I'm not so sure the yellowing you're seeing is just due to lack of fertilization, slimsim. I would contact your local ag agent and rule out Huanglongbing (Citrus Greening/HLB). Chlorosis (lack of nutrients) is symmetrical in its appearance. Your yellow splotches are asymmetrical. And, too late for fertilizing at this point. Maybe a very small amount as you sure don't want to promote a flush, but I am more concerned about how the yellowing appears. Not at all indicative of lack of nutrients. Call your ag agent, send them good photos (better than this, you're shooting into the sun).

Patty S.