treebeard55

Most plants and animals develop, over time, a resistance to the pests and pathogens that are native to their own environments. That's true of human populations, too (which is why smallpox and other Old World diseases were so devastating to Native Americans, and malaria hit Europeans so hard.)

Have you ever considered that when we grow non-native trees for bonsai, we're exposing them to pests and diseases to which they are not adapted? Sometimes that works to the tree's benefit: a local disease can't even get its teeth into an exotic, so to speak. But sometimes it works the other way: an exotic tree has developed no resistance to a local thug-bug, and is helpless.

A case in point is willow-leaf fig in northern Indiana. This species is native to Indonesia, and I'm sure it has a suite of defenses all ready for the local Indonesian microbeasties. But it has no defenses readied for Hoosier bugs, and one of our local scale species has a particular sweet tooth for it. I have to keep a close eye on my Ficus neriifolia all summer, and treat frequently with insecticides.

The same is true for other species, too. I recently lost a veldt fig (Ficus burtt-davyi) to a North American fungus that got into it.

Am I saying we should only grow natives? Certainly not! I love my tropicals -- need them, really, to stave off the grumpies during winter -- and have every intention of keeping them. Then there are other temperate trees -- ponderosa pine, for example -- that still aren't native to my region.

What I am saying is that we need to be aware of the situation. Keep in mind, when you bring a non-native into your collection, that it's not adapted to your local insects, fungi, molds, etc. Keep a little closer eye on your exotics, and be ready to swing into action as soon as you see signs of an infection or infestation trying to take hold. Remember that they don't have the same specific defenses that your native trees have, and so they're probably going to need a little extra defense by -- you.

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Treebeard 55
Steve Moore
http://hoosierbonsai.blogspot.com

The most important bonsai tool is your brain.