MSc Defense- Brendan Metzger


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

Tuesday, January 8th at 9:00 AM
Crop Science Building, Room 202

Thesis Title: Evaluation of Tolpyralate for Weed Management in Field Corn (Zea mays L.)

Advisory Committee:

Dr. Peter Sikkema, Advisor
Dr. Darren Robinson, Co-advisor
Dr. David Hooker
Dr. Alan Raeder

Examination Committee:

Dr. Clarence Swanton, Chair
Dr. Peter Sikkema
Dr. Darren Robinson
Dr. François Tardif


Twenty-seven field experiments were conducted from 2015-2018 at nine locations to evaluate tolpyralate, a new pyrazolone 4-hydroxyphenyl-pyruvate dioxygenase inhibitor, for weed management in corn. The biologically-effective dose of tolpyralate and tolpyralate + atrazine was established in eight common annual weed species, and separately in multiple herbicide-resistant (MR) Canada fleabane and waterhemp biotypes. Co-application of tolpyralate with atrazine improved weed control; tolpyralate + atrazine at label rates provided similar or improved control of eight common weed species, MR Canada fleabane and MR waterhemp compared to current industry standards. Four weed species were controlled equally regardless of postemergence application timing,  and two species were controlled with tolpyralate + atrazine applied pre-emergence; annual grass control declined with delayed applications. Corn was at greatest risk of injury with tolpyralate + atrazine applied at V1 or V3 growth stages, and at 2X rates. Injury was influenced by environmental variables, but did not translate to grain yield loss.