 Bacterial leaf streak has soon become in our most important foliar disease of wheat in North Dakota and Minnesota. The ability of this disease to cause extensive leaf damage on the flag leaf has led to some drastic yield losses, especially on some susceptible varieties. When we look at the prevalence of this disease across the state, we have been scouting for bacterial leaf streak for over 15 years, and data from the last six years from the NDSU IPM survey have shown that we've been finding more bacterial leaf streak when scouting fields at flag leaf to early flowering in the past three years. This suggests that this disease is starting to rise in the current across the state, thus we need to make sure that we have good tools on how to properly identify this disease and what type of management we can do to help prevent yield loss. When it comes to identification of a bacterial disease, it is very important. As we know, the sense that it is a bacterial disease, fungicides are not effective. When we start scouting for bacterial leaf streaks, the first symptoms and signs that you might see are water soaking, bacterial ooze running in a linear manner across a leaf. As those lesions start to mature, you start seeing necrotic areas of the leaf and also chlorosis. On susceptible varieties, you can see complete necrosis of the flag leaf, which can result in some drastic yield loss depending on the timing of disease onset. As the bacteria starts to continue in the growing season, it can splash up onto the head and cause another disease known as black chaff. Black chaff may not result in any yield loss or extended yield loss, but it is a way that the bacteria that can survive on the seed lot into the next year. When it comes to bacterial leaf streak, the three corners of the disease triangle are the conducive environment. It is favored by crop injury, hail, wind whipping, any type of injury to that flag leaf growth stage. The temperature range is quite high, but we start to see more extensive damage from bacterial leaf streak as you get above 80 degrees. High humidity and free moisture are also factors that can be contributing to the amount of disease in the field. We know the pathogen is seed-borne and we also know it is residue-borne, but we do not have all the tools in place to see how this disease is starting to become so rampant each year. We're suspecting that seed-borne nature of it is why we're starting to see more of this disease over the last couple of years. There's susceptible holes. It can be small grains. You can see bacterial leaf streak on wheat and barley, but often the strain of the bacteria are going to differ. Therefore, we have a very complex host pathogen relationship. We also have other grassy weeds and CRP grasses that can be acting as host. Regardless of how we're looking at this disease, management of this is very important. The two primary tools that we have been receiving most questions on are host resistance and the use of a copper-based product. Host resistance is our most important management tool as we have a wide range of variety susceptibility out there. When we start looking at variety susceptibility, we have some that can be quite resistant and others that can be quite susceptible leading to extensive crop loss and leading to greater economic losses. When we look at what is the role of varieties and how do we determine that from a selection standpoint, the best way to look at this is going to those variety selection guides that we produce at NDSU and also they produce at University of Minnesota. We have found that any variety that's rated a five or greater is when you start seeing extensive yield loss. So we tend to want to recommend varieties that are five or less when it becomes to making a selection for bacterial leaf streak. When looking at the role of copper application and whether how they work, results have been inconsistent. A recent trial done in 2020 with a PhD student funded by the North Dakota Wee Commission looked at the application of a copper fundicide applied at Flagleaf. When looking at both the disease data and the yield data from this trial across five varieties, we've found very minor differences. Because of that, we're going to expand on this research and include other products and also other timings for the future. When we start scouting for next year and we start making plans for next year, make sure that we keep bacterial leaf streak at the forefront of a disease that we need to be making aware of. Most important tool that we have is variety resistance and I encourage anyone to make sure you take a look at your variety score when you're making that hard red spring weed selection. My name is Andrew Friskup. I am the extension crop pathologist, serial crop pathologist at NDSU. And if you have any further questions, feel free to reach out to me or your local county agent or county educator to help direct you to some of the resources on bacterial leaf streak.