An OMAFRA field crop pathologist says that no corn hybrids truly resistant to tar spot exist in North America. However, he says there are varying levels of varietal tolerance across all companies and platforms.

Tar spot poses challenge for hybrid genetics

Weather a dominant factor in pathogen development, even in tolerant varieties

Tar spot tolerance is strong in some corn hybrids, according to recent research.  There are no truly immune varieties, however, and as the amount of inoculum in the region grows, […] Read more



Tar spot on a corn leaf, including “fish-eyes” (lower right) that can grow and encompass whole parts of a leaf.

Tar spot detected in Ontario

Scouting is critical to deal with spread

Frequent rains and prolonged wetness are likely the contributing factors for Ontario’s earliest instance of confirmed tar spot. “This is the first time we’ve seen it this early based on […] Read more

Tar spot found in Ontario Sept. 21.

What tar spot’s arrival means for Ontario

Cases identified in Lambton and Chatham-Kent, but impact insignificant overall

Tar spot, a pathogen affecting corn, has moved into Ontario, after five years of international attention. Tar spot can cause significant yield losses if left unchecked. The problem does not […] Read more


tar spot

Tar spot breaches Ontario border

Cases identified in Lambton and Chatham-Kent, but impact insignificant overall

After five years of international attention, tar spot has infiltrated Canada’s Great Lakes defences. A pathogen of corn, tar spot can cause significant yield losses if left unchecked. As of […] Read more