00:00:47:10 - 00:01:06:09

Hilary Sims: Hi there, I’m Hilary Sims. Fusarium crown rot in cereals is often associated with a tough finish – but the characteristic whiteheads are far from the full picture. It’s a significant disease with hidden yield impacts even in a good year – and in this podcast we delve into proactive management tips to help get on the front foot with crown rot this season. First up, I speak with Dr Steven Simpfendorfer, senior researcher with NSW Department of Primary Industries and Regional Development, for his take on the latest research and tips to reduce disease impacts. Later we’ll hear from Riverine Plain’s Kate Coffey and grower Lee Menhenett to learn more about local crown rot trials in their neck of the woods and why the Riverine Plain’s area is surprisingly susceptible to the disease. To start us off, I asked Steven Simpfendorfer to paint us a picture on the prevenance of crown rot across the east coast of Australia. Here’s Steven…

00:01:10:17 - 00:02:52:08

Steve Simpfendorfer: It's pretty similar picture across the country. We've got that risk of crown. Very much I think, individual paddock risk. So it's what the rotation sequence is in that risk. It's very variable as to what were your crown levels in the first place. And then that'll go up and down based on which break crops you're actually putting in and whether it's a host or a non-host like so all the winter cereals are hosts. But then you've got all your pulses, canola and summer crops are non-hosts. So that allows decline of inoculum brings it down to an extent. But we get massive variability because the effectiveness of a break crop depends on the season it's grown and you need moisture for that. Decomposition of cereals doubles. So the risk is there. We certainly are seeing through the data coming through that because crown rot is a stubble borne pathogen. So it survives inside the stems of the cereal plants, is that when we have big production years like 2022, we put a lot of stubble back in the system because we grow better cereal crops. But if that's got the crown rot fungus in it, which it does, it likes moisture to infect. We actually put big chunks of inoculum back into the system because we've just got so much stubble going back in. So we've seen in the testing at last year, some of our highest crown rot levels in 2024 across New South Wales into southern Queensland, where we went back onto 2022 wheat stubble with another cereal crop in 2024. We grew a break crop in 2023, so we've done the right thing. But 2023 was so dry, we didn't get a lot of decomposition of that cereal stubble during 23 that had the crown rot fungus in it. So that's been a bit of a challenge to communicate to industry. But really just see that it's not a single year disease. You have to think about that inoculum within your cereal stubble over an extended period when you get these differential environmental conditions. So it's not something you can get rid of really quickly.

00:02:52:24 - 00:02:59:28

Hilary Sims: And Steve, what do we know about it costing growers in terms of yield loss. You speak of crown rot as a disease with hidden impacts.

00:03:00:08 - 00:04:35:24

Steve Simpfendorfer: There was stuff done around 2018/19 working with SARDI and using actual predicta B data. Soil testing data that was coming in from growers, agronomists, etc. under their servers. And what we're able to do is we know the association of what those DNA levels in paddocks mean as to what percentage of plants get infected. And then we looked at modelling of environmental conditions which relates to yield loss. So yield loss is going to be a lot more in a tough hot finish because the fungus expresses as whiteheads. But what we looked at is the weather patterns across the different regions. So this was across Australia this time and looked at the DNA data. And we basically estimate that on average it's costing growers about $40 million per year. And that's going to vary obviously very much between region and years as to what the finish to your season is. But that was based on actual data that we could support of what's the levels out there in growers paddocks at that stage? And yeah, what's the likelihood of getting that tough finish in those environments where you're going to drive the yield loss. So yeah, it's a significant disease and it's probably got more hidden costs than that because we know even at levels which we don't see whiteheads, it still knocks around biomass and is probably only costing a five to 10 per cent yield loss in those seasons. So even a good year Crown Rock is taking yield off you, but it's not at a level that it whacks you in the face and you can't miss it, which it's just a loop. We're in with growers and advisers in some regions that they only think about crown rot when they get a tough finish. See the whiteheads expression go, I've got a chronic problem that just tells you what the seasonal finish was. It doesn't tell you what your crown rot risk is. Crown rot risk was either testing pre-sow or looking at how much basal browning is there. That's what your true infection levels are. The whiteheads just tell you whether you had a tough finish or not.

00:04:35:27 - 00:04:46:21

Hilary Sims: And you're getting towards the pointy end of the current research investment in crown rot that you've got underway at the moment. Tell me some of the key aspects of the projects or learnings coming out of it.

