Gary W. Moorman, Professor of Plant Pathology
|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.|
Notice: The user of this information assumes all risks for personal injury or property damage.
Warning! Pesticides are poisonous. Read and follow all directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams or ponds.
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