Informational table showing disease name, symptoms, pathogen/cause, and management of Aglaonema diseases. Disease Symptoms Pathogen/Cause Management Anthracnose Circular to oval brown leaf spots have a yellow halo. Spots may become 2 inches in diameter and contain tiny black fungal fruiting structures. Colletotrichum Avoid overhead watering. Bacterial Leaf Spot Small gray or dark green leaf spots enlarge and become irregular in shape, tan, dark brown or black. Pseudomonas cichorii, Erwinia chrysanthemi, or Xanthomonas campestris dieffenbachiae Purchase plants free of the disease. Remove infected leaves and water in a manner that keeps the surface of the leaves dry. Copper Deficiency New leaves are yellow,strap-shaped or distorted. Lack of copper Apply a micronutrient that contains copper. Damaged leaves will not recover. New foliage will form normally Myrothecium Leaf Spot Large gray-brown, oval leaf spots form at leaf tips or margins. Fungal structures form in concentric rings within the spots on the underside of the leaf. Myrothecium roridum Do not apply excessive amounts of nitrogen fertilizer.