NEW AND EMERGING CORN DISEASES: WHAT WE’VE LEARNED ABOUT BACTERIAL LEAF STREAK

2018

  • Tamra A. Jackson-Ziems
  • Dept. of Plant Pathology, Univ. of Nebraska- Lincoln
Project Media

Bacterial leaf streak (BLS), caused by Xanthomonas vasicola pv. vasculorum, was reported
for the first time in the United States in Nebraska in 2016. Since then, the disease has been
confirmed in 60 Nebraska counties and 8 additional states, including Colorado, Kansas,
Illinois, Iowa, Minnesota, Oklahoma, South Dakota, and Texas. Previously, the pathogen
had only been confirmed on corn in South Africa and on sugarcane in numerous other
countries around the world. Numerous other grass and palm hosts were identified in other
countries, as well, including sorghum species. Results from additional host range testing
conducted in Nebraska also confirmed several additional crop, weed, and native perennial
grass species as hosts. Symptoms on corn can be difficult to differentiate from other
diseases, especially the gray leaf spot fungal disease. Typical symptoms of the disease on
corn and other hosts are narrow interveinal streaks that can appear bright yellow when
backlit. The pathogen overwinters in infested crop debris thus, disease develops in the same
areas repeatedly when susceptible hybrids are grown and favorable weather conditions
persist. Severity of the disease varies considerably on corn hybrids, particularly on some
popcorn hybrids that can be quite susceptible. High relative humidity and leaf wetness favor
disease development. Results from additional research trials will be shared, as well as more
information on additional emerging diseases, such as tar spot and Diplodia leaf streak.