Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: 9/2/2010
Publication Date: 11/2/2010
Citation: Gerik, J.S., Klose, S., Ajwa, H., Grenne, I. 2010. Calla lily production without methyl bromide - Pacific Area-wide Program for MBA. Proceedings of International Research Conference on Methyl Bromide Alternatives. p. 34. Interpretive Summary: Several chemical alternatives to methyl bromide were tested for the production of calla lily bulb in a field near Moss Landing, California. The chemicals were tested at reduced rates under standard plastic tarp and virtually impermeable film. The chemicals were applied with the drip irrigation system. Stand establishments with the alternative chemicals was comparable to the standard methyl bromide treatment. Weed control was generally poorer with the alternative chemicals. Pathogen control was better with most of the alternative treatments. Bulb yield was comparable or better with most of the alternative treatments. The greatest yield was obtained with treatments consisting of a combination of iodomethane, chloropicrin, and metam sodium. A successful calla lily bulb crop can be grown with alternative chemicals provided that pesticide regulations allow their use.
Technical Abstract: Cut flower and ornamental bulb industries rely heavily on a methyl bromide/chloropicrin (MB/Pic) mixture as a key pest management tool. The loss of MB will seriously affect the cut flower and bulb industry, and, in the future, will require growers to use alternative fumigants. Therefore, efficacy of reduced label rates of drip-applied alternative fumigants under high barrier film (virtually impermeable film, VIF) to control soil-borne pathogens and to produce a calla lily bulb crop was tested in Moss Landing relative to the standard MB/Pic shank fumigation at 350 lb/acre and an untreated soil. The primary goal of this project is to demonstrate alternative fumigation systems at on-farm trials to facilitate the implementation of alternative pest management strategies by the California cut flower and ornamental bulb industry. Relative to the MB/Pic shank standard (350 lb/acre), reduced rates of all drip-applied fumigants (150-200 lbs/acre) resulted in similar calla densities at 11 to 16 weeks after planting. At 22 weeks after planting, alternative fumigants followed by metam-sodium (Vapam) had significantly higher crop densities than the MB/Pic shank standard, with exception of Pic 60 EC. Weed control of reduced rates of drip-applied fumigants was generally lower than the MB/Pic shank standard. Weed control by alternative fumigants was improved if followed by Vapam 5-7 days after the first fumigant application. Pathogen control was significantly improved by all alternative fumigants relative to the MB/Pic shank standard. At 11 weeks after planting, Pythium was recovered from soils collected in the following treatments: untreated control (UTC), and UTC fb Vapam, Pic60 EC, and MB/Pic shank and drip-applied. Numbers of infected bulbs, randomly collected from entire plot area (N = 12) were 92% in the MB/Pic shank standard (350 lbs/acre), and ranged from 58% (MB/Pic, 150 lbs/acre) to 27% (Midas, 150 lbs/acre) in drip-applied treatments. In general, no infected bulbs were found if alternative fumigants were followed by sequential Vapam application (50 GPA). Bulb yield and quality data were evaluated after crop harvest in November 2008. The greatest yield was obtained with Midas + Vapam treatments. Several of the other treatments had greater yields compared to the Mb/Pic shank treatment, the exceptions being the InLine/Vapam treatments and the Pic treatments. The addition of Vapam provided for greater yield except for treatments containing 1,3 –D where the treatments without Vapam outperformed those with Vapam. The VIF treatments generally had greater yields than the HDPE treatments. In summary, it appears that a calla lily bulb crop can be grown with low rates of alternative treatments. Present and future pesticide regulations could preclude the use of some of the combinations tested in this trial.