Episode 6 - Managing Pecan Scab: Biology, Research and Resistance

From the University of Georgia Department of Pathology, Dr. Clemen Oliveira joins the podcast to discuss his 2025 on-farm pecan scab research trials, a basics in the scab fungus biology, and proper rotation of fungicides. Hosts Dr. Lenny Wells and Andrew Sawyer talk with Dr. Oliveira on the challenge in managing scab in the Southeastern U.S. What is a good scab management program for low-input cultivars? What is the difference between resistance and sensitivity to fungicide? And finally, is there an opportunity for a new fungicide in pecan?

Transcript

0:43

In a nutshell, the pecan podcast, episode six, I am your host, Andrew Sawyer, Southeast Georgia area pecan agent. Join with Lenny Wells, Extension Specialist for Pecanas at the University of Georgia. We are your hosts. This is the first of June, and the one thing I've noticed outside Lenny is it is suddenly raining. Yes, it went from bone dry to soaking wet. Where I live, we actually got two and a half inches yesterday afternoon and it said a 35% chance. I cannot think of a better topic of conversation than disease in our orchards. So the growers are shifting now from our pre-pollination fungicide, which is April and May, to our post-pollination fungicide, which is June through August. There's a difference in all that. And um we have a guest today, and I'm really excited for this guest. He is the newest member on our team under the Department of Plant Pathology, Dr. Clemen Oliveira. Clemen, welcome to the show. All right. Well, first of all, thank you so much for having me here. Uh it's great to be part of this podcast and and talk more about decans and and uh diseases on it. And matter of fact, that today it just marks the one year with UGA. I actually joined June 1st, 2025. So it's quite a coincidence, but it's uh it's it's it's nice to be here today. This is a perfect one-year anniversary. So I didn't realize that myself. But hey, there you have uh I'd love to hear a little bit about your first year. Like, you know, your exact position and um a little bit of your background, if you don't mind. Yep. Well, let's start by um you know what's my position uh is on peanut and pecan pathology. Uh I pretty much continue Dr. Brennerman's legacy on on his program, um, do um research on the below ground diseases in peanuts, but then in pecan the research and extension for disease, uh nematodes. And um and pretty much on my background, uh actually I I grew up on a farm and and um growing up on the farm, we were dealing with so many different challenges. And that really kind of like puzzled me many times. Like, why, you know, why why is this this, you know, what can we do to manage or what can we do to improve our yields or to make a more sustainable production here? And there is that we were dealing with a caterpillar at the time, and we my dad and I uh he I'm a sixth generation farmer. Uh my dad is fifth, uh, and a lot of experience comes with that. And uh kind of going with him and going out of school and and trying to learn a little bit more. So we we have a lot of exchange of experience that we were actually able to solve and and and provide um good recommendations on the on the cattle farm that my shoe my dad should run it. So that was kind of a little bit on my on my early discovery for passion on agriculture. And also that kind of took me to the path of science and and kind of like tried to understand more on those things. So you started a year ago and you pretty much hit the ground running. You did um is it right that you shadowed Dr. Brandham a little bit and y'all got involved in something of an on-farm study in the PCAN that I might let you share that started last year? Yeah, and that's another thing that I'm extremely grateful for. This program um has different, many, many different projects. And I did not have a lot of um uh background on on pecans, on on penis, although it I had in disease. So it was very good to have the overlap with Dr. Brenner for three months, and a lot of that we actually spent the time uh visiting the on-farm trial that you guys started last year. So we were able to visit the state and go to different counties and talk to different growers in county meetings. And that was very, very good. So that was very helpful to to kind of like have a better understanding on the whole system. And as I understand, Lenny, the this on farm scab fungicide trials that we worked together to coordinate starting last year. This was kind of new because it's my understanding that Dr. Brenneman did most of his work on our fungicides and efficacy, mostly out of the ponder farm, maybe one other location. Is that true? Yeah, I mean, I think he always had trials at the ponder farm, and then he would do a few on-farm trials. And he used to do a lot of it was you know, spraying whole trees, and then he kind of hit upon this idea of that he would just spray certain terminals uh of nuts, you know, uh clusters, and so he could do basically a lot more trials with a lot less effort. And so he did it that way for a while and saw that worked great, and uh it was simple and easy to do, so he decided to I think expand that to other locations and and coordinate with county agents, and I think that worked out well because then you can get this kind of generate this kind of information and this data on you know how effective these fungicides are in different locations. And and that was actually how good it was for me to overlap because instead of reinventing the wheel, it was I was able to take on from what he has established and kind of advanced from there. For instance, like uh I I feel not only for the county agents, um, but also for screening of new products. I actually I didn't mention, but I after I finished my PhD at Florida, University of Florida, I was a product development manager. So I was responsible for the Southeast on screening products. And one thing that for my first year that I observed was a lot of fungicide resistance going on and the need for more alternatives. And this the uh this technique that Dr. Brennerman has done over the years with the terminal sprays, I feel that's a very valuable tool to kind of like in the pipeline, so we can have like early screening in the lab, in the patridges, but that really needs to be validated in the field. So it kind of like the three steps of the screening would be early on. We can screen a lot more in the lab. And whatever we see some efficacy in the lab, we can move to these terminal sprays, which which right now we are screening about 13 products in