278: Fungicide Resistance in Powdery and Downy Mildew: 10 Years of Vineyard Research

Fungicide resistance in powdery and downy mildew is a growing challenge in Australian vineyards. Ismail Ahmed Ismail, Senior Research Officer at the South Australian Research and Development Institute, discusses a decade-long national study on fungicide resistance in Australian vineyards. Listeners will learn how spore trapping is being made practical and affordable, the use of phenotyping and genotyping to detect resistance, and why monitoring fungal populations is critical for sustainable disease management across FRAC groups.

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Transcript

[00:00:03] Beth Vukmanic: Fungicide resistance in powdery and Downey mildew is a growing challenge in Australian vineyards.

[00:00:09] Welcome to Sustainable Wine Growing with Vineyard Team, where we bring you the latest in science and research for the wine industry. I'm Beth Vukmanic, executive director

[00:00:19] In today's podcast, Craig McMillan critical resource manager at Niner Wine Estates with longtime SIP Certified Vineyard in the first ever SIP certified winery. Speaks with Ismail Ismail, senior research Officer at the Southern Australian Research and Development Institute.

[00:00:36] He discusses a decade long national study on fungicide resistance in Australian vineyards. Ismail covers, how spore trapping is becoming more practical and affordable. The use of phenotyping and genotyping to detect resistance. And why monitoring fungal populations is critical for sustainable disease management across frac groups,

[00:00:58] we have some great news. I'm excited to let you know that 11 sustainable wine growing on demand courses are live again with fresh department of pesticide regulation credit hours. Attached each course now carries a brand new code and certificate. And you can roll in them for just $10 a piece. Whether you're tackling these topics for the first time or brushing up on past material, you'll earn the credits that you need. Go to vineyard team.org and click online courses to get signed up.

[00:01:27] Now let's listen in.

[00:01:32] Craig Macmillan: Our guest today at Ismail Ismail, he is senior research officer. At the South Australian Research and Development Institute, and today we're gonna talk about the status of fungicide resistance in Australian vineyards. And thanks for being on the podcast Ismail.

[00:01:46] Ismail Ismail: Thank you so much for inviting me for this.

[00:01:48] Craig Macmillan: So you were part of a fairly large group of folks that embarked on a pretty expansive project in multiple parts of Australia looking at fungicide resistance. How did you folks go about picking your sites, first of all, 'cause they're kind of all over the place. Picking your sites, finding your cooperators and did you know or have an indication that there was any kind of fungicide resistance in those areas?

[00:02:13] Ismail Ismail: Yeah. Well, again, thank you for inviting me for this. We'll talk about our project.

[00:02:17] Our project has been running for more than 10 years now. It's initially started with funding from Wine Australia, and now it's a combination between, Wine. Australia and CRC Saafe, which is the new organization our project is run by the cooperation between SARDI and then Curtin University and a AWRI institute.

[00:02:41] basically we started telling people about this project and then if they have any issues in their vineyard or some problem in there. Controlling program for powdery mildew and downy mildew and botrytis grape. They simply can send us a sample and then we identify the site by, sending the sample.

[00:03:02] So the grower is more know about their, their situation than us. When they send the sample, we identify the sample for them. Is it resistance or not?

[00:03:11] Craig Macmillan: So how did your colleagues actually go about constructing this research project? How did you put it together and what kind of methods did you use?

[00:03:20] Ismail Ismail: it's basically we have a, like an industry reference group from the mine industry in Australia. And we always have a meeting every, every year to discuss what the future for this, for this project, and what we have to do and what's what they need actually. So we basically meeting the need. Based on their, on their situation.

[00:03:43] We constructed the project by collecting the sample collecting the data from, from the grower, like the location, the spray diary, the variety, the growth stage, and then the sample will be either leaf or bunch infected. Could be a swab from infected leaves or.

[00:04:04] We now big on spore trapping. So we collect sample from the air. That's a cooperation with Walt Mahaffey in USDA from Oregon. We thank him for that because he is sharing his his idea and his design for, for, for that spore trap. We have developed this spore trap further and make it more practical and reliable.

