Bacterial Leaf Streak is a disease that is found in corn caused by Xanthomonas vasicola pv. vasculorum. This disease is not native to the United States and has not been previously identified before this year. Bacterial Leaf Streak has only been reported in South Africa before this year and now first confirmed in Nebraska and slowly moving through the Midwest including Iowa, Illinois, Colorado, and Kansas.
Identification/ Symptoms
Bacterial Leaf Streak closely resembles other common diseases in the Midwest like Grey Leaf Spot. It is very important that you correctly identify this disease so there is no misdiagnoses. Below are some key features in correctly identifying Bacterial Leaf Streak.
Bacterial Leaf Streak will have long, narrow lesions that are anywhere from less than 1 inch to several inches long.
The lesions will be tan, brown, or orange and will appear between the veins of the corn leaves.
The lesions can also be close to the midrib or across the leaf blade.
Bacterial Leaf Streak lesions closely resemble Grey Leaf Spot (GLS) except the lesions will have wavy margins while GLS lesions are straight and more rectangular. This can be seen in Figure 1
When the leaf is held up to the light, Bacterial Leaf Streak will have long, yellow halos around the lesions. This is seen in Figure 2.
Figure 1: Bacterial Leaf Streak lesions. Figure 2: Bacterial Leaf Streak lesion halos.
Bacterial Leaf Streak appears during the corn's dent stage. Since this is the first year of BLS being spotted in the United States there has not been much study on this disease and the impact it will have on our corn crop. This pathogen survives in infected corn debris and residue from the previous years and will infect the corn plant through natural openings on the leaves.
Management Practices
Unlike foliar fungicides that are used to manage Grey Leaf Spot, Northern Corn Leaf Blight, and so on, it is not expected to efficiently control Bacterial Leaf Streak. Instead cultural practices are recommended such as sanitation of equipment between fields and having a crop rotation or tillage practice to break up the corn debris. These practices can help slow down the spread of BLS and reduce surviving bacterial.
Sources: University of Nebraska- CornWatch & Iowa State University Integrated Crop Management.
