By Lynda Kiernan-Stone, Global AgInvesting Media
- Sep 24, 2015
- 2 min read

Tropical Storm May Have Carried New Corn Disease to U.S. Fields

Researchers believe that winds from a tropical storm in June carried tar spot, a corn disease recently found in U.S. fields for the first time, into the country from Latin America.

The U.S. Department of Agriculture (USDA) has confirmed that the fungal disease, which for years has been an issue faced by growers in Mexico, and Central and South America, has been detected in four locations in Indiana and three locations in Illinois.

It is usually a rare occurrence for a crop disease to enter the U.S. from overseas, but scientists suspect that Tropical Storm Bill, which hit the central U.S in June after moving through the Gulf of Mexico, carried the disease to the country. If true, this would not be the first time a storm transported a crop disease to U.S. fields. In 2004, a soybean disease known as Asian soybean rust is believed to have been brought to the U.S. from South America for the first time during that year’s hurricane season.

It seems that tar spot has arrived too late to be a detriment to the U.S. corn crop this season as harvests are already underway in Indiana and Illinois, and scientists believe that it will probably not be able to withstand the harsh Midwest winter since it needs to survive on living tissue, such as corn plants. Therefore, it is likely to pose little threat to next year’s crop. But the fact that it is in the country at all is a testament to how difficult it can be to keep foreign agricultural pathogens out of a country in the face of Mother Nature.

In no way was this more in evidence than earlier this year when the U.S. suffered its worst animal disease emergency when avian flu spread through the U.S. poultry flock causing the loss of 48 million birds, and in 2013, when porcine epidemic diarrhea virus (PEDv), a virus originating in Asia and Europe but never before seen in the U.S., killed millions of piglets, reducing the U.S. herd.

Experts are wary that the arrival of tar spot may mean the arrival of other, more dangerous pathogens such as the wheat disease stem rot which can wipe out entire wheat fields. First detected in Uganda, it has since spread to Iran and countries in South America.