Tomato Sunscald: Why Too Much Sun Can Be Hazardous to Your Tomatoes’ Health

What does tomato sunscald look like?

Photo: Colorado State University

• Sunscald first appears as light patches on green or ripening fruit
• Most often, sunscald develops on the side of the fruit that faces the sun
• As the patches grow, they may blister and may become grayish-white
• Affected sunscald tomatoes can develop black mold

When does sunscald affect plants?

How can you control sunscald?

Photo: Missouri Botanical Garden

Sunscald is irreversible once it’s impacted a tomato, but its progression can be slowed. You can leave exposed fruit on the vine and cover it with lightweight screen, shade cloth, or straw to protect if from further damage. You can also harvest sunscalded tomatoes and let them finish ripening on a windowsill or kitchen counter.

Can you eat tomatoes affected by sunscald?

How can you prevent tomato sunscald?

• Choose heat-tolerant tomato varieties.
• Don’t over-prune tomato plants, especially in hot climates. If you leave extra branches on plants, you’ll provide extra shade for fruit.
• Cage tomato plants. Caging provides tomato support without requiring pruning, so foliage can provide shade to tomatoes. (Traditional stakes and trellising expose fruit to maximum sunlight, which promotes sunscald.)
• Keep plants healthy and treat tomato problems as soon as possible. Tomato wilts, blights, and leaf spot cause plants to drop foliage, which expose fruit to excess sunlight.
• When the forecast is for extended hot, dry weather, shield plants with a lightweight screen, shade cloth, or straw to protect fruit from over-exposure and hopefully prevent sunscald.
• Consider growing tomato plants upside-down to shade fruit.

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