Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 30, 2008
Publication Date: September 15, 2008
Citation: Scheneider, S.M., H. A. Ajwa, T. J. Trout, and S. Gao. 2008. Nematode Control Fron Shank-and-Drip-Applied Fumigant alternatives To Methyl Bromide. HortScience. 43(6): 1826-1832. Interpretive Summary: Methyl bromide was banned for use as a soil fumigant in the USA as of January 2005. While seeking temporary critical use exemptions for MBr, growers have been searching for alternatives in order to continue to produce clean berry, vine, and tree propagative material and to meet high yield and quality expectations. The objective was to evaluate potential alternatives to methyl bromide for the control of plant parasitic nematodes in shallow-rooted, bedded cropping systems and in perennial nursery cropping systems. Alternative fumigants evaluated were chloropicrin (alone or in combination with other alternatives), 1,3-dichloropropene, iodomethane, propargyl bromide, and metam sodium. These were compared to untreated controls and industry standard treatments with methyl bromide. Fumigation methods included shank injection and drip application. Three year field data showed that some of the alternatives and/or application methods were able to provide adequate control of nematodes comparable to standard methyl bromide treatment. The results are important to growers who rely on soil fumigation for production in searching for effective, available, and economically feasible alternatives.
Technical Abstract: Field studies were conducted to evaluate potential alternatives to methyl bromide (MBr) for the control of plant parasitic nematodes in shallow-rooted, bedded cropping systems, such as strawberry, and in perennial nursery cropping systems in Central California, USA. Chloropicrin (Pic), 1,3-dichloropropene (1,3-D or Telone), combinations of 1,3-D + Pic, iodomethane (IM) + Pic, propargyl bromide (PBr), and metam sodium (MS) were compared to untreated controls and industry standard MBr/Pic treatments. Materials were applied by both shank-injection and drip-application, except MS and PBr, which were applied only by drip. The efficacy on citrus nematode (Tylenchulus semipenetrans Cobb) and/or root-knot nematode (Meloidogyne spp. Chitwood) control was investigated in three trials conducted on soils ranging from sandy loam to silty clay loam. All treatments controlled nematodes near the injection point (center of bed and moderate depths) comparable to MBr/Pic. Drip-applied Pic provided somewhat less control than MBr/Pic at the shoulder of the bed when delivered in 25 mm of water and MS provided no control at the bed shoulder. IM+Pic, both shank-injected and drip-applied, provided nematode control to a depth of 150 cm comparable to MBr/Pic. Telone EC applied to a dry field in 75 mm water did not control nematodes well at either 90 or 150 cm depths, while PBr controlled nematodes as effectively as MBr/Pic at the 90 cm depth, but not at the 150 cm depth. Propargyl bromide at 67 kg ha-1 was effective at killing the nematodes up to 30 cm deep in a strawberry plant bed. The dosage exposure values (within 96 h after fumigation) observed for >99% control of nematodes were much lower for PBr (~ 1 mg L-1 h) than those for 1,3-D+Pic (17 mg L-1 h when applied at 61:35 1,3-D:Pic mass ratio), Pic alone (10 mg L-1 h), and IM+Pic (19 mg L-1 h when applied at 50:50 mass ratio). Drip application technology showed promise for effective alternatives to MBr/Pic. Consistent delivery of an effective dosage of a material throughout the target soil profile is necessary for consideration as an acceptable alternative to MBr for high value crops.