Answer: The best control really depends upon which critter is snacking on the leaves of your tree. It's always best to identify the pest and to use something specific for the pest. Insecticidal soap is great against aphids and it won't harm beneficial insects; Bt works against caterpillars but won't harm other insects. If you decide to use something as broad and powerful as Malathion, be sure to read the label - not all insecticides are safe to use on all plants.
Best wishes with your garden!
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