about 30 different programs and combinations, techniques, and then whatever we see efficacy there, we could move to the whole tree and simulate what growers would do. So I think that's like a very good pipeline. Uh, and and and as Lenny Dr. Wells mentioned, is is is um, you know, you can you can screen way more on the terminal sprays. We've got people that might listen to this that really don't know the first thing at all about pecans and are just listening to it to learn something or whatever. And then you got you know people in the in the west who don't deal with scab, and you know, here it's the worst problem we got. So I just wanted to get you to briefly explain what role the rainfall and the leaf wetness and and all that plays in promoting that scab. Okay, well, uh in terms of the you know the the condition of the southeast and in Georgia specifically, and I'm gonna use an analogy. You know, I talk about uh how the spores of scab is similar to a seed. Like, say I work with peanuts, so I'm gonna use peanut seed. If we put a dead seed in the ground that's not favorable or too dry, that seed is gonna have a hard time to germinate and and do what needs to be done to uptake the nutrition of the soil. And that's very similar to a scab. If you don't have the conditions, the wet, the leaf wetness, uh, this scab is gonna have a harder time germinate and then penetrate the leaf and cause the disease. Now, here in Georgia, we in most recently, I think we are dealing with a lot more hurricane, a lot more rain, rain frequency, and that's what is actually increasing a lot. I mean, over the years we have seen a lot of this scab. And let's compare it to the West. They have way more drier conditions up there out there, and they don't deal with scab as we do here. All right, so Clemen, um, you know, we're in a period right now, June 1st, where we're transitioning over from being so concerned about leaf scab to being concerned about nut scab. And, you know, we have different recommendations, you know, of what to spray for you know, leaf scab. Some materials work better on leaf scab, some work better on nut scab. Could you explain why that is? Well, that's a great question, and and I I think a lot of it we were able to answer with the terminal sprays um and also kind of the you know the whole fruit uh whole um sprays in ponder farm to kind of you know we start the applications and we could do ratings on the leap scab, and we were seeing some materials like phosphates, uh, which is just more systemic, it works by triggering the immune system of the plant, and that we observe less leap scab on with that rating. But then when we evaluate the nutscab, is it it you still see some reduction, but not as good as products like Dodene, Super 10, or mir or mirror other mirror products. And a lot of have to do it's kind of like the motofaction of these fungicides. I would say that's probably one. They are more protectant. So once you spray, either the spores that are there, uh the scab that's uh on the nut, or uh the ones that will land after we spray, well um, if it gets in contact with this fungicide, it it will uh kill it and and you will see more that protection. And I think it seems like I remember Dr. Brennan always mentioning something that you know the it was something to do also with the tissue, and that kind of I think that relates back to what you're saying there about the systemic activity of the things like the phosphates, that they're uh just that tissue, uh I guess the systemic activity of it is absorbed better through the leaf. Would you say that's correct? Yes, and uh and also uh if you think about the leaf, when they're starting to put new flush, the nuts they they don't expand as much. Like the leaf, you have way more uh new flush and new possibilities of absorbing the the phosphates. Yeah, yeah. And I think it's important to point out too that you know, and you touched on this, is it's not that each of these products will work on leaf scab and nut scab, but some are just better suited to others, and and it's our job to to let growers know which stage, which growth stage these particular products work best on, what's the best fit for those. Exactly. And it's very important a lot of times uh, you know, to find the right niche, like what is the best positioning, the position of the fungicides is very important uh in the spray program to uh achieve a good control and understanding the mode of action and and kind of like the system uh and kind of trying to find that the right spot. So it's it's it's definitely a very important topic. Yeah. So uh let tell us why again, as we get into nut scab, why is that season so critical to keep to keep those fungicides on there, stay on a good schedule, use the right product. You know, what is it about June and July basically that that makes it so important uh to keep those uh nuts covered? So typically June and July is the most uh is the is a period on the peacound production that we we have the highest chance for for a scab nut scab to happen. And that's where we really wanna when the the nut sap is forming. So we really want to protect that so we can uh secure and control before shell hardening. Those nuts, I guess, are sizing, you know, especially by the time you get to like late June or into July, those nuts are sizing so rapidly. You know, that's that's why when you if we're getting rain, you know, it's hard to keep them covered uh because we got new tissue exposed, you know, constantly. You know, you put one spray on, uh the nuts, you know, within a week, you got a quarter of that tissue at least that's never been sprayed, you know, as it as it develops and grows. And uh so those disease epidemics can jump on them pretty quick, I guess. And and I think we you know, we live in South South Georgia, and uh during the June, July, that's when we we get a lot of the uh afternoon thunderstorms, so we we start getting a lot more rain frequency. And if even for disease to happen, we in plant pathology we talk about the disease triangle, which is pretty much three things that you have to have aligned to for the disease to happen, which is a susceptible host, a favorable condition, and for scab is uh rain frequency. If you have a lot of rain or um uh high frequency of rain, and then aggressive pathogen. If you have just three things in your orchard, then you you start seeing a lot more the disease, and that's where we can enter with the fungicide to try to interrupt this this triangle, try to interrupt the disease to happen. So June-July is is typically very wet. We get a lot of uh rain frequency. So