Effects of surface seals on Telone C35 emissions and pest control
The primary alternative to methyl bromide in several California cropping systems is 1,3-dichloropropene, chloropicrin, or a combination of the two fumigants. Although these compounds do not deplete stratospheric ozone like methyl bromide, they can have negative human health and environmental consequences related to worker and bystander safety and release of volatile organic compounds (VOC) that contribute to air pollution. Controlling fumigant emissions has become an important goal of regulatory agencies in California and has spurred research on techniques to effectively keep fumigants in the soil and/or to rapidly degrade the compounds before they are released into the atmosphere. Gao et al. (in press) recently reviewed established and experimental techniques for reducing soil fumigant emissions including plastic films, water seals and chemical or organic soil amendments. However, before regulators require and before growers adopt these emission mitigation practices, more data are needed on the effects of these techniques on the primary goal of soil fumigation, namely pest management.
The objectives of this research were to simultaneously evaluate 1) the effects of surface sealing techniques on emissions of 1,3-D and Pic from the soil to the atmosphere and 2) the impacts of the surface treatments on control of soil-borne pests.
Two trials were conducted at the USDA-ARS San Joaquin Valley Agricultural Sciences Center in 2006-07 and 2007-08 to determine the effects of surface seal treatments on fumigant emissions and on control of soil-borne pests.
Telone C35 was applied and six surface seal treatments were imposed over the fumigated and unfumigated main plots.
- Unsealed control
- Composted manure + HDPE film
- Potassium thiosulfate +HDPE film
- Pre-irrigation above fumigant label requirements
- Intermittent water seals following fumigation
- Intermittent potassium thiosulfate seals
Data were collected on nematode control, pathogen survival, weed seed viability, weed emergence, and weed biomass production. No nursery crop was produced at either location. Emission data are presented here.
Table 1. Effect of surface seal treatments on control of citrus nematode with 1,3-dicloropropene+chloropicrin in a 2006-07a field experiment near Parlier, CA.
Table 2. Effect surface seal treatments on soil pathogens following fumigation with of 1,3-dichloropropene+chloropicrin in a 2007 field trial conducted near Parlier, CA.
Table 3. Effect surface seal treatments on weed emergence and biomass production following fumigation with of 1,3-dichloropropene+chloropicrin in two field trials conducted near Parlier, CA in 2006-2008.?
The final results of the pest control aspects of these experiments were published as:
Hanson et al. 2011. Effects of emission reduction surface seal treatments on pest control with shank-injected 1,3-dichloropropene and chloropicrin. Crop Protection 30:203-207. DOI 10.1016/j.cropro.2010.10.011.
Gao et al. 2008. Field tests of surface seals and soil treatments to reduce fumigant emissions from shank-injection of Telone C35. Sci. Total Environ. 405:206-214. DOI 10.1016/j.scitotenv.2008.06.021.
Gao et al. 2009. Effects of manure and water applications on 1,3-dichloropropene and chloropicrin emission in a field trail. J. Agric. Food Chem. 57:5428-5434. DOI 10.1021/jf900245f.
Effect of surface seals and shank designs:
This project was reported on at the International Research Conference on Methyl Bromide Alternatives and Emission Reductions (MBAO.org) in 2007.