Dear gardening enthusiasts,
I'd like to ask for your advice. My 3-years old avocado, planted in a pot, has some problems, please see attached photo of one of its leaves' both sides. Since several days I began to notice these black spots accumulating along the leaves veins, then the leaves turn brownish and fall off. The avocado has already lost several leaves. A Google-search gave no results, maybe some of you have experience similar problems and could share your experience. Thanks!