Tree care - Ask Extension
Good morning. We are moving to West Linn, and have several large maples shaped in the Japanese style, and sereral large rhodi, 8 feet high and in diam...
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Tree care #880809
Asked August 09, 2024, 10:14 AM EDT
Good morning. We are moving to West Linn, and have several large maples shaped in the Japanese style, and sereral large rhodi, 8 feet high and in diameter. We love trees and want to care for them as well as possible. Here are my questions—
Desirable pH for both Maples and Rhododendrons (they are probably different. We will get a soil test for both species.)
When and how much to water them.
Fertilizers: they are different trees and have different needs. We want to be specific.
Any recommended insect or fungus control? They are too big to spray, so it should be systemic through the roots.
For fall Maple leaf drop, is it ok to leave the leaves on the bare dirt on some spaces in our backyard? I would think that they mulch well, and are beneficial for the soil around our pines. I don’t know.
Thank you for this! If you answer, i may follow up with additional questions. The trees are beautiful and healthy now.
Art Bridge<personal data hidden>
Clackamas County Oregon
Expert Response
Thank you for your questions, Art. Here is information about the variety of maple ("Acer") from Japan: https://landscapeplants.oregonstate.edu/plants/acer-palmatum
This has help on care and needs of rhododendrons (and azaleas), which are shrubs, not trees: https://extension.oregonstate.edu/news/give-rhododendrons-azaleas-annual-check-each-spring
Here is is information on problems of rhododendrons: https://ppo.puyallup.wsu.edu/sod-home/education/pr-symptoms/rhododendron/ Many diseases arise due to inadequate watering, or soil that does not drain. They have shallow, fibrous roots that dry out in hot, arid periods, especially with no mulch to keep the upper soil cool and moist.
Don't spray or inject any pesticides unless and until you observe symptoms of disease or insect infestation. They are very hardy.
There is a tension between leaving the leaves, and reducing the risk of dry materials in the face of fire. But fallen leaves provide mulch, decompose to return nutrients to the soil, and provide valuable habitat for wildlife. At least over the winter, leaving the leaves has more benefits than drawbacks.
I hope this is helpful. Good luck!
This has help on care and needs of rhododendrons (and azaleas), which are shrubs, not trees: https://extension.oregonstate.edu/news/give-rhododendrons-azaleas-annual-check-each-spring
Here is is information on problems of rhododendrons: https://ppo.puyallup.wsu.edu/sod-home/education/pr-symptoms/rhododendron/ Many diseases arise due to inadequate watering, or soil that does not drain. They have shallow, fibrous roots that dry out in hot, arid periods, especially with no mulch to keep the upper soil cool and moist.
Don't spray or inject any pesticides unless and until you observe symptoms of disease or insect infestation. They are very hardy.
There is a tension between leaving the leaves, and reducing the risk of dry materials in the face of fire. But fallen leaves provide mulch, decompose to return nutrients to the soil, and provide valuable habitat for wildlife. At least over the winter, leaving the leaves has more benefits than drawbacks.
I hope this is helpful. Good luck!
