S4E12: Identifying Crop Disease with the Plant Disease Clinic

Recorded: 12/17/25

Plant disease can be difficult to diagnose, and thankfully, you don’t have to do it alone! In this episode, Ryan and Justin sit down with Dr. Sara May, Manager of Penn State’s Plant Disease Clinic, to discuss utilizing the clinic, identifying crop disease, and disease trends. 

Hosts: Ryan Spelman and Justin Brackenrich
Guest: Sara May, Penn State

Links:
Plant Disease Clinic
National Plant Diagnostic Network

Photo credit: Amy Duke, Penn State

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Transcript

Ryan Spelman (00:21)
Welcome to another episode of the Agronomy Highlights podcast. I'm your host, Ryan Spellman, and I'm joined here today with my lovely co-host, Justin Brackenridge. Justin, how are you doing today?

Justin Brackenrich (00:32)
You're

doing great, Ryan. How about yourself?

Ryan Spelman (00:34)
Justin, I'm living the dream. Good, good. It's been a while since I've been able to say that. Actually, no, because we've had two episodes back to back with the two of us. Yeah, yeah. There we go. We're back on track. Sorry, Dwayne. We'll get you on the next one. Yeah, so I'm pretty excited about this episode.

Justin Brackenrich (00:52)
Yeah, this is one of your episodes today,

Ryan Spelman (00:54)
Yep, it's another plant pathology episode. So buckle up guys, we're going to talk about plant disease diagnostics. So Justin, maybe you can introduce this a little bit. What do you know about plant disease diagnostics? ⁓

Justin Brackenrich (01:07)
Well So what I do know is that this is a resource right that anyone can use in the state It is used for diagnostics of disease. It does not matter whether it's agronomic horticulture landscape If you think you have a disease you can send these with some paperwork and get an answer and I think this is kind of one of those like underappreciated or maybe even underutilized not that they don't have enough but at least by the agricultural group

of Ryan will agree, but maybe not. Diagnosing all of these diseases and stuff is difficult in the field. And so I think if there is an opportunity to use it and get someone to help you that's a professional that looks at these every day, I think that's awesome. So that's what I know about it. I'm hoping that by the end of this, I'll have a lot more to add of what I've learned, but I'm looking forward to it. I've never met Sarah. ⁓

We talk about these at a lot of our meetings, so now we get to put it all together and learn more.

Ryan Spelman (02:06)
Yeah, definitely. You pass the test, you know a lot about it.

Justin Brackenrich (02:10)
Hardly.

I read Debris Shore, I'll put it that way.

Ryan Spelman (02:13)
There you go. You went and found the resources online and you know that I think you're you're hitting it right on the head that I think this is a very underutilized resource, maybe in our commercial agronomy world, right? Where people are doing grain crops and stuff like that. I think a lot of homeowners and or horticulture producers are a little bit more familiar with this, but diseases can be really hard. You know, even as someone with a strong pathology background, when you're in the field and you have

different bacterial symptoms or fungal symptoms or viruses that all you know can look the same in some way or another without looking at it under the scope. It's really nice to be able to just send it to someone who can tell you what you're looking at. So it is an available free service to anyone who needs it and today we have a great opportunity to learn about how we can use it, how we can submit samples and when we should do that.

I'm really excited to jump into it. So let's just get right into it. we're gonna introduce here Dr. Sarah May. She is the manager of the plant diagnostic clinic at Penn State. we'll let her introduce herself. Hi, Sarah, thanks for joining us.

Sara May (03:25)
Yes, no problem. Thank you for having me on. I'm happy to talk about the Plant Disease Clinic. In the clinic, I'm in charge of our daily operations of...

testing samples and diagnosing samples that are submitted to the lab. I also write the reports that get sent out to the clients and I spend a lot of time communicating with our clients and our extension educators and our master gardeners, sending them information, answering questions about diseases, talking to them about submitting samples or if they got a report from us and they have questions then I work with them on that. So that's the main part of my job and in addition

I also do lot of work with what's called the National Plant Diagnostic Network or the NPDN, which is a national network of labs like mine across the U.S.

Ryan Spelman (04:12)
Yeah, that's great. think the national network is kind of a cool thing because I know like from my experience and the plant pathology world, like everyone kind of knows each other. You guys can bounce samples between each other and work with each other to kind of like solve these national disease movements stuff, which is kind of a cool thing that you guys do on top of the normal local services that you provide. So maybe you can talk about that. Like what's the mission of the clinic? Like how many much are you?

working with commercial operators, normal homeowners, and what is the goal? Just to get people good disease information? Maybe you can speak to that a little bit.

Sara May (04:50)
Yeah, absolutely. So, I mean, our mission is to provide a clinical diagnostic service to anybody who's growing plants in Pennsylvania. So that can be a commercial farmer who's got ⁓ acres and acres of a crop or just someone who has a couple plants in their apartment, some house plants that are looking sick. So our job is to provide a disease diagnostic service. It's a free service in Pennsylvania, which is pretty awesome. And they can send in a sample and we'll try to tell them what's wrong with their plant.

Justin Brackenrich (05:20)
Just Sarah, I want to go back for one second and maybe we can move this but the NPD in this national network. So we also have listeners that aren't just in Pennsylvania that come from other places. Talk to us a little bit about that in is this like an accreditation that someone should look for when sending a lab sample to a lab? Are there other creditations? Are these members of this universities only private labs, etc.? How would someone get something sent that's in a different state?

