Coffee Diseases

Coffee Diseases

Unfortunately, coffee diseases have no natural predators, and although fewer in number than the hordes of coffee pests, coffee diseases are still largely chemically controlled. Although fungicides are not as ecologically harmful as pesticides and herbicides, all chemical treatments are expensive. The best control of coffee plant diseases is careful quarantine, but that is not easy to enforce, especially given the extent of international travel.

One of the worst coffee plant diseases is leaf rust (Hemileia vastratrix). First reported in 1861 in Africa, by 1870 it had completely wiped out the coffee industry of Ceylon, which resorted to tea-growing. The virulent leaf rust quickly spread to every continent in the coffee-growing world, although some countries have thus far been spared. It is thought that leaf rust is spread by spores being carried on the clothes of travelers from one country to another, particularly by people working in the coffee trade. It is lethal for arabica trees, but robusta is resistant to it.

A soil-inhabiting fungus causes another devastating coffee disease, tracheomycosis, also know as vascular fungus, or coffee wilt disease, to which robusta is more susceptible than arabica. In fact, it was this disease that almost totally destroyed the Ivory Coast's original coffee plantations of liberica trees in the 1940s, after which time the Ivory Coast became a large grower of robusta and the developer of arabusta. In the Democratic Republic of Congo, coffee production has fallen consistently since 1994, due to this disease and internal tribal warfare affecting the same regions.

Another very serious disease affecting arabica trees is coffee berry disease (colletotrichum coffeanum). Also called brown blight and red blister, coffee berry disease is a fungus, first identified in Kenya in the 1920s, which may attack a coffee tree in the wake of its carrier, the antestia bug. Rain splashes can also spread residues of the disease, even those from a previous crop. The disease attacks the coffee cherries, causing maximum damage to green cherries, turning them dark with decay. Fungicidal sprays are successful in controlling coffee berry disease only to some extent, and therefore this disease is the subject of much hybridization research.

Hybridization can certainly offer hope for conquering many coffee enemies, as one variety, susceptible to a particular pest or disease, is crossed with another variety which is naturally resistant. Although crossbreeding may eventually see the disappearance of some coffee diseases (thus far what is seen is more the disappearance of flavor), there is a category of coffee enemy to which all varieties are vulnerable; these are the natural disasters that plague many coffee-growing regions.


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