Struggling Citriculture in Florida is a Source for Innovation in Horticultural Science

Abstract

Citrus is one of the most grown fruit crops in the planet, and has very important economic value for several regions across the tropics and subtropics. These include countries in the Northern Hemisphere such as United States of America and Mexico in the Americas, Spain, Italy, Egypt, Turkey and Israel in the Mediterranean, China, India and Japan in Asia, and countries in the Southern Hemisphere such as South Africa, Australia, Brazil, Uruguay and Argentina. This distribution of Citrus culture between both hemispheres warrants transport of fruit between regions on a seasonal basis through regulated trade. However, with commercial transport of commodities and increasing traffic of passengers among countries, new threats have appeared such as the spread of diseases. A dramatic example of this is the spreading of the disease known as huanglongbing (HLB), the yellow dragon disease. HLB is the most economically devastating disease of citrus worldwide, it was described for the first time in southern China in 1919 and is now known to occur in about 40 different countries around the globe. The HLB bacterium belongs to the genus Candidatus Liberibacter, Currently three species are known, Candidatus Liberibacter asiaticus, occurring in Asian countries, Brazil and the USA, Candidatus Liberibacter africanus with its subspecies "capensis", recorded from African countries, and Candidatus Liberibacter americanus present also in Brazil [1]. It has been suggested that each liberibacter species has evolved in the continent after which it is named. HLB symptoms are virtually the same wherever the disease occurs. HLB can be transmitted by grafting from citrus to citrus and by dodder to periwinkle [2]. The psyllids Trioza erytreae and Diaphorina citri are natural vectors [1].