00:04:46:29 - 00:06:32:21

Steve Simpfendorfer: Yeah, so it had a number of aims. It was mainly a northern region project, and we had a little bit of money to do stuff into the Southern region, limited. As you move below Dubbo in northern New South Wales and then then further, it was really to raise awareness of crown rot.  The system certainly changes a lot more stubble retention there in tighter rotations. You know canola is probably dominant and they're running into chronic problems so as to provide testing. So free stubble testing and really supporting that region so that growers and advisers increased awareness. And certainly the link with riverine plains in the project that they've got. We've worked with them through this project to sort of raise awareness in that region as well. And it's just to get people to know about it. There's been a lot of work done on resistance to crown rot, but there's not strong levels of resistance available. Genetic resistant sources aren't there. And to be honest, we've looked for years and years like it's all minor genes. It's not like with rust we can get a major gene and you just don't get infection. This is all about minor genes and the breeding companies have taken this on. They're looking more for tolerance now, which is the ability to maintain yield in the presence of crown rot infection. And what you're looking at, there is a lot of attributes within varieties that interact with the heat stress side of things, which causes the massive yield loss. So it's things that handle heat stress tend to also limit the impact of the crown rot because it doesn't get as stressed in grain fill. So that's totally linked to how this disease expresses and causes yield loss. So a lot of work on that and a lot of regionally based stuff. So putting trials out in growers paddocks mainly through Pete Matthews in New South Wales DPIRD NVT co-location with them. So that's been a great asset for field days and communicating, seeing it out in the paddock, you can have one tonne difference in a lot of these trials just through variety choice. Don't worry about any of the other management, but just through variety this one's going to actually produce one ton more than the worst variety. I think it's really powerful to growers so they can see that there are solutions there.

00:06:32:23 - 00:06:38:13

Hilary Sims: What should growers be thinking about heading into the season in terms of minimising their disease risk?

00:06:38:17 - 00:07:43:25

Steve Simpfendorfer: One of the key things I've got to say, if we talk or I don't get paid, is that when it comes to the crown rot the cereal stubble is not the enemy, it's the amount that's got the crown, not fungus in it. So actually testing and knowing what your infection levels in stubble are, I think then gets into the grower's thought process as well. I know it's got it in there. What do I do with that. So we have situations say after 2022 again big stubble loads big yielding year. You want to sow back in there, but you can't get through it. So the discussion then becomes, well, if you know that you've actually got really high infection levels in that cereal stubble say from 2022 after a big crop, you can't get through it. I've got to either work it to get the next crop in or I've got to burn it. If you know it's got the crown of fungus in it. You actually would have been better off burning it, because all you do of your work is you've just now made sure every plant gets infected. So I think testing is the key thing. So don't look at all stubble and go that's a perverse outcome. I've got to get rid of this stubble. It drives our system. We need the cereal stubble. When we get these big ears and big inoculum inputs, we just need a way to deal with that. So the big thing with stubble is how you deal with that through the system. And some of these things we're actually doing making it worse, like spreading out the back of the header when we harvest lentils, etc..

00:07:43:27 - 00:07:46:19

Steve Simpfendorfer: And what about soil testing to get on the front foot?

00:07:46:21 - 00:09:26:00

Steve Simpfendorfer: If you predicta B soil test, you'll get a good idea of your inoculum levels. The other thing we offer out of the current project is free cereal stubble testing, where they can collect cereal stubble, and we've got a protocol that they can get off us, and we test that and plate for what's below ground above ground to give some idea there. So that's another option. So certainly either those know your risk is certainly the first thing. And to be proactive because you've got to do it pre-sow all your options are prior to sowing in terms of managing it. So if you know you've got a high risk it dictates what particular crop you're going to grow. So you might have to go to a break crop. Or if you're stuck on a cereal crop you go, well if I've got medium high levels durum is off the table, it's just so susceptible of crown rot, then you've got to push into a bread wheat or a barley, your may change variety, based on the tolerance of how they work.  Interrow sowing can be quite valuable too. If you've got guidance. Very careful then on your planting time with any cereal varieties. So if you know you've got a high crown rot risk sowing at the start of the recommended window. So it's a three week recommended window for any variety in your region. If you're at the start of that three weeks versus the end of it, you're roughly half your yield loss because you're manipulating your stress during grain field. Whereas if you delay sowing and you're pushing your crop to full grain under hotter conditions and you've got a crown rot issue, that's where there's going to be tears. So yeah, there's a lot of things like that. Whether you use VICTRATO® or not, which rate you're using can very much should be based on. You will not get an economic response to using this new seed treatment unless you've got crown rot at decent levels in your paddock. Its main active is against crown rot, so it's not something to use everywhere. Given the expense, you've got to target it to where you're going to get a return on investment, where you're stuck in situations to use it, knowing that being proactive, what you then do with your stubble as well.

