Fungicide use in processing tomatoes in New Zealand

Abstract

Fungicide use in processing (field) tomatoes from 1995 to 2009 on the East Coast of the North Island of New Zealand has been documented using data extracted from growers' annual spray diary records. During this period, 26 different fungicides—some of which are also used as bactericides—were used by growers to control a range of plant diseases. The number of fungicide applications to each crop ranged from 10 to 28, with fewer applications in very dry seasons. Inorganic copper (mainly copper hydroxide), applied to control both bacterial and fungal diseases, was the most commonly used material, followed by chemicals in the dithiocarbamate, chloro-nitrile and pyridinamine groups. These four multi-site ‘protective’ fungicide groups accounted for 90% of all disease-control products used during the 15-year period. Site-specific fungicides (e.g. benzimidazoles, phenylamides, dicarboximides, dimethomorph and strobilurins) were used much less frequently. The exclusive use of fungicides at risk from fungicide resistance development (most commonly the site-specific fungicides) was generally avoided and therefore overall risk of the development of fungicide resistance in processing tomatoes in Hawke's Bay is believed to be low. This study demonstrated that the number of fungicide applications per crop has increased about two-fold since 1995 while, during the same period, insecticide applications decreased.