Sara May (05:48)
Yeah, that's a very good question. So we have labs in every state. They're usually associated with the land grant university in the state. And there is a website, NPDN.org, and it has a map of all the states in the US as well as the territory. So if someone is in a different location and they want to find the NPDN lab in their state, they can go there to find that.

are able to connect and communicate information with each other. We don't have any private labs in the network, but we communicate with private labs as well as part of the network. So it's a really great organization where we can keep each other informed about different up and coming diseases. And also if we aren't able to test for a particular disease in our lab, but we think a sample could have that disease, we can let the client know they can send it to a lab in a different state. It's a really great organization.

And we also get funding that supports our labs through the USDA as part of this NPDN network.

Justin Brackenrich (06:46)
So I'm looking at the NPDN directory page online. And we'll certainly share this within our show notes. But this is really interesting because, like you said, you're broken into region and there's different groups within regions. But I would really encourage anyone that's interested in this to look for something that's close to home. I'm not saying we don't want you to send your samples to Penn State, right? Please do that. there are always times that you can get in here. And so I mean, I think this is kind of a really

eye-opening thing for me that's not involved in a lot of the plant diagnostics and diseases in these laboratories. Just what a robust network this is. So I appreciate you sharing that with us.

Sara May (07:25)
Yeah, it's really helpful and that's a good thing to point out because since we are a free lab, we don't currently accept out of state samples. So if someone from another state would contact us, we would recommend that they send a sample to the lab in their state and they're usually more familiar with what's going on in their state. We do have a permit for out of state samples if there's a certain instance where we need to help do testing, but right now we don't accept out of state samples. So that's a good thing to make people aware of, but they can go on that site and they can find another lab in their state.

that they can definitely use.

Ryan Spelman (07:56)
Now, Sarah, does that go for like other labs? I'm thinking if let's say I'm in, you know, the eastern part of Pennsylvania and I might be closer to Rutgers, right? They might see more of the same diseases. Can I send that over state lines to them or should I stick to the Penn State, you know, your service?

Sara May (08:15)
That's a really good question. So yeah, they can absolutely send it to another state that accepts out of state samples. Rutgers does accept out of state samples. They have a permit for it. So they can send samples to there. It differs state by state. And so we aren't currently accepting it, you know, mainly because we don't charge a fee for our samples. So we're serving our Pennsylvania growers and providing a free service for them. But they can check with another lab if they want to send it. There are a lot that accept out of state samples.

Justin Brackenrich (08:43)
So let's get into some of the services that are offered, right? If you say plant diagnostics lab or the plant disease, diagnostic clinic or the plant disease lab, let me get my language straight. That to me sounds like a lot of stuff, right? Those things are really encompassing a lot. So what actual services and testing are you doing at your lab?

Sara May (09:05)
Yeah, that's a really good question because there are so many different diseases that can occur on plants and we're focused on diseases and we can test for and identify a lot of them. On field crops, we can test and identify a lot of the foliar leaf spot diseases, root rot pathogens, ⁓ stalk rots, ear rots, those sorts of things. But there are certain diseases that we can't test for.

And so what I recommend is if there's a specific disease that a client thinks they have or as an extension educator, you see something out in the field and you want to have it tested, but you're not sure if it's something we can test for, definitely email or call us and we can let you know. Or if we do get a sample and we see symptoms of a disease, but we don't have a test for it, a good example in field crops is barley yellow dwarf virus. So we don't have a specific test that we run for barley yellow dwarf virus.

But if I get a sample and I think it's that virus, I can tell the client that they can send it to another lab for testing. So that's kind of how we do it. We can't test for every single thing, but we can test for a lot of diseases and we can look at the symptoms and the information and sort of narrow it down. And if there's another lab that can test for it, we can recommend that they send it to another place.

Ryan Spelman (10:18)
Yeah, know, it's compared to some of the other testing that in the agronomic world we do, which is like lot of soil testing and plant tissue testing. This is actually kind of quite a dynamic process in comparison, right? Like there's not just one protocol for you get a plant in and you test for a disease, right? It depends if it's a virus, if it's bacteria, fungi, and then, you know, all the other questions that come downstream of that. Maybe it's not a disease or maybe it is, you know?

I'm just curious, know, before we go too much farther down that hole, what proportion of your samples do you find are currently like coming from the homeowner versus like a commercial agronomic producer?

Sara May (11:00)
That's a good question. So I don't know the exact numbers off the top of my head of homeowner versus commercial. The amount that we get submitted directly from homeowners, whether they're sending it to us themselves or they're going through their extension office is about 50%. And then

The other 50 % is coming from commercial clients, a lot of those commercial clients are landscape and tree care companies. So it'd be coming from somebody's house, but through one of those companies that's working on their landscape or working on their trees. So we have that aspect of it as far as agronomic crops go, corn, soybean, oats, wheat, all of those, and the forage crops. So only about 2 to 3 % of our

annual samples are coming from those types of crops. About 50 % or more of the samples we get are woody ornamentals. So these would be from people's homes, from the forest, from nurseries that are growing trees and shrubs to plant in people's yards. So that just gives you a general idea of the type of samples we get.

Ryan Spelman (12:06)
Alright so that's marching orders for our listeners. Let's bump up those numbers, okay? We need to show higher representation than 2-3%. So I'm hoping in the next year you get maybe 4-5. That's my goal, okay?

Sara May (12:23)
It'd be great, yeah, it'd be great to get some more field crop samples.

Ryan Spelman (12:26)
Sure, well, and I'm imagining probably from your perspective, it probably helps to get more of one crop, right? Because you get to a better idea for some of the more common issues, some of the symptomologies, that kind of the case.

