Pest Management in Miombo Fruit Trees - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 386

influence shelf life. Dipping fruits in calcium chloride, ascorbic acid and growth
regulators such as Cycocel, maleic hydrazide and benzyladenine has delayed
overripening and increased the shelf life of Ziziphus mauritiana fruits (Pareek,
2001). Postharvest quarantine treatments for fruit flies, for instance, include hot
water dips and prolonged exposure to temperatures below 7.5°C. Marula fly
( Ceratitis cosyra ) larvae are known to survive heat treatment better than medfly
( C. capitata ), but exact treatment parameters are not yet established.
Unfortunately, there is virtually no information on the postharvest treatment
and handling of miombo fruits. It is therefore important that postharvest
procedures be given as much attention as production practices.
Quality control to ensure food safety is another area that requires attention
in the commercialization of miombo fruits. Particular areas of concern in food
safety are the indiscriminate use of agricultural chemicals and poor postharvest
handling, resulting in deterioration in the quality of foods. In the case of
miombo fruit processing, inadequate technologies employed and unhygienic
handling practices coupled with doubts about the quality of the raw materials
used and possible adulteration are matters of great concern. To avoid food
safety problems, a whole range of systems has been put in place, including
GAPs, hazard analysis and critical control point (HACCP) procedures (ICMSF,
1989). This is rarely practised in the developing countries. If miombo fruits are
to be commercialized, quality control needs to be taken seriously.
20.6 Conclusions, Emerging Issues and the Way Forward
The picture emerging from this review shows that tree ill-health may be caused
by a host of stress factors which may be mutually reinforcing. Fruit trees, indeed
any plants, grow to the best of their genetic potential if undisturbed. Any factor
that interferes with the normal physiological processes of plants, such as
competition from weeds, unfavourable weather, insects, diseases, fire and
animals, will affect the health of the plant. The result is usually a reduction in
growth or fruit yield or the death of the tree. Diseases and insects are often
specific within host genera, having become adapted to particular host
characteristics. Some organisms with a broad host range, for example
Armillaria , seem in many cases to be facultative parasites are quite capable of
living as saprophytes in natural balanced ecosystems. Only when stress or
disturbances occur to upset the equilibrium does the pathogenic ability of such
organisms manifest itself. Disturbances common in the miombo woodlands
include the recurrent fires, which are often initiated accidentally or as a
miombo management practice. Much more striking is the damage caused by
non-host-specific pests, which under favourable conditions are capable of
increasing to high population levels.
Our knowledge about the pests of miombo fruit trees is largely incomplete.
Though miombo fruit trees are known to be hosts to a variety of pests in the
natural forest (Lee, 1971; Parker, 1978), no systematic studies have been
conducted on their pest problems. Like most fruit trees, each miombo fruit tree
species is expected to be attacked by two or three key pests, several secondary