Bacterial leaf streak

The pathogen is found globally, but is a primary problem in the US in the lower mid-south and can reduce yields by up to 40 percent.

The bacteria thrives in moist environments, and produces a cream to yellow bacterial ooze, which, when dry, appears light colored and scale-like, resulting in a streak on the leaves.

The invasion of the head of wheat causes bands of necrotic tissue on the awns, which is called Black Chaff.

[14] In the early stages of the disease, translucent water soaked streaks can be seen on the leaves often accompanied by a shiny glaze or clumps of dried bacteria on the leaf surface.

A cream to yellow colored bacterial ooze produced by BLS infected plant parts is also a distinguishing sign of the pathogen.

[14] Bacterial leaf streak of wheat is a seed-borne disease and is primarily transported by seed, but can also be transmitted by plant-to-plant contact within its lifecycle.

Moisture facilitates the release of the pathogen from the inoculated seed, which leads to leaf colonization and invasion of tissue.

Under moderately warm weather conditions (15-30 degrees Celsius) bacteria will begin to release and multiply in the plant parenchyma tissue.

Rain, wind, insects, and plant-to-plant contact may spread the disease in the season and cause reinfection.

[4] After the plant is harvested or dies, the bacteria may overwinter in the soil; although, its survival rate is much greater when crop debris is present.

When the spread is initiated by wind blown soil particles, symptoms will be found most readily towards the edges of the field.

[6] Bacterial leaf streak of wheat is not easily prevented, but can be controlled with clean seed and resistance.

Some foliar products, such as pesticides and antibiotic compounds, have been tested for effectiveness, but have proven to have insignificant outcomes on the bacterial pathogen.

Risk of damages due to bacterial leaf streak is variable, but should not be overlooked because there is always a chance of an epidemic.