[00:04:27] We do pathogen in isolation after the sample arrive to the, to the lab. And then it depend on the pathogen. If it's obligate pathogen, like powdery mildew or downy mildew we have to isolate it basically on, on, in a live tissue. But if it's botrytis, , we, we grow it in the media. So powdery mildew is more challenging.

[00:04:50] powdery mildew and downy mildew more challenging than botrytis in term of the, of the testing. And then once we established that the culture of these pathogens, we, we going to test it. So we tested using two different technique which I think you're going to talk about. And then after we testing this, we, we send the report back to the grower and tell them what, what we find.

[00:05:15] Craig Macmillan: Tell me a little bit more about spore trapping. What exactly is a sport trap? How does it work?

[00:05:21] Ismail Ismail: a spore, if you, if you can imagine it's it's, it's a device. It can catch a spore from the air. So when the, the basically powerdy mildew you, it's floating in the air, they can travel from one side to another side. And then the spore, it's a, a small device with, two rods attached to it, and then it's a spin.

[00:05:43] And that one spin, it's create a turbulent and that turbulent help to attract the, the air inside that turbulent. And then the air presumably have the spore. And then this rod has a sticky thing like a, a Vaseline or. Grease vacuum grease or anything like that. And then the, the spot will stick on it.

[00:06:07] So we run it for different time, but now we run it for one day or two days, and then the grower can take that rod, send it to the, to the lab, and then we analyze it.

[00:06:20] So main focus of our sports driving is to make it affordable low costing, practical so that the grower could do minimum. It.

[00:06:32] Craig Macmillan: Yeah. And that's another technique that I learned about that I was curious that you folks had used was a swabbing where you can, you can like wear a glove and walk down the row and, and touch leaves and clusters and then you can swab that and you'll get a sample that you can use. Are there, are there any downsides to using that technique?

[00:06:49] Ismail Ismail: The swabbing, you only can do it when there is infection. However, we don't want the infection. If it's the infection in the vineyard, the stool light. That's why we focusing heavily in spore trapping because it can catch , the pathogen before getting infected.

[00:07:04] And how we have proved that many, many times. Like we can catch spores before even the, the grower notice there is any symptoms in the field. So yes, swab. It's a complimentary. If you have , a spray program and it doesn't work and you still have infection, then you can send us a sample.

[00:07:23] But if you go on to monitor without any issues, you could use the.

[00:07:27] Craig Macmillan: how expensive are sport traps? I, is this something the grower owns or The university is lending it to them?

[00:07:33] Ismail Ismail: We basically, the sports trap as I said, it's been designed by Walt Mahaffey Group in USDA in Oregon. And then he donated one of of that sports trap to us, and then we, we use it using very basic material. So from. Hardware store. And then it just collect the, the material and build it. It's A PVC vibes and motor and batteries and all of that.

[00:07:58] And then you could combine it together and make it, make it work. In our costing. In Australian dollar, it's around $300 , to make one. Basically this is my de-stress time when I have too much stress, I just go building this. So I'm, I'm the builder for that, so I enjoy going to the warehouse and all of that and collect all the things and then, and build it.

[00:08:21] I built now around 15 of them. I distribute them to the, to the grower, to the, our trials, and we always work with them. What's the issue? What's what they think It's hard. We think it's easy. And then we work with them. So far now, this year we have, I'm really happy with them and the grower are really happy with them.

[00:08:42] 'cause we have less technical issues and less less troubleshooting.

[00:08:46] Craig Macmillan: And that reminds me how many growers have participated in the project?

[00:08:49] Ismail Ismail: We have 15 across Australia, across five states. So every state we have we have two grower helping us with that.

[00:08:58] Craig Macmillan: I was reading one of the reports and in order to do this testing, you did some using phenotyping and some using genotyping. What conditions suggest you should use? One of the other, you mentioned an obligate pathogen where you need to use leap. I'm assuming that's part of the, part of the decision making process.

[00:09:17] Ismail Ismail: Yeah, the phenotyping and the genotyping, it. That's two different technique we use based on the group. We testing for fungicide, for example some fungicide. We already know the mechanism , of the resistance and we know what's mutation we are looking for. So basically we go straight away to the genotyping if that mutation matching , the phenotyping.

