Busting myths on southern rust’s spread

Was this year’s southern rust outbreak caused by a new “super strain”? Can it overwinter in Nebraska? Let’s set the record straight.

This growing season was one for the record books in parts of Nebraska — and not in a good way when it comes to corn disease.

Southern rust, in particular, was more severe in extreme eastern Nebraska than witnessed in recent history — and for the second year in a row. It also showed up in parts of northeast Nebraska where it rarely causes yield loss.

Unfortunately, misinformation can spread quickly. Let’s address some of these concerns before we start making decisions that could affect next year’s crop.

Myth No. 1: Overwintering rust

The southern rust fungus cannot overwinter in Nebraska. Puccinia polysora needs to infect living, green corn in order to survive, and there is no known alternate host.

Thus, the fungus can’t overwinter anywhere the climate doesn’t support corn growth through the winter months.

In fact, our rust fungi are likely blown north into the United States from subtropical locations, such as parts of Mexico, where corn is grown year-round.

The southern rust fungi typically reach Nebraska in late July. However, this year they arrived earlier than usual, with the first confirmed sighting on July 9 — the earliest on record for the state.