MSc Final Oral Examination:Theodore vanhie


Interested Members of the University Community are invited to attend the Final Oral Examination for the Degree of Master of Science of Theodore Vanhie of the Department of Plant Agriculture

Date: Monday, May 11, 2020
Time: 10:00 AM

Delivered via Zoom - To Join the Seminar using Zoom Meeting please email

Thesis Title:  An Integrated Weed Management Strategy for the Control of Canada Fleabane (Conyza canadensis)

Advisory Committee
François Tardif, Advisor
Carence Swanton, Co-advisor
Michael Cowbrough               

Examination Committee
Peter Pauls, Chair
François Tardif
Clarence Swanton
Darren Robinson       


The global increase in the number of reported herbicide resistance weeds continues to rise at an increasing rate, despite current efforts to tank mix and rotate herbicides to mitigate this very issue. The repeated use of glyphosate resulted in glyphosate-resistant Canada fleabane [Conyza canadensis (L.) Cronq.] populations in Delaware, USA, in 2001, and Ontario, Canada, in 2010. Previous research has reported cereal rye (Secale cereale L.) cover crops consistently reduce the density and height of Canada fleabane. In order to develop an integrated weed management strategy, this research tested if fall-seeded rye can reduce Canada fleabane seedling density and suppress seedling growth, then the interaction(s) of multiple selection pressures should improve the level of control of Canada fleabane. In 2018 and 2019, field studies were conducted to evaluate the interactions between fall-seeded cereal rye cover crops, shallow fall tillage, and spring-applied herbicide treatments. It was observed that interactions between treatment groups had an additive effect on improving weed control. The interactions and effectiveness of each imposed selection pressure, however, varied between the two years. This research recognizes with the implementation of an integrated weed management strategy, environmental variables in any given year will have a direct influence on the interactions that occur among the selection pressures imposed.