growth on tomatos
Thank you for the pictures which appear to show blossom end rot on your tomatoes. As the article below states, technically this problem is caused by a calcium deficiency but the real reason is that there is not enough water for available for the plant to transport the calcium to the fruit. Regular, deep watering is needed when there is no rain. http://msue.anr.msu.edu/news/dont_let_blossom_end_rot_ruin_your_vegetables
Remove all infected fruit and watch for any further signs on new tomatoes. The rot does not spread from plant to plant or from fruit to fruit so no need to use fungicides. Always water at the base of the plant to avoid over spray onto leaves and water in the morning if possible, to allow time for the moisture that hits the plant to dissipate. Below is a tip sheet with more info about this tomato disorder. Hope that helps!