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Bacterial Leaf Streak in Wheat (06/28/18)

Bacterial leaf streak (BLS) has been observed on flag leaves in several areas across North Dakota. This disease can look like several other foliar diseases such as stripe rust, tan spot or Septoria blotch.

Bacterial Leaf Streak in Wheat

Bacterial leaf streak (BLS) has been observed on flag leaves in several areas across North Dakota. This disease can look like several other foliar diseases such as stripe rust, tan spot or Septoria blotch. Therefore, I will review the key field diagnostic features that separate BLS from other fungal leaf spots. Early lesions caused by the BLS pathogen will be irregular, water soaked and run lengthwise along the leaf (Figure 1). At this stage, lesions will often harbor cream to orange colored crystalline structures (bacterial ooze). As the lesions mature, tan to brown necrotic lesions will replace the water-soaked areas (Figure 2).

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Fields that were exposed to a thunderstorm with high winds at flag leaf are more likely to see BLS. This is explained by bacteria usually requiring a wounding event to gain access into leaf tissue. Unfortunately, once you have identified BLS in a field, there are no viable in-season management options. Commonly used fungicides at flag leaf or at early-flowering will not have an effect on BLS, and the use of cupric hydroxides to suppress BLS has been inconsistent. Varietal susceptibility information can be found in the North Dakota Hard Red Spring Wheat Selection Guide (A574-17).

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Andrew Friskop

Extension Plant Pathology, Cereal Crops

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