Wheat Crops Safe from New Sorghum Fungus

Date: Nov. 14, 1997
Editor: D'Lyn Ford,  (505) 646-6528, dlford@nmsu.edu

LAS CRUCES -- Two different types of fungus that infect two different crops are causing confusion for New Mexicans.

Some wheat producers have worried that the sorghum ergot fungus, found last month on the eastern New Mexico border, could infect their wheat, but that's impossible, said Natalie Goldberg, plant pathologist with New Mexico State University's Cooperative Extension Service.

"The host plants for sorghum ergot are limited to sorghum and Johnsongrass and possibly a few other weeds or grasses," she said. "We know sorghum ergot does not infect wheat."

Sorghum ergot was confirmed Oct. 7 in a field of seed sorghum in Pleasant Hill, about a mile from the Texas border. The disease can drastically lower yields but does not make sorghum toxic to animals, Goldberg said.

Sorghum ergot is caused by a different fungus than the one involved in wheat and rye ergot. Wheat and rye ergot infects those crops and can make grain toxic, causing a disease called ergotism, she said.

"We have ergotism pretty much under control in the United States," Goldberg said. "We do not see the disease nearly the way we did early on, after its discovery in the 1800s and in the early 1900s. Sorghum ergot does not produce the same toxin as wheat and rye ergot, so we don't have a concern about ergotism."

To add to the confusion, New Mexico has been testing wheat for a different fungal disease, Karnal bunt, which can lower the quality of wheat. Last year, infected seed from Arizona was planted in four southern New Mexican counties: Dona Ana, Luna, Sierra and Hidalgo.

However, Karnal bunt has yet to occur in wheat grown in New Mexico, and tests have shown no evidence of the disease this year, Goldberg said.

"We did not find any Karnal bunt in any county in New Mexico, including in the four southern counties that have been regulated for the disease," she said. "In those counties, we did a little bit more intense sampling and still we did not find it. So we are confident that so far we do not have the disease occurring in New Mexico, and we're really pleased about that."

Goldberg said the bottom line for growers is that sorghum ergot infects only sorghum and not other crops. And while tests continue for Karnal bunt in wheat, that disease has yet to occur in the state.

"We've had two distinctively different fungi but because they were both new in a very short time period, we've had confusion about what they are and what they infect," she said.

For more information about sorghum ergot or Karnal bunt, contact your county Extension agent.