Pest Management in Miombo Fruit Trees - Indigenous Fruit Trees in the Tropics: Domestication, Utilization and Commercialization - page 381

animals. Mycotoxins are produced mainly by the fungal genera Aspergillus ,
Penicillium and Fusarium . Under favourable conditions these fungi grow and
produce mycotoxins in certain foodstuffs such as dried fruits, nuts, spices and a
range of cereals. For instance, patulin, produced by a number of moulds,
occurs in apple juice and other apple-based products contaminated by
Penicillium expansum . Mycotoxins attract world-wide attention because of the
significant economic losses associated with their impact on human health,
animal productivity and domestic and international trade.
Contamination of juices with pathogenic microorganisms has caused
numerous illnesses and fatalities. Fruit juices with pH below 4.6 were once
deemed a minor health threat as a result of their high acidity. Furthermore,
refrigeration temperatures below 5°C represented an additional hurdle to
pathogen growth. The emergence of hitherto unsuspected food pathogens with
acid resistance combined with increases in the numbers of susceptible and
immune-compromised individuals, such as HIV/AIDS patients, the chronically
ill, the very young and the very elderly, has dramatically changed this picture.
Fruit products can also be contaminated with allergenic sensitizers of plant,
microbiological and animal origin. Of all the allergenic contaminants known to
occur in postharvest products, it is the storage mites which have received the
most attention, though beetles, moths and moulds are also known. Thus, for
safety and economic reasons commercial fruit products are subject to strict
regulatory control.
20.5 Strategies for Pest Management
From the discussion above it can be seen that major pest problems could occur
in the orchard from time to time. The other picture emerging from the discussion
is that tree ill-health may be caused by a host of stress factors which may be
mutually reinforcing. Stress factors could include drought, browsing by animals,
damage by insects and pathogens, weed competition, nutrient imbalances,
water stress or excess physical damage (e.g. fire, frost and heat). In order to
reduce pest problems in fruit trees farmers should adopt 'Good Agricultural
Practices' (GAPs). GAPs are the outcome of good crop management, including
integrated pest management (IPM). IPM may be defined as an adaptable range
of pest control methods which is cost-effective whilst being environmentally
acceptable and sustainable (Perrins, 1997). IPM uses pest management
techniques such as sound crop management, enhancing natural enemies and
the planting of pest-resistant crops, and uses pesticides judiciously. IPM is
generally targeted against the entire pest complex of an agro-ecosystem rather
than individual pest species (Sileshi and Ajayi, 2002). Generally, the emphasis is
on anticipating and preventing pest problems whenever possible.
The development of a customized IPM programme takes years of research
and involves many participants including farmers, industry, researchers and
extension. However, the domestication of miombo fruit trees only began in the
1980s (Wehmeyer, 1986) and the short time since then has not allowed much
research on pests and pest management. Therefore, most of the IPM tactics