I agree about the chemical ferts. I just brought that up because so many people around here use them and browning leaf tips are common when they're overused. I'm glad you're using organics.
If you think you have an insect problem you might want to spray them with soapy water or tobacco juice. I've been fortunate enough not to have dealt with insects so far (except once there was a moth invasion), so hopefully someone will reply that has had symptoms like yours.