A HIGH-TEMPERATURE LOW-OXYGEN PULSE IMPROVES COLD-STORAGE DISINFESTATION

Short periods of elevated temperature under controlled atmospheres (Ck ) effectively control insect pests. Cold treatment is also an effectiv e non-chemical disinfestation process. If synergistic effects can be f ound by combining treatments, these may provide opportunities for cost reduction. Tests were performed to evaluate the tolerance of Packham' s Triumph pears (Pyrus communis L.) to a range of temperatures (30-40 degrees C) combined with low oxygen (O-2 <1 kPa). Treatment duration w as 16-48 h and was followed by 1 month storage at 0 degrees C under ai r. When held at 30 degrees C, pears withstood up to 30 h of hypoxia. A fter cold storage, pears ripened slightly faster than controls but wer e undamaged. A temperature of 35 degrees C induced slight skin brownin g, and 40 degrees C resulted in substantial skin blackening. Some trea tments were also tested on survival of lightbrown apple moth (LBAM), E piphyas postvittana (Walker). All developmental stages were subjected to either 16 h at 30 degrees C, or 16 h under hypoxia, or 1 month at 0 degrees C, or a combination of the three treatments. With all treatme nts combined, all eggs, larvae and adults were killed. Only 4% of the pupae produced adults and combined treatments led to an increase in pu pa mortality of 38%. A combined treatment (tolerated by pears) consist ing of 30 h at 30 degrees C under low O-2 plus 1 month cold storage un der air, killed 100% of LBAM pupae, and 100% of 5th instar larvae of b oth codling moth, CI clin pomonella (L.), and oriental fruit moth, Gra pholita molesta (Busck). Implementation of such treatments would not r equire substantial investments for fruit industries equipped with CA s torage facilities. (C) 1997 Elsevier Science B.V.