Bacterial Blights (5702)

Bacterial blights on houseplants can be a problem under warm, moist conditions.  Early symptoms of bacterial leaf spots or blights look like an angular, dark, wet area followed by death of the tissue.  Frequently a yellow halo will also develop around these angular spots.  Under severe disease conditions, the leaf spots may enlarge and run together to form larger spots or turn the entire leaf brown.  If the entire leaf or shoot turns brown, the disease is then called a blight.  Bacterial blights are worse under high humidity or wet conditions, since water will move the pathogens from spot to spot.  Some bacterial diseases can also become systemic throughout the entire plant.

Disease management:  Always inspect plants carefully before purchase and isolate new plants for several weeks before mixing them with the rest of your collection.  Unless you have a greenhouse, bacterial blights will not spread rapidly in indoor environments, and pesticides will not be needed for disease management.  One of the most practical disease management techniques is to pick off and discard infected leaves.  To prevent conditions favorable for disease, avoid prolonged wet conditions caused by practices such as misting or watering your plants in the evening.  Space plants far enough apart to allow good air circulation around the foliage to reduce humidity levels.  If you suspect a systemic bacterial disease, then the entire plant will have to be discarded.

For more information on this subject, Please visit the College of Agricultural Sciences Publications Web site.

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