Researchers are working to learn more about a little-known corn disease that has surfaced in nine states across the U.S. this summer. DTN reports the disease is known for now as bacterial leaf streak blight, which originated in South Africa. Colorado State University says there is limited information about the disease and its impacts on corn production. It’s possible the disease entered the U.S. two years ago as researchers say the lack of information led to a delay in confirming the disease. Currently, researchers have no recommendations for farmers regarding management. Bacterial leaf streak has surfaced in field corn, seed corn, popcorn and sweet corn. Researchers say the disease has been confirmed in Colorado, Iowa, Illinois, Kansas, Minnesota, Nebraska, Oklahoma, South Dakota and Texas.
From the National Association of Farm Broadcasting news service.
Figures 1-3. Pattern of bacterial lesions between leaf veins, symptomatic of bacterial leaf streak. Lesions usually have slightly wavy edges in contrast to the smooth, linear lesion margins of gray leaf spot. Backlighting (Figures 1-2) can be used to highlight the lesions.
By Tamra Jackson-Ziems, Extension Plant Pathologist, Kevin Korus – Coordinator Plant & Pest Diagnostic Clinic, Tony Adesemoye – Extension Plant Pathologist, Julie Van Meter – State Plant Regulatory Official–Nebraska Department of Agriculture
Bacterial leaf streak, caused by Xanthomonas vasicola pv. vasculorum (synonym X. campestris pv. zeae), was confirmed for the first time in the United States in Nebraska in 2016 and has now been confirmed in Colorado, Illinois, Iowa, and Kansas. The disease had only been reported on corn previously in South Africa, although the pathogen has caused gumming disease, a serious disease on sugarcane in several other countries. The disease has been confirmed in corn across many Nebraska counties.
In this video by Market Journal, Tamra Jackson-Ziems, Nebraska Extension plant pathologist, describes bacterial leaf streak, a corn disease that has been located in Nebraska and neighboring states.
Symptoms on infected plants may look similar to other common diseases, sometimes causing confusion and misdiagnoses. Narrow stripes between leaf veins may initially look like the common fungal disease, gray leaf spot. Lesions can be brown, orange, and/or yellow and are often yellow when backlit. Lesions usually have slightly wavy edges in contrast to the smooth, linear lesion margins of gray leaf spot.
Bacterial leaf streak has been observed on field (dent) corn, seed corn, popcorn, and sweet corn in Nebraska. The pathogen biology and disease epidemiology have not been studied enough to be well understood. Its potential impact on yield is not known in commercially available hybrids. The pathogen survives in infected corn debris from previous seasons and is thought to infect the plant through natural openings in the leaves. Irrigation and wind-driven rain, as well as warm temperatures, are thought to exacerbate the disease.
Figures 4-6. Severe lesions of bacterial leaf streak in corn.
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Image credit: Images in Figures 1-6 courtesy of University of Nebraska-Lincoln Institute of Agriculture and Natural Resources Cropwatch.