Experts and BHG readers answer.
Tomato Plants Turning white
The response that you're observing on your tomato and cucumber transplants is typical of sunscald and windburn on new transplants. After growing in a protected greenhouse or other spot indoors, transplants benefit from a gradual hardening off before transplanting outdoors. It's best to place them in a protected spot out of the wind and out of direct sun for a week or so before actually transplanting them to the garden. Since the damage has already occurred on your plants this year, this information is to help you next year. Your plants may recover fully. Make sure they have adequate, but not too much moisture. And it may still help to protect them from winds by erecting a shield on the windward side of the plants.