Novel technologies for the postharvest treatment of Cape Flora to control phytosanitary insect pests

The South African ornamental Cape Flora (fynbos) industry differs fundamentally from other global production regions in that the flowers are grown within their natural distribution range. As a result, they affiliate with their natural insect- and invertebrate counterparts which pose a constant challenge to both producers and exporters alike, in that they cause direct damage as pests or are a hindrance as phytosanitary barriers. The objective of this study was to assess the effect of two new postharvest techniques, used for the control of phytosanitary pests, on flower quality, with the aim of implementation in the South African Cape Flora ornamental industry. Controlled atmosphere temperature treatment system (CATTS) technology and ethyl formate fumigation treatments were applied to Protea, Leucospermum and Leucadendron commodities, after which the post-treatment quality and vase life was assessed. CATTS treatments initially included temperature ramps of 12 and 24°C h-1 up to a 45°C chamber temperature, with an atmosphere of 1% O2, 15% CO2 in N2. These treatments resulted in significant and unsatisfactory flower damage. Ramp rates were adjusted to 30 and 35°C h-1 to shorten the total treatment times. Ethyl formate fumigation trials were conducted using a central composite design (CCD) analysis model, with concentrations ranging from 18.53-152g m-3, with durations ranging from 30 min to 3 h. Intense, yet brief CATTS treatments yielded the most promising results regarding post-treatment flower quality in both Leucadendron and Protea, however the combination of the rapid temperature ramps and controlled atmospheres resulted in significant style wilting in Leucospermum. Ethyl formate fumigation was most successful at lower concentrations for longer durations for all three genera, however the flower quality was still not satisfactory. Further research should include the optimization of previous treatments and inclusion of more Cape Flora commodities.