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United States Department of Agriculture

Agricultural Research Service

Title: Assessment of Fungicide Distribution and Deposition in the Greenhouse with Electron Beam Analysis

Author
item Krause, Charles

Submitted to: Scanning
Publication Type: Proceedings
Publication Acceptance Date: April 28, 1999
Publication Date: N/A

Interpretive Summary: Production of greenhouse woody ornamentals represent approximately 10% of American crop receipts. Unfortunately, bugs and fungus diseases cause millions of dollars of greenhouse crop losses every year. Effective control materials such as insecticides and fungicides must be applied to produce aesthetically pleasing plants. New guidelines for registering, using and maintaining pesticides through the US Environmental Protection Agency were created by the Food Quality Protection Act of 1996 (FQPA-96) and requires information on how pesticides are used. Under FQPA-96, a model or risk cup compares theoretical to actual real world data to establish relative, cumulative lifetime exposure for each pesticide, especially for infants and children. Now research is crucial on how to spray pesticides as their use is curtailed. Assessment used to involve indirect techniques including fluorescent tracers and artificial targets like screens, string and tape. Now a unique, alternative and direct assessment method called, electron beam analysis (EBA), was developed. EBA combines scanning electron microscopy (SEM), that makes highly magnified images, with an energy dispersive x-ray analyzer (EDXA) that does chemical analysis. In various studies, vinclozolin, chlorothalonil and mancozeb fungicides were traced through greenhouses of rhododendrons, poinsettias and euonymus plants and measured using EBA. This knowledge will help protect farm workers, consumers and the environment.

Technical Abstract: Diseases and insects significantly reduce the value of greenhouse crops. representing more than an estimated $5 billion per annum in farm-gate receipts to American agriculture. Excessive off-target pesticide loss leads to reductions in efficacy and crop quality, resulting in increased production costs and potential environmental contamination. Conventional application assessment strategies employ indirect techniques including fluorescent dyes and artificial targets like screens, string and polyethylene tape. Electron beam analysis (EBA) is a unique, alternative assessment method that combines scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA) with digital image analysis. Vinclozolin, in a smoke formulation, was tracked through a greenhouse and measured using EBA (Krause et al. 1989). Distribution of the greenhouse smoke formulation of chlorothalonil fungicide was also measured with EBA. In recent studies, residue of Protect T/O a formulation of mancozeb fungicide, was quantified by EBA in greenhouse canopies of Euonymus spp. EBA enabled identification of mancozeb as angular particles of 1-18 m in size in a droplet (arrows). EDXA of those particles in revealed the presence of Mn. As the use of conventional fungicides is curtailed in greenhouse production, it will become increasingly important for growers to address effective coverage, worker protection and other environmental issues, problems depending on these and similar research findings for solution.

Last Modified: 7/31/2014
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