root rot, leaf spot, powdery mildew, rust, aphids, caterpillars and spider mites

yellowing or wilting leaves, stunted growth, soft or decaying roots, brown or black leaf spots, white powdery growth on foliage, orange or rust-colored pustules, chewed leaves, sticky honeydew and fine webbing

improve soil drainage and avoid waterlogging, remove and destroy infected or infested parts, maintain good air circulation and sunlight, apply neem oil or insecticidal soap for pests, use sulfur or baking-soda spray for powdery mildew and rust, encourage beneficial insects