Effects of phosphine (ECO2FUME®) on ‘Hass’ avocado fruit quality and target pest mortality

Abstract

ABSTRACT Phosphine (PH3) is a methyl bromide alternative with the potential to control surface pests of New Zealand avocados as a pre-export disinfestation treatment. ‘Hass’ avocado fruit were treated with PH3 (as ECO2FUME® (2% PH3, 98% CO2 (w/w); Cytec Industries Inc.)). at 500, 750 and 1,500 ppm for 24, 48 and 72 h at 5–6 °C, along with vials containing mould mites (Tyrophagus communis) and greenhouse thrips (Heliothrips haemorrhoidalis). Fruit were then stored at 5 °C for three weeks, external quality assessed, and internal fruit quality assessed after ripening at 20 °C. PH3 treatments had no impact on external fruit quality, nor on skin colouration, and only minor increase in softening compared to control at 24 h, but not 48 or 72 h. Complete (100%) mortality was achieved for thrips at all PH3 concentrations for 48 h. However, only ∼50% mould mite mortality was achieved at the highest PH3 concentration of 1,500 ppm for 72 h; although this treatment did provide a significant reduction in rots and internal disorders. This initial study demonstrates that longer-duration treatments and higher PH3 concentrations improves fruit quality compared with controls, mainly by reducing rots. These treatments fully controlled thrips but provided only partial control of mould mites.