Bacterial Spot on Pepper and Tomatoes

Need to know

• Bacterial spot on pepper is caused by the bacterium Xanthomonas campestris pv. vesicatoria.
• Leaf spots on affected leaves are at first small, yellow-green lesions with a water-soaked border. These spots may coalesce, giving a blighted appearance. Eventually, these spots turn brown and dry up, leaving holes in the leaves.
• Bacterial spot is difficult to control once it is present.

Overview of bacterial spot on pepper and tomatoes

Bacterial spot on pepper is caused by the bacterium Xanthomonas campestris pv. vesicatoria. Warm and humid conditions favor the disease. The disease organism can be spread by rain or during overhead irrigation.

Symptoms of bacterial spot on pepper and tomatoes 

Leaf spots on affected leaves are at first small, yellow-green lesions with a water-soaked border. These spots may coalesce, giving a blighted appearance. Eventually, these spots turn brown and dry up, leaving holes in the leaves. A tattered appearance of the leaves often results. Fruit spots are raised scabby areas. Fungi may enter these spots and cause secondary fruit rots.

Signs of bacterial spot on pepper and tomatoes 

Bacterial ooze (streaming) may be evident when observed using a microscope. Culturing and other testing are recommended to confirm this problem as symptoms may resemble other diseases.

Type of Sample Needed for Diagnosis and Confirmation

The Iowa State University Plant & Insect Diagnostic Clinic can help you to investigate and confirm if your plant has this disease. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each state's diagnostic laboratory for U.S. residents.  If your sample is from outside of Iowa please do not submit it to the Plant & Insect Diagnostic Clinic without contacting us.

Want to submit a sample? follow the foliar instructions on the annual Herbaceous plant's page. 

Management

Bacterial spot is difficult to control once it is present. The following recommendations will aid in control:

• Use only inspected, healthy transplants.
• Avoid working around plants when the foliage is wet.
• Do not plant peppers or tomatoes in the same spot in successive years.
• Control weeds, especially nightshade and ground cherry. (The bacterium has been shown to survive on these solanaceous weeds.)
• Applications of a fixed-copper fungicide can slow the spread of the disease but will not eradicate existing infections.
• Remove infected plant debris or plow under deeply.

Fungicide applications may be avoided by following good Integrated Pest Management practices like those listed in this encyclopedia article. Often, the only preventative application is effective to manage plant diseases. If the problem requires a fungicide, state law requires the user to read and follow all labels accordingly. For more information, read Proper fungicide use.