Peronospora belbahrii (basil downy mildew).
Basil downy mildew was first identified from Uganda during 1932 and 1937, resulting in significant crop losses (Hansford, 1933; Hansford, 1939). Following these original outbreaks, the disease was reported sporadically in Africa during the twentieth century: in Tanzania in 1960 (Riley, 1960), then again in Benin during 1998 (Gumedzoe et al., 1998). The disease was first identified outside of Africa in 2001, when it was reported from Switzerland (Belbahri et al., 2005). Unlike the intermittent African outbreaks of the twentieth century, the twenty-first century outbreaks of basil downy mildew are persistent, and the geographic range of P. belbahrii continues to expand. Since 2001, P. belbahrii has spread throughout Europe, North America, Asia, and parts of Africa, Central and South America, and the Caribbean. Losses incurred due to basil downy mildew in the USA alone are estimated to reach tens of millions of dollars (Wyenandt et al., 2015).