This is the sugar beet report, bringing you the latest information from NDSU throughout the sugar beet growing season. Cercospora leaf spot is an arch enemy of sugar beet producers. Let's find out the latest with Eric Branch, NDSU and University of Minnesota extension sugar beet specialist. Eric, what's the latest with cercospora leaf spot?

Yeah. So now is the time to prioritize cercospora leaf spot management this time in late June. You know, it's not just the calendar that we expected. There's several things going on in the fields that make this time period, in terms of sugar beet growth and the environment here in late June in the Red River Valley, high risk for cercospora leaf spot development. Row closure, so when the sugar beets canopy over, they create a humid and warm microenvironment, which is really, really conducive to spore germination and disease developments. And also, by late June, across the valley, we are seeing upwards of half the leaf samples, and and probably this week, we expect to see almost all of the leaf samples that are investigated by my colleagues at the USDA to be positive for Cercospora leaf spot infections. That is the the fungus, Cercospora beticola, is inside the leaf and growing and developing, but spots are not present yet. So even before we see that symptom of disease, the fungus is active in the plant, and therefore, in order to really preventative and provide the best opportunity to manage the disease season long, it's important to have these fungicide applications on early enough, which is now in late June.

There are resources out there to help with managing Cercospora. How about NDAWN's Cercospora model?

The NDAWN's program has a great resource on the website for sugar beet cercospora infection risk. And this model incorporates environmental factors, humidity, and temperature, and that total moisture values increase across season and vary on a day to day level depending on the immediate temperature, rainfall, the previous days to provide us a sort of assessment of the risk of cercospora infection. And anytime we see those values hitting six, seven, eight, nine, that's gonna be that high risk threshold. Ideally, we can have a product, a fungicide, a a DMI, or some sort of residual activity applied before we hit that high infection period in order to provide the ideal control for CLS.

Well, one of the challenges with the model is it's only current information. It's not forecasting anything. Right?

Correct. Working with risk infection models is challenging, and that's one of my focuses as an extension plan pathologist is to evaluate the model, continue to evaluate and update this model. We have a project going at a couple trial sites this year just to make sure that we can incorporate and use the data effectively. Of course, we can't predict the weather even twenty four hours, twelve hours in advance. The model does have a few limitations, but it's still a great resource for indicating trends and getting everybody thinking about what's happening in terms of CLS risk across the region.

Eric, what are some best practices for applying fungicide?

Yeah. You know, the number one tool in our fungicide application program every year is going to be, in my opinion, using EBDC, a broad spectrum mancozeb type product in every single application or an alternative broad spectrum partner that is no mode of action, no fungicide is ever gonna go on alone. Having two effective ingredients in each spray is absolutely essential both for controlling disease in season and protecting the efficacy of not just the fungicide active ingredients, but also the genetic resistance in terms of CR plus or other traits that also play a role in our disease management throughout the year. And the second recommendation we have, wholeheartedly recommending and enforcing these if I could, honestly, Bruce, to rotate between chemicals. And our growers do a really great job at this, and it's been part of the practice for many years. But rotating among what I like to call the heavy hitters, the DMI, the FRAC threes, and then the tins as well in order to preserve the efficacy of those throughout future years as well as this year. And finally, tightening the spray intervals, we recommend ten to fourteen days and keeping those on the ten day side or even eight to ten days if there's been an episode of rain. And, again, jumping back to that end on cercospora risk model, this is an example where that can help play a role. Having us think about tightening spray intervals, if we've had those rain, high humidity events, you know, in July and August, and maybe if we haven't had a lot of moisture, fourteen days is okay. Really so much environmental variation, but but a combination of those strategies, I think, can really help to keep our sugar beets looking green all through July and August.

Thanks, Eric. Our guest has been Eric Branch, NDSU and University of Minnesota Extension sugar beet specialist. This is the sugar beet report, bringing you the latest information from NDSU throughout the sugar beet growing season.