Alternative to Methyl Bromide Developed

December 3, 1999

USDA says navel oranges could benefit from a new, chemical-free insect quarantine treatment that can be used as an alternative to fumigating citrus with methyl bromide. The method involves using hot air to keep the center of the fruit at a temperature capable of exterminating infesting fruit flies.

Agricultural Research Service scientists at the newly named Kika de la Garza Subtropical Agricultural Research Center developed the alternative treatment. Last year it was approved for use on grapefruit, tangerines and thin-skinned Valencia oranges. This year, navel oranges were added to the list.

A forced hot air chamber owned by a cooperative of growers in Mexico is being used to treat up to eight tons of navel oranges at a time. A. U.S. produce grower and distributor, Rio Queen Citrus, located in the Rio Grande Valley of Texas, is importing heat-treated oranges and tangerines from Mexico for domestic sales. U.S. distributors exported about 1.18 million tons of citrus in fiscal year 1998 with most of the fruit grown in areas where treatments are required to ensure the fruit is free of fruit flies.

Although citrus treatments with methyl bromide remain exempt from an international phase-out of the fumigant, the citrus industry anticipates the fumigant's cost will increase as less is manufactured. Also, unlike methyl bromide, which may cause the fruit skin to develop a bronze color, the hot forced air treatment causes no impairment to fruit quality.