The most destructive disease of coffee trees, leaf rust.

The most destructive coffee tree disease is caused by coffee camel rust (Hemileia vastatrix). The disease has long occurred in coffee-producing areas such as Africa, the near East and India, Asia and Australasia. It first appeared in the Western Hemisphere in 1970 and was found in Brazil. Once thriving coffee plantations in Sri Lanka and Java were destroyed by the disease. The symptoms are small yellow oil spots on the surface of the leaves, then expand into bright orange to red spots, and finally turn brown with a yellow edge. The rust spores are stacked on the lower surface of the leaves, orange-yellow, and then turn black. The diseased leaves droop and fall off gradually, and the plant dies within a few years. The control method is to spray fungicides in time during the wet season; plantations in some areas have moved to cooler places at an altitude of 1800 to 2100 meters (6000,7,000 feet), where rust is not easy to reproduce. The implementation of quarantine also reduces the chances of long-distance dissemination.