geraniums come into bloom and by june have yellowed leaves. I pluck and throw away, but it continues. looking thro a small lens, I don't see evidence of leaf miner. don't ask for pics...I don't know how and haven't the equipement to do anyway. so my question on the fly is: what causes yellow leaf...there are several patches with at least 15-20 ft apart and they all show signs of this symptom..