Bacterial Speck
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Bacterial speck (Pseudomonas syringae pv. tomato) results in small, circular, brown spots on stems, foliage, and fruit, primarily on tomatoes. Spots on foliage may be surrounded by a yellow border. These lesions coalesce to form large blighted areas in the plant canopy; defoliation may occur in severe cases. Very small specks, which may be sunken or very superficial, appear on green fruit. This disease tends to be more severe under cool temperatures.
Note: This bacterial disease can become a significant greenhouse issues if bacteria are introduced via infested seed, transplants, or trellis materials. Thus, bacterial diseases are of particular concern for transplant producers or growers starting their own plants from seed. These pathogens can spread from initially infected plants through splashing water or by normal trellising activities. Transplants showing symptoms of bacterial diseases should never be set in the field or production greenhouse.
Bacterial speck on tomato foliage.
(Photo: Gerald Holmes, California Polytechnic State University
at San Luis Obispo, Bugwood.org)
Bacterial speck on fruit.
(Photo: Kenneth Seebold, University of Kentucky)
Management:
- Use transplants started from pathogen-free seed.
- Follow good sanitation practices.
- Apply a labeled bactericide to reduce secondary spread.
