On the fruit, the spots appear as raised brown lesions of a couple of millimetres in diameter. The fruit, of course, is downgraded. At the same time, yield is reduced as the leaves are unable to function at full capacity. In fact, they usually start to fall off once the disease gains a foothold. Warm weather, high humidity and free water on the leaves create ideal conditions for the development of the disease. It spreads to other plants through rain splashes and sprinkler irrigation and by people and implements travelling through the land when the leaves are still wet.
Prevention
The disease is caused by the bacterium Xanthamonas campestrus pv vesicatoria and also occurs in tomatoes. There are three strains, and the disease is mainly seed-borne. A fraction of a percentage of infected seed can result in 100% infection in the land. As noted, bacterial spot is very hard to control. The best course of action is to ensure that transplanted seedlings are free of the pathogen.When ordering seed, get an assurance from the seed company that the seed is either certified disease-free or has been treated. This can take the form of immersion in hot water at 51°C for 30 minutes, or soaking the seed in a 10% sodium hypochlorite (bleach) solution for the same length of time. For chilli and paprika farmers who keep their own seed, treatment is a worthwhile precaution, even if no symptoms are visible.
After treatment, sow the seed before it is fully dry. This will speed up germination. The disease can remain in undecomposed organic matter, but when a land is cultivated, decomposition is usually complete before a year is up.
In this case, it’s safe to replant peppers or tomatoes a year later.
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