V Hattingh 1, B Stein 2 & GJ Hallman 3 1 CRI 2 EEAOC 3 IAEA Opportunities for higher temperature treatments

Project origin and objective Identified as a project at the Expert Consultation on Cold Treatments (ECCT) Argentina 12/2013 Reasons: Some fruit types “highly” sensitive to chilling injury Current cold treatments precluded from use in export of such fruit types, eg. satsuma mandarins & lemons

Approach taken Identified highest temperature conditions in such treatments Sought indicators that higher temp treatments may be feasible Suggestions for way forward Considered prospects for the development of such treatments Considered existing cold treatment protocols & reports on development trials

Higher temp treatments developed Range of temperature – time combinations in cold treatments developed (various commodities & pests) CategoryOriginDestinationTemp °CDuration d Ultra lowVariousUSA< LowVariousUSA<-0.322, 24 VariousUSA<011, 13 South AfricaJapan<012, 14 MidVariousUSA<1.112, 14, 15, 20 VariousUSA<1.6716, 17, 18, 22 VariousUSA<2.218, 22 HigherVariousUSA<3 14, 15, 16, 18, 20 ArgentinaJapan3.223, 24

Higher temp treatments developed OriginDestinationTemp °CDuration d AustraliaIndonesia318 AustraliaJapan3.120 AustraliaJapan320 ArgentinaJapan3.223, 24 AustraliaTaiwan320 AustraliaThailand320 AustraliaUSA313, 16 Higher temperature treatments (>2.5 °C) for Fruit Fly disinfestation in citrus fruits

Reduce variables to identify trends Focus on Treatments for individual Fruit Fly species C. capitata - orange USDA T107-a & South Africa to Japan timetemp

Reduce variables to identify trends Focus on Treatments for individual Fruit Fly species B. tryoni - orange USDA T107-d timetemp

Indications of prospects for developing higher temp treatments Researchers mostly report efficacious treatments and not efficacy failures – no evidence found of where the upper threshold may lie for eg. Fruit Flies No treatments adopted with T > 3.2C Additional research or comprehensive review, targeted at this question, would be required to clarify Time – temp trend suggest positive prospects for development of higher temp – longer duration treatments Alternatively temps above a certain point (3C?) could lose efficacy regardless of duration

Potential value of such higher temp treatments Would such higher temperature longer duration treatments address the need that gave rise to the investigation? Higher sensitivity fruit develop chilling injury even at temperatures in the range of 4.5C to 7C, eg. lemons Prospects of efficacious & practicable treatments above 7C seem remote?

Suggestions for way forward It may be more productive to focus research attention on gaining acceptance of alternatives to cold, such as non-host status and alternative treatments? Need for cold treatment for some sensitive fruit types is questionable, eg. lemons could be recognised as a natural non-host for at least some fruit flies