Effect of soil physical factors on methyl iodide and methyl bromide

• Published in: Pesticide Science 1998-05, Vol.53 (1), p.71-79
• Main Authors: Zhang, Wenming, McGiffen Jr, Milton E., Becker, J. Ole, Ohr, Howard D., Sims, James J., Campbell, Steven D.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Chemical control; Fundamental and applied biological sciences. Psychology; methyl bromide; methyl iodide; Parasitic plants. Weeds; Phytopathology. Animal pests. Plant and forest protection; soil fumigation; soil moisture; soil temperature; soil texture; Weeds
• ISSN: 0031-613X; 1526-498X; 1096-9063
• DOI: 10.1002/(SICI)1096-9063(199805)53:1<71::AID-PS731>3.0.CO;2-S

Production and importation of methyl bromide is scheduled to be banned by 2001. Methyl iodide was evaluated as a possible replacement soil fumigant. The effects of soil moisture, temperature, soil texture and fumigation time on the efficacy of methyl iodide for the control of two common weeds, Abutilon theophrasti and Lolium multiflorum, were characterized and compared with those of methyl bromide. The optimal soil moisture for methyl iodide to kill both weed species in sandy soils was 14% water content (w/w). Greater efficacy was obtained when the temperature during fumigation was above 20°C. Compared to methyl bromide, the efficacy of methyl iodide was more consistent in different soils. Time to 100% mortality of weeds was 24 h for methyl iodide fumigation and 36 h for methyl bromide when 200 μM of fumigant was used. On a molar basis methyl iodide was consistently more effective than methyl bromide across the range of environmental factors tested. In terms of application technology and spectrum of activity, methyl bromide can be directly replaced by methyl iodide. © 1998 SCI