PARENT SESSION
Poster Session 24: Agro-Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
The role of wind dispersal in spreading a glyphosate-resistant weed.
Dauer, Joseph*,1, Mortensen, David2, Humston, Robert3, 1 The Pennsylvania State University, University Park, PA2 The Pennsylvania State University, University Park, PA3 Virginia Military Institute, Lexington, VA
ABSTRACT- Quantifying mechanisms and resulting distribution patterns of wind-dispersed seed has long been a goal of ecologists. Development of glyphosate resistance in Conyza canadensis populations highlights the need to understand the role of seed dispersal in an agriculture with declining management diversity (habitat heterogeneity). To this end, seed dispersal patterns were investigated by placing seed traps in transects radiating from a C. canadensis source population. The majority of seed were caught within 100 m, but seed were collected at the most distant traps, 500 m from the source. A circular statistics approach was used to explore potential mechanisms that lead to the observed 2-dimensional pattern. Seed distributions near the source were closely approximated by wind speed and direction. These data indicate seeds readily move within and among fields and can form a foundation for the development of a predictive seed dispersal model at a field and landscape level. This preliminary landscape movement model was used to explore the opportunity for resistant C. canadensis seed to reach field and the ability to establish over a range of land cover types and weed management practices. The rate of the spread of the glyphosate-resistant biotype was positively correlated with the proportion of the landscape where glyphosate was the dominant source of mortality. The findings make a compelling case for maintaining or enhancing the diversity of mortality sources at scales above the individual field. Although weed management practices are generally not made at the landscape level, herbicide resistance in a wind-dispersed species may provide the impetus for changing the scale at which management decisions are made.
Key words: wind dispersal, glyphosate resistance, Conyza canadensis