Informational table showing disease name, symptoms, pathogen/cause, and management of Philodendron diseases. Disease Symptoms Pathogen/Cause Management Bacterial Leaf Spot Translucent spots on leaf margins become reddish-brown with yellow halos. Large spots are tan and irregularly shaped. Xanthomonas campestris pv. dieffenbachiae Purchase plants free from the disease. Avoid overhead watering. Remove infected leaves. Bacterial Blight Philodendron selloum Small very dark green spots on leaves expand rapidly and spread to petioles. Infected leaves collapse in a wet rot that smells foul. Erwinia caratovora pv. Carotovora E. chrysanthemi Avoid overhead watering. Remove infected leaves of plants not severely affected. Water in a manner that keeps the surfaces of leaves and petiole dry at all times. Cold Injury Very dark green to brown blotches form between leaf veins. Temperatures below 50° F Do not place plants near air conditioners. Maintain temperatures above 55° F. Magnesium Deficiency V-shaped yellow areas form on leaves especially in cool greenhouses. Insufficient magnesium Apply one teaspoon magnesium sulfate (Epsom salts) per gallon of water. Tip Curl Leaf tips curl downward and leaf margins brown. Roots die. Over-fertilization Reduce fertilizer rate and leach the soil if slow-release fertilizer is not present. Repot if excessive slow release fertilizer was used.