noun
1. : any of several plant diseases characterized by black spots or blotches: as
a. : apple scab
b. : apple anthracnose
c. : a common destructive disease of roses caused by a fungus ( Diplocarpon rosae ) and characterized by black spots or blotches on the leaves, yellowing of the remaining portions, and premature falling of the leaves
d. : a disease of citrus fruits caused by an imperfect fungus ( Phoma citricarpa )
e. : a disease of peaches and plums caused by a bacterium ( Xanthomonas pruni )
f. : a disease of beets caused by boron deficiency in the soil
2. : a spotting of frozen meat caused by an imperfect fungus ( Cladosporium herbarum )
3. : black grub