November 15, 2004

Methyl Bromide Option Advances

By Gabrielle Kirkland, Staff Writer

REEDLEY, Calif. – Stone fruit growers could soon have their hands on a bug-killing treatment that would replace Methyl bromide in post-harvest use.

The good news doesn’t stop there:  The process is organic-friendly and extends the fruit’s shelf life.  Researchers have found that this treatment conditions fruit in a manner similar to the preconditioning process, according to the California Tree Fruit Agreement .

The procedure blossomed from a quest to use heat and an oxygen-deprived environment to kill insects while maintaining fruit quality.

“I would have never guessed how well this has done,” said Lisa Neven, the Yakima, Wash.-based research entomologist with the U.S. Department of Agriculture who heads the four-year-old treatment project.  “It’s amazing.”

HEAT, ELIMINATE OXYGEN:  The treatment takes place in a chamber that allows the temperature and environment to be manipulated.  A combination of heat a controlled atmosphere is used to eliminate pests.

“Basically it is the physiology of the fruit against the physiology of the insects,” Neven said.

Neven has tested the process, which is funded by the CTFA, on pears, apples, peaches, nectarines and apricots.

The treatment is expected to be used instead of fumigation, which is required by several importing countries.

“We are hoping the method is accepted as a protocol down the road.  It is better for the fruit and consumers,” said Gary Van Sickle, CTFA’s director of research and regulatory compliance.

The idea is simply to create a controlled atmosphere by taking away the oxygen, which speeds insect metabolism.  Van Sickle said the combination of heat and oxygen deprivation kills the pests.

“It is a very realistic alternative,” Van Sickle said.  “Creating a modified atmosphere is nothing new.”

It takes two to three hours.

“The magic temperature seems to be 115 degrees,” Van Sickle said.

Stone fruit shippers are eager to have an alternative to methyl bromide fumigation, Van Sickle said.  As the chemical is being phased out in the U.S., its cost is rising.

JAPAN FIRST:  CTFA plans to focus on research that will apply to Japan and its quarantine pest the codling moth in the next year.  Initial research has shown the process is effective on Japan’s quarantine pest.

The agreement then plans to propose the method to Japan as a potential quarantine treatment, Van Sickle said.

“Japan is very forward thinking and health conscious,” Van Sickle said.  “I think it will appeal to them.”

He expects approval of the process will take at least three years.

The first part of the research focused simply on whether the fruit could withstand the high temperature and retain its quality, Van Sickle said.

Some varieties reacted to the treatment by softening at a slower pace than fruit that wasn’t treated.

“Stone fruit is very delicate, and I thought for sure there would be a problem,” Neven said.

Another common finding was that the treatment stimulated pre-conditioning.  Pre-conditioning usually takes 48 hours, but the research treatment only takes a small fraction of that.

QUALITY RETAINED:  Even one of the most delicate commodities retains its quality.  Apricots have been found to handle the process nicely, Neven said.

Van Sickle said the only drawback to the new treatment is getting a commercial shipper to step in and create a commercial-size chamber.

Estimates reveal that the controlled atmosphere and temperature system is less expensive than using methyl bromide.

CTFA has had some interest from a few shippers in pursuing the program, but most are waiting for an export market to deem the process acceptable.

“They are waiting for a protocol to happen before developing the machinery,” he said.

Since the treatment is for post-harvest use, commodities that use methyl bromide pre-harvest, such as strawberries, would derive no benefit from it.