Poa Annua - Summer time stress

With the temperatures ranging from 96-106 for the last 3 weeks, and the next 3 weeks forecasted to be the same, our Annual Bluegrass has been under a lot of stress.  Annual Bluegrass is a species that does not do well in extreme heat nor extreme cold and snow conditions.  Its growth cycle is also just what its name implies - an annual grass.  Meaning it grows for one season and dies off.  Now Poa is one of, if not the most, adaptable turf type there is and many perennial types of Poa have evolved over the years.  The perennial types still get very weak and take a lot of care during the extreme heat and extreme cold, but they do not die out like a true annual.  Fortunately most of our poa on the golf course is the perennial type.  In the photo below you see the Poa is a lime green, weaker, and typically in the late afternoons it shows stress.  The greener turf is kentucky bluegrass and shows no sign of stress.

Here in a fairway picture below, the poa looks weak, is thinning, and appears to be sunken, whereas the creeping bentgrass is strong, full, and appears healthy.

The poa requires a lot of babysitting in the summer and in the winter, but in the spring and fall when it is 65 degrees and it rains then poa loves life.  Thats why it germinates and strives in the spring here but then struggles throughout the summer, only to do it all over again next year.  Hence the reason why we manage for kentucky bluegrass in the roughs and creeping bentgrass in fairways and thus all the test plost that we try of various growth regulators, cultural practices, and irrigation water management to discourage poa growth.

Another location in the rough where the poa is struggling compared to surrounding desired turf

 

Test plots - Poa Control

Those of you that know me in the industry, and my members here at the club, all know how I love to do research and test new products on small areas of turf or play with rates on old products.  First, for the safety of an application before I go and apply something to everything on the golf course, but also to see if there is a way I can improve our turf conditions even more and maybe find something that would work a little better.

Spraying a small test plot strip last season  on the edge of our practice putting green

Through the season we do small tests on a corner of a green or a portion of fairway with different products at different rates to see the results.  Some things have turned out well, while others have definitely proven to us that it does not work on our soils, our turf, and our conditions.

Last year I blogged about testing a growth regulator to hurt and slow down the poa on our greens to give creeping bentgrass the advantage.  Old blog - Test plots.  The small test area definitely hurt the poa and after our last late fall app in Oct I felt it was probably to harsh for us.

You can see the injured turf on the left edge of the green

Another angle of the regulator hurting the Poa in the front

The test area last fall - application width with 3 different rates

Well this spring as things are greening up, it looks amazing.

Now this spring - look at the reduction in Poa (grayish) turf in the plot area left of the red line

There is about an 80% reduction in our poa, the bentgrass has smoothly taken over and transitioned to be the dominant specie.  The next step would be the question for our greens committee if we want to do a larger test plot and take half of our practice green or half of a green on the course next winter to see the results on a playing area with more traffic.  The initial issue is going to be if we live with the less than desirable conditions for the 5 months over the winter.  Very fun and interesting to see what we can do, and food for thought on future decisions.

The reason we would consider more testing over thw next few years and trying to phase out the Poa is because in our region Bentgrass is definitely the preferred species.  Our summers are quit often over 100 degrees with no rainfall for 3 months, and even though our Poa does well in the spring and fall, it really struggles over the summer and requires a lot of babysittig and inputs from us to nurse it along.

Bent / Poa Combination Greens

We are in the very early stages of the turf waking up.  Minimal visual green-up and no growth yet, but the plants are starting to wake up and starting metabolism.  You can tell that because our mixture of Creeping bentgrass and Poa Annua greens is just starting to become visible.

The bent is darker green and the poa is a lime green / grey color

Up close you can see what appears to be a hiegth difference between the two grasses 

 Spring is always when of the most difficult times to maintain smooth putting surfaces, because the bent will wake up faster and the poa will stay dormant, in a slumber and appear sunken, for a longer period during the cooler days of spring.  Once they are both out of dormancy and fully growing then this growth difference will diminish, but combination greens are a challenge early in the spring. To help offset this difference we will roll greens on a very frequent basis to maintain a smooth surface.