Sara May (12:39)
Yeah, absolutely. The more we get of a certain type of sample, the more we can get an idea of what's going on out there and, you know, can just provide better information for our growers. And yeah, it can be really helpful.

Ryan Spelman (12:52)
Yeah, well actually now I have a I'm going a little off script here. But one question based on that is, is do you guys like ⁓ collect some of this information over time and and like as you get more samples, is there anywhere you report out, you know what you're seeing publicly?

Sara May (13:12)
No, that's a good question. I don't have a public report that we put out, but I'll sometimes present information if I'm giving a talk to a specific group and you know can present information on the different types of diseases that we are seeing on a certain crop or if an extension educator is looking for that information for a presentation they're giving, I can take that from our database and say okay here's how many samples we received of this type of you know crop or crop group and here's the type of

of diseases or problems we were diagnosing.

Ryan Spelman (13:43)
Okay, great. Well, so let's jump into the actual process of submitting a sample and getting it tested and talk through some of that. So, you know, if I'm a farmer and I suspect that there's a disease out there, or maybe I'm a crop consultant, where do I start, right? How do I go about sending a sample to you? You know, maybe you can talk about the difference between a digital and physical sample as well. Maybe we can start there.

Sara May (14:08)
Yeah, that sounds great. So I usually recommend that growers first contact their Cooperative Extension Educator because our Extension Educators often are able to give a quick answer to something that's an easy problem. So they might be able to identify it for you right away and you can skip the part of sending it to our lab. But ⁓ a lot of our growers are already really knowledgeable. A lot of our crop consultants are already really knowledgeable. So

If they're wanting to send a sample, usually means it's something unusual they haven't seen before. So they can send a sample to us. They can either send a digital sample or a physical sample. With the digital samples and with field crops especially, there is a higher likelihood that we're going to need a physical sample that we can look at under the microscope or we can culture from. So they might just want to start off by sending a physical sample.

But with a digital sample, just need several photos of the symptoms that they're seeing, close up photos of the symptoms, but also farther away so we can see maybe the pattern across the whole plant or in the field. And then we also ask them to fill out what's called our clinic form or our specimen information form and submit that with the sample. So they can email that information to us and then I'll get back to them.

I might say, it looks like this disease, you it looks like tar spot, here's what you can do. Or if we can't tell, then I'll say, okay, we're gonna need a sample, here's how you send a sample, here's how much ⁓ of a sample you need. So that's how they would submit a digital sample. And then a physical sample is similar in that they would need to fill out the information form as well. And then collect a sample, we have information on how to do that.

and then they can mail it to us or they can drop it off if they live nearby or if they're coming through the area.

Justin Brackenrich (15:51)
So Sarah, one of the problems that I have, I want to say I appreciate you saying how we're good at diagnosing these things in the field, right? That's a special skill that some of us have, I would say, Ryan, much more than me. But that's what makes this job great. You get to learn. One of the problems that I have, and maybe you can talk a little bit to this, but it seems in my experience when we use this word disease, right, this is kind of an umbrella term that maybe we throw around

kind of unparticularly to one situation we have. When I go out and I'm looking at something, someone calls me and they're like, hey, I got this disease plant or things don't look right. There's like a primary thing and then there's almost always like a second or tertiary or multiple secondary things because it feels like as soon as something goes wrong, then the wheels start coming off altogether. And that's where I really get stuck is,

And where I think this diagnostic, and you can kind of help with this protocol, is a root problem may lead to this depletion in the plant's ability to fight things that then leads to this foliar disease, right? How do you kind of pull all this apart? And when you go out and you look at this plant, what should I be doing to identify these multiple things and working with you all to sort through that?

Sara May (17:05)
Yeah, that's a good question because it can get really complicated when there's multiple factors involved.

In the disease clinic, we're trying to sort through and see what's there and kind of go from there based on the information we have on all the research that's been done on these different diseases. So first being able to identify, is there one of those root rot pathogens there? Is it one of the ones that can really cause a lot of problems or is it something that we might find more on plants that are stressed or in an area where there's a lot of water, like Pythium root rot? And so just being able to make that

diagnosis can give us more information on what's going on and can also be an indication if soil or environmental factors are playing a role. And yeah, it can be a complicated problem, but if we have a good enough sample, we can sort out what the different problems are, whether there's leaf spots involved and root rot, and kind of go from there to make management recommendations.

Justin Brackenrich (18:05)
think it's like every year, right? We get into this mid-year, we're starting to top dress our corn, we're using either urea or a liquid product. No matter how careful we are, we almost always see burn, right? And we start to see this burning happening. And then you go back and you look and now all of a sudden these little sooty molds or these little black spots or something has popped up on it. So I guess that's kind of where I'm leading to this thing is.

For me is is what I would not consider an expert I look at this and it's taken a couple years of working with people that are good at this to say you know, that's not the calls by this disease or this pathogen. What happened is we damaged it This could have been a nitrogen application. It could be insects. It could be hail it, you know the the myriad of problems but then not making this like immediate knee-jerk reaction I gotta get fungicide out there right like because

That's not leading to this. And I think that's where you all as experts can talk us off the ledge by taking a couple of days and sending this sample.

Sara May (19:07)
Yeah, absolutely. That's a really good point because we do get samples like that where we're only finding those secondary sooty mold type fungi growing on something that's been damaged by something else such as a like a fertilizer application. And, you know, and that's information that we would include in the report to hopefully communicate to the grower that, you know, this is an injury and then, there's fungi on it there, but they're not pathogens. They're not causing, you know, the symptoms that they're seeing. And, you know,

We have other labs here at the university that can help with further looking at some of those things, like if there's high salts, there's the ag analytical lab, or if there's an insect problem, even if they send a sample to me and we see an insect problem, we have an entomology lab, the insect identification lab that they can forward samples to. But yeah, it's nice that we're being.

