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. CBS can potentially be harmful in an area where it is not yet present. CBS is spread when wind-borne spores embed in the leaf litter under trees and are carried long distances by air currents. Rain splash may move spores short distances from infected fruit and/or leaf litter. Human-assisted movement of fruit and infected nursery stock is the main form of long distance movement.
The detection of CBS in Botswana called for an emergency incursion response which is accepted internationally and in accordance to the international standards. The management strategy for the pest has been drawn and implemented with immediate effect. The strategy involves 1) conducting a delimiting Survey 2) implementing eradication procedures and 3) Implementing internal controls and 4) Maintenance of pest free areas in Phikwe district, North West, Chobe, Ghanzi and Kgalagadi districts