Good grief…Goss’s wilt has infiltrated the eastern Corn Belt. Prior to this year, the bacterial disease has mostly been a west of the Mississippi phenomenon.
Todd Thumma, Syngenta agronomy service representative, says he picked up evidence of the disease last year in northwestern Illinois. “It came in late in the season and it looks a lot like anthracnose die back at that stage so some growers may not have recognized it as a problem.” He says the symptoms are sometimes mistaken for Northern Corn Leaf Blight at this time of the year.
It’s important to identify Goss’s wilt because hybrid tolerance is the main defense mechanism. “Shredding stalks, burying residue and crop rotation are all management measures,” Thumma says. “However, once Goss’s wilt infects a field, it is present. Hybrid selection is your best defense mechanism.
There are no in-season controls. Fungicides have no activity on Goss’s wilt because it is bacterial and not fungal, he adds.
Goss’s wilt is carried by storms and overwinters in residue. “Bacterial diseases require some type of wounding to infect a plant,” says Suzanne Bissonnette, director of the University of Illinois Plant Clinic. “Goss’s wilt, caused by the bacterium Clavibacter michiganense subspecies nebraskensis, finds easy infection from tissue damage after hail, high winds and heavy rainfall.”
Once infected, the symptoms move rapidly. Large tan to gray lesions that run lengthwise on the leaves with dark flecks or freckles are typical. Lesions may appear shiny in sunlight due to bacteria oozing on the leaf surface. Plant wilt can also be a symptom because the bacteria infect and effectively clog the xylem in the plant. On wilted plants, splitting the stalk may show dark streaking of the vascular tissue. This is easiest to see if you cut the stalk at about a 45-degree angle.
Bissonnette says numerous field corn leaf samples have come in over the past two weeks. Repots of the disease have come from Sangamon, Knox, Livingston, Bureau, Edgar, Shelby, Woodford and Piatt counties.
Fields that are corn-on-corn, fields that have detected or undetected Goss’s wilt from previous seasons, fields with high corn residue and fields with weed hosts such as green foxtail or shattercane are at a higher risk for infection, she adds.
Bissonnette says in states where the disease occurs regularly, yield losses of up to 50 percent in very susceptible hybrids have been noted. Research indicates that dent corn inbred A632 and hybrids in which this and related inbreds are used are highly susceptible, she adds.
Thumma recommends growers impacted by the disease check Goss’s wilt ratings as they plan for the coming season. “Ask how they’ve conducted the tests too,” he recommends. “We field verify our hybrids in Nebraska under natural and inoculated disease conditions to make sure we put that tolerance to the maximum test.”
For more information on Goss’s wilt:
Goss’s wilt spreads across Illinois, University of Illinois
Pioneer Corn Insect and Disease Guide: Goss’s Wilt
Jennifer Shike contributed to this report.