We're able to do that with samples when they're sent in and say, no, this is not a primary pathogen when we just see that, you know, sooty mold growing on ⁓ a fertilizer burn. That's a good one.

Ryan Spelman (20:09)
Yeah, no, it's the secondary pattern. Like I have one example that I remember was I had a field where the farmer was asking me about downy mildew. He had a lot of downy mildew all over the place on his soybeans and I found them in patches, right? And so that was a case where we pulled up the soybean plants and you saw that there were no nodes, right? So there was something else that was stressing it that was leading to

⁓ a disease issue, but that wasn't the real problem, right? There was actually an acidity problem that he had in the soil. And that's kind of what we landed on. So it is dynamic and just because you see a disease doesn't mean it's always the problem you're facing. So to that, you know, message, is that something that, how involved are you guys with that process, right? If you get a diagnostic sample in, are you trying to like, if you got that downy mildew sample at that soybean plant, would you say,

yeah, that's down email, Badoo. That's what you have. Or do you go through that process of explaining to the producer, the person submitting the sample, like that might not be your actual issue. These are the other things you should test for or do that. Could you maybe talk a little bit about that?

Sara May (21:17)
Yeah, that's a great question. And that is an important part of what we do. So if we get a sample where we're, you know, maybe we're finding a disease like Downy mildew, but we see it looks like the primary problem is actually a nutrient problem or a pH problem. That's what we're going to be communicating to the client. And ⁓ so we'll be recommending that maybe they send it to the nutrient analysis lab, or we're just giving that information so that they can, you know, assess their ⁓ production and try and determine if that's what the cause is.

And a lot of that also though relies on the type of sample and the information that we get. So if someone just sends us a couple leaves and you know, what are these spots on the leaves? That's what I'm worried about and we say, okay, well that's downy mildew. But if they send us a lot more information and a better sample that includes like the entire plant, maybe they send some pictures and they show us like, okay, this whole area is declining. And we look at it we can say, well, there's a little bit of downy mildew there, but the real problem

looks like it might be a nutrient problem or a problem with the soil. Maybe there's too much moisture, that sort of thing. That's what really helps us because we're just getting a little snapshot in our lab of what's going on out in the field with the samples that we get.

Justin Brackenrich (22:30)
And so my least favorite metaphor that we use is tool in our toolbox. But when it comes to diagnostics, like we've got to have the whole toolbox, right? And maybe we've come full circle from where we started. But with you all as a lab, if you get a sample of Downy Mildew, you can't begin to diagnose that it's a pH problem or a rooting issue unless you've given you all the sample to do that, right? So like IE.

If you're sending a sample, it's good to send maybe the root and soil sample and the leaf sample. Maybe we should be also sending some fertility samples at the same time because the more information we have, the better we can put this picture together. in your mind, as the person that's running and managing these samples, is there such thing as like too much information to provide you that I don't need a root sample for everything. I don't need a soil sample.

What would you say to like picking what you send and when you send it?

Sara May (23:28)
Yeah, that's a really good question. I mean, we always say that more is better, you know, more of a sample or a larger sample. Also, more information is better. So having the information filled out on the form that we provide and also sending pictures so you don't have to only send pictures if you're submitting a digital sample, you can email pictures to us as long as we have the information like your name and address and the type of sample. We can connect it to the physical sample when it gets here or you can always print pictures.

Sometimes people send me thumb drives with pictures on them. So that can be really helpful because I can look at those and I can see, okay, this is a bigger problem or a different problem than just the leaf spots that are here. It's a difficult question. Like when do you just send a little bit of the foliage versus, like you said, the entire plant, including the roots and the lower stem. But you can always call and ask us and, you know, if you're really seeing something that looks like just strong symptoms of a leaf spot and it's like, yeah, I really think that's

a leaf spot but I don't know which one it is then yeah you can just send some leaves and we're happy to look at them.

Justin Brackenrich (24:31)
And I don't want ⁓ everyone to take this story that I'm going to tell and run with it. But one of the experiences I recently had, we were talking for the started, I was telling Sarah that I was sending plants out of our flower bed. We did a bunch of landscaping at home. And if anyone does much landscaping, you recognize the price of installing shrubs. And so my like midsummer panic was all of these hydrangeas were just starting to die. And you make these these decisions and I sent in leaves.

And the response that I got, which was very good, is we're not seeing any type of disease. However, this could be environmental or it could be one of these soil borne type things. So then I had to take another two weeks, right, to get the soil sample and send it. So I'd say this story to say, I think, unfortunately, what I may have learned from this is you're going to get the whole plant every time I send something. Because if you were trying to make these diagnostic decisions in your

looking at your produce or your agronomy where it's more important than my hydrangeas, two weeks or 10 days could be a huge difference just trying to go back and forth in the mail and collect samples. So if you are concerned, if you think there might be more to this picture, my advice would be send it all the first time and let them have it. And the worst they're gonna say is, Justin, quit sending us these bags of dirt, it's not helping.

Sara May (25:46)
Yes, that's a very good story. That's a good point. If you can send more at the beginning, it helps us. It saves me time from having to look at something and not find anything and then write a report and all of that. So the more you can send us, then the more tests that we can run and the more we can look at it, it can be helpful for figuring out exactly what's going on.

