Although the five tomato plants in my raised bed are generally doing well, one other plant (a "big boy" variety in an adjacent container) has developed unsightly spots on 2 of that plant's approximately 6 green tomatoes. Initially these spots were whitish depressions about the circumference of a quarter. Then they become discolored. Can anyone tell me what this is and how to treat it? Also is there any danger of it spreading to other plants? So far it hasn't even spread to the other tomatoes on the same plant.). Attached is a photo.