Having studied black pine growth and care fairly intensely for the last 7 years, I couldn’t help but to throw a few corkbark black pines in the mix as well. Presently, 5 corkers are on my benches, and their response rate is truly different from one to another, and definitely different than their standard-barked counterparts just a couple feet away. It is true, in my experience, that they can still be vigorous, but each are slower-growing than standard. They are longer-needled, more brittle, and more susceptible to pests/diseases. The more I work with corkbark black pines, the more I appreciate standard black pines, and well-developed corkers!
Over the last few years, I have been studying the effects of candle-cutting, timing, and methods for pushing growth back toward the trunk. This is very much a work-in-progress. Even with 3 years of photographic results on several cultivars, it’s going to take 5 more to really understand the implications of the work. Here is a preview of the article. This cultivar is ‘Taihei’, and produces wings of spiraling cork as the tree ages, and has long, thin, lighter green needles.
To digress…I have started working on this one with Kathy Shaner, and it will be interesting to see how we proceed horticulturally.
In June ’10, I decandled this tree, just a couple weeks earlier than I normally start with black pines. Just like with “regular” black pines, the weakest candles from the current season’s growth are removed first to give the new buds (that will form at the cut) a “head start”. Medium & strong candles were removed a couple weeks later. In this case, 6/11 and 6/30
The surprise was the response; or lack thereof. Although the tree was healthy and strong, it did not respond uniformly by issuing new buds that grew into new shoots. This meant the tree went into the 2011 growing season with nearly no growth from 2010, and only 2-year old needles to grow on. Luckily, it did grow well in 2011:
So the main questions now are, do corkbark black pines tolerate summertime decandling? If not, what is the best way to develop ramification and short needles? Since the tree responded badly to this attempt in 2010, it was allowed to grow freely in 2011. In 2012, I took a different approach.
First, in early spring, I removed lots of needles! 12-14 pairs were left on weaker parts, +/-10 pairs were left on medium parts, and 6-8 pairs were left on the strongest parts. Why? It serves to allow light to get into the tree, and it also balances the relative strength of the tree a bit. Here are the shots:
The result? Tremendous back-budding, and new buds developing at the base of this year’s candles as well:
Now, it will be allowed to grow for the balance of the season. Stay tuned! More results on other corkers to follow…