking. For us it was a conversation about the types of grasses we have on our greens. The answer is a mix of the original South German Bents (Creeping Bentgrass) we were seeded to, a few others that had been sprinkled in over the years, and lots of perennial bio types of annual bluegrass (Poa Annua). For a deep dive into Seed So which is better? Well that depends who you ask. Oakmont CC loves their Poa and who could argue with the conditions we have seen there over the years? By and large creeping bent is considered a better grass for a variety of reasons: it uses less water, is more disease and heat tolerant, has better roots. With summers here getting hotter and more humid I suggested we try and favor Bent. This began the journey of our shift in how we water greens and even fertilize them, but that is more recent. We went from basically daily watering to essentially weekly. Deep and infrequent favors bentgrass and its ability to put down deep roots. This gives it the competitive edge over poa especially in the heat of the summer. Other changes in the program were to step up the chemical regulation of growth. Again, slowing the poa so the bent could out compete. My goal was a slow transition that would not effect ball roll or the overall appearance of the greens. The poster child was number 2. This green had the most poa at approximately 80%. The picture below shows vandalism in 2002. We stripped the damaged sod and replaced with sod from the nursery. The ring of bentgrass was clearly visible in a mostly poa green for many years. Today you cannot find it if you tried. The last picture, in the collage, is recent showing where I seeded the remaining poa areas and topdressed with white sand. Easily a complete swap in percentages. Most of the other greens simply converted over without anyone noticing. 

2 green from mostly poa to mostly bent

The other way we have helped the conversion is to toss a few cup cutter plugs from the nursery into the larger patches of poa. The nursery was constructed from aerifier plugs so it would match the existing greens but also seeded with bent. The dry conditions of the nursery favored bent and so there is not much poa left. These plugs would then spread to increase our bent population.

2 green this winter showing some plug work

The areas of poa left on two green have not been happy all year. My guess is the reduced fertility this year is really stressing it to the max. It looks awful on two and also back in the nursery where I moved some plugs back in January. I decided it was time to start seeding these areas. The pictures below show some seeded areas on 2 and 3 greens.

seeding process. straight sand and sprayed area

After a conversation with a friend who used to make his own dyed sand I decided to try it. I mixed up a batch and spread it on some plywood to dry. Even dried the surface still had a crust making it look wet. It was a paste when I spread it out. Reminded me of the paste glue we used in kindergarten only green.

dying sand

It has become standard fair to cut cups and have the entire plug stay together. In the past during the hot summer months the roots would shrink and the plugs would break apart into pancakes. I was reminded of this recently when I swapped out a few more plugs from the nursery to number 2. The difference in rooting depth of the two grasses is real and evident in the pictures below. Notice the roots hanging below the bent plug which is at least twice the depth of the poa plug.

regular greens plug vs straight poa plug

2 green poa plugs looking weak in nursery

There have been side effects to this new program. The poa has been a bit off color for years. Thank-you for not getting fixated on color. If I could change the culture in America that grass always has to have the deep green you see in fertilizer commercials I would. The surrounds took a beating for years. It needs more water than we had been giving it and went dormant for many years. We have figured out a solution, albeit not a great long term one, and we have improved them in the last couple of years. Lastly, another big change is with more bent grass walking has become noticeable. Or maybe better put shuffling has become an issue. Anyone dragging their feet really stands up the bent grass leaving the green a mine field to put on. That is an entire blog post itself i will save for the future.