[00:09:43] If it's expressing that mu mutation, it's responsible for the resistance because sometimes in pathogen, on organism you have a mutation, but it's not actually the main cause of the resistance. So there is another mechanism helping that to do this. A good example for that, the group 11, or we call it QI group 11 we have a mutation called G143I. It's very linked to that resistance. Once you identify that mutation, you straight away you have resistance.

[00:10:17] So the, the phenotyping is actually testing the, the actual fungicide against the pathogen in the lab. So we grow the pathogen on the leaves in the lab, and then we expose it to the first construction of the fungicide.

[00:10:35] Once we identify that. The pathogen can grow on field rate or what we call labor rate. What , they recommend then we call it resistance. Then if it's grow below that, we, we have like a, a cutoff, like one microgram active ingredient and 10 microgram active ingredient of that fungicide. We call it reduced sensitivity, and if it's grow on the field, right, we call it, or the labor, right. We call it resistance.

[00:11:05] So we test this, and then we link it to the, to the genotyping analysis. So once the genotyping analysis and phenotyping matched together, then we could say, we don't need any phenotyping anymore because genotyping can do the job. However, that's not the case for most of the other fungicide group, like group three or some of the fungicide, group five, group 13.

[00:11:30] We don't know the mechanism at all. So we have to rely only on phenotype.

[00:11:37] Craig Macmillan: let's talk first about powdery mildew. You, focused on powdery mildew and downing mildew, I believe, as part of this big project. What things did you learn as part of this project? Like you just mentioned things that we don't know the mechanism about or like FRAC group three I'm very interested in. 'Cause that was a very early one that was identified as developing resistance fairly quickly, at least in the United States. What were some of the key findings that you had regarding powdery mildew and, and resistance.

[00:12:06] Ismail Ismail: we fund which is, I think everyone in the world find the same thing. That's the QI. Resistance. It's, it's it's very stable. It can stay for a long time in the vineyard, we have resistance for Qi Group 11, and it's the mutation is very fit, so mean it can survive longer time in the vineyard. then it's very linked to the phenotype. So once we have the, the mutation, so you don't have to do the, the testing at all. So that's make it easier for us. We can adapt. A new technology like a QBO hydrobot QBCR or hydrobot sequencing to identify a large number of samples. We can, they can send because only they could do much with phenotyping because you know, it's logistic and you have to do it by hand and all of that.

[00:12:56] With the genotyping, for qi, you can do hundred of sample in one go. So that's what we learn. We learn as well for group three or dmi. The mechanism, it's not very clear. We have a mutation called Y36F, but it's not always linked to the resistance. It's an indication of resistance. You can call it a warning sign for the resistance, but it's not actually have a hundred percent link. They have a different mechanism, like they call it copy number or gene expression could be involved in that, in that mechanism of resistance.

[00:13:32] As DHI, which is a group seven. We don't have any genetic resistance and pheno resistance so far in Australia, which is a good news. We have we have identified resistance in, in a group 13, and then we have identified resistance in a group 11.

[00:13:47] We and group group three

[00:13:50] Craig Macmillan: now this is a question I just thought of. When we're talking about genetics, if I have been using. FRAC group 11 in the past, and I'm starting to have some issues and I send it off and it's like, sure enough, the mutation's there, you're gonna have a problem. Should probably not use FRAC group three materials. In that case,

[00:14:13] can I allow a certain period of time to go by? And maybe that mut, maybe that mutation. Doesn't disappear, I guess, but is is, can I, can I delay or, or just lengthen the time between frac group 11 sprays, like maybe by years, like, can I, well I get that material back at some time, I guess is what I'm trying to say.

[00:14:34] I.

[00:14:35] Ismail Ismail: That's very, very good question. We actually on this question, I think in many group around the world, they do this. Try to identify what's the time limit. I can withdraw the QI until I, it's safe to bring back. We have honor students here in our group to study that. It's fairly stable so far, and then I don't want to disappoint anyone, but it just, for some grower, they said we have in spray QI for five years and we still identified.

