Field evaluation of fungicides to control postharvest rots of avocados in New Zealand

Abstract

Copper is the only fungicide currently registered for use on avocado orchards for controlling fruit rots that are expressed postharvest. Two additional fungicides that performed well in previous tests were evaluated as spray applications to 12 orchards, four in each of the three major avocado growing regions of New Zealand (North of Kaitaia, Whangarei and Bay of Plenty). Pyraclostrobin/boscalid and fluazinam were at least as effective as copper in controlling avocado rots, and are suitable alternatives to copper. Fluazinam should be applied in winter because in combination with the additive di-1-p-methene it damaged leaves during the spring flush. Pyraclostrobin/ boscalid would need to be used judiciously to prevent build up of resistance in fungal populations. Copper could still be applied, but in combination with these fungicides, thus reducing the numbers of applications of copper and therefore the risk of copper accumulation in soil.