00:09:26:02 - 00:09:30:21

Hilary Sims: That was a really great summary. Just to wrap up now, what would your key takeaway messages be?

00:09:30:27 - 00:10:30:07

Steve Simpfendorfer: This is actually a manageable disease. But the problem is for growers and advisers, particularly if you're pushing into new regions. It's something that we've got to break that thought process, that this is just a disease of a tough finish. It's just bad luck. I had a tough year. Yeah, I got crown rot. I walk away and not worry about it. It's manageable, but it's not a disease that you can manage if you only address it every time you have a blowout, every time you have a tough finish and you see a lot of whiteheads, you've just built your knocking levels up too much. So certainly knowing that is my key message. So be awareness. There's testing there and we're here to help. You've got state based pathologists. We do a lot on it out of Tamworth. Happy to do stubble testing. Discuss management options. If you want to put demonstration trials into show stuff to your growers. Happy to talk about that. But it's not one to ignore. If you just try to address this every time you're going to get wet years again and you end up with pink grain, white grain, fusarium head blight problems, and then every now and then you're going to get that really tough finish and get a lot of whiteheads and have irate growers saying, what the hell's going on? So gotta manage it every year.

00:10:32:18 - 00:10:52:16

Hilary Sims: My next guest is Riverine Plains senior project manager Kate Coffey. Kate's part of a project group working with Steven to better understand crown rot risks in the Riverine Plains region, and has her finger on the pulse of the latest research and grower practices. Kate starts by describing how the focus on crown rot came about. Here's Kate.

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Kate Coffey: This project started back, I think it was about 2022 when we had a stubble trial project at Murchison, which is the southern part of our catchment, and we had done a wheat on wheat rotation and Steven Simpfendorfer contacted us and said, well, why don't you do some testing with us to see if there's any crown rot? And crown rot is something that doesn't really get mentioned much around here. So we did the testing, and we were quite surprised to find out that the levels were high. So based on that information, also what Steve had been doing in terms of his project, we knew that there were significant levels in this region, but it's just something that's not really talked about by the farmers around here. And it seems to be more of a northern New South Wales problem rather than, say, our area, which is sort of southern New South Wales, northern Victoria. So we're interested to see what the levels were in the region and then also what was the impact and what farmers could do about it.

00:11:47:13 - 00:11:51:18

Hilary Sims: What do you think it is about your area that makes it so susceptible to crown rot?

00:11:51:21 - 00:12:13:02

Kate Coffey: One of the main one is that we have quite short rotations and there's a lot of cereal canola rotations, and because crown rot is stubble bourne and we're retaining a lot of that stubble, that stubble is carrying the disease, because we're not having very much of a break between cereal crops. So we're sort of prone to the crown rot for that reason.

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Steve Simpfendorfer: And tell me more about the trials that you've recently completed.

00:12:16:13 - 00:13:24:10

Kate Coffey: We had a GRDC NGN project which was around engaging with farmers, firstly to test their paddocks because there's not much testing going on. So back last year, I think we tested about 20 odd paddocks, and we found that 75 per cent had the crown rot in medium to high levels, which means they can cause quite significant yield loss. So then we went back to those farmers and suggested some management strategies, which included looking at a crop that was less susceptible, such as barley versus wheat. So then we had a couple of people actually do trials for us. So one of them was comparing barley to wheat in one paddock. Another paddock, we'd heard of some work done in northern New South Wales that looked at a higher seeding rate. And that sort of appeared to reduce the crown rot so we tested that as well. And the final one was looking at a different source of nitrogen, because there has been some research that shows nitrate, which is present in urea, exacerbates the crown rot. So we looked at a different format of nitrogen, which is called eNpower urea, to try and reduce the amount of nitrate that's available to the crop earlier.

00:13:24:15 - 00:13:28:20

Hilary Sims: And do you have any key findings from the research on these topics that you've done so far?

00:13:29:01 - 00:14:17:12

Kate Coffey: Because they're not replicated trials, we can't sort of make conclusive findings. So we really only found trends. The other site that we have, which was where we originally identified the crown rot, we found really clear findings. So that was where we have a site at Murchison where we identified the crown rot a couple of years ago. So since we identified that high level, the farmer after the second year wheat, burnt the wheat stubble. Then he sowed faba beans the year after. And then he sowed canola last year, and he's basically taken those levels from high at the end of the wheat rotation, and they're now below detection. So that site clearly showed that the crop rotation over two years drastically reduced those crown rot levels to where they're not going to have an impact on his wheat that he's going to sow this year. So that's a really clear finding that we've found.

