Goldberg recommends keeping the root zone moist enough to easily form a ball. This should be possible even with urban watering limitations, she said. Thorough, deep watering that wets the entire root zone of the plant is better than frequent sprinkling. Because the problem is not caused by a disease, blossom end rot is not contagious. However, other plants growing under the same conditions are susceptible.
Problems typically are worst in the heat of summer.
In New Mexico, the disorder is most common in tomatoes, bell peppers and chile, although it also affects squash and melons, Goldberg said. Blossom end rot begins as a brown spot that enlarges to cover up to half the fruit as it matures. With age, the blemish becomes sunken and leathery. Eventually, fungi or bacteria may invade, giving the fruit a black or watery appearance. Affected fruit ripens faster.