close-up of a leaf of merry with brown spots caused by fungal diseases

spot natural garden brown nature fungus plant damage leaf macro fungi fungal agriculture diseased biology infection closeup tree outdoor green leaves disease summer rhododendron pathogen environment pest pathology parasite growth growing azalea downy diseases healthy rose repellent problem aphid blight chlorosis canker chancroid cercospora chlorotic fusarium oxysporum phytophthora zonata merry