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Unhappy/Sick Acer shirasawanum Sensu (in container)

Posted by peapod13 8 South Sound WA (My Page) on
Tue, Jun 28, 11 at 21:35

I have a Sensu, which I bought in late January or early February. Early this spring, I bare rooted, did some minor root pruning/correction (ie removed circling and "j" roots) and potted into a 20" cedar container in the 1:1:1 gritty mix from the container forum.

For several months the tree seemed to be very healthy.

As time went by, I noticed the leaves seemed droopy during the day, but seemed to perk up at night. I wasn't sure if this was related to temperature change from night to day (although it has been a very cool spring, even for western WA), or possibly due to the roots not being able to keep up with transpiration during daylight hours. So my first "experiment" to see if I could make things better was to thin the tree some to reduce the amount of transpiration. This seemed to work for a while, but eventually the droopiness came back and eventually got worse.

Over the course of several months I've done things like adjusted watering, adjusted fertilizer amount and timing (been using Foliage Pro in a 1/4 dose on a weekly schedule, but I've adjusted that to the recommended "maintenance" dose), moved into more shade, almost full shade now, and finally in desperation I moved the tree into a 2 gallon nursery container and planted it into the ground.

When I moved the tree (I know this isn't recommended while the tree is in leaf) I noted that the root mass seemed smaller than when I repotted earlier this spring, indicating I may have a problem with root rot or pests.? It has been a very wet spring here, even by our standards, so it's possible this particular root stock didn't like the wetness even in a free draining soil like the 1:1:1 mix. For a note of comparison, I have 5 other trees in the 1:1:1 mix and 5 additional trees in a mix close to the 5:1:1 mix. All of those trees are doing great, even with the cool, wet spring we've had.

Noting the small root mass would be fairly close to the surface in the container, I covered the top with some moss I dug out of the side yard. I also clipped one of the small limbs with only 2 leaves on it and split the limb open to see if I could find any signs of verticulum wilt.
Here's that picture.


Here's a picture of one of the leaves from that limb.

Here's a picture of the tree from today.

As the pictures show, the tree is still quite droopy, but the leaves aren't browning or wilting. The branch I cut open doesn't seem to show any signs of black streaking, so I don't think it's verticulum, but I'm certainly no expert or even all that experienced for that matter.

I have a thread where I've been following the growth of all my maples, including this one, with links and pictures going all the way back to February, if any of that would be helpful in diagnosis.

"This link may be helpful"

Any help or advise would be greatly appreciated.


Follow-Up Postings:

RE: Unhappy/Sick Acer shirasawanum Sensu (in container)

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Wed, Jun 29, 11 at 0:52

If that dish in the bottom picture is what the tree is in now and is as shallow as it looks, that is your problem. Get your maple out of that saucer and into a normally shaped, taller pot so it is not sitting in a puddle every time it rains or you water.

Water traveling down a soil column in a container backs up when it hits the bottom of the pot until it is half way to the top, then rushes out the holes. Before draining out it floods the bottom half of the soil column. Wide, shallow containers are typically chronically wet below the half-way mark.


  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Wed, Jun 29, 11 at 0:55

I went over your rather long account and saw the tree is now in a 2 gallon nursery container, with most of it below the soil.

It might do better with the pot on top of the ground. Definitely do not let it root out of the holes and into the ground for any distance.

RE: Unhappy/Sick Acer shirasawanum Sensu (in container)

Thanks for looking. Sorry if my post was too long, just trying to give enough information.

Burying trees in pots is recommended in several bonsai books I've been reading. It acts as a raised bed of sorts and allows the plant to remain in a pot but still recieve several benefits of being planted in the ground. (Also recommended by my local nurseryman.)

Allowing the roots to grow out of the holes in the bottom of the pot isn't a concern as the root ball is only about the size of a softball, but is mostly small fine roots.

Thanks again for looking.


RE: Unhappy/Sick Acer shirasawanum Sensu (in container)

The leaves never did brown, but they did turn crunchy.

I guess I' ve got the only tree that's ever died with green leaves on it.

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