NPIPM:Bacterial leaf streak on corn
Authors: Byamukama, E. and Yabwalo, D.
Causal Organism
Bacterial leaf streak (BLS) is caused by a bacterial pathogen Xanthomonas vasicola pv. vasculorum"
Symptoms and Signs
BLS starts as narrow long (varies from ½ an inch to several inches) tannish- orange brown lesions between the leaf veins. As symptoms advance, the lesions expand and become wavy at the edges of the lesion. They may coalesce to form larger lesions. When the symptomatic leaf is held against light, the lesions appear transparent. The typical sign for the BLS pathogen is bacterial streaming when the symptomatic leaf is cut and put in water (streaming is seen under a microscope). The main distinguishing symptom of BLS from other diseases with close symptoms such as gray leaf spot is the wavy margins. The symptoms can develop as early as V7 growth stage
Disease Impacts
Information on the extent of yield loss caused by BLS is not yet available. However, the heaviest yield loss is likely to depend on the level of susceptibility of the hybrid, the time of infection (corn growth stage and weather conditions).
Life Cycle and Epidemiology
The BLS pathogen is thought to survive on corn residue and in soil. Transmission by seed is also possible but has not been verified yet. The bacteria are splashed onto corn leaves and, if conditions are conducive (warm and humid), infection takes place. The pathogen can also be splashed to neighboring plants by raindrops, especially under windy storm.
Management Approaches
• BLS is caused by bacterial pathogen and cannot be controlled by fungicide application. Proper diagnosis should be done to ensure a fungicide is not applied when the disease is not fungal.
• BLS is more common in corn planted in fields that were previously planted to corn and in high corn residue. Rotate away from corn and practice tillage where practical to reduce source of inoculum.
• Clean equipment between fields to avoid spread of the pathogen to other fields.
Other Online Resources
Jackson-Ziems, T. 2017. Bacterial leaf streak of corn. https://cropwatch.unl.edu/bacterial-leaf-streak
Crop Protection Network. Bacterial leaf streak of corn. https://cropprotectionnetwork.org/encyclopedia/corn-disease-management/foliar-diseases/bacterial-leaf-streak/
