DR JEREMY BURGESS / SCIENCE PHOTO LIBRARY DR JEREMY BURGESS / SCIENCE PHOTO LIBRARY
The surface of a pumpkin, Cucurbita pepo, with developing black rot. Above centre is a sunken lesion caused by the Ascomycete Didymella bryoniae. The site of the original infection is at the centre of the lesion, which has grown radially, dissolving the skin of the pumpkin to produce a granular appearance. At the outer edge of the circle of growth, and beyond, are smaller centres of secondary infection (white areas). Infection also softens and liquifies the internal tissues of the pumpkin. D. bryoniae is the most common cause of rotting of stored pumpkins. Other symptoms include areas of black skin on the fruit ( bottom, to left of centre). Storage rots in pumpkins may be caused by premature harvesting, and mechancial or insect damage to the skin. The risk of rot is also greater in fruits stored at temperatures below 10 degrees centigrade, and by exposure to high humidity.
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