Although rare because here in Utah, are climate is not humid and moist much of the time, we still can be affected by tomato bacterial spot. There have been a few cases this summer.
“Bacterial spot can infect tomato and peppers, and although spots can occur on both leaves and fruit, they are most commonly found on fruit. Spots are brown to black in color, circular, and surrounded by a yellow halo. They are slightly sunken and scabby.

The pathogen that causes this disease may be introduced to a field on infected seeds or transplants. It can then survive up to a year on plant debris that was infected the prior year. The pathogen becomes active once temperatures heat to the 80s and 90s, and when several hours of moist conditions occur. The bacteria are splashed onto leaves and fruit, causing infections. If conditions stay moist, new infections will continue until the plants are removed.” – Utah State Extension Small Fruits and Vegetable IPM Advisory

What to do about it?

The IMP advisory says that it’s all about good sanitation around the tomato plant. Remove weeds in the garden. When watering, avoid the foliage of the plant. Try to water right at base of the plant. Use mulch to help avoid splashing when watering. Pruning helps create good air flow, allowing the soil at the base to dry in between waters. It’s good to pull off the bottom leaves of the tomato plant. Lastly, remember to stake up the plant as it grows. Keep the branches and foliage off the ground.
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