Dead Zone?

11 years ago

I have a beautifully landscaped property that I obsess over hours per day. I can't take credit for the original job, that was done 30-40 years ago but I do take credit for bringing it back from the edge of extinction from the neglect of the former owners. But there is one small patch of land, no bigger than a small rhododendron upon which nothing survives. When I first bought the home, I filled a dumpster with ground ivy that had been allowed to grow unchecked through bushes, trees and flower beds. Much of the border evergreens were skeletons that first summer, but in time they've all come back. So, it didn't surprise me that this one boxwood was struggling. It was right outside the dining room window, under a three foot overhang and shaded by a large maple tree that allowed for sunlight for maybe one hour in the morning. I replaced it with a 4' tall rhododendron that bloomed and thrived most of that first summer, but soon started dropping leaves --- leaves that appeared to be wilted from lack of water. By the second summer, it produced no new growth and the remaining leaves fell off. I removed it, dug out a wheelbarrow full of earth and replaced it with the best garden soil I could buy and amend, and replaced it with a second rhodo --- watered and fertilized it carefully, but it is now failing. All the original leaves have fallen off, the new leaves started out vibrant but have now started to show signs of distress. What should I do next? Statuary?

Featured Answer

akamainegrower

11 years ago

Pure guesswork, but... Two gallons a day every day is way too much water. The roots may be rotting away because they are constantly immersed. The branch by branch collapse glimpsed toward the rear of the bottom photo is characteristic of fungal root rot diseases. Even though you replaced much of the soil, the pathogen could still have been present. Excessive wetness would have only encouraged it. Garden soil is generally too fine and easily compacted for rhododendrons. They need something like partially decomposed bark that is coarse and allows a lot of air to circulate around the roots. The top of the rhododendron root ball should remain slightly above grade. All in all, the problem is most likely at the roots.

The bite marks at the leaf margins are almost certainly from vine weevils. Those in the center from any number of caterpillar species. Nothing needs to be done about this unless it becomes much more serious.More or less comes with the territory if you are going to grow rhododendrons.

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Comments (6)

sequoiadendron_4
11 years ago
What kind of plants are near this area where you have planted the rhodi? Also, you mentioned an overhang. Is the plant actually under the overhang, or partially under it? What direction does that side of the house face, N,S,E,W? Are you watering the rhodi
onthebrinck
Original Author
11 years ago
The rhodo is between a pine bush [sorry, I'm not good at identifying conifers] and a boxwood. The house faces SSE --- slightly angled to due south. And yes, I give it about 2 gallons of water per day ... rain or shine. I've taken some pictures that might help with my description. You might also help with what's eating at it.
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onthebrinck
Original Author
11 years ago
Thanks ... I have followed your advice. You are absolutely correct! When I dug up the rhodo, the root ball was exactly the same as I had planted indicating to me that none of the roots had ventured out into the compacted earth. I dug a larger hole, mixed in the most shredded pine bark I could find and raised the entire plant few inches above grade. I'm sure this will work.
akamainegrower
11 years ago
What you did is fine, but I hope you also cut/disentangled/distressed the roots and soaked them in water before replanting if the root ball was dry. The peat based medium rhododendrons are potted in becomes very difficult to rewet once it dries out. This can happen even when you have a suitable planting medium such as the one you created. Should there be a dry spell, water at the base of the plant with just a trickle. This is much better than wetting the entire area. I am still a little troubled by the wilted branch in the rear of the bottom photo. If you noticed no rot in the roots, then some sort of root rot fungus is not at work. There are other fungal infections, however,that can cause individual branches to die back like the one in the picture. Best to prune this one back to healthy tissue and keep an eye out for any reoccurrence.
onthebrinck
Original Author
11 years ago
The ball was heavy and damp, but I did use a small fork rake to expose some of the roots all around the ball before replanting. I'm watching it like a hawk. Thanks, again.