|Klose, Susanne - UNIVERSITY OF CALIFORNIA|
|Ajwa, Husein - UNIVERSITY OF CALIFORNIA|
|Greene, Ian - GOLDEN STATE BULB GROWERS|
Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Proceedings
Publication Acceptance Date: August 31, 2007
Publication Date: November 1, 2007
Citation: Klose, S., Ajwa, H., Gerik, J.S., Greene, I.D. 2007. Acrolein as Potential Alternative to Methyl Bromide in California-Grown Calla Lilies. International Conference on Methyl Bromide Alternatives and Emissions Reductions. Interpretive Summary: Acrolein at three different rates was compared to the standard methyl bromide/chloropicrin treatment for disease and weed control for hybrid calla lily production. Acrolein reduced Pythium numbers relative to the untreated control by about 50%, while methyl bromide/chloropicrin fumigation led to a complete control of this pathogen. No changes in Pythium control were found between different Acrolein rates. Fusarium survival decreased markedly with increasing Acrolein rates. Reductions in pathogen numbers were significant for the highest Acrolein rate tested in this study. At 8 weeks after planting, calla lily stand densities were similar in the Acrolein and methyl bromide/chloropicrin treated plots. Stand counts were significantly reduced in untreated plots with only 50% of the densities found in fumigated plots. There were no statistical differences in total numbers of resident weeds in plots treated with methyl bromide/chloropicrin and all Acrolein treatments. The trial is continuing with yield data to be collected at its conclusion.
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 methyl bromide (MB) will seriously affect the cut flower and bulb industry, and in the future, will require growers to use alternative fumigants. Therefore, three different rates (100, 200, and 400 lb/A) of Acrolein (acrylaldehyde-2 propenal) were evaluated relative to an untreated control and the standard 2/1 mixture of MB/CP to control weeds, and the soil-borne pathogens Pythium and Fusarium oxysporum in commercial calla lily systems in Central Coastal California in the 2006-2007 growing season. The economic viability of the tested Acrolein rates was evaluated by plant growth, yield and flower bulb quality assessments. Preliminary results of this field trial showed that sensitivity of calla lily towards Acrolein was low. Acrolein at rates from 100 to 400 lb/A had no negative effect on crop quality and appearance at 21 days past germination. Acrolein at a rate of 400 lb/A was sufficient to kill about 50% of the propagules of native Pythium spp. and 73% of Fusarium oxysporum in soil immediately after fumigation, indicating that Acrolein can provide some control of these important plant pathogens. Weed control of Acrolein at 400 lb/A was similar than those provided by MB/Pic. However, Acrolein at the high rate controlled only 60% of the volunteer crops (Zantedeschia spp.). Stand density evaluations suggested that efficacy of Acrolein for pathogen control decreased over the course of this field trial resulting in increasing death rates among calla lily crop as the disease pressure increased. Although a fair control of key pests, with the exception of volunteer crops, was provided by Acrolein up to 4 months after planting, in particular, pathogen control efficacy decreased markedly during the following months as indicated by significantly lower stand densities and flower counts. Long lasting pest control is crucial for an economical production of this 18-month crop. Therefore, significantly higher application rates than tested in this trial and improvement of its pathogenic action over the entire calla lily growing season by combination with other pesticides seem to be required for results equivalent to the standard MB/CP fumigation.