- Author: Brad Hanson
Today I wanted to follow up on my post from a few weeks ago about volatile organic compounds (VOC) from herbicides and other non-fumigant pesticides. In case you missed it, the discussion on February 27 was about an online VOC calculator developed by California Department of Pesticide Regulation (CDPR). This tool allows users to compare calculated VOC emissions of individual pesticides or season-long pesticide programs.
In the same area of the CDPR website, there is a document called "Conservation Management Practices Guide: Reducing Volatile Organic Compounds (VOC) Emissions from Agricultural Pesticide Applications". This paper gives some background on the problem, related lawsuits, and what DPR (and California pesticide users) are doing to meet reduced VOC emission goals. Not all VOCs are from agriculture - many commonly used commercial, industrial and home products also contribute VOC. However, agricultural pesticides such as fumigants, insecticides, fungicides, and herbicides are important VOC contributors in some ares of the state.
In some air basins, soil fumigants are the primary contirbutors to agricultural VOC. But in the San Joaquin Valley, non-fumigants are responstible for about 65% of the pesticide VOC. Formulation has a lot to do with the VOC content of specific pesticides. For example, products formulated as emulsifiable concentrates (EC) tend to have the highest emissions due to the solvents used to emulsify the active ingredient. These products typically have a strong "chemical" smell (think Goal 2XL, Prowl EC, Lorsban, Eptam, etc. Solid formulations like wettable powders (WP) water dispersable granuals (WDG), granuals (G) etc. typically have the lowest VOC content. Other liquid formulations like soluble concentrates (SC) are somewhere in the middle. DPR is working with pesticide manufacturers as much as possible to reformulate products with high VOC emissions but this is not neccessarily fast, easy, or without impact on efficacy and must be considered on a case-by-case basis.
The management guide (in the link above and attached below) discusses several steps growers can take to help reduce VOC emissions from pesticide applications. Most of them make a lot of sense to me from a VOC standpoint as well as from the standpoing of farm economics and general environmental stewardship.
- If fumigating, use low-emission techniques during the May-October peak ozone season.
- Use appropriate integrated pest management (IPM) practices (makes sense for many reasons!). Monitor pests, properly identify, and treat only when neccessary.
- Reduce total pesticide use by reducing treated acreage or number of applications (think strip sprays in orchards). Also spot treated isolated problems instead of treating whole fields may be possible in some situations.
- Use low VOC formulations or alternatives if feasible (see my previous comparison of GoalTender vs Goal and Prowl H2O vs Prowl EC).
- VOC are more likely to contribute to ozone problems during the summer. Making pesticide applications before May or after October can help reduce the environmental impacts of the VOC that are emitted.
As members of the agricultural research, advisory, and producer communities, our pesticide choice, rates, and application techniques impact pest control efficacy and the environment. Although these goals are sometimes seem at odds, making educated and informed decisions give us the best chance of the most positive overall outcome.