SAREP-funded methyl bromide alternatives highlighted at conference

by Jenny Broome, SAREP

The “2003 International Research Conference on Methyl Bromide Alternatives and Emissions Reductions” in San Diego in November included a session on SAREP- funded methyl bromide alternative projects. The annual conference, sponsored by Methyl Bromide Alternatives Outreach, in cooperation with the Crop Protection Coalition, the U.S. Environmental Protection Agency, and the U.S. Department of Agriculture, is devoted to the sharing of information on current and ongoing research into methyl bromide alternatives.

More than 400 international researchers, growers and others attended the gathering, which featured sessions concerning research on alternatives to methyl bromide for preplant, post-harvest, and structural uses, international concerns, and California and Florida issues.

Under the Clean Air Act and the Montreal Protocol, production of methyl bromide, a widely used fumigant in agriculture and forestry, will soon be phased-out due to its ozone-depletion qualities. Efforts are continuing to develop and implement economically viable and environmentally sound alternatives. Since 1994, agricultural and forestry researchers from governmental, academic and private institutions, as well as extension agents and users, have gathered together at the annual forum to share information on a variety of laboratory, field, and on-farm research and technology transfer topics.

SAREP Associate Director Jenny Broome moderated the session “Pest Monitoring and Stress Avoidance in Crop Production Systems,” featuring presentations by principal investigators from UC Davis, including John Duniway, UCD plant pathology department, and Greg Browne, USDA-Agricultural Research Service/UCD plant pathology department. In addition, a poster presented by Clyde Elmore, UCD vegetable crops/weed science department, outlined results of the joint work conducted by Elmore and James MacDonald, UCD plant pathology department, and others. (See summaries of these projects in “Methyl bromide alternative results for strawberries”)

Other research results presented at the conference included the following biological approaches of potential interest to our readers:

• Work in Morocco on grafting tomato plants onto rootstock with resistance to Fusarium, Verticillium, Pseudomonas, Meliodogyne, Pyrenochaeta species, and Tobacco Mosaic Virus. The rootstock (L. hirsutum x L. esculentum) is known as Beaufort or Big Foot RZ or King Kong RZ. The study compared this novel system where researchers planted 10,000 plants per hectare grafted with two stems per plant to ungrafted plants grown at 20,000 plants per hectare in covered production systems in Morocco. They found higher costs but also higher yields that resulted in the system paying for itself. Yields ranged from 134 to 174 tons per hectare. In Morocco, currently 25 percent of tomato production is grafted (950 ha out of 3800 ha). The research was highlighted in a recent report by the United Nations Environment Program, available on-line at www.agrifood-forum.net/publications/index.asp
  
• UC Cooperative Extension farm advisor Oleg Daugovish and colleagues presented work on the biofumigation potential of mustards used in crop rotations with lettuce and celery to control Scerotinia minor, citrus nematode (Tylenchulus semipenetrans), and various weed species. Oriental mustard (Brassica juncea) and yellow mustard (Sinapis alba) suppressed nematodes, while only oriental mustard reduced Sclerotinia minor sclerotia growth. In the treatments with oriental mustard, lab examination of sclerotia of the pathogen, revealed them to be covered with a biocontrol fungus, Trichoderma sp. No weed suppression was observed in the field, but in the lab aqueous extracts of the oriental mustard completely inhibited germination. There is a need to identify specific allelochemicals responsible for the effects and also determine the concentrations needed to be effective in the field. The biofumigation may well be a combination of direct kill based on the isothiocynates present as well as a selection of indigenous biological control agents that can survive the chemicals and multiply rapidly in the soil after fumigation. See abstract 6-1 and also ceventura.ucdavis.edu.
  
• Mycofumigation work was presented by Nina Zidack of Montana State University. Muscodor albus is an endophytic fungus isolated from a cinnamon tree in Honduras that can kill other microorganisms via production of volatile microbiocidal compounds. M. albus and other species of Muscodors produce seven different chemicals; one is naphthalene that is repellent to certain insects. These fungi produce alcohols, esters, ketones, acids, and lipids, which can reduce growth of pathogenic fungi; esters seem to be the most inhibitive. Substrates used to produce the M. albus mycofumigant influence the gases released; particular substrates can stimulate the fungus to produce more of the active compounds. Researchers looked at its effectiveness in potato field experiments and found the mycofumigant as effective as the standard chemical controls for control of Verticillium dahlia and Rhizoctonia stolen canker. They also found seedling diseases caused by Aphanomyces and Pythium species reduced in sugar beet microplots. These researchers and scientists at Davis-based Agraquest are studying the effects of the mycofumigant on nematodes, smuts, post harvest pathogens on fruit, several vegetable diseases, and decontamination of human waste. (Agraquest has submitted a production registration package to US-EPA for a reduced risk product, Arabesque Biofumigant, with M. albus as its active ingredient.) Researchers are also looking into the identification and exploitation of water-soluble antimicrobial compounds produced by M. albus.

In addition to research on alternatives to methyl bromide, policy issues related to the regulation of ozone-depleting chemicals were discussed. The Montreal Protocol does allow for some Critical Use Exemptions (CUE) for agricultural uses of methyl bromide past the January 2005 phase-out date. The CUE requests must specify the quantity, be for a specific time period (one year), and only for agricultural uses where it is determined that there are no economic or technically feasible alternatives. In addition, applications for CUEs must describe steps taken to minimize use, minimize emissions, address recycling and stockpiling issues, as well as efforts to secure alternatives. In mid-2002, several U.S. commodity organizations submitted Critical Use Nominations (CUN) requesting CUEs to the US-EPA. US-EPA staff consulted weekly with appropriate USDA scientists in evaluating the CUNs and the industry’s assessment of the technical feasibility and economics of potential alternatives to methyl bromide in specific cropping systems in the U.S. The US-EPA then submitted the U.S. request for CUEs to the United Nations Environmental Program (UNEP) in January 2003 through its Technology and Economic Assessment Panel’s (TEAP) Methyl Bromide Technical Options Committee (MBTOC). The MBTOC reviewed the requests and then made recommendations to the parties (countries) that signed the Montreal Protocol.

The final decision on these requests was expected to occur at the 15th Meeting of the parties to the Montreal Protocol, Nov. 10-14 2003, in Nairobi, Kenya. However, at this meeting delegates decided they needed more time to discuss complex questions related to these exemption requests for countries in the developed world. The UNEP has now scheduled an “extraordinary meeting,” in Montreal in March 2004. Crops/uses for which CUEs were requested include strawberry, cucurbits, eggplant, pepper, tomato, sweet potato, cut flowers, nursery, orchard replant, commodity storage, and food processing, predominantly in North America, Australia, and Europe. The applicants had argued that the current available alternatives are not technically or economically feasible. They had asked parties to the Montreal Protocol for exemptions that amount to approximately 15,000 tons of methyl bromide for the year 2005, of which the U.S requested almost 10,000 metric tons. The amount requested by the U.S. represents 39 percent of its baseline amount or nine percent more than is currently allowed. Delegates to the meeting felt they needed more time to find an agreement that balances the interests of growers and other users of methyl bromide with international agreements to repair the Earth’s protective ozone layer that filters out harmful levels of ultra violet light from the sun.

For more information on the Montreal Protocol and Critical Use Exemptions please see www.unep.org/ozone/index-en.shtml.

For further information on research projects into alternatives, as well as an up-to-date summary of the science behind the phase-out and the process for the phase-out, please see the 2003 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions–Conference Proceedings, available in PDF format at http://mbao.org/2003/mbrpro03.html. SAREP contributed funding to help support the work presented in abstracts # 44, 44A, and 112.