INSECTICIDE PRACTICE FOR APHID CONTROL IN POTATOES

Insecticide use for aphid control in potatoes by mainly Canterbury growers was assessed by a New Zealand-wide postal survey in 2001-02 and by examination of spray diaries from Canterbury (11 seed and 13 process growers) in 2003-04. Only 22 % (16 growers) of seed and 4% (12 growers) of fresh potato growers responded to the postal survey, with Canterbury growers making up 93 % of the respondents. Overall results indicate that most seed crops received a single seed/tuber treatment as well as approximately five foliar applications. Most process crops (2003-04 only) were seed/tuber treated with 0 or 1 foliar applications. For fresh crops (2001-02 only), 59 % were seed/tuber treated and 14 % had 2 or 6 foliar applications. Seed/tuber treatments were mostly imidacloprid but also phorate. Foliar applications included organophosphate, carbamate, synthetic pyrethroid and pyridine-azomethine insecticides. Insecticide use patterns are discussed in relation to the effectiveness of aphid/virus control and the risk of insecticide resistance