# Presentation: 446089

## Irradiation as a Phytosanitary Treatment

**Irradiation as a Phytosanitary Treatment**
**Guy J. Hallman**
**USDA-ARS, Weslaco, TX**

## International Anti-Food Irradiation Week

**International Anti-Food Irradiation Week**

- Nov. 21 Milford Square, PA and 4 other international locations in late Nov.

**Notes:**
Scientists are not advocates for food irrad., but search for solutions to problems and irrad. Is a good solution for phytosan. Problems.  Milford Square plant run by CFC Logistics (GRAY-STAR Genesis cobalt machine)

## Comparison of Phytosanitary Treatments

- Treatment   Cost  Speed   Logist.    Accep.   Toler.

- Cold            low     slow      easy       high       mod.
- MeBr           low     fast       easy       mod.      mod.
- Hot water    low     fast       easy       high       low
- Irradiation   mod.   fast       mod.      mod.      high
- Hot air         mod.  mod.     mod.      high        mod.

**Notes:**
Major commercial trts. In order of use.  Can argue over qualifications.  Apply post-pack (logistics): cold, MeBr, irrad. Organic not accept MeBr or irrad. Hot water used on longans in HI.

## Cold, heat, and fumigation treatments kill pests fairly quickly; irradiation does not.

- Irradiated pests are prevented from completing development or reproducing.
- This makes irradiation more difficult to research and regulate.

**Notes:**
This does not directly concern marketers

## A rule of thumb is that arthropods increase in tolerance to irradiation as they mature (i.e., adult is most tolerant followed by pupa, larva, and egg when same effect measured)

- Phytosanitary treatments need only be effective against stages occurring in shipped commodity
- Because there is no independent confirmation of efficacy, such as  a dead insect, irradiation treatment must be regulated to a higher level than other treatments

## Pests differ in tolerance to radiation

- Pests    Latest stage present  Possible dose (Gy)
- Aphids		adult				100
- Whiteflies		adult				100
- Fruit flies		late larva			150
- Weevils		adult				175
- Borers		late larva			200
- Thrips		adult				250
- Borers		late pupa			350
- Mites		adult				350

**Notes:**
Copitarsia early larva.  Codling moth in cherry mid larva.

## Current Commercial Uses

## 8 fruits from Hawaii to mainland since 1995

- 2270 metric tonnes per year, mostly papaya

## Guavas from Florida to California and Texas since 1999; 150 Gy,  7¢/pound

- Guavas from Florida to California and Texas since 1999; 150 Gy,  7¢/pound

## Sweetpotato from Florida to California since 2000; 165 Gy, 7¢ per pound

- Sweetpotato from Florida to California since 2000; 165 Gy, 7¢ per pound

## Sweetpotato from Hawaii to mainland since 2003

- 400 Gy
- 25 metric tonnes per week

## Other fruits from Florida to California beginning in 2004; 150 Gy

## Mangoes from Australia to New Zealand beginning Nov. 2004

**Notes:**
150 Gy for only fruit flies; 250 Gy for other pests, such as mealybugs and thrips

## Irradiation is the most tolerated phytosanitary treatment for fruits at doses required for fruit flies and other pests

- Commodity Tolerance

- Because commodities are most economically treated in standard pallet-loads and radiation is attenuated by distance and density, a commodity should be tested for tolerance to irradiation at up to 3 times the minimum absorbed dose required for pest control

## Low-oxygen storage may reduce efficacy of irradiation to some groups of insects especially where adults may be present

## Can be more complicated to use

- Phytosanitary Irradiation

- Poses no health risk to consumer
- Requires near fool-proof certification
- Effective at relatively low doses
- Broadly tolerated by fruits
- Does not reduce nutritional value of fresh produce

- In summary