Using radio waves, rather than chemicals, may be the best, post-harvest process for debugging dried fruits and nuts, according to a team of researchers led by a Washington State University professor.


Radio waves that generate heat to kill the insects hiding in nuts and dried fruits are a good alternative to methyl bromide, the most common form of post-harvest pest control, says the professor, Juming Tang, a scientist in WSUs Agricultural Research Center.


Use of methyl bromide, a fumigant, has been linked to ozone depletion and was banned in developed countries, including the U.S., in 2005, although temporary exemptions have been granted in some uses. Developing countries have until 2015 to end use of the chemical, WSU says. The school says that finding an alternative to the fumigants use is among the U.S. Department of Agricultures highest priorities.


An intensive five-year laboratory study and three-month pilot trial in a commercial walnut-processing plant have shown convincingly that radio frequency treatments can effectively control post-harvest insect pests in in-shell walnuts without reducing product quality, WSU says.


The research on walnuts is only part of the teams research, it says. Engineers, entomologists, and plant physiologists from Washington, California, Texas, Hawaii, Israel, and the United Kingdom are exploring radio frequency energy as a method to control insect pests in a variety of products, including fruit trees, nuts, and legumes, the school says.


The same technology also may be extended to other commodities that require post-harvest pest control when they are shipped to other markets, such as lentils to India, Tang says.


Tang led a team of scientists that included representatives from WSU, the University of California at Davis, and the USDA. The results of their research were published recently in a scientific journal.