Interested Members of the University Community are invited to attend the Final Oral Examination for the Degree of Master of Science of Sydney Wardell Boersma, of the Department of Plant Agriculture

Wednesday, April 24, 2019
Time: 9:30 AM
Location: Room 202, Crop Sciences Building

Available in Ridgetown via intercom in RDC Boardroom- Please inform of use

Thesis Title: Residual herbicide impact on cover crops utilized within cropping systems for weed suppression in Ontario

Advisory Committee:
Dr. Darren Robinson. Advisor
Dr. Peter Sikkema, Co-advisor
Dr. Nader Soltani                          

Examination Committee:
Dr. Milad Eskandari, Chair
Dr. Francois Tardif
Dr. Darren Robinson
Dr. Peter Sikkema                                                                           

ABSTRACT

Cover crops provide multiple benefits and can be incorporated into various Ontario cropping systems. In this study the cover crops annual ryegrass (Lolium multiflorum Lam.), and red clover (Trifolium pretense L.) interseeded into V4 corn were evaluated for weed suppression. The second cropping system studied was the planting of the cover crop oilseed radish (Raphanus sativus var. oleiformis) for weed suppression after winter wheat harvest. A major concern with cover crops is whether the herbicide program incorporated on the main crop will affect the establishment and growth of the cover crop. In the case of interseeding cover crops an additional concern is whether the cover crop will compete with main cash generating crop. S-metolachlor/mesotrione/atrazine, S-metolachlor/mesotrione/bicyclopyrone and S-metolachlor/mesotrione/bicyclopyrone/atrazine applied PRE resulted in 91-99% red clover, and 74-94% annual ryegrass injury. S-metolachlor, atrazine and S-metolachlor/atrazine, applied preemergence (PRE) caused 73 to 86%, <1% and 83 to 89% annual ryegrass injury, respectively. In the intercropping studies annual ryegrass and red clover had no effect on grain corn yields. Bromoxynil/bicyclopyrone and bromoxynil/pyrasulfotole applied POST in winter wheat did not injure or reduce oilseed radish biomass, and bromoxynil/bicyclopyrone followed by oilseed radish in 2017 reduced total overall weed density, but not common lambsquarters density. Bromoxynil/pyrasulfotole at the high rate and latest application timing resulted in dandelion control greater than the herbicide free control.