This is Part Four of a seven part series on some quirks that can be found with tomatoes. If you are interested in the other Tomato Quirks articles, here are the links:
What Is Sunscald?
Sunscald occurs when the green or ripening tomatoes are exposed to direct sunlight for extended periods during very hot weather. This exposure to direct sunlight can cause hard and discolored patches on the ripening tomatoes. These patches will then blister over time and eventually become sunken. Once the area has begun to sink on the tomato, it will grow a paper-like, thin, grayish-white substance. The sunscalded area may also begin growing black mold which will rot the tomato, and render it inedible.
How Can I Prevent Sunscald?
Sunscald can be prevented and controlled in many ways. Try not to remove too much foliage from the tomato plant when pruning. The extra foliage can help shade the fruit during extremely hot weather, and block the direct rays from the sun.
You can also use a shade cloth to shade the plants during the hottest part of the day. Use the shade cloth to build a tent over your tomato plants.
Growing the tomato plants upside down can also help to prevent sunscald. The leaves of the plant, and the container that houses the plant, will shade the fruit much better.
If you feel that sunscald might be an issue, or is an issue with your tomatoes, you can pick the fruit when it is still green, and allow them to fully ripen indoors. Place the tomatoes in a window sill, or under a skylight if possible. Just as long as the tomato receives some indirect light, it should ripen just fine.
When sunscald is in the early stages of development, it is best to pick the tomato and let it finish ripening indoors. The tomato is still probably edible – just cut away the affected areas. If the tomato shows any signs of black mold or rot discard it immediately, or add to a compost pile.
Part Five of Tomato Quirks will be on tomato splits and holes. Be sure you don’t miss it by subscribing to our RSS feed, or by bookmarking us.