A pale, bleached or blistered patch on the exposed side of a pepper may be sunscald, particularly after hot, sunny weather or a loss of leaf cover. Look at the fruit's position on the plant before treating the patch as a disease. Sunscald damages exposed tissue; extra fertilizer will not restore it.
University of Maryland Extension describes light-colored, blistered areas on the sun-facing side of affected fruit and identifies foliage loss as an important route to exposure. The appearance is consistent with sunscald, but it is not a complete diagnosis for every pale or damaged pepper. University of Maryland: Sunscald of Vegetables
Keep the pepper on the plant long enough to read its position
A harvested fruit no longer shows whether its damaged side faced the afternoon sun or sat beneath a recently pruned branch. Before picking several examples, photograph them on the plant. Include the leaf canopy, the side of the fruit with the patch and a label identifying the row.
Then compare nearby protected fruit. If patches cluster on exposed shoulders while fruit under intact foliage remain unaffected, exposure deserves close investigation. A pattern involving shaded fruit, widespread rot or declining plants calls for a broader diagnosis.
Use a short record rather than an unqualified statement that “the house has sunscald”:
| Record | Useful detail |
|---|---|
| Fruit position | Upper or lower canopy; exposed side; edge or interior row |
| Canopy change | Pruning, broken branches, pest damage or disease |
| Timing | First affected harvest and preceding hot or bright periods |
| Distribution | Affected fruit compared with fruit inspected in the same area |
For example, finding 8 affected fruit among 40 inspected in an exposed row means 20% of that row sample was affected. This is an illustrative calculation, not a measured loss rate for a whole greenhouse. Record an interior-row sample separately instead of combining unlike locations.
Protect the next fruit through the canopy
Minnesota Extension associates pepper sunscald with inadequate leaf cover during hot, dry weather. Its guidance also emphasizes consistent moisture. In a greenhouse, the practical question is whether the crop is retaining a healthy canopy and whether irrigation is supporting it through periods of high demand. University of Minnesota: Growing Peppers
Review recent pruning and branch support alongside the crop's pest and disease record. Maryland recommends maintaining healthy foliage and controlling pests or diseases that remove leaf cover. Repeatedly removing foliage without noting which fruit become exposed can make the cause difficult to see. University of Maryland: Sunscald of Vegetables
A shading change should be evaluated against the crop's light requirement and the actual conditions at the affected rows. This diagnosis does not supply a universal shade percentage. If a screen failed to close, a vent stopped working or a cooling interruption coincided with the damage, resolve that equipment fault. The greenhouse cooling and ventilation response guide covers that separate operational task.
Grade the damaged fruit and watch later harvests
Keep clearly affected fruit out of saleable grades when the damage fails the buyer's specification. Maryland advises removing sunscalded fruit; the damaged patch will not disappear as the fruit matures. University of Maryland: Sunscald of Vegetables
Evaluate any correction on later fruit from the same locations. A reduction in newly damaged fruit is more informative than repeatedly inspecting an old patch. If lesions expand, become wet or rotten, or occur alongside stem and root symptoms, submit fresh material for diagnosis. Sun exposure may explain the first injury without explaining everything that subsequently develops on it.
Published: 2026-10-05
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