Olive anthracnose

Olive anthracnose is the most important fungal disease of olive fruits worldwide. It occurs in humid olive-growing areas of many countries and causes heavy yield losses and lowering of oil quality. Several species or genotypes of Colletotrichum have been indicated as responsible for olive anthracnose in different countries, including C. gloeosporioides, C. acutatum (both in a broad and narrow sense) and the molecular groups A4 and A6 of C. acutatum, C. fioriniae, and C. simmondsii. Recently, the molecular group A4 of C. acutatum has been described as a new species named C. clavatum. Conidia of the different species and genotypes of Colletotrichum causing olive anthracnose are the infective propagules; they are produced in acervuli on infected drupes and are dispersed by rain splash and via windblown rain droplets, causing secondary infection cycles. Mummified drupes on the tree have been regarded as the inoculum reservoir. The incidence and severity of anthracnose vary considerably depending on the environmental conditions, the susceptibility of the olive cultivar and the virulence of the pathogen's population. Susceptibility of the drupes to anthracnose increases with maturity, although green fruit of susceptible cultivars may be severely affected in favorable environmental conditions. Control is based on integrated disease management that includes chemical treatments, selection of resistant cultivars and early harvesting.