Treatment for declining trees

I’d like to know what other bonsaiers do when a tree begins to decline. I’d like to know how you diagnose the cause and your treatment and success rate

I opened your thread with high hopes that others had chimed in and I could pull from the wisdom of the masses. Alas…

I believe Ryan would suggest that “the balance of water and oxygen” would be of foremost importance when it comes to rejuvenating trees that are declining.

A root check might be in order. Are there actively growing roots? Is there an area that seems to hold more moisture? Does it smell? A restorative repot MIGHT be in order, though all efforts to hold off until the appropriate time would be my recommendation.

Adequate siting, with appropriate sun/shade and protection from wind would also be a place I’d look.

Watering. Does water pool? Is it too dry? Has the tree been potted too high in the pot so that the soil directly beneath the trunk dries out too quickly?

Check for insects and fungus! I believe the Mirai approach is to apply fungicide preventively, and insecticide as warranted (and I think he’s going to insecticides less and less). Also, check for spider mites and treat accordingly. (That is, spray 'em off. Don’t fool with a miticide until you see if you can keep them in check by spraying them first.)

Finally, fertilization. I’ve started to see more and more allusions to organically-fed trees being healthier. Even a mention in a *.edu research paper about how mycorrhiza can increase fungus resistance.

That ought to be a start to the conversation. What’ve you found that works?


The featured piece of content of “Improving Percolation” was pretty good in how determine if the balance of water and oxygen is off and how it can be improved.

Also borer identification and removal is good for pines and junipers

I don’t believe there has been a featured piece of content yet on fungal issues.


But seriously: @bwaynef’s advice is good. Tree decline is usually due to one of the following:

  1. Too much/too little water (or standing water)
  2. Too much/too little oxygen
  3. Too much/too little sunlight
  4. Too much/too little heat
  5. Disease or pests.

Investigate, and if you think the tree’s off in one of those areas, adjust as needed.

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