Assessing and mitigating risks to plant diversity in agroecosystems from biotechnology-based PGR herbicide use

Plant biodiversity contributes to multiple services and functions in agroecosystems but has been in decline in many agricultural regions for decades._ The impending commercialization of genetically modified soybean and cotton resistant to plant growth regulator (PGR) herbicides including dicamba and 2,4-D will likely lead to a dramatic increase in the use of these compounds and may pose a significant new risk to agricultural plant biodiversity, with important potential consequences for crop productivity and agroecosystem sustainability._ In response to the spread of glyphosate resistant weeds, the biotechnology industry is developing genetically modified soybean and cotton resistant to 2,4-D and dicamba, which are both well known to be volatile herbicides prone to drifting off of targeted fields._ Many plant species are extremely sensitive to these herbicides, and increasing frequency of PGR drift may cause direct injury and yield loss to susceptible crops and decreased quality and diversity in non-crop plant communities. My PhD research will address these risks through meeting the following objectives: use a detailed floristic survey combined with_ species area curve modeling to explore the relative contributions of crop and non-crop habitats to agricultural plant species diversity at landscape scales quantify the extent and concentration of PGR vapor under different formulations and application conditions use published literature and meta-analysis to describe the susceptibility of economically important crops to drift rates of dicamba and 2,4-D use experiments on natural plant communities to quantify the effects of drift doses of dicamba to non-target vegetation and associated insect communities, including beneficial species. In meeting these objectives, this research will also highlight key opportunities to mitigate these risks while using PGR herbicides effectively, for instance using appropriate application timings and low volatility formulations._ PGR resistant cultivars are likely to affect most of the 31 million ha of soybean and 3 million ha of cotton grown in the U.S., and our research will work to ensure that this biotechnology is commercialized within a robust understanding of potential benefits and risks to agroecosystems.

Contact

  Dan Grear
  ecologyservice@psu.edu