Perennial Crop Nurseries Treated with Methyl Bromide and Alternative Fumigants: Effects on Weed Seed Viability, Weed Densities, and Time Required for Hand Weeding

• Published in: Weed technology 2008-04, Vol.22 (2), p.267-274
• Main Authors: Shrestha, Anil, Browne, Greg T, Lampinen, Bruce D, Schneider, Sally M, Simon, Leo, Trout, Thomas J
• Format: Article
• Language: English
• Subjects: 1,3-dichloropropene; broadleaf weeds; Bromides; chloropicrin; Convolvulus arvensis; Crops; Fumigation; grass weeds; Herbicide; Herbicides; Ipomoea purpurea; Malva parviflora; manual weed control; methyl bromide; methyl iodide; Montreal protocol; mulch films; perennials; plant density; plant nurseries; plastic film; Plows; Portulaca oleracea; seed viability; Seeds; soil fumigation; Sorghum halepense; species differences; stratospheric ozone; Tillage; Viability; Weed control; Weed Management - Other Crops/Areas; Weeds
• ISSN: 0890-037X; 1550-2740
• DOI: 10.1614/WT-07-122.1

Data on the efficacy of alternative fumigants to methyl bromide for weed control in perennial crop nurseries in California are needed because few herbicides are registered for this purpose. Field studies were conducted from 2003 to 2006 in four commercial perennial crop nurseries in California. Treatments included a nonfumigated control; methyl bromide (98%) (MeBr) with high-density polyethylene (HDPE) film; iodomethane (50%) + chloropicrin (50%) with HDPE film; 1,3-dichloropropene (1,3-D) with HDPE film; 1,3-D (61%) + chloropicrin (35%) with HDPE film; 1,3-D (62%) + chloropicrin (35%) subsurface drip; and 1,3-D (61%) + chloropicrin (35%) with virtually impermeable film (VIF). All the fumigants reduced the seed viability of common purslane, johnsongrass, and tall morningglory but were not as effective on little mallow and field bindweed. Although total weed densities and the level of control provided by each fumigant differed between locations, weed density was generally reduced by all the fumigation treatments, compared to the nonfumigated control. At three locations, alternative fumigation treatments usually resulted in hand-weeding time similar to MeBr. Reductions in weed seed viability, weed emergence, and weed densities suggest that these alternative fumigants will provide weed control similar to MeBr in perennial nurseries.