that actually overlaps with also with the nut development, which is very important right now for growers to be on top of the of the sprays and using the right materials there for nut protection. That's a great point, too, about the disease triangle. You know, I just I just got back from Spain from uh looking to looking at some orchards over there, and uh the conditions there are completely opposite from here. Uh they're more like you would have out in New Mexico, and that's one thing about pecans is they're grown over kind of a pretty wide range of climates. And each of those locations, whether they're you know, some may be arid environments, some may be humid environments, uh, and they're gonna have different issues that they face. And I think every single episode we've done, we've it we've mentioned pecan scab at least once, uh because we are here in the southeast, uh, and pecan scab is the biggest problem that we face in growing pecans. But like you said, if you don't have each of those three factors, the host, the pathogen, and the favorable conditions for disease development, you don't have disease. And a good example of that is in a lot of these um arid environments, you know, they grow uh pretty much two varieties, western slo western sly primarily, and and some Wichita as well. But I think you don't you won't find much of that here in the southeast where where it's where it's humid. And uh you have some Wichita's in the uh but tell us tell us why there are Wichita's in your planting at the Ponder Forum. So for in yeah, for disease, in terms of a pathologist, that's like a dream cultivar. Because every year, typically it doesn't matter how dry it can be, we typically see some level of scab on Wichita because they are very, very susceptible. I would never recommend a Wichita to a grower, but in the southeast, uh here in Georgia. But for our screening, for our you know, for the purpose of trying to evaluate new products, uh new uh programs, Wichita's are very uh suitable for that uh because they're they have a very high disease pressure. Um I want to touch for a minute on um the the products that we're using right now for nut scab. And so as we mentioned, anything that's labeled for pecan is you know is gonna have some activity on on nut scab, but as we mentioned, also we want to try to keep we want to use the best products at the at the right time. And so kind of what we do as we get into this time of year, we're rotating uh kind of that combination of Dodene 10 or just Dodene, uh full rate of Dodene by itself. Uh we're rotating that with Meribus Top. Could you kind of give us a brief overview of of each of those products and and you know what they bring to the table there? Yep. Uh so pretty much uh the Dodin and Tuper 10 has been like their older chemistries, um they have been uh used for a longer time. And despite that, they show has uh we have seen very good uh field efficacy with them, and even with the on-farm trials with the county agents last season, we saw very uh very satisfactory uh control with those two products and and also not only a standalone but also a combination with half of the rate. When we talk about mirror, we have two products. We have mirrors prime and mirror top. Traditionally, the growers has uh we use mainly mirrors top in here, and they were this this mirror stock was, I believe, if I'm not mistaken, came to the market in 2019. So it is uh fairly newer. And the main difference between the Dodin and tin uh when it comes when we comes in when it comes in terms of uh fungicide resistance is that dodein and tin has a lower medium risk for that. When you talk about mirvas, they have a higher risk for fungicide resistance. And and that also has to do with the mode of action. Usually fungicides that have a single uh site, AKA, they target a single site in the fungi to kill it. Those usually are have higher control levels, but they also have higher resistance levels. That's why we bring to the spray program fungicides that are lower in uh fungicide resistant like Dodin and 10. And that's why it's extremely important to do this rotation. Yeah, and so like you mentioned, the DOD and tin have been around for a long, long time. And really, your trials, Dr. Brennerman's trials, have always shown that Dodin and 10, even now, still works great, right? It's one of the best nut scab materials. And we even validated that on fungicide sensitivity tests in the lab, where we give the best option for that chemistry to be exposed to different populations of scab, and we didn't see much uh shift on reduced sensitivity. Super tin does have a little bit more, but I was reading from one of Dr. Brennerman's uh study, the resistance is not really stable in the population, so it kind of those sparks don't survive, so we still see that the good efficacy. Yeah, and that's and that's a good point to make. I think a lot of times uh you've seen with with some of these races of scab where you you have some resistance developing, that there's also a fitness cost to that. Could you explain that? So, yeah, so the fungi is evolving year after year. So they they they they are trying to overcome what we are what the environmental conditions are. So let's say we use a lot on the same fungicide, so the fungi will naturally have some mutations, and then that mutation will be installed on that population. But what when we talk about fitness cost is that it's a cost for that population to survive. Typically, uh some of them can be installed and they will survive and they will be become the primary on your orchard. But when there is a fitness cost, then you don't you don't have um that population surviving. So then even though they do develop a type of mutation, they are not able to survive. I guess that kind of helps if you say if you do say rotate off of that chemistry that you're having some resistance to for a while and kind of give that race time to kind of die out, then you know that's why I guess that helps sometimes to be able to stay off it a while and then come back to that particular fungicide. Uh once that race dies up. Let's get specific for a minute. So, what if say if a grower has some resistance to say uh one of the the ten fungicides in their orchard? And so it may not be such a good idea for just for them at that point to include ten in their in their program. What would Your recommendation be to them at that point when they get to this point in the season and they would normally be rotating dodene 10 with mirbus top? What would what would uh you tell them to go to in that situation rather than the 10? Rather than 