|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.|
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