Location: Forage Seed and Cereal ResearchTitle: Effects of precipitation on molluscicidal efficacy Author
Submitted to: Seed Production Research at Oregon State University
Publication Type: Experiment Station
Publication Acceptance Date: 2/28/2009
Publication Date: 3/31/2009
Citation: Gavin, W.E., Fisher, G., Dreves, A., Banowetz, G.M. Effects of precipitation on molluscicidal efficacy. Seed Production Research at Oregon State University. 2009. p. 55-61. Interpretive Summary: A study ws conducted to compare how precipitation common to western Oregon affected the utility of slug baits for controlling slug damage in grass seed fields. Six commonly used bait formulations were exposed to specific amounts of precipitation before being tested for their efficiency in controlling slugs and reducing the amount of slug damage to new crop seedlings. All six formulations were effective, even after six days of weathering, but two of the formulations were effective after 12 or 15 days of weathering, respectively. Costs of utilizing these baits ranged from $14 to $22.50 per acre. An iron phosphate bait was most susceptible to weathering, but also was most effective during the first 24 hours of the trial.
Technical Abstract: Weathering of slug baits due to rainfall common to western Oregon when new stands of grass seed crops are established may reduce the efficiency of the baits and consequently, increase the cost per acre of slug control. This study conducted field and greenhouse trials to quantify the impact of weathering on the effectiveness of six commonly used baits. Slug mortality under controlled conditions was monitored, and the reduction of slug damage to newly established grass seedling was quantified. Relative to untrreated control plots, all the baits provided slug control, but there were significant differences in their sensitivity to weathering. Two metaldehyde baits were the most weather resistant while an iron phosphate formulation appeared more deteriorated due to precipitation. The iron phosphate bait, however, provided the greatest slug control during the first night after application. Cost of applications ranged from $14 – 22.50 per acre. A granular formulation of metaldehyde provided the most effective seedling protection, suggesting that an abrupt cessation of feeding occurred after the bait was ingested. All of the products reduced the numbers of slug eggs produced during the first three days of exposure of slugs to the bait.