Fusarium graminearum is a fungus that causes disease in corn, wheat, barley and oat. Not only do these diseases affect yield, but the fungus produces toxins that helps it gain access to the plant. These mycotoxins are harmful to humans and livestock and are regulated in the grain trade. Left unchecked, contaminated grain and yield losses can cost producers and the grain trade $ millions in epidemic years. Originally in Ontario we had one strain of F. graminearum that produced the mycotoxin deoxynivalenol (DON) using 15-A-deoxynivalenol as a precursor molecule. We called these 15 ADON strains. Recently by routine surveying we have noticed that a new strain producing a new toxin called 3ANX along with 15 ADON is showing up in the field. Preliminary experiments have shown that these NX strains result in 3-4 times the amount of DON in grain in diseased plants, compared with the 15 ADON strains. As these NX strains become more common in Ontario, we worry that DON contamination will become more intense than it is today. This project will identify their expected impact in Ontario.