Opinion: biological fruit pest controls assist South African exports
By Hortgro executive director Anton Rabe
The area-wide medfly (Mediterranean fruit fly) mitigation program in the South African deciduous fruit industry started in 1998 with a pilot project in the Hex River Valley with the release of sterile male medflies. Currently it has been implemented in seven of the production regions covering more or less 33,000 hectares (ha). Plans are underway to roll the program out to six more regions over the next few years covering around 54,200 ha (70%) of deciduous fruit production by 2015-16.
The program is jointly funded by producers and the national Department of Agriculture, Forestry and Fisheries (DAFF), whilst the International Atomic Energy Association (IAEA) has continued to support the industry since the inception of the program with expertise and research visits.
Biological methods have export appeal
South Africa’s fruit growers are increasingly targeting new export markets to ensure the future growth and profitability of their industry. In addition, access to current export markets needs to be maintained. The substantial export base currently in place was achieved with a range of pest control methods including the use of chemicals.
It is generally accepted in the fruit industry that the Sterile Insect Technique (SIT) as part of an area-wide integrated approach towards pest control, could potentially become the backbone of a set of biological pest management techniques to maintain and grow the exports of South African fruit growers. SIT allows for the control of a range of phytosanitary pests (South Africa also has codling moth and false codling moth SIT programmes), as well as the overall reduction of the use of synthetic pesticides, with its concomitant increase in insect resistance as well as residues, increasingly rejected by consumers in export markets.
Low risk approach
As the program is rolled out, producers of other crops within the target areas are integrated into the program to ensure effective mitigation takes place throughout such regions. Given the topography of most of the production regions and national traffic flow through the main production regions, an approach of low prevalence-low risk is followed rather than trying to obtain pest free status. This ideal is, however, possible in some sub-regions that should attain this status in due course.
The program is managed and coordinated on a regional level by the national industry body representing deciduous fruit producers, with strong producer and technical support to ensure all the key success elements addressing the unique conditions in sub-regions, are focused on. These elements include monitoring, host plant management, sanitation, ground and aerial baiting and an intensive information and an awareness campaign to ensure that the stakeholders in the broader community play their part in ensuring success. School educational programs are conducted in some areas to ensure communities and future consumers are informed about the rationale and basics behind the program.
Strike when the time is right
The release of steriles only commences once low fruit fly counts have been achieved. Production of steriles is currently at 15 million per week and takes place in a modern production facility in Stellenbosch on the premises of the Agricultural Research Council (ARC), which remains a partner in the venture. The production facility can be expanded with adding further production equipment to produce about 50 million steriles per week, which will serve the needs of the deciduous fruit industry once the program is fully rolled out.
A focused winter strategy is a vital element of the medfly program. M3 “attract and kill” traps are used extensively in gardens and around farm and town dwellings during the winter months. This ensures that medfly counts are reduced where they stay during the winter months prior to them migrating back to orchards during spring and summer. This strategy has caused a major decline in orchard counts during the past summer, which augers well for a further implosion of populations in the coming 2012-13 fruit season.
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