4^th Meeting of the ad hoc Panel on phytosanitary risks 
of composted organic waste

York, 2006-12-05/06

The Standard PM 3/66(1) Guidelines for the management of plant health risks of biowaste of plant origin was adopted in 2005-09 but at the Working Party on Phytosanitary Regulations in 2005 it was considered that an additional meeting of the ad hoc Panel on Phytosanitary Risks of Composted Organic Waste would be useful to prepare additional appendices describing composting processes.

The Panel met in York, UK at the kind invitation of the British NPPO. Warm thanks are due to Mrs Sansford for the very fine organization of this meeting. During the meeting the Panel improved the standard in particular it clarified of the section treatment processes.

Regarding the preparation of appendices describing composting processes Mrs Pietsch (DE) and Mr Ryckeboer (BE) had cooperated in preparing an English translation of the text published in 2003 by the Bundesgütegemeinschaft Kompost eV describing a validation system for determining the sanitation effect of biowaste treatment processes. The Panel noted that the direct validation process described in the EPPO standard stated that no indicator organisms should be detected at the end of the process whereas the German validation system allows for tolerances of these organisms. Given this important difference, the Panel conluded that it was not possible to add the German composting process descriptions to the EPPO Standard. Nevertheless, the processes described are suitable for low risk waste and the Panel agreed that a reference to it should be added into the text of the Standard.

It also discussed Specific composting standards in particular PM 3/53 Fermenting (composting) of bark of conifers following a request by EPPO Panel on Phytosanitary Treatments that it should be re-assessed. The reasons were that the cost of milling the bark and the need to add nitrogen and phosphorus sources to enhance thermophillic activity were found to exceed the commercial value of raw bark. Thus, it was recommended that this EPPO Standard should be re-examined to specifically address the need for a low intervention, low cost system for quarantine heat treatment of bark using natural processes. The Panel commented that the composting process should ensure freedom from quarantine pests but that no studies were available to support this for composting of bark. Consequently it confirmed the conclusion of the Panel on Phytosanitary Treatments that a revision of the procedure was not possible without further work being carried out.

The Panel also commented a paper presenting some research that had been carried out by the Dutch plant protection service which concluded that it was possible to eliminate Phytophthora ramorum during the tunnel-composting process of rhododendron waste. The Panel considered that further detail should be provided to be able to accept this document as a possible Standard for composting plant material infected with Phytophthora ramorum.