Friday, 24 May 2013

Learning to Manage the Seed Head

Seed head popping up prior to mowing.
I've always been a manager of Poa annua greens and I always dread the onset of seed head each May. It seems that just as my greens have recovered from aeration they get all soft and bumpy again due to the sea of white seed heads. YUCK. Over the past few years the issues I have been experiencing with the seed head have gone from borderline major to practically non-existent. Of course it could be that changing climate that is to blame but my ego would like to think that it is because of what I am doing that is making the difference. Here's to me!

Way back when I was new to the grass growing business I remember mowers stalling out trying to push through the puffy greens. The greens were more white than green and any attempt at achieving anything considered greenspeed was futile. We would fight the poa by aggressively verticutting to thin the puffy inflorescence filled canopy and would reduce nitrogen inputs to try and slow the growth of the ghastly seed head. Looking back I can say that those two attempts to overcome the bumpy soft conditions were complete failures.
This used to happen EVERY May.
The past two seasons the issues pertaining to the Poa annua seed head have virtually disappeared. Last season I implemented an aggressive rolling program. I was in experimental mode and wanted to see what the limits were for lightweight rolling on putting greens. We practically rolled the chlorophyll out of the greens last year but in the process I noticed a few interesting things. On my study green I noticed that there appeared to be less seed head on plots that were rolled more frequently. Of course my observations were hardly scientific but it at least highlighted a possible impact on seed head by rolling. So aside from the obvious smoothing effect of the roller there could be other impacts that actually reduce the amount of seed head that the plant produces. I really wish I had more time this year to study this further but that will have to wait until another year.
Literally more seed head than grass blades in 2011.

This year I have not been rolling as often as last year simply due to labor restraints. Even if I had the additional labor required to roll daily or 2x daily like last June I don't think I would. Just because my test green showed that rolling 3x a day could maybe reduce fusarium and seed head on Poa annua doesn't make it the best approach. It would be foolish to throw all your eggs into one basket when tackling an issue. Instead I have rolled as often as I can (4-7 times a week) with the understanding that it can be one tool towards achieving my end goal. In this case my goal is have smooth, firm greens all while not using traditional pesticides to get the Poa through the seed head stress. Rolling has been a very important tool for me to manage the problem of bumpy seedy poa greens. It smooths the canopy, maybe reduces number of seed heads, and allows me to skip mowings and cut higher to reduce any stress that I can on the plant.

About as bad as it has been so far this year.
The next thing that I think is having a big effect on the seed head this year is something I have already talked a lot about. Demand based fertilizer applications using the growth potential formula developed by PACE Turf. Specifically I think it is the nitrogen that is having the most profound impact but it could also be helped due to the fact that I have applied almost no phosphate to my greens in 2 years. Having said that there is plenty of phosphate in the soil so the plant is not going without.

With my old fertilizer methods based on the classic cool season growth rate chart I was applying more nitrogen than my turf actually needed. As nitrogen is one of those things that can be luxury consumed I was having a big impact on the turf health by fertilizing in this manner especially if the plant didn't actually need it. Was the excess nitrogen applied in the spring used to build carbohydrate reserves for seed head production further increasing the amount of seed heads on my greens? I don't know the answer to that but it a sneaking hunch that I have.

Then just when the plant would start producing seed heads I would cut the food supply off further stressing the plant out. What do plants do when under stress? The same thing I try and do after a few glasses of wine. Try and reproduce. Key word: Try.

Last year I kept my nitrogen applications consistent through the seed head cycle and was pleasantly surprised at the outcome. This year I have applied less than half the historic nitrogen amounts and have been further surprised. I hypothesize that the lean conditions as well as rates based on the changing needs of the plant have helped reduce the severity of the seed head this year. Again, who knows?

In Canada we don't have any products registered for use in controlling Poa annua seed head but I see this as a blessing. If I had these products the seed head wouldn't have been an issue and I wouldn't have sought other means to solve this issue. This year I have also stopped the use of Primo Maxx plant growth regulator so this is also not a contributor to what I am seeing.

Three years ago if you would have asked me that I would be getting compliments on the smooth fast greens in May I would have probably called you crazy but here I am blown away at how great Poa annua greens can be right in the middle of the seed head flush. Again, this could all be delusional rhetoric, I'm no scientist. Give it a try and let me know what you think.
Sorry, no graphs just another bad picture of grass.