 I'm Michael Vunch, I'm the plant pathologist at the Carrington Research Center with NDSU. I'm here to talk to you about over a decade of research conducted to improve the management of sclerotinia head rot on sunflowers. Anyone who grows sunflowers knows that sclerotinia head rot has been a long intractable problem that has limited the acreage of sunflowers in eastern North Dakota into Minnesota and up into Manitoba. And we started this research screening hybrids and breeding lines for susceptibility to head rot. Trying to find resistant hybrids and it was very frustrating because we could never get replicable results. And so then we took a step back and we asked the question, well, are there differences in susceptibility during bloom? And what we learned is that sunflowers increase dramatically in susceptibility as bloom progresses. So a sunflower that only has 10% of disc flowers, those little flowers in the interior of the head, either in bloom or completed bloom are a lot less susceptible than a sunflower with 90% of those disc flowers in bloom or completed bloom. And so then we went back and screened hybrids again and then we got highly replicable results because what we started to do was we inoculated every single head across every hybrid only at that period when the sunflowers are most susceptible to head rot. So every head and every hybrid was inoculated at the same growth stage, i.e. at the same relative susceptibility within the bloom period. And that took care of all the noise and we were finally able to separate hybrids. What we learned is that among confection, non-oil types, there are only small differences in susceptibility in general. There are a few that are moderately better than others, but there aren't big differences in susceptibility among the non-oil types. But within oil seed sunflowers there are huge differences in susceptibility with the best hybrids often having one-fifth or one-quarter of the level of head rot as the most susceptible hybrids. But even then, as anyone will tell you who works in the sunflower industry, the most resistant hybrids under a year that's highly favorable for head rot will still develop too much head rot and unacceptably high levels of head rot, in which way better than the more susceptible hybrids but still unacceptable levels. And so then we turned our attention to evaluating foliar fungicides. Could we control head rot with a fungicide application properly timed? We tested this with nozzles applied to a high clearance tractor amount of boom that's above the canopy and also with drop nozzles attached to that high clearance boom. I know a drop nozzle is a bit of a stretch but we wanted to just see if we could get fungicides to work under any circumstances. What we learned is that we could only get very modest control of head rot when head rot pressure was low. And even then it was not enough control to cover the cost of the fungicide. Almost all the yield response that we got from the fungicide was through control of other secondary diseases, not head rot. And when head rot levels got too high we got absolutely no activity from the fungicide and we ceased to even get a yield response because the impact of the head rot was so damaging it obliterated all yield gains from controlling secondary diseases. And so we were not able to get fungicides to work and we tested applications at early mid-late bloom. We tested them with adjuvants, without adjuvants. We tested different nozzle types. We tested different fungicides. We tested everything you can imagine and we could not get them to work and it was a simple reason why and it's because we could never get satisfactory coverage to the front of the sunflower head. Even with drop nozzles at the optimal timing for getting coverage we could still only average about 20% of the front of the head covered with a fungicide. And as anyone knows who grows sunflowers the front of that head is covered with lots and lots of disc flowers all of which are susceptible windows for sclerotinia and lots of buds depending on the stage of bloom. And every one of those buds is going to open up to form a disc flower that becomes a susceptible window for sclerotinia. And so if you're only getting coverage up to about an average 20% of those it's not enough. And so the take home message from that is save your money on a fungicide for head rot. It's not, you're not going to get your return on it. You're not going to get your turn. Use the fungicides to manage rust or other fuller diseases but not head rot. So we then turned our attention to a novel approach from a company up in Canada called Bee Vectoring Technologies that had used honey bees very successfully to carry a biological control agent to the flowers of strawberries to protect them from a blossom mediated disease called protritus graemold. And they've also used this successfully in blueberries for other blossom mediated diseases. Basically the company gives you a dispenser that dispenses this biological control agent onto a basically a tunnel that the bees must pass through to exit their hive or go back into the hive. So the bees carry this biological control agent out with them into the field and every time they pollinate they're carrying the biological control. And so every successive ring of disc flowers as it opens every morning gets visited by bees if you have enough bees carrying this biological control agent, delivering the biological control agent every day to every successive ring of disc flowers. And what we have found in testing now conducted since 2017 has been really promising. We're averaging about 50% control and study is conducted here up in Langdon and third sites in other locations across the state. This has been done with various methodologies. It's been highly, highly replicable. And what we're testing now is how effective. From what distance away from the hive are we getting control from that biological control agent? What you see behind me, there's long strip of sunflowers. And what we've found right now, thus far, this is our third year doing these studies is that if it's just a strip of sunflowers about 80, 100 feet wide, we're getting control 750 feet away from the bee hives. And even though we're only looking at two to four bee hives, I deposited. Okay? I mean, not many bee hives. Okay? 750 feet away. All right? Which is very impressive. If that strip of sunflowers is a part of a larger field, we're seeing a drop off an activity at about 350 feet, which would suggest that we just need more hives. All right? In the strip behind me, you'll see that there are sunflowers of differing maturity. Some of them have already come to the end of bloom. Some are in the middle of bloom. We're also testing this strategy with various hybrids differing in susceptibility with the goal of figuring out whether we can stack partial resistance with this biological to get really consistent control. And thus far, the results have been very promising. If the results from this year's trials are successful, we will transition to doing on-farm trials. Thank you for your time. I can always be contacted via email or via my phone number 701-652-2951. At the Carrington Research Extension Center with NDSU. Thank you.