Citrus black spot (CBS) is a citrus disease caused by the fungus Phyllosticta citricarpa (previously known as Guignardia citricarpa). This fungus affects citrus plants throughout subtropical climates, reducing both fruit quantity and quality. It has a significant economic impact, mainly owing to the external blemishes that make citrus fruit unsuitable for the fresh market. Premature fruit drop caused by some infections may contribute to further economic loss. The distribution of CBS is restricted in Botswana.