Pests and diseases

Major pests in coffee:

Coffee Borer Beetle:
The coffee borer beetle is a small black beetle that bores into the lower portion of the coffee fruit and lays eggs in the seed endosperm. The coffee borer beetle thrives in humid conditions and dense crop spacing. The best means to limit infestations are through proper plant pruning and ensuring that all coffee is harvested and no coffee fruit is left in the fields between harvest.

Black Twig Borer:
The black twig borer is native to Asia where it is a serious pest of Robusta coffee, but has spread to coffee growing regions throughout the world where it attacks Arabica coffee as well. Females bore into branches, twigs, and suckers, leaving a pin-hole sized entry. The plant is destroyed through tunneling as well as pathogens introduced by the borer. The black twig borer thrives in humid conditions since humidity facilitates the ambrosia fungus upon which the borer feeds in its younger stages. Infestations can be controlled by pruning (specifically removing unwanted suckers) and shade reduction.

Nematodes:
Nematodes are worm-like organisms that are 0.1-5mm in length. They attack the root system of plants, feeding on the sap. They can form knots in the roots that inhibit the plant from properly feeding. Symptoms of a nematode infestation are galls, splits, scales and decreased mass in the root system, and chlorosis and defoliation in the upper plant. C. canephora is more resistant to nematode infestations, and thus using seedlings engrafted in C. canephora rootstock is a means of limiting outbreaks.

Major diseases in coffee:

Bacterial Blight:
Bacterial Blight, also called Elgon Die-back, was first identified in Garca, Sao Paulo, Brazil, thus its name "garcae." It normally occurs in seedling nurseries and affects plant leaves and tissue. Leaves initially appear to be water-soaked, followed by the appearance of necrotic brown lesions surrounded by yellow rings. The leaves eventually dry, curl up, blacken and die; however, they do not fall from the tree.

Coffee Berry Disease (CBD):
Coffee berry disease (CBD) is caused by the fungus Colletotrichum kahawae. CBD was first documented in 1922 in Kenya. It attacks coffee berries at any point  in their maturation; however, only symptoms detected on young berries can be clearly diagnosed. The disease can appear in "active" form and "scab" form. In the "active" form, dark-colored indented spots appear on the coffee bean and are followed by a pale pink crust as the spores develop. The berry is destroyed in a matter of days and reduced to an empty, blackened and dried out pouch. The "scab" form is a much milder attack where several small concave spots form on the berry.

Coffee rust:
Since the first occurance of coffee rust in Brazil in 1970, it has spread to every coffee growing country in the world.  Because of the destructive and widespread nature of the disease, many countries, including Sri Lanka and Ethiopia, replaced much of their arabica coffee with disease resistant robusta coffee. Coffee leaf rust is spread by wind and rain from spores from lesions on the underside of the plant. The rust diesease in coffee is prevented by spraying with copper-based fungicides at 3-5 kg/ha at 4-6 week intervals during the rainy season.