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

Date: Tuesday, December 22^nd, 2020
Time: 11:00 AM  

Delivered via Zoom 

To Join the Seminar using Zoom Meeting:  

https://zoom.us/j/94411607814?pwd=NkIvQ2hvVU45b1JKVlFaSVZVZCtoUT09 

Meeting ID: 944 1160 7814 

Passcode: 926273 

Please contact me at moc@uoguelph.ca if you wish to be added to the list to attend the examination portion of the defense.  

Thesis Title: Characterisation of resistance to ALS inhibitors in Chenopodium album (L.) populations in Ontario 

Advisory Committee
Dr. François Tardif, Advisor
Dr. Istvan Rajcan
Mr. Mike Cowbrough

Examination Committee
Dr. Katerina Jordan, Chair
Dr. Francois Tardif
Dr. peter Sikkema
Mr. Mike Coubrough               

ABSTRACT 

Four post-emergent acetolactate synthase (ALS) inhibiting herbicides were evaluated for resistance against two susceptible (S) and two suspected resistant (R) populations of Chenopodium album (L.) (common lambsquarters) using whole plant spraying and enzyme inhibition assays. Thifensulfuron-methyl (sulfonylurea), imazethapyr (imidazolinone), thiencarbazone-methyl (triazolinone) and pyrithiobac-sodium (pyrimidinylthiobenzoate) were all applied at varying doses. Above ground biomass and visual injury data were taken nine days after treatment. Resistance to thifensulfuron-methyl was confirmed in the two suspected resistant populations and cross resistance was discovered to the three other classes of ALS inhibitors. ALS inhibition assay revealed 157- to 729-fold-resistance to thifensulfuron and up to 6930-fold to pyrithiobac, confirming resistance due to enzyme target site modification.