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Bacterial Leaf Streak: What Northern Plains Wheat Growers Need to Know

August 14, 2019

BLS

Mother Nature has been relatively kind to northern plains wheat growers this season, gracing them with moderate temperatures and timely rains. She’s thrown a few storms in the mix, however — and it only takes a few rain or wind events to create a costly stressor: Bacterial Leaf Streak (BLS).

 

“BLS is becoming increasingly prevalent in our area, and it can cost growers as much as 40% of their yields,” warns Grant Mehring, Northern Region Technical Product manager for WestBred® wheat. “Northern plains wheat fields have been a hospitable environment for it to take hold in this season, but fortunately, there are telltale signs that growers can look for to identify it and steps they can take to reduce it in the future.”

 

Mehring shares five things that growers should know about Bacterial Leaf Streak:

 

  1. BLS is spread by winds or rain. While bacteria are ever-present, to spread they need wind, rain or even minor hail events — all of which cause the lesions on leaves to open. Bacteria then spreads from leaf to leaf (and plant to plant) as they are thrashed together.

 

  1. It’s easily detectable. Early on, you’ll see leaves browning or yellowing, with a bit of bacterial ooze. (If you hold a leaf up to the sun, you’ll notice it looks shiny.) As it progresses, infection appears as streaks of orange or brown; you might see hot spots in your fields where wheat looks completely orange and leaves are all but gone.

 

  1. It robs yield by reducing photosynthesis. To maximize yield potential, plants require nutrients from the soil, which are directed to the plant through photosynthesis. This process requires green leaves and sunny days to drive nutrients into the grain of the wheat plant. BLS interrupts photosynthesis because less of the leaf is green and more is dead. Keeping leaves healthy can limit yield loss from bacteria.

 

  1. It’s not treated with fungicides. Many wheat diseases are carried on the leaves, and fungicides can treat them. Bacteria, however, is a very different organism, and treating the fungus leaves more room on the leaf for BLS to set in.

 

  1. Variety selection is the best (and only) way to reduce BLS occurrence. There are no bactericides or cultural chemical controls, but there are wheat varieties that are moderately resistant to BLS. In fact, this is the #2 disease to select for, with #1 being Fusarium Head Blight (Scab). WB9719 is moderately resistant to BLS. WB9479 and WB9590 can also provide some protection, however are considered moderately susceptible. All three varieties offer excellent standability.

 

BLS has been a popular topic at all field days, where Mehring says growers like to see wheat varieties firsthand to examine the color, head size and overall health of wheat plants. He encourages growers to scout for both Fusarium Head Blight (Scab) and Bacterial Leaf Streak this summer and to contact him at 701-373-1591 for questions or additional tips on this yield-robbing disease.

Source: Grant Mehring, WestBred Technical Product Manager

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