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Pepper Meltdown - What’s Actually Happening?

As peppers set fruit, there are often concerns about mushy spots and alarming black fuzz on fruit. While the first instinct is often that this is caused by a disease, it is often a physiological disorder at the root of the problem.

Sunscald on a bell pepper. Photo: Marissa Schuh, University of Minnesota.

Sunscald is an issue in peppers in a way that it isn’t in any other vegetable. It is easy to identify shortly after it happens: look for flattened, tan areas on the sides of fruit exposed to the sun.

However, the longer these fruit are on the plant, the longer the damaged tissue is exposed to moisture and opportunistic bacteria and fungi in the environment. The weakened tissue can get infected by all kinds of secondary pathogens that can cause the original sunscald site to become covered in spores, and the entire fruit to get soft.

Sunscald has provided an entry point for pathogens. Caption: Howard F. Schwartz, Colorado State University,

Sunscald can be somewhat varietal, so if one variety isn’t super leafy and has lots of mushy peppers, that could be a clue that sunscald is the original culprit.

These fruit will never be marketable, so they can be removed to focus the plant's energy on marketable peppers.

The same series of events can happen with blossom end rot. This symptom of calcium deficiency, whether caused by lack of calcium or lack of water to move calcium, produces underdeveloped areas on the pepper fruit. These rotted spots provided an entry point to opportunistic pathogens, which can lead to total pepper meltdown.

Blossom end rot on bell peppers, some of which are already showing signs of secondary infection. Photo: Paul Bachi, University of Kentucky Research and Education Center,

Blossom end rot tends to be the worst in the initial set of fruit, so lots of mushy peppers early can be a clue that blossom end rot is the original issue. Pick off these fruit so that the plant stops wasting its energy on them. The issue often self-corrects for the next round of fruit set.

These physiological issues are far and away the most common causes of mushy pepper spots. While diseases like alternariaanthracnose, and phytophthora can attack pepper fruit, it isn’t common.

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