Ryan Spelman (26:08)
Yeah, so this is probably a good segue into talking about when you're submitting a sample, like what makes, so we talked about, you know, what you might want to think about, sanding. Maybe it's the full plant, a few leaves, the full plant in the soil, kind of depending, it's, it's very dependent on what you're looking at, right? now how do we make sure that this gets shipped and doesn't come to you rotten or, you know, do you have some tips and trips on?

on how to take a quality sample, how to send that sample in a way that it's not gonna deteriorate and, or maybe, know, and times to avoid or send it, you know.

Sara May (26:42)
Yeah, that's a really good question. we have good instructions ⁓ on our website. We also have an instruction form that we can mail to people so they can review how to send a good sample. But generally we recommend shipping it quickly is helpful, especially in the summer when we have really hot temperatures. So people can send it overnight and if they send it UPS or FedEx, it will get to us the next day. If they send it U.S. mail, it'll go to another

distribution location at the university before it comes to us so it might take an extra day. So if you can send it faster then that just helps to keep the material from from breaking down and shipping especially when we have a lot of herbaceous material. So if you're sending flowers from your garden or you're sending you know something like a soybean that has a lot of leafy material it can break down a little more quickly.

But if you're sending woody branches and leaves that are from a shrub, they might not break down quite as fast. But if you can get it to us quickly, that's important. If you're sending roots, which is great, we can definitely take a look at the roots and test them for different pathogens. We recommend that you either...

wrap the roots in a separate bag and secure it at the base of the plant. Or you can collect a separate root sample and put it in a separate bag. you're, you know, let's say you've got a large shrub or something like that, you can fill up a sandwich bag with about one to two cups of roots that we can look at. We just want to prevent the soil from getting any soil that's attached to the roots from getting on the rest of the plant material and shipping, because there can be lots of, you know, microorganisms in there and then they start to bacteria and fungi that aren't associated with what

whatever problems occurring and the leaves start to rot. So that's what we recommend for that. We don't do testing on soil other than we occasionally check for phytothera root rot from soil. So you don't have to send us soil. We just need the roots that we can test.

Justin Brackenrich (28:38)
So I'm gonna kind of review in this aspect of I'm sending you a sample, right? So I've gotten on the website. We're gonna share the website on the show notes. So anyone's interested in that, please get in there and check it out. If not, I would say, you know, start by contacting your extension person. The first step is to go out and collect your sample. And I think it's important that while you're collecting,

All the fungal and disease people will probably make fun of me for saying this, but I think there's also an importance to the pattern that it makes within the field sometimes. And Sarah may elaborate on that, but don't just run out real quick, yank this thing up by the roots and then run to the house and start working on your sample, right? Take a minute, visually inspect what you see. Then we go through the process that she just described. That's filling out that form. They're gonna ask for your location. This is not like a location so they can track you and send a... ⁓

Fungicide drone in the middle of the night to clean everything up, but it's so that they can look at some of this information Then that sample is gonna go provide the best you can Now it's gonna make it through the US Postal Service or UPS or whatever your choice shipper is I assume people can also drop them off at the lab if they're close to State College Now you get it Sarah. You're unpacking every day's Christmas morning You've got all of these packages. You're unwrapping all of these plants. Where do you go from here?

Sara May (29:54)
Yeah, that's a very good question. And I think you summed it up really well, how to collect a sample distribution in the field is really important for determining could this be a disease problem? Could it be something abiotic, like a nutrient problem? So that's really important. Yeah, once we get the samples, we open them up, we log them into our database that we have so we can keep track of the sample and not lose any of them. And we start to triage and look at what needs to be done first.

We look at everything under the microscope to see what might be going on. We review the information that you fill out on the form. And that helps me to start to narrow down what are we going to test for.

because we can't test for every possible disease that can occur on a plant to try and figure out what's going on. It's kind of like when you go to the doctor's office, they can't test for every possible problem, right? So you show up and you describe your symptoms. You say, I have a sore throat or I have a cough. Well, they're not going to X-ray your foot. So it's the same idea. We're looking for the information on the symptoms that the plant is showing. Is it yellowing? Does it have spots on the leaves? Do the roots look like they aren't growing well?

And that helps us to narrow down to what diseases can we run tests for. And so we might have certain tests that we can run that are actually really similar to the COVID test, like an at-home COVID test that you might take, an antibody-based test, and we might do culturing, or we might put something in a moist chamber, which is just a plastic bag with some wet paper towels in there so we can look for fungi and bacteria to develop.

So we mainly need that information so we can figure out what tests are we going to run and do we need a better sample or a different type of sample.

Ryan Spelman (31:34)
Yeah, that's, it's, it's funny, you know, there, are all these different routes you can go, right? Like you're kind of indicating, maybe if you suspect a virus, you can pretty quickly use a test. just thinking in my head, like for some of these diseases, right? Like you have like TARSBOT, which would be an obligate biotrope, right? Is how do you deal with something like that? Right? Is it more just like looking at it under a scope and, seeing the structures because you can't really

culture it and do anything, put it on a plate and look at media. Is that kind of your approach to stuff like that?

Sara May (32:08)
Yeah.

Absolutely. Tarspot's a great example because we don't culture it, but it does produce the structures of the fungus on the leaf and the spores inside those structures that we can just look under a microscope and identify it. So ⁓ that's a lot of the work that we do is looking at samples under the microscope and looking for those structures that we need to make an identification. And if we think it's something else, then like you said, we might culture it. We might run a test for a virus or something like that. And yeah, there's lots

of different things that we can do.

