You got a certificate???? How do you do that?
Where can the best gojis be bought? It sounds as though pesticides are rampant since they are prone to insects--they -as you have seen- drop their leaves. (or so says wiki, etc)
Then again, my understanding is that bugs or pests of any sort will only "attack" those plants that invite such, by being low on minerals, and so forth.
Much as in humans, parasites will not be an issue unless the terrain has gone all out of balance... In this way, maybe the pests are doing a service to the plants, causing what to us manifests as a leaf drop that promotes a re-leafing (?)