Combination high-temperature controlled atmosphere and cold storage as a quarantine treatment against Ctenopseustis obliquana and Epiphyase postvittana on 'Royal Gala' apples
1999
Whiting, D.C. | Jamieson, L.E. | Spooner, K.J. | Lay-Yee, M.
Third and fifth instar brownheaded leafroller, Ctenopseustis obliquana (Walker), and lightbrown apple moth, Epiphyas postvittana (Walker), infested on apples were exposed to a high-temperature controlled atmosphere (HTCA), 2% O(2), 5% CO(2) at 40 degrees C, and hot air (HA) at 40 degrees C, and mortality responses determined. Mortality responses of third fifth instar C. obliquana were similar regardless of treatment type (HTCA or HA). Mean lethal time (LT) estimates for C. obliquana larvae exposed to HTCA were less than those for larvae exposed to HA. No C. obliquana larvae survived 6 h exposure to either HTCA or HA. E. postvittana was more tolerant of both HTCA and HA treatments than was C. obliquana, and fifth instars were the more tolerant life stage. HTCA was significantly more effective against this species than was HA. Third and fifth instar E. postvittana were treated with two HTCA exposures (6 and 8 h) lethal to C. obliquana, and then exposed to cold storage (CS) at 0 degrees C for 7 weeks. The combination of HTCA with CS enhanced treatment efficacy against both life stages. Although a few individuals of both life stages survived exposure to 6 h HTCA + CS, exposure to 8 h HTCA + CS resulted in complete kill. 'Royal Gala' apples (Malus domestica Bork.) subjected to HTCA or HA for 6 or 8 h, were either cooled by immersion in water at ambient temperature, or not cooled in water, and then exposed to CS for 7 weeks, before being transferred to 20 degrees C for 7 days and assessed for quality. No significant damage was observed in control, HTCA- or HA-treated apples not cooled in water, though a very low incidence of cavitation and breakdown was observed in water-cooled apples.
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