10. So uh when you start seeing kind of reduced sensitivity, uh um one one of the things is probably do like a fungicide sensitivity test, which the lab here uh at Tiefston has been offering, to kind of do like screening on the different the different chemistries and so we can better understand what we are dealing with, what is the sensitivity profile on your on your orchard. Based on that results uh which represent a small portion of the population of the orchard, but it does give us a good direction on the rotation. Probably if he has like we find out that there is tin, or we are seeing a little bit reduced sensitivity, probably we should kind of not rely so heavily on that chemistry and rotate with different uh different other products and try to kill those that population that was having that resistance with the tin. Yeah, what I what I see most growers do in that situation is they'll just leave the tin out, and instead of using the half rate of dodene and the half rate of tin, they'll just go with the full rate of dodene. Yeah. And and would would it be okay in that situation to kind of stay with the half rate of dodene and then maybe put something like a cordophosphite in there with it? Um they probably could, and and actually that's another, you know, one of uh Andrew was asking me about my first year, and that's one one thing that I kind of um excited about and trying to get it more is more information on on more products, more what what else can we bring to the table that whenever a grower uh has those results, uh that he can rotate it. Because you know, right now we are mainly with three different, four different products, which is the Dodin tin and Mirva's top and prime. So then which pro top and prime, they have the same um frack group, the fungicide class group. So it's pretty much we're narrowing down to three. So it'll be very valuable to the industry to have more products that actually deliver that are affordable and deliver good control and they are able to rotate. Yeah, and that that kind of brings me to something I wanted to mention, and then I want to get more into what you just said. So when we talk about rotating uh fungicides, explain exactly what that means because I think a lot of growers think that when we tell them to rotate, they're rotating. I think they just look at rotating the particular product that they're buying. But that's not really what we're talking about here. Um explain what exactly rotating means, because I think this is a key point, um, and it's very key in ensuring that the products that we have that work continue to work. Yeah, that's a very good point because you know a lot of times you see the you'll see the different name, and you're like, well, okay, this is a different, a different, it's a different product. Well, I'm rotating, but actually what's really important is to look at what we call the frac group or the fungicide class. Because the we have the fungicide class, we have the frac group, um, then we have the active ingredient uh for that product, which is those complicated names that it's very hard to pronounce, and we have the trade names. And a lot of times you can have different trade names with the same mode of action, with the same uh active ingredient. And that's not a true rotation. That's um what's gonna do is actually gonna continue uh increasing the selection pressure for fungicide resistance. And so if you go to the uh the bottle and the label, uh there are two ways you can look at, but I would say the easiest one is just to look at the frag group, which is the number. So there is this like fungicide resistance uh committee, it's a global committee, and they uh organize all of the different fungicides in different groups and they give the name uh the numbers. So when you do the uh when you when you rotate, you what you want to rotate is this this fungicide class groups in order to prevent fungicide resistance and help increase the longevity uh and effective effectiveness of this um this product. And that class or whatever number that class turns out to be, um, that's gonna be labeled pretty prominently or you know, displayed pretty prominently on the label, correct? Yes. So it's easy to check for that. Mm-hmm. And actually there are those groups that can um go further and access, that is a website I I use very often. It's called Agrian, and that's you can just type the trade name and they are gonna give you all of the different um label of the current the most current label uh for that product. And I guess so different fungicide classes or or some of them are going to be more susceptible to uh the development of resistance or insensitivity. And I think historically one of the most one of the most susceptible as and that we've always seemed to have trouble with, has been the group three fungicides. Could you touch on that a second? And and just I want to you know, this won't be all of them, certainly, because there's so many we could never list all of them. Your group and I want to really touch on this because this is an extremely important issue uh for us where we're growing pecans uh here in the southeast. And so I want to get specific with this and really talk, kind of get in depth with it. But so your group three fungicides are going to be things like products that have a group three fungicide in it, they may also have another one in there with them, but uh sometimes they may not, but but some that that do, uh things like absolute, mirror's top that we have mentioned, you've got things like Sevia, uh the old products that we used to use, like Enable or Orbit, Tebiconazole is one. The way I try to look at it, and you tell me if this is correct, all of these, if you're when you're talking about your rotation, you treat all of these as if you're using as if that's all one product. Would you say that? Correct, correct? Yeah, that's a very simple way to say the you know, whatever product it was either by itself or mixture with the group three, which is what we call DMI fungicide, uh, which is the one that you mentioned, the absolute, quadrus top, mirror stop, all of those contain an active ingredient that belongs to the class DMI, which is the the the frag group three. So that's if you're using uh so if you're using like a mirror top, and then you say, okay, on this next one, I'm gonna use mirrors prime or I'm gonna use absolute or quadrus top, that's not really rotating. Now, um, and that's that's the thing, the the for the mirrors top and prime, um, if you use mirror prime instead of top, you will be rotating the group three, which is uh in mirrors