First report of citrus black spot disease caused by Phyllosticta citricarpa in Benin

Abstract

In Benin, citrus production represents an important activity in the national economy and source of income for farmers. For a decade, the majority of orange orchards in Benin have been affected by a disease that is expressed by the appearance of spots on the fruits (Lokossou et al., 2009). A preliminary study conducted on farmers’ perception on the presence of this disease revealed positive answers from all 417 interviewed orchardists. In July 2021, 15 orchards were randomly selected for inspection in four orange production districts in Benin: Djidja (7°20’N, 1°56’E), Zakpota (7°15’N, 2°11’E), Lalo (6°56’N, 1°56’E) and Bopa (6°35’N, 1°57’E). Between 50 to 100% of the trees in the inspected orchards were affected by the disease. Disease symptoms consisted of numerous tiny to middle-sized dark brown to black spots, ranging in size from 3 to 10 mm in diameter. The tiny spots had a grey centre with a dark brown to black border surrounded by a green or yellow halo, depending on the maturity of the fruit. In cases of severe infection, the fruits were completely covered with black spots, and rot (Fig. 1). The leaves also had numerous black spots. In cases of less severe infection, symptoms were limited to the fruits. Four fruits per orchard, in total sixty fruits, showing black spots were randomly selected each of the inspected orchards.