1. BACKGROUND

Summary

Methyl iodide, (MI) or iodomethane is a liquid pre-plant soil chemical. This material was originally developed by researchers in California, USA where the bulk of initial testing was performed (Duniway et al., 2002 ). It is an attractive replacement due to its soil mobility and broad-spectrum of activity. It is not associated with ozone depletion and rapidly breaks down when exposed to UV light. Since the 2002 report, numerous studies show that MI provides similar efficacies to methyl bromide in trials (Ajwa et al., 2003; Porter et al., 2006b). A great deal of research has been conducted evaluating MI as a drop-in replacement for MB. Recent studies are focusing on lowering the dosage rate and validating performance when used in combination with chloropicrin (Browne et al., 2003; Dickson et al., 2003; Elmore et al., 2003; Ren et al., 2003; Schneider et al., 2003).

Product characteristics

• composition : CH3 I
• liquid with a low boiling point (42.5°C) and a high vapour pressure (at 20°C, 398 mmHg)
• water solubility g/l at 25°C : 14.2
• broad spectrum like methyl bromide
• accepted by EPA as a non-threat to the ozone layer (ODP : 0.0015)

2. RECOMMENDATIONS FOR CROPS

Trial results

In California, USA, it has been tested in carrot, peach, cut flower, strawberry production systems, nurseries and vineyard replant (Schneider et al., 2003; Schneider et al., 2005; Ajwa et al., 2005). In Florida, it has been tested alone and in combination with chloropicrin for control of Phytophthora capsici, root-knot nematode and yellow nutsedge. Disease control and yields of bell pepper were equivalent to MB when it was combined with chloropicrin (420 kg/ha and 84 kg/ha MI and pic) (McMillan et al., 1997).
Additional studies have been conducted to compare rates for nutsedge and nematode control (Dickson et al., 2003; Gilreath and Santos, 2004). Gilreath and Santos (2004) found that the best control of nutsedge was achieved using 392 kg/ha of the 50/50 (MI:Pic) formulation. In studies conducted in Huelva, Spain, Florida, USA, and Australia shank applied MI:Pic produced marketable strawberry yields comparable with or better than MB:Pic (López-Aranda et al., 2005; Mann et al., 2005).

Current indications are that the cost of this product will be priced higher than MB for many crops, making its adoption more likely in higher-value crops.

3. EXPERIMENTAL PERMITS AND REGISTRATION

In U.S, in October 2007, the Environmental Protection Agency(EPA) has granted commercial registration for one year to Midas®. This fumigant will be widely available through select fumigant distributors.
It received experimental use permits for large scale trials in the US from October 2006 and Australia in 2007. It is also registered in Japan for non-food uses (post harvest timber insect pests). Registration of MI in Japan for monosporascus root rot and necrotic spot disease in melon and root knot nematode, bacterial wilt and Fusarium wilt in tomato is expected soon (pers. comm., Anonymous, Alternative Technology Development Programme Japan Fumigation Technology Association 2006). These registrations are particularly significant as methyl iodide is considered a one-to-one replacement to methyl bromide for most uses.

4. REFERENCES (2002-2007)

• Duniway, J.M. (2002). Status of chemical alternatives to Methyl Bromide for pre-plant fumigation of soil. Phytopathology 92, 1337-1343.
• Ajwa, H.A., Klose, S., Nelson, S.D., Minuto, A., Gullino, M. L., Lamberti, F. and Lôpez-Aranda, J.M. (2003b). Alternatives to Methyl Bromide in strawberry production in the United States of America and the Mediterranean region. Phytopathologia Mediterranea 42, 220-244.
• Porter, I.J., Trinder, L. and Partington, D. (2006b). Special report validating the yield performance of alternatives to Methyl Bromide for preplant fumigation. TEAP/MBTOC Special Report, UNEP Nairobi, May 2006 97pp.
• Browne, G., J. Connell, H. Becherer, S. McLaughlin, S. Schneider, R. Lee, and Hosoda, E. (2003). Evaluationof rootstocks and fumigants for control of almond replant disease. In: 2003 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions, Nov. 3-6, 2003, San Diego, CA. p. 11.1 –11.2.
• Dickson, D.W., Mendes, M. and Hamill, J. (2003). Comparison of Methyl Iodide formulations with Methyl Bromide, and an untreated control on the management of root-knot nematodes, weed and yield of tomato in Florida. Proc. 2003 Annual International Research Conference on Methyl Bromide Alternative Reductions and Emissions Reductions, MBAO, pp. 22-1-22-4.
• Elmore, C., Roncoroni, J. and Tjosvold, S. (2003). Treatment combinations to improve efficacy in field-grown flowers. Proc. 2003 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions, San Diego, CA. p. 112-1
• Schneider, S.M., Rosskopf, E.N., Leesch, J.G., Chellemi, D.O., Carolee, T.B. and Mazzola, M. (2003). United States Department of Agriculture—Agricultural Research Service research on alternatives to Methyl Bromide: Pre-plant and post-harvest. Pest Management Science 59, 814-826
• Ajwa, H., Shem-Trov, S., Klose, S., Fennimore, S. and Roth, K. (2005). Strawberry yield and weed control with shank and drip applied Midas. In:. Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions, San Diego, California, USA. Paper 7.
• McMillan, Jr., R. T., Bryan, H. H., Ohr, H. D. and Sims, J. J. (1997). Methyl iodide a direct replacement of methyl bromide as a soil fumigant for sweet peppers. In: Annual Internatiomal Research Conf. on Methyl Bromide Alternative Reductions and Emissions Reductions. MBAO, pp: 40-1
• Gilreath, J.P. and Santos, B.M. (2004b). Purple nutsedge control with Iodomethane. Proc. 2004 Annual International Research Conf. on Methyl Bromide Alternative Reductions and Emissions Reductions, MBAO, pp. 51-1,51-2.
• Lôpez-Aranda, J.M., Santos, B., Gilreath, J., Miranda, L., Soria, C. and Medina, J. (2005). Evaluation of Methyl Bromide alternatives for strawberry in Florida and Spain. Proc. 2005 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions. Paper 9.
• Mann, R.C., Mattner, S.W., Gounder, R.K., Brett R.K. and Porter I.J. (2005). Evaluating novel soil fumigants for Australian horticulture. Pp 34-1 – 34-4 In: Annual International Research Conference on Methyl Bromide Alternatives and Emission Reductions, Oct 31 - Nov. 3 2005, San Diego, Calif

Contacts

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Methyl Iodide leaflet

Writing Date : 2008-08-29
Latest update Date : 2008-08-29