I would like to buy a fertilizer injection system to make things a lot easier with fertilizing my trees. Tired of the watering can thing. Also might be able to use it to apply insecticides and other sprays. I have been looking at Chapin and Ez-Flow. I'm sure there are others. Any advice from experience would be nice. I would like to have some adjustments to regulate amount per gallon etc. I don't mind spending $100.00 +- for one that is good. Help appreciated.