Irradiation at doses less than 1 kGy is an effective phytosanitary measure with minimal adverse effects on the quality of most fresh produce. There are internationally recognized guidelines for the use of irradiation as a phytosanitary measure and for the conduct of trade in irradiated fresh produce. A generic dose of 150 Gy is internationally recognized as sufficient to ensure the sterility or inability to reproduce of all fruit flies of the family Tephritidae on all hosts. Irradiation offers a cost-competitive, non-chemical alternative to several other phytosanitary measures and can be used to decrease dependence on fumigation with methyl bromide. In the last decade trade in irradiated fresh produce has increased steadily with over 20,000 tonnes traded in 2015. The US and New Zealand are the main importing countries and main exporting countries are Mexico, Australia, Vietnam, Thailand and India. Many different irradiated fruits are traded with guava, mango, sweet potato and dragon fruit pre-dominant. Several issues present barriers to the wider adoption of phytosanitary irradiation including the 1 kGy limit, labeling requirement, the limited number of country approvals, and restrictions on the use of modified atmosphere. The development of small-scale cabinet style x-ray machines could provide farmers and packinghouses with in-house treatment capability, and accelerate adoption of the technology.

• Peter A. Follett(USDA ARS, Hilo, Hawaii, USA)