[00:15:07] So the problem with the QRI, it's, it's fit. So the mutation, it doesn't compromise anything of, of competition. They can survive. It's, it is not, it's not really affecting that. The organism

[00:15:21] however the population will be different. So if you rotate or if you change your chemistry, you are minimizing , the mutation or the, the bad population of, of that.

[00:15:33] To the minimum. So you can always rely on numbers. So if you got very low number , of mutation, then you can, I can't recommend that, but that's , my opinion personal opinion on this. So with the drawing, it's really good to reduce the, the, or to reduce the population of the of, of the mutation. For certain time.

[00:15:59] We don't know actually now how many we have to wait and how, what's the ratio going to do. In our project, we developed that the high thro QBCR with QRI, with G143A mutation, and the students doing this. And now we could monitor the population because the, the direct QBC could give us a ratio. So if we start with 50% mutation.

[00:16:25] In this vineyard, and then they, they withdraw , that chemical, after one year, what will happen, it's become 50 or become 20%, or become 10% an indication. And, and this our research, it shows it's drop. It's drop by the time, which is Makes sense because there's no pressure on on that.

[00:16:46] Craig Macmillan: So there's hope,

[00:16:48] Ismail Ismail: Yes. Yeah.

[00:16:50] Craig Macmillan: in your opinion, there might be some hope. And I, I hope that work continues. 'cause I think one of the things that at least personally scares me is you know, this idea of selection pressure pressure on a population from a stressor like a fungicide.

[00:17:04] Because this is something that I've thought about is if we have a population that is showing resistance to FRAC 11, and you say, okay, well no problem. I'll just not use FRAC 11 and I'll rely heavily on. Seven. And so you do rely heavily on seven and then, then you start to develop resistance to there.

[00:17:21] And one of the concerns in my mind is, are we gonna run out of frac groups? You know, I mean, we do have the multi-site, we have a lot of the unknown. We don't know what the mechanism is, we don't know how they work. We have some, we've never seen resistance, at least not according to the international FRAC.

[00:17:39] How would you counsel a grower in Australia based on what you've seen on how to design their powdery mildew control program?

[00:17:48] Ismail Ismail: We are big in on monitoring, so the, we encourage them always to monitor, always to, to look after the, what's the population look like. And that's our project provide a free service for them so they can send sample anytime. Especially now, we establish the QBCR. Hydro, but it's easier and, and quicker.

[00:18:08] That's one thing. The other thing we have a crop life here in Australia and we have what we call it, the , the dog book, which mean you have to monitor and they give a limit how many time you could supply , certain group. And then if you stick to that, to that recommendation.

[00:18:27] And then to stick to the labor rate. Always do rotate your, your chemical that that's the, the best way to do it. But always the monitoring, it's give you if you are doing good or you're doing half half or, or, or something like that. the main case, it's just, just rotate your, chemical.

[00:18:46] Don't rely on one even. And that, that's the bad, the bad thing about good chemical because if you get to get a good chemical, they will use it all the time and abuse it. And then I think we have an example in Europe, they lose one of the QI or frack 11 two. So it's, it's very, very real. It you keep using the same chemical.

[00:19:07] Craig Macmillan: In terms of rotation it's another thing that I've wondered about. I've, I've had the opportunity to see a whole wide range of fungicide programs here in California and What I see some folks doing is rather than rotating within season they rotate between years.

[00:19:23] Ismail Ismail: Yeah,

[00:19:24] Craig Macmillan: So I might try to not have the same frac group back to in, back to back

[00:19:28] Ismail Ismail: absolutely. Yes.

[00:19:30] Craig Macmillan: That's a good, that's a good

[00:19:31] Ismail Ismail: That's a good thing,

[00:19:31] I should add to the, what we learned from powdery mildew and that QI is a cross resistance. So once you get one member of that family frac 11 resistance, you automatically you get the other one. So that's, that's a tricky part of qi.

[00:19:50] There is a new technology, I think it's been started, the US using the UV control to kill everything. And that's, that's a good thing.

