Sunscald isn’t an infectious disease, it occurs when a fruit (usually a tomato or pepper) is directly exposed to sunlight and high temperature. The side of the fruit facing the sun becomes whitish, blistered and papery and the damage may eventually lead to infection by rot-causing organisms. Sunscald most often occurs after plants have lost leaves to disease or have been pruned too heavily, but it can also occur on plants that don’t naturally have a lot of leaves. You can’t do anything for the infected fruit, though if it hasn’t started to rot you can cut off the affected part and eat the rest.
Image: Howard F. Schwartz, Colorado State University, Bugwood.org