Interested Members of the University Community are invited to attend the Final Oral Examination for the Degree of Doctor of Philosophy of Katiani Eli of the Department of Plant Agriculture                         

Date: Friday, February 18th, 2022
Time: 10:00 AM 

Via Zoom:https://zoom.us/j/91285815257?pwd=KzhwZDB5L2RnM0RrYTZKaEh3OFFjUT09 
Meeting ID: 912 8581 5257
Passcode: 565721 

Thesis Title: "Management of Fusarium graminearum and its mycotoxins in Ontario maize" 

Advisory Committee
Dr. Art Schaafsma (Advisor) 
Dr. David Hooker (Co-advisor)
Dr. David Miller
Dr. Cheryl Trueman

Examination Committee
Dr. Helen Booker, Chair
Dr. Dilantha Fernando, External Examiner
Dr. Art Schaafsma 
Dr. Manish Razaida 
Dr. Dave Hooker

ABSTRACT 

In the Great Lakes region of North America, gibberella ear rot (GER), caused by Fusarium graminearum Schwabe, affects grain quality due to the production of mycotoxins, resulting in multi-million-dollar losses annually. The management of GER requires an integrated approach using prediction tools, agronomic practices, genetics, and fungicides. The objective of this research was to determine effective management strategies for F. graminearum in grain maize in Ontario. Specifically, the efficacy of fungicides, including a novel carboxamide fungicide (pydiflumetofen), was evaluated for management of mycotoxin accumulation in small misted plots and field experiments from 2017 to 2019. The optimal fungicide application time was also investigated. The impact of agronomic practices such as plant population density, the effect of plant stress caused by in-row-plant developmental variability, and the effect of incorporated refuge genetics on mycotoxin accumulation was also investigated in small misted-plots in 2019 and 2020. A survey was conducted on F. graminearum isolates from southwestern Ontario to determine the mycotoxin profile and the range of sensitivity of strains isolated from wheat kernels, maize kernels and overwintering maize stalks to fungicides currently recommended to manage GER and fusarium head blight (FHB). The results show that the best fungicide timing to reduce mycotoxins accumulation and GER severity was at full silk stage. Relatively high plant population densities and in-row-plant developmental variability increased mycotoxin concentrations because of plant competition rather than environmental conditions, highlighting the importance of reducing plant competitive stress as a strategy to reduce mycotoxin concentrations. In this study, there was no l difference in DON accumulation between the Bt component and the non-Bt component in each of four not-Bt refuge-incorporated hybrids tested.  However, there was evidence that hybrids varied in susceptibility to mycotoxins. Lastly, the majority of isolates in Ontario are able to produce both 3ANX and 15ADON. The chemotype was not affected by isolate source (wheat grain, maize grain, maize stalks) and all isolates tested were sensitive to the main fungicides used to manage GER and FHB in Canada. 

Publications: 

Eli, K., Schaafsma, A. W., Limay-Rios, V., & Hooker, D. C. (2021).  Effect of pydiflumetofen on Gibberella ear rot and Fusarium mycotoxin accumulation in maize grain. World Mycotoxin Journal 14:495-512.  https://doi.org/10.3920/wmj2020.2638 

Eli, K., Schaafsma, A., & Hooker, D. C. (2022). Impact of agronomic practices on Fusarium mycotoxin accumulation in maize grain. World Mycotoxin Journal (in press). 

Eli, K., Limay-Rios, V., Hooker, D. C., Miller J. D., & Schaafsma, A. W. (In review). Trichothecene mycotoxin profiling of Fusarium graminearum isolates from wheat and maize, and the baseline sensitivity to pydiflumetofen and other fungicides. World Mycotoxin Journal.