Ryan Spelman (32:38)
So because there's all these different routes you guys can go, right? Is there a standard amount of time of turnover that you have between getting the sample in and making your report to the customer?

Sara May (32:50)
Yeah, that's a good question. in our busy months in the summer, it's usually about a two to three week turnaround. And that depends on the volume of samples that we're getting, how many do we have to process, and the time that it takes to process certain samples. So if we have to culture something and wait for the fungus to grow and form the structures that we need to make the identification, that can take a week or more.

for that to happen. So it can take two to three weeks in the summer. In the winter when it's a little bit slower and we don't have as many samples and in the late fall and early spring, it's usually closer to one to two weeks.

Justin Brackenrich (33:28)
I think there's a good point to be made here in that when we're thinking about disease, along with some of these others, we try to be as reactive as possible. I think that it takes two to three weeks, right? This is nothing against them, but they're growing something, right? They just can't always look at them. But I think this really stresses the importance of scouting because I know we've talked about collecting samples and if you've ever heard Dr. Collins talk about it, she has this picture that says like dead plants tell no tales.

And so if you've waited, if you've seen it start and you've waited and you say, I'm going to give it a week. And then after that week, now you say, I guess I'll do something about it. You've now given this stuff potentially up to a month head start, right? So if you start to see something happening, you need to go out and collect that sample and get it sent to the lab so that you still have time to make whatever treatment is recommended and salvage whatever that crop may be.

Sara May (34:25)
Yeah, that's a very good point. mean, the disease can spread and develop. And if you wait too long, then you're to have to wait for us to be able to process it and wait for us to be able to identify it in the lab. And then it could be a lot farther along. And I like that.

description that you mentioned, the dead plants tell no tales from Dr. Collins because it's very true. If something is too far gone, then you're going to get a report from me that says insufficient sample. It's going to say it was too dead, it was too far gone, and we can't tell anything from it. So we definitely, ⁓ we like to say as diagnosticians, we can't do autopsies. So we need a sample that is starting to show the symptoms.

⁓ or even a range of symptoms is optimal. That's what I usually say to clients, collect a range of symptoms. So it's just starting to show, you know, some browning or some leaf spots to, okay, it's farther along and you can send some stuff that's even a little more dead. But usually on stuff that's really dead, we can't determine what caused it. There's too many other microorganisms and fungi and bacteria decaying the plant material and breaking it down and we can't figure out what was the main cause.

Justin Brackenrich (35:31)
think that's what you just mentioned in something we maybe should talked about earlier, but this idea of sending different levels of infection within the sample, right? And if we're using like color or a visual assessment, like sometimes things are different within a hybrid of a specific crop that you may go out and say, well, this doesn't look the same as that corn plant, but it's everywhere, right? And sending you all something that shows the healthy plant.

as well as the infection at different periods can help with that because so much of this diagnostic, at least in the field, is visual and plants are subject to changes in color and visual appearance with their environment and their cultivar and their hybrid. So I think that's something really we need to maybe discuss more too is what you're looking for in the variation of severity within this.

Sara May (36:21)
Yeah, I think that's really helpful. Sending a range of symptoms is good and even what you're talking about with sending something that's showing the healthy plant versus the not healthy plant, especially if we're talking about something that's very, you know, subtle. It's a color change or maybe a little bit of spotting or speckling and we, you know, can't quite tell, but there is a difference there. That can be really helpful for me in the diagnostic lab, especially because I'm looking at such a huge range of different host plants. Like if it's a plant in Pennsylvania, then, you know, you can send it to us for

looking at for disease problems. So I'm not used to seeing the same things if you're specializing in one area and you're seeing lots of different cultivars of something and you know what they normally look like. yeah, sending a healthy sample as well can be really useful for us.

Ryan Spelman (37:09)
Yeah, that's a great point. you know, one of the things that we've danced around a little bit in the scouting conversation is define like recognizing something as a disease versus a disorder. So I figured maybe we can talk for a second about that as well. How can we when we're scouting, we're looking for something if we suspect a disease.

We're looking maybe for a range of symptoms. Maybe there's a certain pattern and let's keep this in the context of maybe a field crop, right? Do you have any tips for people trying to decide is, I, what am I seeing? Is it a disease or is this like a disorder, a nutrient deficiency, something like

Sara May (37:45)
⁓ That's a really good question. I don't know if I have any great tips. I guess a lot of times if we see something show up fairly suddenly across a large portion of a field, then a lot of times we think that might be some sort of disorder or an injury. So something like a herbicide injury that may have occurred or frost injury, something like that, or a nutrient problem that's showing up on a large percentage.

of the crop versus a disease that might start in one little area of the field and then it's going to start to spread. Maybe it's spores that were, you know, blown in on the wind and then it's going to gradually spread throughout the field or maybe it's going to be spotty throughout the field. So those are some of the distributions that we tend to associate with those different things. But I've been doing this job for a long time and I still get tripped up where I will.

get a sample. I just had this happen the other day and I was looking at the information from the client. Okay, 90 % of the crop is showing symptoms. There's browning on the leaves and you know, maybe this was cold injury that happened, but they're not sure. And I was like, yeah, this sounds more like a abiotic problem. Maybe it was some sort of cold injury. And then I put it under the microscope and there's a disease there. So they don't always follow those exact patterns, but ⁓ there are some things that you can start to clue in on.

on whether or not it's a disease problem or some sort of disorder.

