United States Department of Agriculture
Animal and Plant Health Inspection Service
4700 River Road
Riverdale, MD 20737
June 26, 2008
Ms. Louise Van Meurs, General Manager
Plant Biosecurity, Biosecurity Australia
Department of Agriculture, Forestry, & Fisheries
GPO Box 858
Canberra, ACT 2601, Australia
Dear Ms. Van Meurs:
We appreciate the opportunity to comment on Biosecurity Australia's (BA) draft Import Risk Analysis (IRA) for stone fruit (apricots, nectarines, peaches, plums, and hybrids of the four species) from California, Idaho, Oregon, and Washington. We respectfully request your consideration of our comments on the following sections of the pest risk analysis and recommended mitigations for the following pests:
- Apple maggot
- Peach twig borer
- Lesser appleworm
- Cherry fruitworm
We would like to comment on the host status of stone fruit from California, Idaho, Oregon, and Washington for apple maggot. In particular, we question the host status of "peach" for this pest.
On pages 48 and 49 of the draft IRA, BA cites several sources as stating that apple maggot (Rhagoletis pomonella) is native to North America, widespread throughout California and Oregon, and present in Washington. BA notes that, while the primary host of apple maggot is hawthorn (Cratageus spp.) and its main commercial host is apple (Malus domestica), it also has adapted to other commercial fruit hosts, including peach, apricot, and plum.
We were surprised to see "peach" listed as a host of apple maggot and ask that "peach" be removed from the list of host fruits . When we investigated the sources cited in BA'S draft IRA and the referenced literature, we found that the only reference to peach as a host of apple maggot is Bush (1966) who cites an article by Porter (1928)
We believe that Bush erroneously referenced the Porter article since Porter mentioned "pear," but not "peach" as an occasional host of apple maggot. Porter stated that "pear was a host of apple maggot, although no adults had been reared from it." According to Porter, "Injury to pears seems to be not more than occasional, and probably occurs only when the pear trees are not far from heavily infested apples," (Porter, 1928). This is almost the same language attributed to "peach" by Bush. Thus, we believe that Bush's citation was in error. We are including the citations for the two articles mentioned above.
While plums and apricots are cited in the literature as hosts of apple maggot, our experience shows that plum and apricot are unlikely hosts of apple maggot in the western United States. In inspection data for the four States, we found no interceptions of apple maggot in any of the stone fruits.
- Washington-3,078,195 cartons of apricots; 1,054,215 cartons of peaches/nectarines; and 1,323,872 cartons of plums/prunes inspected (1999 - 2006).
- Idaho-91,500 cartons of peaches inspected (2000-2005).
- Oregon-72,143 cartons of plums/prunes inspected in 2006 and 2007.
- California-26.5 million cartons of apricots, peaches, nectarines, and plums inspected (2003 - 2006).
Furthermore, Washington State reported no interceptions of apple maggot during export inspections of 842.58 million cartons of apples in the 1993/94 through the 2005/2006 shipping seasons.
Peach Twig Borer
Our comments for peach twig borer [Anarsia lineatella Zeller (PTwB)] address BA'S request for advice on mitigation measures for this pest for which BA has not developed previous policy. On page 157, BA observes that risk management measures in addition to its standard 600-unit inspection are required for PTwB. BA suggested that potential mitigation measures for peach twig borer could be methyl bromide fumigation, establishment of pest free areas, cold temperature disinfestation, or a systems approach based on a combination of measures.
Our recommended mitigation for this pest is a systems approach consisting of a combination of measures conducted in the orchards and packing facilities based on integrated pest management guidelines established by field experts in the exporting States (i.e., the University of California Pest Management Guidelines).
Our proposed systems approach consists of:
- Mandatory dormant and bloom spray aimed at PTwB;
- Orchard monitoring, including orchard trapping and treatment based on degree-day modeling;
- Orchard fruit cutting and shoot strike survey;
- Packing house cull cutting; and
- Regulatory inspection.
We have enclosed a copy of our systems approach proposal for PTwB to our comments.
