tar spot

tar spot (uncountable)

1. A fungal disease affecting various plants and causing dark spots on leaves.
   • 1990, R. S. Mehrotra, An Introduction to Mycology, page 335:

     Species of Phyllachora cause diseases in plants known as leaf tar spots. P. maydis, responsible tor the maize tar spot, is one of the few species that can cause severe leaf damage.

   • 1996, F. H. Tainter, Principles of Forest Pathology, page 459:

     Large and small tar spot are apparently more abundant in the eastem and westem United States, respectively. […] Premature defoliation can occur if tar spot is severe.

   • 2003, Randy C. Ploetz, Diseases of Tropical Fruit Crops, page 47:

     Tar spot is a relatively minor disease in the Americas, but it is very common and often is present on 50% of the leaves in a grove.

• tarpots