Bacterial Speck of Tomato
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Bacterial speck (Pseudomonas syringae pv. tomato) can affect leaves, stems, and fruit. On leaves, lesions are small, circular, and brown in color; spots may be surrounded by a yellow border or “halo.” Over time, lesions coalesce and form large blighted (suddenly dead) areas in the plant canopy. Defoliation may occur in severe cases. Differentiating leaf symptoms of bacterial speck and bacterial spot can be difficult. On green fruit, lesions are small (specks) and tend to be somewhat sunken. Disease is more likely to occur when conditions are cool and rainy.
Bacterial speck on leaf.
(Photo: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org)
Management:
- Plant pathogen-free seed and transplants
- Disinfect tools and implements
- Avoid overhead irrigation or working with plants when leaves are wet
- Apply a bactericide
- Promptly remove and destroy diseased plant material
- Rotate with non-host crops
- Destroy crop residues after harvest
- Deep plow to bury residual inoculum
