Blueberry fruit quality and control of blueberry maggot (Rhagoletis mendax Curran) larvae after fumigation with sulfur dioxide

Abstract

Postharvest fumigation of fruits and vegetables is an important tool for managing pests and diseases that can cause devastating loss if not properly controlled. Sulfur dioxide (SO2) may have promise as replacement for methyl bromide, which is expected to be phased out. However, SO2 is known to cause injury to small fruit such as table grapes (Vitis vinifera L.). We extend previous research on SO2 fumigation by focusing on an economically important fruit pest genus and through quantitative and qualitative measurements of highbush blueberry (Vaccinium corymbosum L.) fruit bleaching. This study assesses fruit damage due to SO2 fumigation at concentrations ranging 0–2.2 % (v/v) as well as the effectiveness of SO2 as a fumigant prior to cold storage for control of blueberry maggot, Rhagoletis mendax Curran. We show that fruit quality traits such as firmness, total soluble solid content, and titratable acidity are largely unaffected except at the highest SO2 concentration (2.2 %). SO2 caused bleaching and discoloration of blueberry fruit in a dose-dependent manner. Damage was also cultivar-dependent, with cv ‘Bluecrop’, and ‘Jersey’ more susceptible than ‘Draper’, ‘Elliott’, and ‘Liberty’. We show that R. mendax can be effectively controlled using a short-term (2 h), high concentration (22,000 μL L−1) SO2 fumigation followed by >14 d of cold storage at 0.5 °C. However, this treatment for control of R. mendax would likely result in damage, affecting fruit marketability.