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4th IPM Symposium

Tracking Pesticide Risk Trends and Tradeoffs
Dr. Charles Benbrook*
Co-PI WISC-FLA RAMP Project and
Benbrook Consulting Services

Abstract :

Many people wonder whether progress has been made in the last ten or twenty years in reducing the risks associated with pesticide use. The General Accounting Office, in its August 2001 report, posed some key, tough questions -- Does IPM really reduce pesticide risks? And if so, to what extent? Are USDA's IPM research and education programs optimally focused on pesticide risk reduction?

The IPM community owes the general public and policy-makers credible answers to such questions. Traditional measures of pesticide use like "pounds applied" and "rate of application" have served for years as proxies for risk. But low-dose chemistry has pulled the rug out from volume-based measures of risk. The transition in the 1990s away from broad-spectrum toxicants to often very-low dose biopesticides that work through specific, targeted modes of action further limits the utility of weight-based measures.

Biotechnology has added some tough new challenges to the already long-list of unanswered questions. While herbicide tolerant crops have not reduced the volume of active ingredients applied, there has been a wholesale shift to glyphosate and away from ALS-inhibitors. All things considered, has this shift toward a lower-risk herbicide been worth the accompanying weed shifts and acceleration of resistance to glyphosate?

On the Bt transgenics front, EPA's recent approval of Cry 3Bb, MON 863 corn for rootworm control was predicated on the notion that it will markedly reduce corn insecticide use and related risks. But what exactly are the risks from today's corn insecticides and application technology, and on what basis are they deemed significant?

A credible comparative assessment of the risks stemming from alternative corn rootworm management strategies and options is yet to be done. Such an assessment should ideally encompass everything from longer rotations to MON 863 corn and conventional cultivars, to applications of modern, low-rate and reduced risk insecticides and seed treatments, to area-wide biointensive insect suppression programs. Insights would probably point to something most IPM practitioners intuitively recognize - the best way to manage corn rootworms, if cost and risk reduction are major goals, will entail complex, changing combinations of many tactics, each targeted to where it will do the most good, rather than heavy and repeated reliance on a single silver bullet.

This key IPM principle leads to an important point anyone trying to measure IPM system and pesticide risk trends must deal with. The impacts of a given practice, system, or pesticide is fundamentally site and circumstance specific. From the farmer's perspective, the impacts of a pesticide or IPM practice are a function of pest pressure, climate, biological interactions, and the production system within which it is deployed, and when and how it is deployed. For the most part, context drives pesticide risk and efficacy outcomes more so than the inherent properties of products. Generally safe pesticides can be used ineffectively and unsafely, and risky high-tox products can be used in ways that reduce risks to levels most people find acceptable.

So measurement systems and risk indicators must be designed in ways that take context into account. "Context" encompasses not just biotic characteristics like pest pressure, but also all the factors that can reduce pesticide exposures to nontarget organisms from people to birds to soil microorganisms - formulations, application methods and equipment, timing, use restrictions and safety precautions on labels (i.e., setbacks from streams or field re-entry intervals), and application rates.

Powerpoint Presentation : Tracking Pesticide Risk Trends and Tradeoffs

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American Farmland Trust