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What Works in Hawaii Is Also Good in Texas

A citrus pest that frequently shows up in Texas—the Mexican fruit fly—succumbs to hot-forced-air treatments, according to 3 years of laboratory tests by ARS scientists.

Entomologist Robert L. Mangan and plant physiologist Krista Shellie, who are with Agricultural Research Service at Weslaco, Texas, experimented with grapefruit, Valencia oranges, and tangerines from Texas' Rio Grande Valley. They killed the insects by heating fruit until their centers reached 113^oF and holding that temperature for at least 110 minutes. The heat also protected against spoilage organisms.

Federal officials are considering the findings in proposing heat treatments for Texas citrus.

Though gentler on citrus than methyl bromide fumigation or cold storage, heat treatments take time and could cause costly delays in fruit-handling operations. To sidestep this problem, Mangan and Shellie combined hot-forced-air with another technology—controlled atmosphere. They heated fruit with air containing only 1 percent oxygen, compared to the 21 percent in normal air.

"Low oxygen," explains Shellie, "puts fruit in a slow-ripening, sleeping state while it helps kill fruit flies."

Pairing the techniques, Mangan and Shellie trimmed treatment time for grapefruit from 5 hours to 3-1/2.

In 1996, growers in the Rio Grande Valley produced about 332 million pounds of fresh-market citrus with a value of $57 million. The Weslaco scientists are seeking corporate partners to commercialize their citrus treatments.—By Dawn Lyons-Johnson,

Agricultural Research Service Information Staff, 1815 North University Street, Peoria, IL 61604, phone (309) 681-6597.

Robert L. Mangan and Krista Shellie are in the USDA-ARS Subtropical Agricultural Research Center, 2301 S. International Blvd., Weslaco, TX 78596; phone (956) 565-2647, fax (956) 565-6652

"What Works in Hawaii Is Also Good in Texas" was published in the January 1998 issue of Agricultural Research magazine. Click here to see this issue's table of contents.