Agriculture Reference
In-Depth Information
7
COFFEE
( Coffea arabica )
Coffee is a member of the family Rubiaceae, a large family
comprising mostly trees and shrubs. Coffee is produced
from Coffea arabica and C. canephora . The former is the
major economic species and is indigenous to the highland
forests of Ethiopia.
Arabica coffee is of superior quality and used mainly for
filtered coffee while Robusta coffee from C. canephora is
used to produce instant coffee.
Coffee trees are densely foliated, evergreen shrubs growing
2-4 m tall and 1-2 m in diameter. Flower buds develop in
leaf axils, mostly on one-year-old wood during winter. The
fruit form clusters and ripen to a red or yellow colour.
Trees f flower and fruit once a year.
Coffee plants prefer a relatively mild, frost-free subtropical
climate with well-drained soils. The crop is propagated by
seeds, generally. Several areas in coastal Queensland and
New South Wales are suitable for coffee production, with
most production occurring on the north coast of New
South Wales and the Atherton Tableland of Queensland.
The major threats to the industry are the biosecurity
threats coffee rust and berry disease.
CERCOSPORA SPOT
Cause
The fungus Cercospora coffeicola .
Fig 7.1 Cercospora leaf and fruit spot symptoms.
Symptoms
Dark brown to black spots develop on leaves and are more
common on and near the leaf margins. Often the lesions
have an ash-grey centre and tissue surrounding the spots
may yellow prematurely. On cherries (berries), the lesions
are dark grey with an ash-grey coloured centre and usually
less than 5 mm in diameter but can spread to cover the
whole cherry.
Importance
Cercospora spot can cause defoliation of seedling plants in
nurseries where nutrition is poor. The disease can be a
problem in mature plantations where the plants are under
high light intensities with inadequate nutrition. The disease
makes conventional processing of affected cherries
difficult. Infected cherries may also ripen before the bean is
mature; this leads to 'off ' f lavours of the processed coffee.
Under high disease pressure, this disease can be a major
problem regardless of nutrition and if protective fungicide
sprays have not been applied.
Source of infection and spread
Spores of the fungus are spread by wind. Warm, humid
weather favours the disease.
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