We have operated a similar systems approach program for oriental fruit moth (OFM) in stone fruit exports to other countries. That systems approach has reduced significantly the likelihood of entry of OFM into those countries. Of 3,657,862 cartons of stone fruit exported to Mexico from California under the systems approach, 7 OFM were found from 2003 through 2007. All were detected during phytosanitary inspection in California. There were no detections of OFM in systems approach stone fruit at the Mexican border. Additionally, out of 3,078,195 cartons of apricots; 1,054,215 cartons of peaches/nectarines; and 1,323,872 cartons of plums/prunes inspected from Washington State from 1999 through 2006, only one OFM was found in 2004. No OFM were found at export inspection of 9 1,500 cartons of peaches from Idaho from 2000 through 2005.
Cherry Fruitworm and Lesser Appleworm
In the draft IRA, BA evaluated the risk presented by the entry, establishment or spread of cherry fruitworm (Grapholita or Cydia packardi Zeller) and lesser appleworm (Grapholita or Cydia prunivora Walsingham) as similar to OFM (Grapholita or Cydia molesta) in occurrence in stone fruit in the four States, behavior, and risk profile. Cherry fruitworm and lesser appleworm are considered by BA to be present in California and the Pacific Northwest States and to be "potential pests of stone fruit" (page 96).
We respectfully disagree with BA'S assessment of the likelihood that cherry fruitworm will be associated with apricot, nectarine, peach and plum fruit and question the sources cited. Weires and Riedl (1991) cite Chapman and Lienk (1971) as their source for their listing of the hosts of cherry fruitworm. Weires and Riedl indicate that cherry fruitworm has been reported from "apple (shoots and fruits), cherry (fruits), hawthorn (fruits), plum (fruit), rose (shoot tips), peach (fruits), and blueberry (fruits)."
Chapman and Lienk, however, do not cite any of the 4 stone fruit species as hosts of cherry fruitworm. They report that cherry fruitworm "has been reported breeding in the shoot tips and fruit of apple and in the fruits of cherry, hawthorn, and blueberry." We believe that Weires and Riedl erroneously cited the Chapman and Lienk publication with regard to the host status of "plum" and "peach" for cherry fruitworm.
We looked for reports of interceptions of cherry fruitworm in any of the stone fruit and could not find them. Our export inspection data also shows no finds of cherry fruitworm in any of the State inspections. Unless BA can provide reports of cherry fruitworm in apricot, peach, nectarine or plum, we ask that this pest be removed from BA'S analysis.
With regard to lesser appleworm, Weires and Riedl, citing Chapman and Lienk, report that lesser appleworm "utilized the fruits of native species of hawthorn, plum, crabapple, cherries, shadbush, and probably rose. Following the introduction of fruits from Europe, the species expanded its host range to include apple, European plums and prunes, and the fruits of Photinia."
Lesser appleworm has been reported infrequently on apples in the Pacific Northwest States. However, there have been no interceptions of lesser appleworm in apples in the last 8 years. We have no reports of it being intercepted in the fruit of apricots, nectarines, peaches, or plums. Our inspection data bears out our statement: lesser apple worm was not found during export inspections of stone fruits in any of the four States.
We appreciate BA'S time and effort in drafting this IRA and hope that the information provided in this letter and accompanying systems approach proposal for peach twig borer will be helpful as you finalize the IRA for California and Pacific Northwest apricots, nectarines, peaches, plums, and hybrids of the four species. We look forward to continuing our dialogue as you complete the IRA and finalize your policy for California and Pacific Northwest stone fruit. Should you have additional questions, please do not hesitate to contact us.
Thank you for your cooperation in dealing with this high priority issue for the United States.
Craig T. Fedchock
Assistant Deputy Administrator
Phytosanitary Issues Management
Plant Protection and Quarantine
Disclaimer: The department received this submission in hardcopy only, which has been converted into an accessible format to meet Australian Government accessibility requirements. While due care was taken to ensure the information was reproduced accurately, the PDF should be considered the original document for official purposes.