Avocado Production in Asia and the Pacific - United Nations in ...

Australia. As it migrates into orchards from surrounding cover it is difficult to control and
requires a protective insecticidal programme for the duration of the fruiting season. The redshoulder
or monolepta beetle can cause substantial damage to leaves and fruit if it swarms
into orchards. Also migratory, it is difficult to control and daily inspection of trees with spot
spraying of swarms is the most effective method to contain this pest. Queensland fruit fly in
eastern Australia and Mediterranean fruit fly in west Australia can damage fruit, but are of
minor importance. Several species of leaf-webbing caterpillar can cause damage to fruit in
the autumn months and can be controlled by strategic applications of targeted insecticides.
Integrated Pest Management systems developed for citrus orchards are gradually being
introduced into avocados.
5.6 Diseases
Phytophthora root rot caused by Phytophthora cinnamomi is a major international
disease of avocado and is present in all countries producing this crop. All areas in Australia
producing avocados are affected by this disease. Phytophthora root rot is successfully
controlled by trunk injection with potassium orthophosphonate using a 20% a.i. solution
which is injected at the rate of 15 ml per metre of tree diameter. Despite the spectacular
success of phosphonate treatments, an integrated approach of biological and chemical control
is still recommended in the high-risk subtropical areas of northern New South Wales and
Queensland. Anthracnose, a serious fruit problem in most environments, is controlled by
regular spraying with copper-oxychloride and a post-harvest treatment of prochloraz
(Sportak). Verticillium wilt is a disease of lesser significance. It is a soil-borne disease
which attacks the vascular system but seldom kills plants, and there is no effective fungicidal
treatment.
6. HARVESTING OF FRUIT AND ORCHARD YIELDS
6.1 Maturity standards
Fruit of all cultivars must reach a minimum of 21% dry matter and ripen naturally
without shrivelling before it can be harvested legally and sold.
6.2 Harvesting
Fruit is hand-harvested from trees when mature using an array of picking aids. On
the larger orchards, trees are harvested with the aid of hydraulic ladders (cherry pickers)
while on the smaller properties picking poles are used to reach fruit. For most cultivars, fruit
needs to be clipped with a ‘button’ retained on the pedicle end. This reduces the risk of
stem-end rot invading the fruit as it ripens. Fruit is picked into large bins usually mounted
on trailers to facilitate their movement to the packing shed. It is important to keep the fruit
out of direct sunlight after picking to prevent it from heating.
For early-maturing cultivars and those with a fruit size problem, fruit is normally
picked over two harvests removing the larger fruit first hence allowing the smaller fruit to
grow. Generally, late hanging of fruit, which is often practised to market when prices are
higher, drives the trees into biennial bearing. Due to the number of cultivars and the wide
range of latitudes at which the crop is grown, avocados can be harvested year-round in
Australia although the peak of production is during the winter and early spring months.
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