Bacterial Speck

Plant Health Clinic Disease Note Issue 16
Sherrie Smith and Jason Pavel

Bacterial Speck- Pseudomonas syringae pv. tomato. Photo by John Gavin, University of Arkansas System Division of Agriculture Cooperative Extension

Bacterial Speck- Pseudomonas syringae pv. tomato. Photo by Sherrie Smith University of Arkansas System Division of Agriculture

Bacterial Speck is caused by Pseudomonas syringae pv. tomato. Lesions on leaflets are round, dark brown to black. Large areas of tissue may be killed as spots coalesce. Lesions on stems and peduncles are elongated. Fruit lesions are minute specks that are dark and rarely exceed 1mm (.04inch). A dark green halo may be associated with the fruit spot.

How do I prevent bacterial speck?

Practice a three year rotation where no peppers, tomato, eggplant, or potato are grown in that spot. Additional measures consist of using clean transplants, seed treatments, elimination of cull piles near production areas, and the timely application of bactericides when necessary. Practice a preventive copper + mancozeb spray program from bloom until the firstformed fruit are 1/3 their final size. Kocide is labeled for tomato in Arkansas for bacterial diseases.

Bacterial Speck- Pseudomonas syringae pv. tomato. Photo by Sherrie Smith University of Arkansas System Division of Agriculture

Take aways:

• Practice crop rotation.
• Clean up all crop debris.
• Avoid overhead irrigation.
• Use preventative fungicides from bloom until first-formed fruit are 1/3 their mature size

This work is supported by the Crop Protection and Pest Management Program [grant no. 2017-70006 27279/project accession no. 1013890] from the USDA National Institute of Food and Agriculture.

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