CONTROL BY FUMIGANTS OF WINTER EGGS OF EUROPEAN RED MITE, PANONYCHUS ULMI (ACARINA: TETRANYCHIDAE), ON HARVESTED APPLES

Abstract

AbstractSeven fumigants, used alone or in combination, were tested in the laboratory for toxicity to winter eggs of the European red mite, Panonychus ulmi (Koch), on harvested apples cv. Red Delicious. Fumigation with ethylene dibromide (EDB) 6 mg/l. for 4 h at 25°C, and CO2 90% for 72 h at 18°C or for 48 h at 25°C killed 100% of the eggs; CO2 75% for 60 to 168 h killed over 98% of the eggs. No injury or off-flavour of fruit resulted from the treatments though the extended period of storage, ca. 200 days, to break diapause in the eggs did reduce the fruit quality in the usual way. Post treatment storage under controlled atmosphere (CA) conditions did not increase the percentage of eggs killed with 75% CO2. Mixing CO2 with EDB, ethylene oxide, or dichlorvos did not increase egg mortality. Ethylene oxide, dichlorvos, methyl bromide (MBr), and HCN were each ineffective and combinations of MBr + EDB, and MBr + acrylonitrile were also ineffective. Carbon dioxide is a safe, effective fumigant for controlling P. ulmi winter eggs and other pests on harvested apples.