More Mossy Thoughts

I've been thinking a lot about moss lately. My casual observations on my moss study have been very interesting so far this year. The small study green had zero moss when the study began this spring but had a history of heavy moss infestation in the past. Obviously this was the perfect spot to study moss. The only problem I've had so far this year is that almost no moss has developed on the putting green at all! What the hell?

Moss is losing the battle here in early May

Well as always I have a few thoughts and observations to share that could explain why. Who knows?

What I am thinking is that moss is affected by traffic or wear only at certain times of the year. Early this spring and summer I noticed that the existing moss on my putting greens was dying. It was black and basically being taken over by the turf. I was "wearing" my greens daily with a lightweight roller. By the time summer had arrived the moss had all but disappeared in the typical areas on my putting greens. I thought I had figured it out. Before this I had never seen moss disappear. Historically if I had moss it only got worse, not better.

Moss explosion on my irrigationally challenged
putting green.

Summer arrived and suddenly the rain stopped. Beginning late July the moss started to come on very strong. It wasn't coming on in the typical areas this time though. Instead it was developing in areas that the turf was thinning due to being either too dry or too wet. I actually found that the dry areas were worse than the wet which is contrary to most people's views so far. My upper practice green was and still covered in moss despite being grown in full sun. It has a very very very poor irrigation system that is gravity fed and maybe gets 20psi on a good day, even less when I'm pulling water for my irrigation ponds. Either way this putting green was constantly excessively dry and thus the moss population exploded. I wasn't able to roll more than 1x daily as the turf was pretty stressed from the heat and as a whole was quite weak.

Back to my moss study green. Even though it has historically had serious moss issues I was easily able to keep it adequately watered this summer. The fact that it was grown in almost full shade made my job easier as the plant water use was much less that it would have been if it was in full sun. The average canopy temperatures were often 10C less than my other putting greens. Some areas were severely thinning due to the excessive wear brought on by rolling up to 8x a day and guess what? Still no moss. There is some moss on areas that aren't rolled ever and recently on the 1x daily plots. All other plots are free of moss. This suggests to me that wear definitely has some kind of affect on moss and that it's not just thinned turf that allows moss to invade.

Rolled 8x daily plot with 2hrs of sunlight each day. No moss despite
the thinned turf conditions.

What I would like to know is how moss is affected by traffic at different times of year. What is it's growth cycle? When is it the most vulnerable? Maybe the answer is heavy rolling in the spring and better control of soil moisture and light rolling in the summer. Who knows? It will be interesting to see how the moss population on my upper practice green is affected once the rains start back up and adequate soil moisture is once again reached. I am going to mark out a few plots on the green to compare as the season progresses with my normal daily rolling program.

Control plot left and 2x daily rolled on the right.

I am continuing the moss study and will keep it up until I figure this out, probably a few more years yet.