From the U.S. Department of Agriculture AMS docket on the sunset of certain compounds in the National Organic Program, a letter from the Northwest Horticultural Council:

105 So. 18th Street, Suite 105
May 20, 2010
Ms. Valerie Frances
Executive Director
National Organic Program
Room 2646 So., Ag Stop 0268
1400 Independence Ave, SW
Washington, DC 20250-0268
Dear Ms. Frances:
RE: Document Number: AMS-NOP-09-0074
Sunset Review- Additional Comments on Antibiotics

The Northwest Horticultural Council (NHC) represents the growers and shippers of conventional and organic deciduous tree fruit, specifically apples, pears and cherries, in the Pacific Northwest states of Idaho, Oregon and Washington. We are writing on behalf of the organic tree fruit producers in these states concerning the sunset review of antibiotics used in their operations.

The NHC has previously provided a letter with background on fire blight including pictures of the devastation caused by this disease, NOP Proposed Amendments to the National List of Allowed and Prohibited Substances, Document Number AMS-NOP-09-0081, March 15, 2010 and a letter dated April 6, 2010, which was entered into testimony at the Sunset Review Meeting in Woodland, California, April 26-29, 2010, in support of the retention of antibiotics until a suitable alternative is identified.

We offer the following comments to address the use of the alternative material, peracetic acid (peroxyacetic acid or PAA), for fire blight treatment.

The tree fruit industry has been aggressively seeking a range of alternatives for fire blight control and closely following the research being done in the U.S. and around the world. The following are reports from various sources:

University of California, Riverside reported that PAA was evaluated in 2003 and 2004 in a mixture with hydrogen peroxide. The peroxide being the oxidizing agent and the PAA, the stabilizer, which maintained persistence after application. Fire blight control research using this product was discontinued as a result of its inconsistency, marginal to low efficacy and its phytotoxicity to fruit and leaves. ‘…During years 1 and 2, PAA did not work at all in commercial orchards where the disease was moderate. The treatment, however, caused consistent phytotoxicity on the fruit.’ (Dr. James Adaskaveg, Department of Plant Pathology and Microbiology)

Oregon State University suggests that PAA has not demonstrated the level of efficacy required by the scientific community. PAA may work on equipment surfaces but quickly dissipates on organic surfaces. ‘Epiphytic Erwinia amylovora associates intimately on surfaces of pear and apple flowers (more so than non-pathogens) and thus are not sufficiently exposed to fast acting oxidizers. A peracetic acid application may hit a few cells of E.a., but it would be only a relatively small proportion of what’s there. If conditions were right, these would be quickly replaced (a few hours).’ (Dr. Ken Johnson, Department of Botany and Plant Pathology)

The lead Washington State University scientist working on fire blight states ‘I am not aware that this product has been tested and shown to be effective for the control of fire blight. In all my years of attending ISHS World Workshops on Fire Blight (since 1986), I have no recollection of any reputable scientist claiming efficacy for this substance…’ (Tim Smith, Chelan County Cooperative Extension).

Reputable scientists in the area of tree fruit research diseases have confirmed that peracetic acid is not acceptable as a commercial replacement for currently registered antibiotics.

If the NOSB proceeds in following its plan to sunset antibiotics, we request that the efficacy data that support the effectiveness of approved alternatives be made available for scientists with research backgrounds in this area to review.

Dr. Johnson of Oregon State University has recently submitted a proposal to USDA NIFA to continue research in the area of identifying non-antibiotics programs to treat fire blight in organic apple and pear. This proposal has been attached for your review. We request that the NOSB not allow the use of antibiotics to sunset in organic fruit production until alternative products are developed in a program such as his.

Thank you for the opportunity to comment. Please feel free to contact the Northwest Horticultural Council if you require additional background information.

Sincerely yours,


Deborah Carter
Technical Issues Manager