There is white powdery stuff growing up the branches on my holly. Is this a fungus?
White Powder on Holly Branches
Certified GKH Gardening Expert
Yes, this is most likely a fungus called powdery mildew. It is common and can affect holly shrubs, but will typically not seriously harm them. A spray of whole milk diluted in water has been shown to help kill powdery mildew fungus. These articles discuss other ways to treat and prevent powdery mildew: