Once you are sure you have correctly identified the critters, disease, fungus mold etc. that is infesting or affecting your tree and it is severe enough to merit use of a spray the following guidelines should be followed.
carefully read any labels to make sure you have the correct product, don't use unlabeled bottles or other guesswork.
follow the instructions meticulously, high doses can kill or damage your plant.
fish, bees and birds are often sensitive to pesticides and other sprays, take the necessary precautions.
make sure pets and children are kept out of spraying vicinity while preparing, during and after spraying.
pets and children should not be able to interfere or ingest any material from the sprayed plants for a suitable period.
avoid polished surfaces and clean all equipment after use.
suitable ventilation is necessary before the room or area may be used again.
if accidental ingestion or contact with the pesticide occurs keep all labels and take them with to the doctor, taking care to follow initial instructions as soon as possible.
Prevention is better than cure, inspect regularly and possibly even set up a routine spraying regime.
Bonsai common pests - Guidelines for spraying | Ecency
