Bacterial leaf streak disease (BLS) of corn has been found again this year in the south east part of the state. In one field, BLS was wide spread but the severity was low. BLS symptoms may be confused with gray leaf spot, a fungal disease, as the symptoms look very similar. Therefore accurate diagnosis is necessary before making the decision to apply a fungicide which will only control the gray leaf spot pathogen.
The most distinguishing feature of BLS is the irregular, tan, brown or orange striped lesions with wavy margins that can appear on the leaf blade or can be concentrated around the midrib (Figure 1). Gray leaf spot has regular rectangular lesions between veins that are tan in color (Figure 2).
Source of Inoculum and Impact on Yield
BLS is caused by bacteria, Xanthomonas vasicola pv vasculorum. The BLS bacteria survive on corn residue and is splashed onto plants by rain. The bacteria is thought to infect plants through natural openings. It is not known at this time if the bacteria can be transmitted through seed or if there are alternative hosts. The impact of this disease on corn yield is also not yet known, but yield loss is expected to be minimal if mild symptoms are observed after the corn has reached dent growth stage.
Nothing can be applied in-season to control BLS. Currently, cultural practices used to manage other bacterial diseases such as Goss’s wilt should be used to manage bacterial leaf streak. These include crop rotation and tillage to bury residue where practical.