What is causing black spots and yellow leaves on my holly tree?
Sounds like the holly has an infestation of aphids. The black is from the aphids-they suck the sap from the leaves and have a waste product called "honey dew" and a black mold grows on this honey dew. If you control the aphids you will control the "black". Spray the leaves (top and underside)with a systemic insecticide for aphids-check with a local garden type store for the correct insecticde for your area. good luck.
My hollys are doing the same thing. You see, they're not evergreens, but not exactly deciduous either.
Every spring the old leaves die off, turning yellow and often with black spots. Those fall off and within a week or so the new, fresh little leaves emerge. Good luck. If this still concerns you, take a few leaves to a local garden center and show them. Someone there should be able to help you. (05/06/2008)
Shosha was right. My tree is back to its beautiful full green self. The yellow leaves with black spots are now mulch. Thanks everyone. Hilda C. (06/12/2008)