Ryan Spelman (39:12)
Yeah, that's a good point. You know, I think when I was, you know, taking plant pathology courses, you know, we always learned the more uniform something is, the more likely it's like a biotic or a biotic, you know, a disorder, we would call it. But in practice,

that's not really always the case, right? Because sometimes disease infection can go along with an environmental cause. As you're saying, you know, maybe sometimes there is some sort of frost event or something that damages tissue, but then that is a good place for disease to start, right? So you might see it at the same leaf on every plant. And before you think, okay, well, maybe that's a disorder. Maybe there was something that happened at the growth of that plant at that time that damaged it. But actually, no, that's where the disease is starting, right? So

So these things aren't as simple as the textbooks would tell you, right? I'm sure you get like a front row seat to that oftentimes.

Sara May (40:09)
Yeah, definitely. It's not always black and white and we have some diseases that can show up and spread really fast. So it can look like it all of a sudden the whole field turned brown, but it was actually a disease. yeah.

Justin Brackenrich (40:22)
So if you think I've been bad at identifying and naming, see I've been very careful of the names that I've thrown out with any of these diseases. I did use sooty mold, but you know, I'm feeling pretty comfortable with that. If you think I'm bad at that, you should hear me try to work through fungicides and the names of those, right? And I think an important part to this is this discussion of, you talked about barley yellow dwarf virus.

That becomes a point of identification, not a point of like control, right? We can't go out and we could manage the vectors or things like that, but we can't go out there and posthumously treat a virus. When it comes to bacterias, we have a couple small options. And then when it comes to fungicides, that's where you really open up this whole big array of products and stuff. How does your report come back and help me make this decision of what direction and what options I have or

⁓ when it becomes this thing of Maybe we need to try a different cultivar or look for better options starting next year

Sara May (41:21)
Yeah, that's a great question. So we do provide management recommendations on our report. And if we find a disease, we'll give that information, including what fungicides will be recommended. And I'll often provide fact sheets or information from like the agronomy guide that has specifics on, know, if it's a fungal disease, what fungicide could be applied and other, you know, IPM type practices. Like you mentioned, is there a different cultivar that they could grow that has resistance? Is there a different

timing of planting or harvest that would help manage the disease. All of those sorts of things that you would want to include. And we can also reach out to our faculty that are studying these diseases to get more information if it's needed. But we do provide that and ⁓ sometimes there aren't a lot of options, unfortunately. So if it is something like a virus or like a bacteria like you were mentioning, unfortunately, a lot of times the report is just saying, okay, here are the limited options that you have. But we do provide those.

recommendations.

Ryan Spelman (42:21)
Great, yeah, so they do get some management recommendations. That was going to be my next question. And I'm glad that they do. It makes our jobs easier too, right? So as the extension educator that's going through some of these with folks, it's really helpful to have that. And you have a lot of connections within the building too to help you make those.

So Justin, unless you have something, another question on the process of it, I figure we can move on to talk about maybe some of the things you've seen in the last year and field crops or some trends. Justin, is there something else that you want to cover?

Justin Brackenrich (42:53)
One just like kind of quick thing again. So when you're giving back results and maybe I'm wrong. So if I speak out here, you tell me what you're returning to people for these fungicides is an active ingredient, not necessarily a product.

Sara May (43:06)
Yeah, that's a good question. it depends. Sometimes I'm giving an active ingredient and saying like, you can apply something with azoxystrobin in it. Sometimes it will be actual products. I'll either list it in the report or if I'm sending them a fact sheet, you know, from like the crop protection network or from our Penn State agronomy guide, those usually list actual products that they can use. And so, and then they can always contact me or an extension educator. have our,

email and our phone number on every report that we send so if they're looking for more specific recommendations we can try to give those as well.

Justin Brackenrich (43:41)
So that was the direction I was kind of going is if you get something back, it's still the responsibility of the producer or the sprayer or the agronomist to make sure this is a labeled product and

And so once you get this right, the crop protection network is an excellent place to go back because not all things are labeled in this state to treat a specific disease or fungus. And specifically, if you're listening to a different state, you also really need to make sure that those things match too. So once you get it back, right, as we say with everything, the labels, the law, and we have to make sure whatever we're treating is labeled in the state you're applying it.

for the pathogen you're actually using it to treat.

Sara May (44:18)
Absolutely, yeah. And that's very important. It's important that the person applying it is double checking that, making sure it's labeled for the crop they're applying it to, the state that they're in, and there are...

web resources where they can check that. We try to stay up to date and give the best information we can, but I'm not perfect. like I said before, I get a lot of different samples and different hosts, and I try to make sure I double check everything. But there's always the chance that I list a certain product and it's not recommended anymore for that crop. So we do recommend that the client make sure before they apply anything that they're checking that label.

Ryan Spelman (44:56)
And Sarah, on the management side too, like, do you give recommendations when it comes to like, is it more acute or like, is it more long term recommendation as well? Maybe it depends on the pathogen. I'm just thinking, you know, let's say I get a sample, you identify that there's a certain type of a stock rot pathogen or something like that, right? As a producer, I get that sample back and I'd think, okay, I should look at the biology of this pathogen and I know

well, this pathogen can overwinter in wheat and corn, and maybe it's time for me to think about my crop rotation. How do I manage this long-term? Because otherwise I could continue to see this be an issue. Is that some of the recommendations you do, or is that kind of the onus is on that producer to go take your identification, your recommendation, and then go study up on it and kind of learn what they need to do in their system over time.

