URBANA, Ill. — In Illinois, it’s getting so one can’t tell their Burkholderia andropogonis from the common Clavibacter michiganensis subsp. nebraskensis anymore. And when that happens, it’s time to call in a plant pathologist.

Another new corn disease, "bacterial stripe," has been confirmed by the University of Illinois Plant Clinic and reported to the Illinois Department of Agriculture and the USDA. Common in appearance to other bacterial leaf blights, bacterial leaf stripe is new to corn in Illinois and may have made the leap from Johnsongrass, sorghum, rye or clover to corn leaves.

"Primarily where we see this disease is on sorghum. We had a sorghum sample come in last season with this disease, but what’s new is corn being the host," said Suzanne Bissonnette, director of the U of I Plant Clinic and state liaison to the federal Integrated Pest Management program. "What’s a little unusual is that on sorghum, you get a very distinct stripe but on corn, what we saw this year was sort of a diffuse yellow discoloration not nearly as distinctive as you would see on sorghum."

Bacterial stripe foliar discolorations run parallel with leaf veins, with brown necrotic streaking evident in the center of the lesion as the plant matures. Lesions can range from 2-5 inches or more in length.

The bacterial stripe pathogen, submitted from Champaign County in September, was identified by process of symptomology, bacterial colony characteristics and DNA sequencing. To date, positive leaf samples have been submitted from only that county, though Bissonnette encourages farmers from around the state to mail suspected leaf samples to the plant clinic on the U of I Urbana campus; call 217-333-0519 to learn more.

‘We don’t have a good idea of distribution in the state. One of the other hosts of this organism besides sorghum is Johnsongrass, so those growers with Johnsongrass issues may be the ones who want to keep an eye out for this disease next season."

She would not speculate on what kind of crop and financial losses farmers might incur if bacterial stripe were to infiltrate cornfields next year. "I have no data at all to show any yield loss or anything like that. We got it identified late in the season," she explained.

Researchers still have much to learn about how the disease could affect Illinois corn before they begin to issue any sort of advice to producers, though some of its mysteries have already been revealed.

"The difference between this and other bacterial diseases and tar spot is that this disease is known to occur in the Midwest. We don’t need to re-answer the question of whether it can survive overwinter here; it can survive here. So the big question is, why did it go to corn?" Bissonnette pondered.

She also wonders how easy bacterial stripe will be for farmers to identify in the field. "The concern I have as a diagnostician is that we have other bacterial leaf diseases that most people are familiar with – Goss’ wilt, Stewart’s wilt – and now we have bacterial stripe," she said.

"Telling the difference between those (diseases) in the field is going to be very difficult. I think it is going to require some lab diagnostics, particularly for seed producers, if any other countries show any interest in this disease having shown up in Illinois."

Producers should begin scouting their hybrid corn leaves and plants in early July 2016, Bissonnette advised. "This is something the clinic will be working on this winter. We need to set up some protocols so that we don’t miss it in our sampling, as well," she said

"It’s just one more interesting thing that’s happened to the corn crop this year."