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  • Author or Editor: Jeanne Briggs x
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Field research was conducted at a container nursery to investigate fungicide movement in runoff water. Fungicides were applied as either a preventative treatment to all container plants, or as a component of an integrated pest management (IPM) program in which fungicides were only applied to plants showing signs of pathogen infestation. Thiophanate-methyl and chlorothalonil were applied in July and August 1998, and metalaxyl was applied in September 1998. Runoff water was sampled on the day after application (first irrigation after pesticide application) through three pulse irrigation cycles. Total amounts of thiophanate-methyl and chlorothalonil in runoff water were 7% and 4%, respectively, of applied amount in July. In August, 2% and 4% of thiophanate-methyl and chlorothalonil were found from the preventative treatment. Of the applied metalaxyl, 25% was detected in runoff water for the first irrigation event after application from the preventative treatment. Metalaxyl is a highly water soluble pesticide and nontarget losses from the granular application contributed to the large amounts detected. Total amounts of thiophanate-methyl, chlorothalonil and metalaxyl detected in runoff from the IPM treatment were 25% of amounts from the preventative treatment. No treatment differences were found in container plant salability or in the number of culls at the end of the study.

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This study investigated effects of two pesticide applications regimes, Integrated Pest Management (IPM), in which pesticides were only applied to affected plants when damage was noticed, and Traditional, in which pesticide applications were made on a scheduled and preventative basis, on growth and health of container grown plants. Field research was conducted at a large wholesale nursery in the piedmont region of South Carolina. An isolated portion of the nursery contained eight beds that housed 25 species of woody and herbaceous ornamentals. IPM beds were subjected to weekly in-depth scouting of indicator species, and all other plant materials in both treatments were visually checked for problems on a weekly basis. The study began in June 1998 with weekly scouting ending in late October. Monthly scouting continued through the winter of 1999. Runoff water was collected from the treatments after all pesticide applications and analyzed to determine concentrations of chemicals. Plant health was rated at study's end to allow comparison between treatments. Amounts of isoxaben detected in runoff water were 7.9 g for the traditional treatment and 0.9 g for the IPM treatment. Amounts of thiophanate-methyl and chlorothalinol were similarly lower for the IPM treatment. Preliminary results indicate that plant growth was similar for both treatments.

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The pesticides isoxaben, trifluralin, chlorpyrifos, and thiophanatemethyl were applied at recommended rates to a 4-ha growing bed at an operating container nursery. Runoff samples produced by overhead irrigation were collected from three waterways, 300 feet long × 6 feet wide. The waterways were a sodded hybrid bermudagrass, a plantation of common cattails (Typha latifolia), and a gravel–clay waterway used as a reference. A 2-ha area drained into the sodded waterway, which flowed into the cattails, and a 2-ha bed flowed into the reference waterway. Samples were collected throughout the duration of runoff on day of treatment and at 1, 2, 8, 15, and 22 days after treatment. Runoff volumes were recorded over time as measured at weirs. Analysis was by HPLC following solid-phase extraction. Only isoxaben was detected at 2 days after treatment. Initial concentrations of all pesticides were lower in the vegetated waterways than in the reference.

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