Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: August 27, 2004
Publication Date: November 1, 2004
Citation: Gerik, J.S. 2004. Soil fumigation for freesia production. Proceedings of International Research Conference on Methyl Bromide Alternatives. No volume number, pgs. 85-1 - 85-4. Interpretive Summary: With the impending phase-out of methyl bromide for soil fumigation, flower growers will require alternative methods to control weeds and diseases for continuous production. Fumigants such as Midas ™ InLine ™, Vapam HL ™ and Multiguard ™ are possible alternatives to methyl bromide. These fumigants can be delivered in drip irrigation systems, permitting better distribution through the soil by the irrigation water. Three trials on 2 sites were conducted to test the efficacy of the before mentioned fumigants for the control of weeds and disease for the production of the cut flower, Freesia. It was found that Midas preformed as well as a combination treatment of methyl bromide and chloropicrin. InLine preformed as well as Midas, but Multiguard required the addition of Vapam HL to perform as well as Midas and InLine. The study shows that Freesia can be produced following fumigation with Midas, Inline, or Multiguard plus Vapam HL.
Technical Abstract: Hybrid freesia (Freesia x hybrida L.) is grown in field soil under shade on the coast of California for cut flower production. A variety of weed species can quickly overgrow the sparse canopy of the crop. The crop is susceptible to Fusarium oxysporum which causes a classical yellows disease. Pre-plant soil fumigation with methyl bromide/chloropicrin is commonly employed as a means of weed and disease control. The soils are usually fumigated with a 98/2 formulation using the hot gas method. Two experiments were established to evaluate alternative fumigants applied through drip irrigation tape for freesia production. A freesia flower trial was established in Nipomo, CA. The treatments were 5 InLine (1, 3 dichloropropene, 60.8% + chloropicrin 33.3%) rates (251, 377, 502, 628, & 706 kg/ha) compared to the water control. The trial was planted with corms on 24 November 2003. A second freesia trial was established in Encinitas, CA in a greenhouse. The treatments, made on 15 October 2003 in 3.8 cm of water, included 448 pounds per hectare Midas (iodomethane 47.5% + chloropicrin 47.5%), 706 kg/ha InLine, 672 kg/ha (ai) Multiguard (furfural), and 672 kg/ha (ai) equal parts Multiguard and Vapam (metham sodium) and a non-treated control. The trial was planted with corms on 5 November 2004. Populations of P. ultimum were reduced by all treatments in both trials. All rates of InLine reduced the populations equally. Multiguard alone reduced the populations to a lesser extent than Midas, InLine and Multiguard plus Vapam. Populations of F. oxysporum were not significantly reduced in the Encinitas trial. In both trials the incidence of Fusarium yellows was not significantly reduced by any of the treatments. Initial weed populations were reduced with all treatments, but weeds continued to emerge throughout the growing season in all treatments. Both trials were conducted from late fall into the winter when weed pressure is lower. Although methyl bromide/chloropicrin was not directly compared with the treatments in either trial, observation from adjacent plantings and conversations with the growers indicate that none of the treatments in these two trials performed as well as the standard treatment of methyl bromide/chloropicrin.