I’ll keep this photo essay short on words and long on images: Jorge Trak studied repotting techniques in February. We covered a lot more trees than I show here, but this Trident was one of the better documented of those we did photograph…
Posts Tagged ‘Japanese maple’
Now that I have your attention… This post is about a common bacterial disease called Pseudomonas syringae, which frequently affects Japanese maples yet is relatively easy to control. It is often misidentified as Verticillium wilt, as both cause tip dieback. The Pseudomonas bacteria form purply-black stem discolorations, which is the result of a toxin produced by the bacteria which kills cells. Twigs, branches and eventually the entire tree may die. Older and stronger growing trees are less susceptible, as are some varieties. Do not prune maples in the fall (especially in the Northwest) as this disease enters any wound and is encouraged by wet, cool winters. Any cut, at any time of year, should be sealed immediately with a liquid sealant.
Control is three-fold. The first is keeping your Japanese maples strong, healthy, and damage-free. The second and third are related: If you can keep your tree dry during wet and cold periods, that is half the battle. The other is chemical control, which is by copper sulfate or similar bactericide. ZeroTol (an oxygenator, essentially a very strong form of hydrogen peroxide) is excellent. Top spray and bottom drench is recommended.
If you have problems with this disease, try a chemical drench after repotting or after heavy root work. And if you live in an area with wet, cool weather in the fall through spring, seasonal prophylactic spraying is a sharp idea.
Clearing away leaves and especially seeds of maples—like bigleaf or vine maple—is essential after leaf fall as these commonly planted landscape trees are frequent carriers of the disease. Keep leaves and moss away from trunk bases, too.
Some of you may have been following the development of this Japanese Maple. I just took the brilliant red leaves off yesterday; we’ve had a lot of sun here in Portland and they did not last longer than 1 1/2 weeks. But it was a beautiful fall.
In any event, the small trunk to the right—which was originally an airlayer of a branch from this tree—has grown well and feels well ‘locked’ into the nebari. The nebari is bigger than it looks, it is just covered at present with soil to establish the young trunk. I’ve been piling cake fertilizer near it to stimulate the fine feeder roots that are the ones that fuse into a solid mass eventually. The upper roots were so active that they were growing right up into the cakes. I had to literally cut off the fertilizer balls yesterday.
One of the downsides of this higher rate of fertilizing is that the apex of the tree gets stronger, so I removed leaves in the top part of the tree during the growing season. It will take a couple years before this tree settles down again, but we did need that strength to fuse the smaller trunk in. The roots were so active that the tree has risen almost half an inch in the pot since this spring.
I will be repotting the tree next year, and the two photos here show the new front I’m thinking about for it. The shift is subtle, but that small difference allows an arc to the trunk that supports the flow of the tree to the right. Also, the branches are more interesting from this new view, and the small trunk pushes to the rear…which is not textbook for a parent/child style, but at least it is not a flat tree.
The small trunk was left to grow wild this year. Next year some light wiring will direct the branches and a main leader will be selected.
A post from last year was something of a quiz that asked how to improve a particular Japanese maple. This is a follow up post…
The lower right branch was airlayered off and integrated into the nebari on the right side to create, eventually, a double trunked tree. The parent tree has been tipped slighted to the right, and branches have been moved around a bit, in particular upwards.
Later this year or even next year the branches of the new trunk will be wired, but for now it is best to leave it alone.
The different color of leaves and timing of leaf emergence is common when you have a part of a tree with great roots, and another part—the recently airlayered part—that is on few roots.
These are the two previous posts: