Commodity Treatments: Responses of Nectarines, Peaches, and Plums to Fumigation with Methyl Bromide

Symptoms of methyl bromide injury are slight to severe brown blotchy areas on peaches, slight to severe pitting and browning of nectarines, and localized brown or purple discoloration and pitting of plums. Fumigation did not significantly affect weight loss under our experimental conditions. Injury generally increased with increasing dosage of methyl bromide, and the rate of ripening subsequent to treatment generally was slowed as the dosage increased. The effect on ripening was particularly apparent in plums, which change color as they ripen, but also was apparent in nectarines and peaches, which change firmness with ripening. Less injury occurred at high (26.5°C) than at low (4.5°C) temperature, and less injury occurred in field-run fruit than in fruit fumigated after packinghouse handling. Individual cultivars of nectarines, peaches, and plums differed greatly in their susceptibility to injury from methyl bromide fumigation. Inorganic bromide residues were less than 10 parts per million (p/m) in nectarines and plums and less than 12 p/m in peaches fumigated with dosages up to 48 g/m3 methyl bromide. Organic bromide residues in all three fruits were less than 5.0 p/m after 2 days and less than 0.30 p/m after 7 days in cold storage