Pepper -Which came first? Sunscald or Alternaria infection?

Alternaria sp. fungus that has infected a bell pepper with suncald.

This bell pepper sample had a round, necrotic area with black fungal growth, on the surface of the fruit. Based on the symptoms of the sample, it appeared to be sunscald, an environmental problem. This problem arises when the pepper is exposed to high levels of sunlight under high temperatures. The dead tissues are only present on the side of the fruit that is exposed to sunlight.

In addition, this sample appeared to have a black fungal growth, covering the sunscald area.  This is an Alternaria sp. (a fungus pathogen) that can invade the damaged tissues (from sunscald or other issues) on the fruit and can continue to cause injury. 

Alternaria sp. is controlled by avoiding conditions that predispose peppers to infection.  There are no approved fungicides or biocontrol agents known for postharvest application to pepper fruit.  If possible, planting should be scheduled so that harvest does not occur during very hot or cold weather, or drought.  Grow pepper cultivars that provide good shading of fruit and be sure that the fertilization includes adequate calcium.

Bell pepper with sunscald.

Certain varieties of the peppers can be more sensitive to sunscald. In lieu of the recent high temperatures and sunlight, it is recommended to plant varieties of peppers that are more tolerant towards the condition.  For example, if you continue to have problems with sunscald, you may try to grow another pepper variety. You can also try to encourage more of a canopy to shade the peppers from the sun (culturally as well as adding fertilizer (N).