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Hilary Sims: Would you say that growers have a good awareness to crown rot in your area?

00:14:21:11 - 00:14:57:25

Kate Coffey: I think the awareness is quite low, and I think because most farmers are focused on the leaf diseases such as stripe rust, and those leaf diseases are a lot more visual and they can cause very significant yield loss that is visual. So they're focused on those diseases and therefore they're not focusing on crown rot because we probably haven't seen the visual symptoms which is the whiteheads. So I think potentially it is causing significant loss. But because it's not visually seen in the paddock, I don't think farmers are potentially prioritising it over other diseases, which they're quite focused on.

00:15:00:07 - 00:15:24:03

Steve Simpfendorfer: Lee Menhenett is a local riverine plains grower based at Arcadia, south of Shepparton, Victoria. He's hosted crown rot paddock trials on his property for Riverine Plains previously, and I caught up with him to learn about his experience managing the disease and what his research involvement looks like this year. He starts off by describing his farming operation and rotation. Here's Lee.

00:15:24:21 - 00:16:17:17

Lee Menhenett: We farm southern part of the Goulburn Valley. The rainfalls somewhere between 520 and 550mm a year annual. Mix of soil types from sandy loams over clays to some soda salts. So we've got some sodic soils as well. And so we've got some lighter loamy, a country that also runs through into some heavier clay country as well. A bit of a mixed bag as far as soil types go. We run two wheats in a row. That's obviously why we see a little bit of crown rot. So two wheats in a row and then we have a double break up. So we roll from the wheat stubble into a faba bean crop. And then after the faba beans, we put generally a Clearfield canola in after the faba beans and then come back into two years of cereal. And that seems to work for the system from a storage perspective, from a weed rotation point of view and a disease point of view.

00:16:17:23 - 00:16:26:04

Hilary Sims: And Lee, you're involved in trials with riverine plains. Where are you seeing crown rot in your paddocks, and what does your involvement in the trials look like this year?

00:16:26:12 - 00:17:11:24

Lee Menhenett: We tend to see it on the lighter soil types more than the heavier soil types, so it's hard to put an absolute figure on what that yield reduction is just based on whiteheads. But you know, there's potentially a greater loss as well that we're probably not even detecting and not even seeing, because maybe some decreased ability of the plant to mobilise moisture and sugar in the stems just by that, even that browning and the narrowing of the stem down lower. So we're actually looking this year at doing a few trials, particularly with the new seed dressing VICTRATO®  where we'll do strips through the paddock and try to get a little bit more of a handle on what those yield differences may be. Assuming that we get good protection from the VICTRATO® , then hopefully we pick up what yield penalties we've been getting with the crown rot. We're looking at the second wheat, so not so much the first wheat.

00:17:11:26 - 00:17:16:11

Hilary Sims: And what do you do currently on farm to help mitigate your disease risks?

00:17:16:18 - 00:18:09:12

Lee Menhenett: Part of our normal plan on mitigating disease risk is the primary function I suppose is rotation. So we try to make sure that we rotate. We get those two break crops in where we can. So that's the primary thing. So go into faba beans following the wheat crop and then canola following the beans. So you get that double break and we retain the stubble. So it never really burn or anything like that. On top of that, we'll see how we go with the VICTRATO®  as well.

00:18:09:15 - 00:18:14:28

Hilary Sims: And Lee, just to finish up, what are some of your key messages to other growers with a similar setup to you?

00:18:15:06 - 00:19:13:00

Lee Menhenett: Just being aware that you have an issue through testing monitoring as well. You know, not only do you have issues with just whiteheads when you get those tougher finishes, but potentially, you know, there's a bit of a sleeper going on down the base of the stem at the crown, where it's not really shutting down complete supply to the head, but it's restricting it enough where it's going to actually be impacting yield. And so, you know, having closer looks of that and just to see whether or not there is any crown rot present down at the base of the stem, and not only just the whiteheads would probably be the other thing. And, you know, I think when we're retaining stubbles probably trying to get them broken down quicker by burning or something like that, if you have to. So really taking advantage of having that double break by making sure that the stubble's broken down as well and not carrying over any more disease from year to year.

00:19:19:23 - 00:19:43:11

Hilary Sims: That was Arcadia grower, Lee Menhenett. And before him was Riverine Plain’s Senior Project Manager, Kate Coffey and senior researcher with NSW Department of Primary Industries and Regional Development, Dr Steven Simpfendorfer. More information on this topic can be found in the description box of this podcast, or online at GRDC.com.au. I’m Hilary Sims and you’ve been listening to a GRDC podcast.