Response of ‘Hayward’ kiwifruit to high-temperature controlled atmosphere treatments for control of two-spotted spider mite (Tetranychus urticae)

Abstract

Abstract The response of ‘Hayward’ kiwifruit [ Actinidia deliciosa (A. Chev.) C.-F. Liang et A.R. Ferguson var. deliciosa ] to high-temperature controlled atmosphere (CA) treatments for control of two-spotted spider mite ( Tetranychus urticae Koch) was investigated. Mean LT 99 values for two-spotted spider mite inoculated onto kiwifruit and exposed to 0.4% O 2 , 20% CO 2 (CA) at 40 °C, were 5.4 ± 0.1 h and 8.1 ± 0.3 h for the non-diapausing and diapausing forms, respectively. ‘Hayward’ kiwifruit were subjected to 40 °C for 7 or 10 h in CA (treatments identified as giving 100% mortality for non-diapausing and diapausing two-spotted spider mites, respectively) or in air. Following treatment, fruit were cooled in ambient water or ambient air, stored at 0 °C in air for eight weeks, then held at 20 °C overnight and assessed for quality. Relative to non-treated controls, no significant damage was observed with fruit subjected to 40 °C air treatments. With CA treatments, no significant damage was observed with fruit treated for 7 h followed by hydrocooling. The 7 h CA treatment without hydrocooling and 10 h CA treatments with hydrocooling showed only slight damage, while the 10 h CA without hydrocooling had moderate fruit damage. The main disorders found were vascular browning and rots. Following storage, flesh firmness of fruit treated at 40 °C in air for 10 h or in CA for 7 and 10 h, with and without hydrocooling, was lower than that of non-treated controls.