By Pierce Paul
Bacterial leaf streak (BLS), a foliar disease of corn caused by the bacterium Xanthomonas vasicola pv. vasculorum, was reported in the US for the first time in Nebraska and has since been found in several other states out west, including Kansas, Colorado, Iowa, Illinois, Minnesota, South Dakota, Texas and Oklahoma. It has not yet been found in Ohio and neighboring states.
BLS has a very close resemblance to other common foliar diseases of corn such as gray leaf spot (GLS). Like GLS, it is characterized by the presence of rectangular-looking lesions on the leaf that are tan, brown, or orange in color. However, lesions of BLS have less well-defined margins and may be narrower and longer than those of GLS. But one of the biggest differences between lesions of BLS and those of GLS is that BLS lesions have wavy margins with a yellow halo that is easily seen when leaves are held up against the light – there is a “windowpane” (translucent) aspect to BLS lesions. Although very early GLS lesions are also translucent when observed against the light, mature lesions are not. BLS lesions first appear on the lower leaves, later moving up the plant, and may occur singly or in clusters, eventually expanding and damaging huge sections of the leaf.
Being a new disease, there are still lots of unanswered questions about BLS, such as how and when it infects the corn plant, how it spreads within and between fields, whether or not it is seedborne, hybrid resistance/susceptibility, its survival from one growing season to another, its impact on grain yield, and the efficacy of tillage and crop rotation as possible management strategies.