Monday, March 22nd, 2010


I would like to start this post with a video by my friend Darren Davis from Olde Florida Golf Club. This is one of the videos we filmed at Miramichi Golf Club for the Golf Channel last October. I thought this video would be appropriate with greens aeration scheduled April 5th and tees scheduled next week. Click on the box below to begin the video.

Bentgrass vs Poa annua

Modern golf course putting greens today are primarily seeded to bentgrass but eventually will convert to Poa annua within twenty years. Here in the Northwest we are home of some of the finest Poa putting green surfaces in the county. This doesn't come without a price. Unlike bentgrass, Poa is very shallow rooted and requires much more water to survive in the dry summers. It is also less disease resistant than bentgrass and requires many more fungicide applications. The reason why it is so prolific is its ability to produce copious amounts of viable seeds at a very low mowing height. This ensures it survival under times of stress.

The greens at Stone Creek Golf Club are now entering their tenth year of existence and are no different than most greens in the northwest for their age. Some greens have up to ten percent and others less than one percent Poa. Many factors contribute to the degree in which a green will convert. The first green to usually see a fair amount of Poa is normally the practice putting green. This is usually the first place golfers walk to after putting on their golf shoes which contain Poa seeds embedded from previous rounds of golf at other courses. Another factor is the surrounding turfgrass. If there is an area that golfers are regularly walking through that contains a high amount of Poa, the seeds will travel by foot and appear to spread from that direction as if a disease were taking over. You will be able to see an example of this on our eighth green.

How we manage our cultural program is one of the most important factors in slowing the conversion. Mainly it is the amount of irrigation that we use. Our greens were seeded to a variety of bentgrass called PennLinks. This grass is very deep rooted which means it has the ability to withstand low water conditions by drawing its water from deep in the soil profile. If we over irrigate bentgrass then the roots will not search out the deep water and will only rely on the shallow water. Since Poa thrives on shallow water this is where it will begin to take over and spread.

There are generally two types of irrigation practiced, light/frequent and heavy/infrequent. As you can guess the light/frequent method will benefit the Poa and the heavy/infrequent will benefit the bentgrass. Many homeowners have asked me how to get rid of the Poa in their lawns and I tell them to turn off the water. The first thing they do when they install a new lawn is program their irrigation clock to run 5 minutes a night seven days a week and all they are doing is encouraging the Poa to spread. Instead what they should be doing is watering maybe two times a week but with the same accumulative amount of water. This doesn't have to be applied in one cycle rather it can be done in three to four cycles over the period of one night. This allows the soil to be drenched then dried over a period of time, allowing the roots to search deeper and become healthier.

There are chemical control methods involving growth regulators which have limited success and can come with a risk. Some growth regulators can suppress the seed head production which is used by many courses with Poa greens to smooth the putting surface in the spring when they are seeding heavily. This has some success with Poa in bentgrass but if applied more than once it can have a drastic effect on the bentgrass itself.

At Stone Creek we have decided not to fight the Poa but to encourage the bentgrass instead, allowing to Poa to do what it does naturally but to also encourage the bentgrass in a way that gives it an advantage over the Poa in the long run. Once accepting this practice we have seen tremendous results on our putting surfaces. We are using wetting agents to ensure that the water penetrates the soil profile and doesn't allow the soil to become hydrophobic. We are using a product called Revolution by Aquatrols. This is applied monthly and followed by an extremely deep irrigation cycle which helps the water penetrate the profile. This helps use achieve the heavy/infrequent watering cycle that is so desirable for the bentgrass.

Another way we can promote the bentgrass is to incorporate new bentgrass seed on a regular basis. Since we planted the greens at Stone Creek new varieties of bentgrass have been developed and have more desirable qualities than the older varieties. We have been interseeding our greens with two more recent varieties called Penn A-1 and Penn A-4. These varieties are much more aggressive and form a tight canopy thus creating a much smoother putting surface and even have the ability to compete with the Poa. We have been incorporating the seed into the greens each time we aerify, allowing it to establish in the holes created. Currently you can see the caches of seeds coming through the holes from last fall. It is amazing after such a cold spell in December that it is still there. Since we have been interseeding we have seen a notable difference in the texture of the greens. My thought is if Poa can reseed itself so prolifically why can’t we allow the bentgrass to do so artificially?

In this photo to the left, you can see a discolored patch of bentgrass in the middle which is a natural occurrence.Within that patch you will notice some lighter green patches of grass. This is a great demonstration of the success of interseeding bentgrass. This seed was sewn last fall during our aerification and is now establishing itself.

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