Bacterial leaf streak and black chaff on small grains

Bacterial leaf streak (BLS), also known as black chaff, is a disease of wheat, barley, triticale, oats and many other cool- and warm-season grasses (Figure 1). BLS is more prevalent with warm, humid weather.

Impact on farmers

Severe outbreaks are commonly associated with weather incidents that damage leaf tissue. The disease can be found across the globe and, although not new to the region, has become more prominent in Minnesota, North Dakota and South Dakota since 2008.

The disease’s impact on grain yield and quality isn’t well-documented. However, yield losses up to 40 percent have been reported.

Unlike many fungal pathogens, BLS is a sporadic disease, occurring in some fields but not others. Even within a field, symptoms can be very patchy; some areas can appear severely affected, while immediately adjacent areas are completely devoid of symptoms.

Stages of bacterial leaf streak infection
Figure 1: Stages of bacterial leaf streak infection: A) Early symptoms of bacterial oozing, B) dried bacterial ooze and C) advanced necrotic symptoms.

About bacterial leaf streak (BLS)

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Management options

Fungicides and seed sanitation

Fungicides don’t control BLS. There are few bactericides labeled for use in wheat and barley (copper-containing compounds such as Kocide, Cuprofix Ultra and Champ). However, early trials show that while these can provide some control of BLS, results are often inconsistent.

Seed sanitation has also shown to be ineffective in Minnesota.

Genetic resistance

Consequently, as with many plant diseases, genetic resistance offers the most economic and effective control at this time. There are significant differences in how wheat cultivars react to BLS. Barley screening results are also available.

Variety trial results: Relative disease resistance of hard red spring wheat cultivars

Variety trial results: Relative disease resistance of barley varieties

Madeleine Smith, Extension plant pathologist; Ruth Dill-Macky, small grains pathologist, College of Food, Agricultural and Natural Resource Sciences (CFANS); Rebecca Curland, researcher, CFANS; Carol Ishimaru, plant pathologist, CFANS and Jochum Wiersma, Extension agronomist

Reviewed in 2018

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