top, they have what we call the diphenogonazole that belongs to the group three, and then you go to mirrors prime, they have the the rotation there is the fluidoxanyl, which is another fungicide group. What MIRVASTOP and Prime has in common is the group seven, which is uh what we call STHI fungicide, and that's the the component called PD flumatophen. That's that's where um if you use top and then prime, there will not be a true rotation just because of the the group seven. Okay, so it's not the group three in that case, it's the group seven. Okay, and I would like you mentioned Mirabis, the Mirabis Top came out 2019, somewhere in there, 1819, somewhere in there. And it has been a phenomenal product. Uh I mean it has worked great on scab and has really kind of been a game changer for us because we were getting to a point where scab was getting really hard to control in some of these wet years on some particular varieties, and Mirabis Chop really helped with that. And it continues to be a great product. But could you touch on some things that you're seeing with that and and kind of to emphasize why this rotation stuff that we're talking about is so important? Mm-hmm. So I think to touch on that, it's important to um talk about very briefly on first of all how the fungicide resistance develops. And that's across all products. So in your in your orchard, you have millions and millions of spores. And the spore is pretty much the seed of the fungi. It's gonna germinate and it's gonna put out roots, if I can say, but those are what we call uh hyphae, and those are gonna penetrate the leaf tissue and update the nutrition. So we have a lot of millions in that. It's very and and what we have observed for scab is that it's very diverse. There is a lot of diversity between this population. And a small percentage naturally will have some of these mutations, some of these spores that can overcome the fungicide. And can, you know, you spray the fungicide and the spore will not die. And that's the key. If you spray the same mode of action over and over and over, you spray once and you kill all of the sensitive. All of the ones that's gonna remain is the ones that are resistant. Then you spray it again and again and again, and what was actually a small percentage of their population may become a primary one of the main population, um the main uh spores with that resistance in their population. And that's what we want to avoid. We want to rotate so that we don't increase this spore that has this resistance. So that's that's where here is uh the the importance of rotation. Yeah. Could you touch on a little bit about the difference in in sensitivity and then just full-blown resistance? Yeah, that's um I would say that is not a straightforward answer for that question. There is a lot of debates on it because there are different types of resistance. And this is where I I want to highlight, you know, each orchard is different, each case needs to be treated differently because we have different types of fungicide resistance, we have different mode of actions. And for instance, there is one resistance that if you have that mutation and that is not the fitness cost, it's a yes or no question. If you have that fungi, that population with that mutation, uh, you can spray the highest rate and it's not gonna work. But on and that's that's a more straightforward. That's a kind of, you know, we if we if we find out the gene on that population, we already know it's resistant, so don't spray. But there is other type of resistance, which is um where the fungi produce more of the target gene or the target site to compensate for the fungicide. And then and that's a more it has more overspression, what that's what we say. And that's when we start seeing shift on sensitivity, but not completely field failure. And that's where we need to be careful because we we can rotate and we are able perhaps to bring it down the population to levels that we are not going to be concerned. So, yeah, so this fungicide sensitivity uh it's it's a very, you know, it's not as straightforward, it's biology. Yeah, so I guess that's important for growers to hear that if they have their orchard sampled and check for insensitivity to the different fungicides, it depends on exactly which one we're talking about, but just because they have a little some insensitivity, it's not always just the kiss of death, you know, in that situation. Yes. Yes. If I see a reduced sensitivity, it's not a panic thing, it's not something to be extremely worried to lose your sleep over. It's just a sign that we need to rotate and we need to have new products perhaps on the spray program to do that rotation so that we bring that down and then we continue um you know having a good efficacy. That's how that's how it is. Yeah, um to mention uh related to this, and and you just kind of opened the door for that, I think, with uh with your answer there. We were talking the other day, and and you mentioned to me that there are a couple of other products. One of the issues we have with with Pecan Scab is that it's such a problem for us, and we've only got this a certain number of chemistries that work on pecan scab that are labeled for use. But uh you mentioned to me the other day that that there might be an opportunity to get a couple of more here coming up uh in the in the near future. Could you tell us you know whatever you can about that at the moment and why that's so important? Mm-hmm. So, first, why it's so important. Well I think that covers all our um discussion about fungicide resistance management and the alternation. Uh so I think that's that would be very important to to have more options to the grower so that the grower can can choose uh on different product to do this rotation on the spray program. Some of the things we are uh screening a lot this year is um different chemistries. Some chemicals they are actually labeled on Apple and has shown efficacy on Apple Scab. And that is perhaps a chance for being registered for pecans. Now, the the not so good news is it's probably not gonna come to the market in the next three, five years. It's gonna depend on EPA for that registration, so it's not like uh uh something that's gonna be coming soon, from what I heard. But you never know how you know things move in EPA. Uh and this this update can change. Now the other one was actually a product that has already been labeled for pecans and is Xyram. Has not been apparently not used, and I think you can comment more on that. And Xyram, uh, from what I was reading from other uh studies is it provides a moderate