Avocados infested with late stage eggs were subjected to a warming temperature spike (ca. 4.2°C for 1 h)
at 6–9 days into the treatment and subsequently allowed to resume the treatment until conclusion (12 days at
B1.1°C, 14 days at B1.67°C or 16 days at B2.2°C). Insertion of a ca. 4.2°C temperature spike into the treatment
at 6–9 days had no effect on the efficacy of the quarantine cold treatment when fruit were allowed to resume the
treatment to completion. Infested fruit which did not receive a ‘heat shock’ treatment (recommended to improve fruit
quality) and subjected to cold treatment for 6–16 days at either B1.1, B1.67 or B2.2°C (fruit center temperature)
had no survivors in the fruit by the 9th day of cold treatment. Infested avocados subjected to a ‘heat shock’ treatment
for 10–12 h at 38°C prior to cold treatment (as above) had no survivors in the fruit by the 8th day of cold treatment.
Results of this study indicate that a transient (warm) temperature spike of ca. 4.2°C of the type experienced during
an in-transit cold treatment of Hawaii grown ‘Sharwil’ avocados will not compromise the efficacy of the treatment.
This study also reconfirmed that the T107 (a) cold treatment (as stated in the APHIS treatment manual) is efficacious
against Mediterranean fruit fly eggs in ‘Sharwil’ avocados, and that use of a ‘heat shock’ to prevent chilling injury
during the cold treatment did not extend survivorship of fruit fly eggs. Studies on the effects of prolonged (18–28 day)
cold storage on fruit quality indicated that avocados can be stored at quarantine cold temperature (pulp, 1.1–2.2°C)
for up to 24 days without significant loss of external and internal quality compared to fruit quality at 12–16 days
storage. Also, shelf life, Gray Flesh discoloration (of internal tissue), and disease were not affected by the prolonged
storage duration. © Published by Elsevier Science B.V.