Tagged along on TreeStuff’s Facebook page last night for the Plant Health Care webinar. Albert Cooper touched on a lot of great information regarding soil fertility and soil compaction. If you didn’t see it I suggest you get over to their Facebook page and check it out. It’s a nice refresher and a good watch.

One subject that did come up (and I didn’t expect it to when talking about fertilization) was the topic of CODIT (Compartmentalization Of Decay In Trees). Albert mentioned that trees technically don’t ‘heal’ themselves at all. What they do is replace tissue after they’re damaged, but they never really heal a wound in the sense of replacing cells they already have with new ones. Damaged cells, and even old cells (heartwood) die and decay, and new tissue grows over that damage. Trees don’t heal. Interesting.

I always refer to a tree’s wound-wood that it puts on around a good pruning cut as the tree ‘healing’ itself. But when I consider this process in the light that Albert spoke of it, it makes perfect sense. Therefore, and again Albert makes this point, we should be really concerned about the negative impacts of making large pruning cuts.

“Is it the best thing for the tree?” and “Is it the healthiest?” are two of the rhetorical questions that Albert posed in his talk that are still echoing in my mind today.

Of course this is wishful thinking in some cases, I totally understand. Sometimes big cuts are necessities. But I do think that large pruning cuts are detrimental to a tree’s integrity in any case. We just need to understand when it’s warranted. A pruning cut is an Abiotic stress folks, and the larger the cut, the more painful. Just because you see would closure with healthy tissue, doesn’t mean there isn’t decay present behind the healthy tissue. It’s an easy thing to lose sight of.

The good news is that trees are highly developed to carry on this process of CODIT. Just because wood is dead, does not mean that it isn’t structurally sound, either. Again, think of heartwood as being a core of static mass. But this is a dangerous line to walk, both in an arborist’s shoes and a tree’s, and in the grand scheme of things no one is advocating for weak, decaying wood here. But in order to preserve the benefits of trees, we need to understand their weaknesses, and how to avoid exposing them.

Here’s another surprise for some people too, maybe: roots get cut, and roots decay, and roots also compartmentalize as well. The point being, large root pruning cuts can also be very detrimental to a tree. And this is where Albert makes the connection for us between CODIT and tree fertilization.

Assuming we’ve already done our soil test, and determine that we have a fertility problem, a fertilization program can help stressed trees deal with their sometimes challenging environments. And their wounds. In the crown and underground. Trees that are exposed to heavy pruning, construction damage and compaction need some sort of supplement in order to battle those stresses. In order for trees to grow new cells and compartmentalize, they need to be healthy. CODIT is a process that requires energy. Sometimes a good fertilization program can help stressed trees get the nutrients they need in order to compartmentalize and build tissue faster. Remember, CODIT is chemically and physically driven.

Not so much to heal, but to seal.