COFFEE

Diseases

Leaf rust (Hemileia vastatrix)

This is an important disease causing economic loss particularly in Arabica coffee. On the lower surface of the infected leaves, small pale yellowish spots appear early after the first rains in the season. These spots soon increase in size and number, and many such spots coalesce at severity causing premature defoliation. Severe defoliation leads to debilitation of the bushes and results in poor cropping in the succeeding seasons.

Control

Spray susceptible coffee with 0.5% Bordeaux mixture or 0.03% ai Plantvax 20 EC 3-4 times a year: Bordeaux mixture 0.5% in February-March as pre- or post-blossom spray, Plantvax 20 EC 0.03% ai in May-June as pre-monsoon spray, Plantvax 20 EC 0.03% ai or Bordeaux mixture 0.5% in July-August in mid-monsoon spray (if incidence of leaf rust is severe), and Plantvax 20 EC 0.03% ai or Bordeaux mixture 0.5% in September-October as post-monsoon spray.

Black rot (Koleroga noxia)

A disease more in occurrence in endemic areas with heavy rainfall, saturated atmosphere with 95-100% RH, thick overhead shade, low over-hanging branches, sheltered from sunlight and wind in valleys or continuous mist during monsoon. The affected bushes have blackening and rotting of leaves, twigs and developing berries. There will be defoliation and berry drop in the affected branches. The entire block affected looks totally debilitated with heavy damage to crop.

Control

Centering and handling of the bushes prior to the onset of monsoon and protecting endemic patches with spraying Bordeaux mixture 1%. If incidence is observed during the monsoon, remove the affected twigs and burn them. Spray with Bordeaux mixture 1% during break in the monsoon.

Coffee Berry Disease

This disease is caused by the fungus Colletotrichum coffeanum and affects green or immature coffee berries and the coffee flower at any stage in its development. Infected berries often show dark sunken spots that spread and coalesce to cover the whole berry. As the fungus sporulates, a pale pink crust of conidia appears on the lesion. Depending upon the timing of the infection, the bean can also become infected.

In some cases, a milder scab-like disease occurs.

Losses of up to 75% of a crop have been reported.

Overhead spraying of fungicides can protect the flowers and berries without necessarily protecting the rest of the plant. Effective fungicides include benomyl, captafol, chlorothalonil, copper formulations, dithianon, thiabendazole, and thiophanate methyl.

Last updated: 23-05-2008