level of control. And you may be asking, well, we should just provide moderate, why is why would be useful for the peacend growers? And I think the the the answer, the main thing there is a multi-site fungicide. And we were talking about different fungicide motorfactions. When you have a multi-site, it means that the fungicide is gonna uh interrupt the life cycle of the disease in different in different targets in the fungi. When you have a single site, it's just one specific. And you can already probably imagine that when you have a multi-site, you have very low, way lower risk for resistance. So the benefit to the growers would be this fungicide resistance uh management. And that uh the latest update I heard was that mainly in the bat in the in the past it was more a supply demand uh issue, but they were trying to get more of availability perhaps for next season or two years from now. Yeah, so if you could say include that in some kind of a where they're using it at a time of the season where it's you know, scab is not such a big it's always a problem for us, but you've got certain times of the year where they're you've got some leeway, I guess. You got some cushion there, I guess I should say. So using it at one of those times, or maybe even using it, you know, say during the nut scab season, maybe using it, say one of those situations where 10, you know, they've got some 10 insensitivity and they want to rotate off that, maybe they could include that with the dodene, you know, in that situation. Yeah, any any anything we could do to introduce more modes of action into the picture is gonna help. Absolutely. And that's and then whenever we are seeing some reduced sensitivity shift on with some of the products in in that situation of your orchard, uh, if we have more options that like, okay, no, just use one here. So that really, really gonna help. Absolutely. And Clemen, if you'd like to go this route, you know, when we do the podcast, or sometimes I want to hold a question for the next time you're on. However, I already can see this is going to be a big question for growers. And this is a lot of our conversation at meetings and in casual discussion, but discussing the rainfall and the challenge, can you help us a little bit with understanding the fungicide, what we call rain fast? How long does it need to stay on these leaves before we lose complete effectiveness? In 2025, I would say, at least in my area, that might have been our biggest challenge. So, yeah, that's a good question. Actually, uh I got it last last week in one of those questions on, you know, I spray my fungicides, uh, but it rain within six hours. What do I do? And actually, I did some digging on the on what has been done, and Dr. Brennerman has uh done a little bit of study. I'll be honest, this is an area that needs more research, uh, but based on what we know, uh phosphides, for instance, um ideally you want to wait six to twelve hours before rain. The DMI strobolins, um, diffract 3 and 11, which is absolute max, stop guard, quield, quadrstop. Uh, they do have some like systemic activity, and generally they're better after rain than the protectants like dodine and thin. So, ideally, you want to allow it for like seven hours to half a day before it rains. Uh, the sulfactant uh may help with uptake uh on that. Just one note, do not mix sulfactant for each phosphide. Um, that that would work for the for this group, DMI and strobilines. And for the protections like dodine, less and tin, those are the most prompts for uh wash off. And rain within one hour after spraying can make them largely effective. And any rain within 24 hours may really reduce the control. So uh now for mirrors, I don't there is not much study on pecans. Uh we, you know, a lot of this study that this information I provided was even from other uh crops uh that we translated to pecan, but for mirror it doesn't have, but we are assuming assuming more um on the groups, the DMI on the group three. And so it it probably would you need to treat ideally for seven hours to half a day. You know, I've and this has always been a a question that we've gotten, and it's always been difficult to explain. And for me, the dodene, the tin, you know, all those sprays that are just kind of more of a protectant. Um I just can't get my head around. I'm not I'm not saying I'm right. I'm just saying that because I've I've been told otherwise on this. But I just can't get my head around with those protectant materials once they're dry on the leaf, it would make it seem that they've done all they're gonna do at that point. And and I know we we hear that you know they they think longer actually than the uh than the systemics, but um I don't know. I just always had a hard time getting my head around that. And then you know, and and I think they will do what they need to do on the spores that are there. I think where I now what I see is like maybe the spores are gonna land after the air spray. That's where they probably probably gonna help more. But how many spores I mean if you live one one more day, like how many spores are gonna lay there after you spray it? So yeah, this gets really hard to manage from a practical standpoint for growers that are out there doing it. So let's say you go out and you're you're you spray and you know that rain comes in after you know after that at some point. And so then you gotta decide, well, do I need to go back and spray again? You can't always get 24 hours, you know, or 12 hours. And so there's gotta be a practical limit to you know when you say, okay, that's good enough. I may have to come back and spray, you know, I may have to shorten my interval, but I don't have to turn right around and spray again. And I can't think kind of the rule of thumb that has generally been used on that is that say if you sprayed and you get a rain within an hour, anything that didn't get that hour, you you kind of need to go back and hit again. But if it was beyond that, from a practical standpoint, it's hard to go back and respray the whole thing. thing just from a financial standpoint and and you know it's just it gets complicated I know um because I used to a long time ago I would I would press the pathologists on this well why can't you just go out there and and spray some stuff and and at different intervals just take a hose and wash it off you know and and kind of then see what the effect is but it was explained to me that you know rainfall is a lot different than washing it off with a with a sprinkler with a hose or something. You're looking at apples and oranges basically when you're