An assessment of alternative postharvest technologies for the disinfestation of fresh Cape Flora cut flowers for export from South Africa

[摘要] ENGLISH ABSTRACT: A successful industry has developed around the export of fresh Proteaceae cutflowers from South Africa. Phytosanitary insects are a barrier to export, as SouthAfrican Proteaceae associates with a considerable entomofauna. The developmentof alternative postharvest disinfestation technologies could reduce theseinterceptions and promote market access. Surveys on export material wereconducted to determine which pests are most problematic when exportingProteaceae. A total of 82 interceptions were made, comprising of eight insect ordersand 26 insect families. Although many interceptions were as a result of solitaryindividuals, multiple interceptions consisted of many individuals of western flowerthrips (Frankliniella occidentalis) and protea itch mite (Procotolaelaps vandenbergii).These pests were selected as the key pests on which to focus for disinfestationusing alternative postharvest technologies not yet utilised for Proteaceae. ControlledAtmosphere and Temperature Treatment Systems (CATTS) technology wasassessed as a potential disinfestation tool for fresh Proteaceae cut flowers. Thetested commodities were Leucospermum ‗Veldfire', Protea magnifica ‗Barbi',Leucadendron ‗Safari sunset' and ‗Jade pearl', and Geraldton wax ‗Ofir' (Myrtaceae).CATTS treatments consisted of temperature ramps of 35°C/hour and 30°C/hour from23°C to 40°C, with a 15 min soak at 40°C, and 35°C/hour and 30°C/hour from 23°Cto 50°C, with a 15 min soak at 50°C, under modified atmospheres of 1% O2, 15%CO2 in N2. Treated stems were subjected to vase life studies after treatment, orfollowing air- and sea-freight storage simulations at 2°C for 3 or 21 days respectively.Leucospermum ‗Veldfire' did not withstand treatments, as style wilting reducedoverall quality. Protea magnifica ‗Barbi' withstood some treatments, maintainingcomparable quality to control stems in the vase immediately after treatment. BothLeucadendron commodities withstood treatments well, and maintained marketablequality following treatment, air- and sea-freight simulations. Geraldton wax ‗Ofir'maintained quality in vase immediately after and following air-freight simulations.CATTS treatments of 35°C/hour and 30°C/hour to 40°C in 1% O2, 15% CO2 in N2resulted in 100% mortality in western flower thrips and protea itch mites within 24hours of treatment. Postharvest fumigation treatment with ethyl formate (EF) wasalso assessed as a potential disinfestation technology. Concentrations ranged from18.53g/m3 to 151.47g/m3 EF, and durations ranging from 30 mins to 3 hours for thesame cut flower commodities listed above for CATTS treatments. Further trials onGeraldton wax ‗Ofir' consisted of 10g/m3 and 20g/m3 for 1 and 2 hours. Alltreatments resulted in reduction in overall quality of treated fresh goods. EFfumigations of 18.53g/m3 for 1 and 2 hours achieved 100% mortality within 24 hoursof treatment in western flower thrips and protea itch mites, but excessive postfumigation damage renders EF unsuitable. The information generated from thisstudy has highlighted the most problematic phytosanitary pests in exportconsignments of fresh Proteaceae from South Africa. It has also highlighted apotential postharvest technology for integration into current disinfestation strategies,and refuted another. This information can assist in the development of postharvestdisinfestation strategies, ultimately reducing the phytosanitary pressures andpromoting the export of fresh Proteaceae cut flowers from South Africa.

[发布机构] Stellenbosch University