Field evaluation of insulation wraps for frost protection of kiwifruit trunks

Abstract The temperatures on plant trunks inside insulation materials used as trunk wraps for kiwifruit (Actinidia deliciosa) were recorded during winter field conditions. Insulation wraps had an influence on the daily maximum temperatures of wrapped trunks, the lag period and the night minimum temperatures. Insulation wraps which, when compared to uninsulated trunks, reduced the daily maximum temperature, provided long lag intervals and increased night minimum temperatures were expected to be the best insulators. Polyurethane foam wraps, hay in a black polythene sleeve, and sawdust banks provided the best insulation. However natural wraps have disadvantages which reduce their suitability as trunk insulators for kiwifruit.