doing that. Yeah so and I know uh I actually was part of um with some one of my colleagues in Florida they were doing for strawberries but of course strawberries are very different from pecans the size but USGA in um Fort Fort Meyer no in Fort Pierce they do have a facility that you can even simulate hurricanes and that's where I think there are very few locations facilities in the US uh that you can actually put the pecan tree oh I'm sorry the pecan I I don't know the pecan size how big you can put the transplant and then simulate the rain and then you can see how far they spore like you put like a leaf with spores in the beginning and you see how far this port travel yeah and and also so but again that for pecan it gets very challenging because you need to put in a grant proposal for to to build one of those for us here to to look at oh that would be awesome because because the idea of that is not only to recommend to the growers but also do a advisory system not to say that the scab is coming but to say scab is really coming so use your nervous or no scab is okay it's like not too it's like it's it's not it's a moderate level so then you can use those like um not so good pro I mean moderate level control that would be ideal yeah so rainfast is very it's just complicated to figure out there's a lot of variables to test but in a nutshell tell me gentlemen if I'm wrong but your protectants are 10 and elast and they need the longest time on that leaf to work. And so I separate that from all our other products which have some systemic activity they make and work with rainfall sooner after spraying but 10 and elast need as long a time after spraying to dry as possible. That's correct. And I think and and Clemens comment helped me get that backward in my mind of how why that that is I mean it it made sense to me because what you're really getting with that protectant is it's still going to work you know if it rains within two hours after you spray the protectant is still going to work but it's not going to work as long so we generally are on two week intervals let's say so if you put that sode spray on you get a rain in three hours versus forty eight hours it's still gonna work for a time it's just not gonna work as long and so then it becomes even more important to shorten your animal one thing I do want to go back to before that I think we can touch on real quick related to scab whenever yeah so in dealing with scab we have to spray fungicides on a lot of our varieties to to be able to grow them and make those pecans. But you don't have to spray every variety the same way because you have different levels of resistance with different varieties. Desirable pawnee we may spray you know nine, ten, eleven times with something like Lakota or Avalon you know you may only need two or three sprays to make those and then you've got varieties that'll be everything in between. What would you say Clemen for for something like an Avalon or Lakota you some of the some of those varieties that have really high levels of of scab resistance on their own what would be a good program for them to use on that because you still you know you don't have as much scab but you may have other diseases that jump on them. So it's still important to to protect them. Yeah and that's a very good point because um you know we those are resistant to scab which we sure would recommend to to have you know one or some some sprays just to keep that population down and not uh adapting to that res to that cultivar but when we don't spray for that uh and typically the what drives the earth spray program is scab but if you are not spraying for scab you're probably going to start seeing more intrachinals uh we have the leaf diabetes so you have other diseases I feel that we probably would need to look more at different spray programs um kind of just to address that how many we would need phosphates or you know I I believe absolute max like the group three and 11 has good efficacy we are actually uh today as well we are having uh I'm having my first student and she's gonna work on picking an track nodes and I I hope to kind of be um generating more information and especially on how does M trach nodes respond to these different chemistries. Yeah that's that's great that's great to hear that she's gonna be working on that and um you know I think we've talked before about what it is kind of important and something we need to do is is try to take some of these low input varieties and try different different types of scab programs on those with with with two or three sprays and different times different products and kind of see what works best. I mean I know right now kind of what I'm using on those is I like use a phosphite say in April may come in with a uh something like a absolute or a mirror's top say in in June and then maybe in July do like an a Dodeine 10 spray or something just to kind of have multiple chemistries there at work and uh and kind of make that last spray one that's not really susceptible to any kind of scab resistance um or as susceptible. But just to throw different different modes of action at it it's not a lot of spraying but it but it I think it would help in some of those diseases like you're talking about. Absolutely and I and I think Andrew kind of doing some a little bit of those sprays right now and trying to us to find out you know what what would be the the most um or best recommendation for the growers. Well thanks to to you guys uh Clemen last year when did the on-farm scab susceptible you know that the entire you know base scab trial you guys showed me truly how to do this I've been wanting to do a low input what I call spray program for years I didn't really understand how to do it but we were able to execute it this year and so what we've done is we we just chose a variety that I see all over East Georgia XL County agent uh in Appling County Will Brown and County Agent in Ware County Austin Bagby and then I have another location up closer to my way so we got three locations and what we're doing is we got we're doing a four spray program and I would like to think a four spray program is going to be plenty sufficient. So it's gonna be basically late April late May late June early July and then August but then we got uh two additional three spray programs an April May and June and then a May June and July and then those will be compared to a control and I'm actually very happy to report we did our second sprays last week and most of our locations have held on to the flowers that's the hard part about this is we got to put it out there