Coffee is one of the most important agricultural products on the world market, and is the most widely grown tropical tree crop. Various Latin American countries such as Colombia, Brazil and Central America depend heavily on coffee production for foreign currency earnings. More generally, the economies of about 50 countries depend on this crop, which is grown on 11.2 × 106 ha and which produced 5.3 × 106 tons of green coffee in 1992 and 5,603 metric tons during 1995. The supply of coffee consumed world-wide primarily comes from two cultivated species: Coffea arabica and C. canephora, which account for 75 and 25% of the world market, respectively. These two varieties are commercially known as “arabica” and “robusta”, respectively.