Effects of application shanks and surface seals on fumigant emissions and nursery pest control efficacy with 1,3-D
The objectives of the perennial crop nursery Area-wide project are complementary to our recent research on alternative fumigants, alternative application techniques, and integrated practices to maintain broad spectrum pest control in tree and rose nurseries. A partial list of recent research projects included in, or contributing to, the nursery industry sector project is presented in Table 1.
Fumigant emission concerns drive many of the regulatory decisions (currently in place or under consideration) that affect the adoption of MB alternatives in California. Some regulations may limit the effectiveness of the alternatives when they are used (ie. rate restrictions, excessive soil moisture requirements, township caps). Thus, the first three years of this project were focused on testing and demonstrating the effects of several emission reduction techniques including: water seals, improved tarps, and the Buessing application shank (McKenry et al., 2003) on fumigant emission and pest (nematodes and weeds) control in both simulated nurseries and on-farm trials in production nurseries. Our overall goal with this work was to simultaneously test the effects of several fumigant application techniques on fumigant emission and pest control efficacy in order to encourage science-based regulatory decisions and more effective use of methyl bromide alternatives in the nursery industry. Specific objectives proposed in 2007-2009 were to:
Determine the effects of a modified (Buessing) application shank on 1,3-D emissions compared to standard application shanks.
Demonstrate effective nematode control with currently approved 1,3-D fumigation treatments in field nursery situations and determine if VOC mitigation procedures affect efficacy.
Determine the effects of approved nursery treatments applied with winged or straight shanks and several surface treatments on weed, pathogen, and nematode control efficacy and crop growth parameters.
Results and More Information
A total of four field fumigation trials were conducted between 2007 and 2010. In 2007 and 2008, a simulated nursery trial was conducted near Parlier, CA to allow simultaneous monitoring of 1,3-D emissions and weed, pathogen, and nematode control. A corresponding trial was conducted each year in a commercial production field with the nursery industry cooperation to allow monitoring of pest control and nursery crop productivity. In each trial, a 2 x 4 factorial experimental design was employed to test 1,3-D (Telone II at 332 lb/A) applied with two application rigs (standard shank or Buessing shank rig) and four surface treatments (HDPE tarp, Vapam cap, water seals, and VIF tarp). The two-site strategy was used because most production nurseries have very low populations of resident nematodes after many years of effective MB fumigation. In 2007, the emission trial was conducted at the University of California Kearney Agricultural Center and the nursery trial was conducted in a garden rose nursery near Wasco, CA. In 2008, the two trials were initiated at the USDA-ARS San Joaquin Valley Agricultural Sciences Center and in a stonefruit tree nursery near Hickman, CA, respectively.
Table 1. List of treatments used in the field trials conducted at KAC in 2007 and at SJVASC in 2008 to evaluate effects of surface seals and application rigs on nematode, pathogen and weed control with 1,3-D
Table 2. Effects of 1,3-D with surface seal/soil treatments on Fusarium and Pythium spp. propagules at KAC in 2007
Table 3. Effects of 1,3-D with surface treatments on broadleaf and grass weed density and biomass at KAC in 2007
Table 4. Effects of 1,3-D with surface treatments on broadleaf and grass weed density and total weed biomass at SJVASC in 2008
A report on the pest control aspects of the two research station trials conducted in 2007 and 2008 was published as:
Jhala et al. 2011. Effects of surface treatments and application shanks on nematode, pathogen, and weed control with 1,3-dichloropropene. Pest Manage. Sci. (in press). DOI 10.1002/ps.2249.
Additional reports are being finalized and will be added in the future.
Various aspects of this project have been reported on at the International Research Conference on Methyl Bromide Alternatives and Emission Reductions (MBAO.org) including: