PRE-HARVEST RIND BREAKDOWN IN NEW ZEALAND AND A COMPARISON WITH SIMILAR PROBLEMS REPORTED IN OTHER COUNTRIES

Pre-harvest rind breakdown is an occasional problem on mandarins, tangelos and oranges in New Zealand. It usually affects fruit at or soon after colour break and is often referred to as ‘on-tree’ oleocellosis. It is normally associated with extreme wet, cold weather events and with gusty winds. In the Gisborne region in July 2011, some exposed, wet orchards of mainly navel oranges, were adversely affected with up to 50% fruit marking and 60% fruit drop in the worst cases. This prompted a more detailed examination of the condition, a review of the local meteorological and other factors that may have caused the rind breakdown, and some recommendations for growers. These are described, together with a brief comparison of similar pre-harvest rind defects and their management obtained from international literature and correspondence. The condition most closely resembles pitting of ‘Pineapple’ orange described in Florida, pitting of ‘Fortune’ mandarin reported in Spain, rind staining of navels and tangelos in Morocco, mandarin rind disorder in California, rind spotting of Clementines in Greece and ‘pateta de rata’ or ‘colapso de la corteza’ on ‘Navelates’ in Spain and Chile.