[00:20:00] Craig Macmillan: Yeah, we'll be, we'll be following up on that technology in the future. I'm sure that's a very intriguing and exciting idea. And I'm hoping that we can work out the. The logistics on that, but we're certainly making progress from what I understand.

[00:20:13] How, how big of an impact would you say powdery mildew is having on the growers in your study? How bad is it?

[00:20:22] Ismail Ismail: For powdery mildew impact would be 76 million a year in Australia. For downy mildew 63 million and for botrytis 52 million.

[00:20:33] It's the main thing for, for the grower, the main thing, it's powdery botrytis and then downy, it depend on the area and the location and the season weather. But powdery, we have to spray all the time. Dent and their budget

[00:20:51] Craig Macmillan: and actually that's a great transition. I wanted to ask you about Downey mildew. Dying mildly can be absolutely devastating. Very, very fast. Just I've, I've only seen it once in my career and it was absolutely heart stopping. And then I find out there's growers in other parts of the world, other parts of the United States, and it's like, well, this is just kind of a thing we have to deal with, you know, and, and I just happen to live in an area where we don't see it.

[00:21:14] Tell me about tell me about downy and and resistance.

[00:21:19] Ismail Ismail: Yeah, downy. It's a, it's a new thing in our project. We just started like four, four years ago, five years ago. And because downy, it's not always there in Australia as we have dry climate, but we have a bucket like a Hunter Valley or Yarrow Valley, which is all the time. They have downy.

[00:21:39] Yeah, as we said, it's devastating. I, I've being in hunter valley, it just, you hammer everything and it's introduced botrytis as well after that because from that wound and all that, it's a serious one. We are testing against three group FRAC, group group four, uh, and then with group 11 again and group four.

[00:22:01] So far, we have identified resistance in a group four, which is metalaxyl. We have 43% of the sample has been sent to us. Almost a half of them have metalaxyl resistance. And as you know, because metalaxyl, it's it's curative kind of, so it's farmers are really heavy. Rely on them because once you get down, you have to treat it as.

[00:22:27] You have to. And so, and sometimes the weather, because it's, when the weather is, is good for the downy, you can't spray or raining, you can't spray. So the down already established, so we have to, to use a metalaxyl

[00:22:40] we got nine, 9% of FRAC 11 resistance. And then we don't have a, any, any resistance for group four, which is, which is good so far.

[00:22:51] We always encouraging grower to send more sample for that. From this, particularly for this, for this area we trying to do spore trapping as well This year we haven't gotten the result yet, but we, we try that to capture the downy release or release before it goes to the, to the, to the leaves.

[00:23:11] And hopefully we get something from, from that.

[00:23:14] Craig Macmillan: I know that botrytis was not, your focused in this project, but I was wondering if you could tell us anything about Pettus.

[00:23:20] Ismail Ismail: Yeah. Botta, it's one main thing in our project, and it's been taken care of by Curtin University, by F Lopez and Lincoln Hava. They, they. Deal with all the sampling and the research over there. We just coordinate this research in, in our, in our group. Basically they, the same thing. They ask grower to send sample if they have any issues in, in their vineyard, and they go out to collect sample.

[00:23:45] As you know, botrytis, it's easy to deal with as they, it's not obligate parasite. You can grow it in the, in the lab and in the media so you can test many and hundred of some. So the result shows that they have tested 373 isolate around from 43 vineyard from Western Australia, south Australia, Victoria, new South Wales, and Canberra.

[00:24:10] And it shows 15% resistance to group FRAC nine, and then 10% to group FRAC 12 and 10% for group FRAC 17. They have identified already some mutation linked to the, to these groups, and it's linked very well. And we have developed a marker as well for Hydrobot QPCR to identify this. And then basically when we collect sample using the spore trap, again, we test the sample now for three pathogen.

[00:24:42] We tested for bio mildew or qi, and for four. For group, group nine and four for downy as well. We, we just now started that downy, so that will be monitoring the, what's the, the botrytis around around.

[00:25:05] Craig Macmillan: Do you think that there is potential for commercialization of this testing? It sounds like throughput, QPCR is a really great technique, but one that you know you're gonna find at a university predominantly. Do you think there's potential for this to be commercialized outside the university?

