Integrated Weed Management is not compatible with current farm and machinery types and government policies prop up the GM model
The paper below, by French and US researchers, doesn't appear to be peer-reviewed but it is a clear and fascinating account of the dynamics that are locking in US Midwest farmers to the GM herbicide-tolerant crop farming model.
A discussion of the market and policy failures associated with the adoption of herbicide-tolerant crops (No. 18-959)
Bullock, D. S., D'Arcangelo, F. M., and Desquilbet, M. (2018). Toulouse School of Economics (TSE)
https://ideas.repec.org/p/tse/wpaper/32982.html (open access)
* Weed resistance to herbicide-tolerant (HT) crops is developing in the U.S. Midwest.
* Large-scale use of integrated weed management (IWM) is not expected to arise.
* The main obstacle to IWM is the nonprofitability of longer crop rotations.
* Self-reinforcing mechanisms foster the dominance of herbicidal weed control.
Weed control in the U.S. Midwest has become increasingly herbicide-centric due to the adoption of herbicide-tolerant (HT) crops in the 1990s. The scarcity of the use of integrated weed management (IWM) practices, including biological and mechanical controls, is concerning for two reasons. First, herbicides create negative health and environmental externalities. Second, weed resistance to some herbicides is increasing, which creates incentives to use additional herbicides. However, it seems certain that weeds will develop resistance to those herbicides as well, so applying “herbicide upon herbicide” is socially problematic. In this context, we develop an economic framework to clarify the interplay among the different market failures that either contribute to the herbicidal “lock-in” or make it problematic. We then analyze the evidence for and perceptions of these market failures based on twenty-four semistructured interviews with farmers and experts conducted in 2017, as well as discussions in the academic literature. To this end, we put into perspective the possible self-reinforcing effects in the adoption path of HT crops, such as increasing farm size, changes in farm equipment, increasing incentives for simplified crop rotations, and the loss of practical knowledge of IWM practices.