SPRAYS ON NEW ZEALAND KIWIFRUIT - USE PATTERNS AND OUTCOMES

The ARGOS project is examining the effect of management practices on sustainability in several agricultural sectors in New Zealand. In kiwifruit, ARGOS has established 12 clusters of participating orchards where each cluster has an Organic 'Hayward' orchard, a KiwiGreen 'Hayward' orchard and a KiwiGreen ‘Hort16A’ orchard in close proximity. The 2004–2005 spray diaries for all growers were analysed, and small insects and mites present on leaves from each orchard in 11 clusters were surveyed in late summer 2005. Spray use varied both quantitatively and qualitatively with management system. The average total use of all pesticides, including plant management compounds, for Organic, KiwiGreen 'Hayward', and KiwiGreen 'Hort16A' orchards was 5.30, 7.62 and 9.33 applications per orchard respectively (p=0.001). With insecticides, the number of scale sprays used did not vary with management system, while more leafroller sprays were used in Organics than in either KiwiGreen cohort (p<0.05). Most leaves examined had insects or mites present, with mites the more common. More leaves were infested by insects in Organic orchards than in either KiwiGreen system (67% versus 39% and 47%, p<0.02), but mite infestations overall did not differ among management systems. Psoccids, or booklice, were the most common insect found, while armoured scales were the commonest pest. Significantly more scales occurred in Organic orchards (15.2 per 50 leaves) than in either KiwiGreen system (3.5 and 4.2 per 50 leaves, p=0.001). A range of mites was present, some abundantly. There were fewer predator mites on KiwiGreen ‘Hayward’ leaves than in either other cohort (p<0.02). Tydeid mites, detrital feeders, were equally abundant on either type of KiwiGreen orchard but were almost entirely absent from Organic orchards (p<0.001). The reverse applied for Czenspinksia mites, another detrital feeder, which were more abundant in Organic orchards than either KiwiGreen system (p=0.001). Production practices clearly influenced the arthropod fauna present. The low incidence of tydeid mites in Organic orchards probably reflects the use of oil for scale control in this system.