[blak spot for 1; blak spot for 2] 
| 1. | Plant Pathology. a disease of plants, characterized by black spots on the fruit and foliage, twig lesions, defoliation, and rotting, caused by any of several fungi, as Diplocarpon rosae, or bacteria. |
| 2. | British.
|
| black spot n. Any of various fungal or bacterial diseases of plants, resulting in small black spots on the leaves or on other parts. |
black spot
common disease of several plants that is caused by species of Pseudomonas bacteria or by many fungus species in the genera Asterina, Asterinella, Asteroma, Diplotheca, Glomerella, Gnomonia, Microthyriella, Placosphaeria, and Stigmea. Infections occur during damp periods and appear as round to irregular black leaf spots, sometimes on petioles, stems, and flower parts
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