Alternative yet to be approved
An alternative methyl bromide treatment appears to suppress decay and delay fruit ripening.
Industry adoption of a controlled atmosphere and temperature treatment to replace postharvest methyl bromide fumigation faces commercialization hurdles as well as approval barriers by foreign countries. But the treatment could be a tool to improve the fruit storage quality of organic apples.
The science behind any new quarantine technology is only part of the equation. Both the U.S. Department of Agriculture's Animal and Plant Health Inspection Service and the foreign country, like Japan, must approve new treatment and protocols, a process that can be very lengthy. Moreover, the technology must also be commercialized, economically viable, and accepted by industry.
The controlled atmosphere and temperature treatment system known as CATTS, which uses high temperatures, low oxygen, and high carbon dioxide levels to kill pests like codling moth, Oriental fruit moth, and Western cherry fruit fly, is nearing the end of its scientific phase. USDA researchers have studied the treatment system for more than a decade and are now working to expand its efficacy from killing pests in bins to eliminating them in packed boxes of fruit.
But it could have a way to go before commercial --adoption.
Manager of the Washington Tree Fruit Research Commission Jim McFerson said that while CATTS holds potential, methyl bromide postharvest fumigation has been used by the industry for years, is a proven and effective quarantine treatment, and considered to be a cost-efficient practice. The industry is comfortable with methyl bromide fumigation and knows how it works and what to expect.
"We have a program in place that commercially meets all of our needs," he said, referring to methyl bromide postharvest fumigation.
McFerson added that the Washington State tree fruit industry currently doesn't have enough commercial experience with CATTS.
"There's a world of difference between research and commercial reality," he stressed.
One of the surprising spinoffs of CATTS is improvement in fruit quality of both apples and stone fruit. The treatment seems to suppress decay and delay ripening for fruit treated at harvest.
Harold Ostenson, manager of organics for Stemilt Growers, Inc., of Wenatchee, Washington, sees several potential uses of the controlled atmosphere and --temperature system on organic apples.
Research shows that CATTS has potential to reduce scald in organic apples and maintain fruit firmness and pressure better after treatment. Scald is an issue for organic apples because there are no scald treatments available. Additionally, organic apples cannot use MCP (1-methylcyclopropene) to help preserve firmness during storage.
Ostenson said the treatment could also be used to --predict scald.
Granny Smith apples that had a propensity to scald showed scald within 24 hours of the controlled atmosphere and heat treatment. Ostenson believes that CATTS could be an important scald predictor and used as a marketing tool for storage operators to know which lots of fruit to pack first.
He points to industry reports that forecast Washington's organic apple production to double by 2009 to around 14,000 acres compared to 2006 levels estimated at around 7,000 acres.
Chain stores want to supply organic fruit year round, he said, but added that in the past, industry frequently has been unable to provide organic apples year round due to storage issues and supply.
"If we're going to go from a niche market to the big time, we need to solve these storage problems," Ostenson said, adding that CATTS could be a tool that actually improves pressure and helps warehouse operators make smarter decisions.
USDA's Dr. David Obenland in Parlier, California, has been testing the treatment on stone fruit. He, too, has found fruit quality benefits from the treatment. In his tests, he found that CATTS inhibits some fungi and slows down ripening.
"It's quite spectacular on brown rot," he said. "It's especially good on brown rot in apricots, but it doesn't inhibit all pathogens," he said.
Another benefit he measured was that it inhibits ripening. "In some instances, for fruit that must travel long distances, that could be a good thing," Obenland said.