Sara May (45:53)
No, that's a great question. absolutely do try and include that information, especially because unfortunately a lot of the times when we're getting a sample, it's too late to do much during the season that we're in and they're going to have to do something next year. So we'll include that information about rotational crops and tillage and those sorts of things that they can start next year or with a lot of the samples that we get from someone's ⁓ yard, a lot of the trees and stuff. If we find a disease on it, the

management will often be the following year when the new growth is coming out on the tree is when you might want to apply a fungicide or raking up the leaves in the fall will help to prevent the pathogen from overwintering. So we do try to include as much of that information as we can in the report and it's also often in the fact sheet or the information from a guide. They can definitely look up more information. There's lots of great extension publications out there to find more.

about a disease that we might diagnose, we tried to give as much management information as we can.

Ryan Spelman (46:53)
Great, yeah, well, there's so much out there. so I'd imagine if you wanted to, you could write a book on every single sample that you give back, right? So it can be a real challenge to highlight all the information they need to manage that in one place. And so it's really great that you do go through that detail to do that. And so.

So maybe we can move on here to some of the things that you've been seeing in the last season or two in field crops and if you have any insights for us as an educator, right? So are there any, I'll ask a very general question here. Are there any like emerging diseases that you've seen, anything that comes to mind when you think of emerging diseases that we might not really be aware of that have been going on in field crops in the last season or two?

Sara May (47:37)
That's a good question. I don't think there are any big ones that you wouldn't know about. ⁓ We've had Tarspot on corn for a number of years here in Pennsylvania, so that's probably one of the newer ones. There is a disease called corn stunt.

that's been found in New York and several other states. So that's one that we're looking out for, but it hasn't been found yet in Pennsylvania. So that's one of the ones that we're watching for to see if it shows up here. But other than that, we don't have any big important diseases, which is kind of a good thing for field crops.

Ryan Spelman (48:09)
Yeah, that's a good thing. I mean, because you're kind of on the front lines, right? So with Tarspot, I mean, we started to see that maybe, you know, three years ago now, maybe four years ago now. And now we're learning how to manage it, you know, and that's kind of where it gets kicked over to us, right? Where now folks are starting to notice it on their own fields, right? So that's definitely a big one. So, corn stunt, I'm curious, just because I have heard a little bit about corn stunt, you know, in the eerie area, stuff like that.

What is it and what should people look out for if they're kind of on that New York border?

Sara May (48:43)
Yeah, that's a good question. So cornstun is caused by a bacteria-like organism called a spiroplasma. And the symptoms are stunted plants, as the name suggests. Yeah, stunted plants and also often the leaves look very red or have red streaks on them. And so those are the main symptoms. And if you Google a cornstunt, you can find pictures of it. And it's spread by a leaf hopper called the corn leaf hopper. And sometimes there's also a

diseases associated with it. There's a virus and a phytoplasma that can sometimes be associated with these symptoms so it's kind of a complicated disease but it's been found in some different areas and I know our researchers in entomology and here in plant pathology have been watching out for it. They've been looking for the leaf hopper to see if it will show up here in Pennsylvania so we haven't found ⁓ anything yet but it's something that we're on the lookout for.

We don't currently have a specific test for this disease in our lab, but we can look at the symptoms and say, okay, I think that's corn stunt. And since it's one that we're worried about showing up here, we have connections to labs that are testing for it. So if a grower has symptoms on their plants, they can contact us and we can make sure it gets tested if it looks like corn stunt to see if it's something that might be here in PA.

Justin Brackenrich (49:59)
So I would never even try to get it all right, but I was one of the ones, I think there were three groups, three educators last year that were actually doing corn leafhopper traps in the state. And I was one of them that did that. fortunately, we have a wonderful entomology department that was willing to look at all of the little insects and all the little things that show up on there. But if you're interested in that, that project is going on. It's a collaborative effort.

And you would be shocked at the amounts of insects and I don't want to say bugs, I hope no one's listening, but that you would find in a cornfield on a sticky trap in seven days. It is kind of an interesting concept. You've never looked at it or never thought about it. It was pretty amazing and pretty cool for someone like me that doesn't do a lot with insects to see. So it is happening and I'm sure they'll let everyone know if they find it anywhere.

Sara May (50:47)
Yes, absolutely. It's a great project, so I'm glad that they're on the lookout for it.

Ryan Spelman (50:51)
Yeah, go ahead. No, no, What were you going to say?

Justin Brackenrich (50:52)
good.

I was thinking we were moving towards a wrap. I think we've covered a tremendous amount of ground. We've talked about the lab itself, how you can connect to your labs or other labs around you to work through this process. We've talked about taking good samples, where to get the paperwork, how and when to send them. Sarah's done an excellent job explaining what the lab can and can't do. I think it's important that we also recognize what we can't do with things.

And then the last thing I've got to say is send more samples, right? We talk about extension being a kept secret, but I mean, this is a huge resource that a lot of states probably don't have access to. They have a lab, but it may not be free. so, use this as when you can. unfortunately, if things don't get used, things don't get kept. And so I would encourage everyone to send samples, keep Sarah and her team busy.

you know, figure out what all of these little diseases and things are that we've got running around in Pennsylvania.

Sara May (51:53)
Awesome, yeah, I would agree. We're happy to help and look forward to getting more samples in the next year.

Ryan Spelman (51:59)
Awesome. Well, thank you, Sarah. We'll work hard to give you guys more to do because you're not already busy enough, I'm sure. So thank you again, Sarah. It was really great to have you on today. And I hope everyone learned a lot about this resource that we do have here. So thank you to Sarah and thank you for our listeners for coming through to the end. And we'll catch you on the next episode of the Agronomy Highlights podcast.