Leaf blight - a disease that has a fungal or bacterial in nature. More often exposed to citrus, dieffenbachia, dracaena. At the same time on the plant leaves appear brown, oozing spots that the spread of the disease grow in size, coalesce and affect the entire leaf entirely. Leaf spot can also be caused by nematodes. Control measures. Removal and burning of affected leaves. Spraying of systemic fungicide, reducing watering and stop spraying.