Submitted to: HortScience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/3/2007
Publication Date: 8/1/2007
Citation: Zasada, I.A., Elmore, C.L., Yakabe, L.A., Macdonald, J.D. 2007. Evaluation of Propargyl bromide as a soil fumigant. HortScience. 42:1212-1216. Interpretive Summary: The California floriculture industry is a large and important component of the state's agricultural economy, with a reported value of approximately $1 billion. This industry has relied heavily on the use of methyl bromide, a soil fumigant being phased-out of use, for the control of damaging soilborne pests such as weeds, nematodes and fungi. Therefore, it is important to develop alternatives to manage the pests now controlled by methyl bromide. The emphasis of this work was to evaluate an alternative soil fumigant (propargyl bromide) and several standard soil fumigants in an interdisciplinary study for the control of a plant-parasitic nematode, a fungal pathogen and five weed species. Propargyl bromide was as effective in controlling the nematode and fungus as the other soil fumigants but at much lower rates. Weeds varied in their sensitivities to propargyl bromide, with three weed species being controlled by an intermediate rate of propargyl bromide but two weed species not controlled by even the highest rate of propargyl bromide. The latter two species were not controlled by the other soil fumigants. These results are significant because they demonstrate that propargyl bromide is an effective soil fumigant against a range of soilborne pests and will be used by scientists developing new methods for managing pests of the floriculture industry.
Technical Abstract: The cut flower and bulb industry has relied heavily upon the use of methyl bromide as a key soil treatment for soilborne pest control. Due to the phase-out of methyl bromide it is important to develop alternatives to manage pests now managed by methyl bromide. The emphasis of this work was to evaluate an alternative soil fumigant, propargyl bromide, in an interdisciplinary study. Three sites were selected in California to represent different soil types and environments. Propargyl bromide was applied at rates ranging from 28 to 168 kg/ha in buried containers and compared to standard soil fumigants. The citrus nematode (Tylenchulus semipenetrans Cobb) and Fusarium spp. were both controlled at the lowest rate of propargyl bromide, 28 kg/ha. Weeds varied in their sensitivity to propargyl bromide. A 100% reduction in common purslane (Portulaca oleracea L.) and pigweed (Amaranthus retroflexus L.) germination occurred at 112 kg/ha propargyl bromide, regardless of location. Results for annual bluegrass (Poa annua L.) control were more variable across sites and years, but >90% control was consistently achieved with 168 kg/ha propargyl bromide. Cheeseweed (Malva parviflora L.) and field bindweed (Convolvulus arvensis L.) were never consistently controlled by propargyl bromide. When compared to the standard soil fumigants methyl bromide, iodomethane and metham sodium, propargyl bromide provided comparable control of all soilborne pests. While higher rates of propargyl bromide, >112 kg/ha, were needed to control weeds, these rates were almost half that required of the other standard fumigants.