GreenMan1966

So, here's my couple o'pennies.

For landscape trees, whose wounds are typically much larger than bonsai wounds I can faithfully recommend a 3-pronged approach.
1) Use clean tools and leave clean cuts
2) Spray wound with Lysol or similar disinfectant
3) Use a tar-based sealant spray

The disinfectant protects the tree from having any pathogens sealed into the wound, and the sealant helps preserve moisture (by preventing evaporation) around the cambium while keeping the exposed heartwood dry (by preventing penetration) to prevent rot.

Now, for bonsai, I use a couple of approaches. For my in-ground trunk chops I use Lysol followed by Vaseline. It works fine for my purposes and is easy to apply. I'll always be regrowing the apex and likely refining the cut at some point later anyway so I just want to preserve excess cambium dry-out at the wound.

For potted plants in training, I use my own homemade blend of vaseline and wood glue with a dab or two of latex paint for color - I mix a gray batch and a brown batch. It typically dries a lighter color than the mix appears but does a great job at protecting the wound until the tree sends callous over the wound. If you try this out, don't hesitate to apply it thickly and it does dry a bit thinner than it applies.

I make my mix in little cheap-but-sturdy tupperware thingies and simply mix until it feels right - roughly 1 part vaseline 2 parts wood glue. It mixes well pretty quickly and you'll know it's right when it feels sort of 'fluffy'. Then add your paint or ink, whatever's handy. Without tinting it will likely dry fairly clear, which will work fine but may look goofy until healed.

Very CHEAP and it works...

Keith Jarvis, Nashville TN
Tennessee Certified Nursery Professional 1997-2003