This is my current experiment, and I am not recomending it at this time, until I know the long term result with my own bonsai. For full sized trees, aborists have generally been moving away from sealants, and going with dressings. Most organic stores sell wound dressings, and I am using one made by the local organic nursery here (Green Sense Tree Goop) (
www.beorganic.com)(
www.greensense.net).
It is a pastey powder that you mix with water. It is water soluble and has to be reapplied. It consists of diatomaceous earth, molasses, and manure.