before that nut crop is actually set because you got to get that early April spray. I'm gonna call it late April spray but it's an early spray. In one of our locations the Excel did shed a lot you know so we're down to just a few trees that are holding on to them but in two other locations the tree has virtually held everything. So hopefully we'll have some information at the end of this year and Clemen we may work is this into your more detailed program next year. That'll be great. That'll be I think that's a very and that and and that's also another opportunity here to like you know thank you all of the county agents and you Andrew to lead in that because what we got the results from that last year county on farm trials and this year again is very very valuable information. And um and I think this the spray program uh on those more resistant cultivars is also another thing because that way we can test in different locations and understand better that geography uh in the in the state of Georgia. And back to Linny's point what we did too I'll mention this we're mostly keeping the sprays the same we're just looking at different timings. So as we continue this we can start messing around with different sprays. So there's a number of places where we're seeing some scab on low inputs and it's generally in a deep southeast location. So growers that I talk to are doing different things. Some are spraying a few early sprays some are spraying a few late sprays they're letting the scab completely inoculate into that tree. Then they're spraying it after the fact and they're still getting good control. I think the viability of the low input it's not that they don't ever get scab. It's that are we able to control it in just three or four sprays. So if we can on our end nail down the timing of those, we may be set up for a while because that variable cost budget is so much different in three sprays than it is in greater than 10 sprays. Yeah and that's exactly what I was about to mention. If if we've got something we can spray two three even four times it makes all the difference in the world in your net profitability. So that's great. Uh Clemen we've when we have the pathologist on we really need to hammer nut scab but you know there's other issues in PCAN there seems to be an issue that's coming up as that is in young trees nematodes can you touch on just some of your thoughts there and you know we may kind of close out the show here with you introducing that and maybe this lends us to coming back later and talking in you know much more detail. Well and and actually that's um nematodes are are um where I did my most of my studies on it was on nematodes below ground so I kind of specialize on below ground um microbes and diseases that affect the root system so a nematodes was my um main one that I study in Florida and wow yeah that's another another one and I would say the for pecans we have the pecan root knot nematode that is uh emerging we typically don't see because it's the below ground so we don't see as much we can't um predict but when you you just you only see when you actually have a very severe infestation in a point that's like even very hard to manage or is nearly impossible when you already have this high infestation. So um and for for this genus of nematode is actually the most uh important economically globally it has so many different uh species it goes for peanuts cotton vegetables but one unique thing about this pecan rudinal nematode is go specifically to pecans and trees like hickory and oak tree so it's it's very specific it and particularly the other ones they they have more a wide range roast anyway I think we can actually discuss more about in the next episode and uh it will be that is I will be uh I will have to say that we have a lot that we don't know I actually we have more that we don't know that we know because they are they are somehow one I would say one of the least studied uh root knot nematodes um that cause um severe damage to the agriculture today I see it as you know I think scab will also I think scab will always be our more significant topic of disease if we can for anything from the cost of controlling it. You know, we didn't talk as much about that but we all understand that high variable cost but it also seems like nematode might be our most pressing issue especially for young trees. That's very true. And it's especially the these nematodes one of the best ways to actually manage them is actually avoidance. Try to not have it. What I'm trying to say is does your field has history or not kind of even wrap sample before or uh try to have transplants free of uh you know that has no no nematodes on them because it once you have it nematodes are impossible almost impossible to eradicate a lot of times the nematocytes they do work on the uh they do have activity the problem is to get the nematicide where it it needs to be when you talk about strawberries vegetables we have a very uh small root system compared to pecans so you can imagine that these nematodes are all over these roots of the pecans and you can also see how difficult it would be to get the nematicide down where it needs to be so it's not the nematocyte is not working it's just the system doesn't allow the nematicide to go get in contact with the nematodes and manage it. So it's very very hard to manage um right yeah I'm actually gonna have to run to a peanut meeting now we have a peanut tour committee we went long had a lot to talk about well and we share clemency so we appreciate all that you do for us and PAN and uh under your department and uh thanks for being on with us today. It's incredible conversation. Well thank you for having me here and thank you guys for all the you know the one year I definitely could not be uh understanding more of the needs of the industry without this this great team that the peacound tree uh uh the pecan team and pecan industry thank you claim and you're a big part of it so yeah thank you hey Andrew there's one thing I do want to mention before we close this out today it's very very important we're recording this on June the 1st yeah and today June the 1st or 2026 is the 100th birthday of one of my heroes Andy Griffith about that so big posthumous birthday to Andy that would be a great ending to get a good thanks again for episode six in a nutshell the PCN podcast gentlemen thank you and uh look forward to being with you again thanks Andrew Andrew thank you all for listening stay tuned for the next episode you can get more information on the University of Georgia Pan blog in a nutshell the Pan Podcast