[00:25:20] Ismail Ismail: We hope so. We developing all the technology, all the technique and protocol procedure. I think it's, it's ready for anyone to pick it up. Whether they they want to use it or not. That's, that's the thing. The technology is there. , It's robust and it's we're still developing it, but for few market we have developed, it's, it's quite practical.

[00:25:43] I hope some of the company, I know there is like a one in California, they do this they have sport trap and they have QBCR to combine together. And then they don't use it for, for resistance in particular, but they use it for epidemiology and detecting the, disease.

[00:26:00] And that's my bit on it. So I would like to use this technology for resistance. So you could have two birds in one stone, so you could monitor. Using the marker of resistance. So that would be very attractive to the grower to know, to information in the same time.

[00:26:21] Yeah.

[00:26:21] Craig Macmillan: Yeah. What is one thing that you would tell growers wherever they are on the planet on this topic?

[00:26:28] Ismail Ismail: I would tell them, resistance don't. Recognize borders. we have to work together. It doesn't matter if you're doing good and your neighbor is doing bad, , all of them actually, they can transfer with machinery, with you, with the wind.

[00:26:43] So we need a collective effort to to, combat. This. By just, just sticking to the roles they have created for, for this organization like frac recommendation. Every country have, I think, I believe they have recommendation of the resistance management. Always do the rotation.

[00:27:06] Use the labor rate stick to the limit of the number you can spray in a. You get yourself about the fungicide activity. You don't change one fungicide name from one name to another, but they have in the same group, you have to identify, you have to know what's the group meaning and what's the member inside this group.

[00:27:29] So you have to educate yourself and understand this. Always use the multi-site mode of action just to hammer if you get something. Really bad, so you always complete that.

[00:27:40] Craig Macmillan: That sounds good. Where can people find out more about you in your work?

[00:27:44] Ismail Ismail: We have several resources to do this. We got what do you call it? The AWRI dog book, the Agrochemical book. That's it's a guide for, for all the chemical being used in, in Australia and how they use it what's the limitation of that?

[00:28:03] We have a crop life Australia as well. They have all the chemical and then all the recommendation and the resistance management.

[00:28:11] And of course you have the frac website, which is have all the information about management.

[00:28:17] We got the Australian Fungicide Resistance Extension Network that's in Curtin University. It's run by GRDC. I think they have good resources for to understand the resistance.

[00:28:31] And then I think now most of the label have a section of resistance management, so they could always go back and check what they, they have to do.

[00:28:42] Craig Macmillan: Fantastic. Thank you. Our guest today was Ismail Ismail. He's senior research officer at South Australian Research and Development Institute. And thank you for being on the podcast, Ismail.

[00:28:56] Beth Vukmanic: Thank you for listening.

[00:28:57] Today's podcast was brought to you by Nutrien Ag Solutions. Okay. Nutrien Ag Solutions is the retail division of Nutrien, the largest crop inputs company in the world. As a part of their collective mission of feeding the future, Nutrien Ag Solutions provides full acre solutions through their trusted crop consultants at more than 2000 locations in North America, south America, Europe, and Australia. For more than 150 years, they have helped growers achieve the highest yields with a wide selection of products. As well as financial custom application and Precision Ag Services,

[00:29:34] make sure you check out the show notes for links to Ismail, the Australian Fungicide Resistance Extension Network, a number of other research articles plus related sustainable wine growing podcast episodes. 266. Soft pesticide trial, powdery mildew, downy mildew, botrytis and sour rot 235. Battling fungicide resistance with glove sampling, a technique that was mentioned in this interview. 219 intelligent sprayers to improve fungicide applications and save money. And 117 grapevine mildew control with UV light. Another topic that was brought up during the interview.

[00:30:12] If you'd like the show, you can do us a big favor by sharing it with a friend, subscribing and leaving us a review. You can find all of the podcasts@vineyardteam.org/podcast and you can reach us at podcast@vineyardteam.org.

[00:30:26] Until next time, this is Sustainable Winegrowing with Vineyard Team.

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