Are herbicides a once in a century method of weed control?

Abstract

The efficacy of any pesticide is an exhaustible resource that can be depleted over time. For decades, the dominant paradigm - that weed mobility is low relative to insect pests and pathogens, that there is an ample stream of new weed control technologies in the commercial pipeline, and that technology suppliers have sufficient economic incentives and market power to delay resistance - supported a laissez faire approach to herbicide resistance management. Earlier market data bolstered the belief that private incentives and voluntary actions were sufficient to manage resistance. Yet, there has been a steady growth in resistant weeds, while no new commercial herbicide modes of action (MOAs) have been discovered in 30 years. Industry has introduced new herbicide tolerant crops to increase the applicability of older MOAs. Yet, many weed species are already resistant to these compounds. Recent trends suggest a paradigm shift whereby herbicide resistance may impose greater costs to farmers, the environment, and taxpayers than earlier believed. In developed countries, herbicides have been the dominant method of weed control for half a century. Over the next half-century, will widespread resistance to multiple MOAs render herbicides obsolete for many major cropping systems? We suggest it would be prudent to consider the implications of such a low-probability, but high-cost development. © 2017 Society of Chemical Industry.

An ecological perspective on managing weeds during the great selection for herbicide resistance

“…The first wave of HT crop cultivar development and adoption, beginning notably with the release of glyphosate‐tolerant soybean and maize cultivars in the late 1990s, revolutionized weed management in field crops. Never before had weed control been so easy or inexpensive, and this drove rapid market penetration of the technology in the following decade . Although the choice to plant a HT cultivar may seem to be a clear‐cut matter of private property, pertaining to the control of weeds within the boundaries of a single management parcel, the potential for landscape‐level movement of herbicide‐resistance traits, through seed and/or pollen movement, makes this a decision that influences a public good, herbicide susceptibility.…”

“…In a landscape where HT cultivar adoption drives cost‐effective use of a particular herbicide SOA, individual producers would have no incentive to refrain from using that HT cultivar in order to protect the long‐term efficacy of the associated herbicide because they would lose money by using a more expensive program when their neighbors continue to use the HT crop combined with the inexpensive herbicide option. This is an example of a common pool resource problem, also known as the ‘tragedy of the commons,’ and explains how herbicide resistance can become an externality of HT cultivar adoption, since it is not priced into the use of the product . It also demonstrates the current lack of industry stewardship, and future necessity of industry participation in any comprehensive solution to this problem, since the price landscape will need to be altered to affect producer behavior at large landscape scales …”

“…Evolution of herbicide resistance, and eventual loss of control, appears to be nearly unavoidable in weed control approaches based solely on herbicides . Evidence from controlled environmental and epidemiological studies indicates limited, or no, fitness costs of many herbicide sites of action (SOA) in corn and soybean production systems.…”

Herbicide resistance evolution can be tamed by diversity in irrigated Australian cotton: a multi‐species, multi‐herbicide modelling approach

“…Herbicide resistance is the evolved response of weed biotypes to survive doses of a herbicide that would kill normal individuals of the same species and is a well‐established problem in industrial agricultural systems across the world (see also Heap I, http://www.weedscience.org for the standard comprehensive picture of the problem at a global level). Experts in herbicide resistance have advocated for increased diversity in weed management systems as the appropriate response to the evolution of herbicide resistance for several decades – perhaps informally since the first identification of evolved herbicide resistance as a phenomenon.…”

Pest Management Science in 2017

“…November brought perspectives on quantum chemistry in environmental pesticide risk assessment and on the differences between progress of biopesticide adoption in the EU and other areas . Davis and Frisvold have a thought‐provoking review of the implications of past herbicide use on future use. Our December issue contains a commentary on rodent management strategies and a review on the role of intracellular proteases in insecticide resistance …”