Q.What causes discoloration on edges of Holly leaves?
My holly plant has very dark green healthy looking shiny leaves, but just the edge of each leaf is black, like someone ran a small paint brush all around the edge. Would this be a disease or something not right in the soil?
I have not been able to identify anything by the description you have given.
Are there any other markings on the leaves? Yellowing, spots, fungus marking, insect holes?
It certainly could be caused by heavy conditioned water, for example softened water, heavy flourides.
You could treat the plant with Neem Oil, as it acts as both a fungicide and pesticide.
https://www.gardeningknowhow.com/ornamental/shrubs/holly/diseases-of-holly-bushes-pests-and-diseases-damaging-holly-bushes.htm
http://www.aces.edu/pubs/docs/A/ANR-1087/ANR-1087.pdf
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
