|Hi My Crab Apple tree on my balcony has developed spots on its leaves - some seem to have a spiky growth coming out of the spots....I live in the city on the 18th floor facing NW.
Hopefully someone can help figure out what it is!
|Based on your description I think your tree is suffering from cedar apple rust. Certain varieties of apple and crabapple are more susceptible to this problem than others. Once the symptoms appear it is too late to spray for it that year. Please contact your Cornell cooperative extension for a more specific diagnosis and the most up to date recommendation for applying fungicide -- what to use and how/when is best to apply it. Alternatively, you could consider replacing it with a more resistant variety.|