 My name is Dr. Amanda Scheer. I'm still a relative newcomer to the commercial HORT team. I started back in October of last year. I'm an assistant professor and extension plant pathologist with Auburn and Alabama Cooperative Extension. I have responsibilities in cotton, peanut, small grains, forages, ornamentals, and turf. Today I'm going to mainly talk about some common diseases of ornamentals in Alabama. So initially, my title said the top 10 common disease or top 10 diseases of ornamentals. As I was putting the presentation together, I quickly realized to give each disease its due justice. It's going to be really tough to cover 10 diseases in 15 minutes. So I just picked a subset from this list here. So to get some ideas, I reached out to Dr. Cassie Connors, who's the director of our plant diagnostic clinic. And I basically just wanted to see what, you know, types of diseases she's been seeing in the last year or two. This year we've had a very wet year. So they've seen a lot of phytophthora root rots, rhizoctonia diseases, several bacterial diseases like bacterial wilt, bacterial spots, blights, and canker. She's also seen some bitrosperia, di-bac, and other canker diseases. A lot of foliar diseases of shade trees causing early leaf drop and limb di-bac, especially in lilin, cypress, maples, hollies, and ligustrum. And the last couple of years she's also seen bacterial leaf scorch becoming more common, probably due to the warmer winter temps that we've had the last couple of years. So in terms of this presentation today, I'm going to focus on three bacterial diseases. I might do this type of presentation in multiparts to get to that top 10. But as a theme, I picked these three bacterial diseases to talk about today. So the first one is fire blight. It's a bacterial blight. It's a bacterial disease caused by Irwinia amylovera. It's a very persistent problem on flowering pear trees and other ornamentals in the rosaceae family, including flowering crab apple, rose, blackberries, hawthorn, you name it. This disease is also a big problem on some commercial fruits such as pears and apples. Our other extension plant pathologist, Dr. Ed Secora, actually posted an alert on ASIS webpage mentioning that he's seen the disease in the last couple months on pear trees. In terms of ornamentals, it's a big problem when you have warm, humid conditions during flowering. This really favors disease development because you have very active growth. So in terms of symptoms, you have this blackened or burned appearance of damaged or diseased flowers, twigs, and foliage. One of the most characteristic symptoms of this disease, you get what's called a shepherd's crook symptom, which is pictured here on the right hand side of your screen, where you have this burned appearance of the whole twig or branch, as well as the leaves, but you see it starts to hook over. So kind of a shepherd's crook. So in terms of control, there are some resistant varieties. And if you're interested in those, I'd be more than happy to provide them to you. It's very important, especially in the landscape, to plant some of these resistant varieties just so you don't have this disease show up. If you do have some of these symptoms and you notice it and it is fire blight, what you can do is you can prune some of the diseased wood. But if you're going to do so, do it in their dormant season or extended dry periods. The pathogen is less active during this time and is less likely to spread to other parts of the tree or other trees if you have to prune multiple trees. The biggest thing and most common theme of all three diseases I'm going to talk about today, you really have to sanitize your pruning tools. You can do this with a 10% bleach or 70% alcohol solution. And this just helps prevent pathogens spread when you're going to different parts of the plant or between trees. I know that the 70% alcohol is still kind of hard to come by due to COVID. And there are, but I have been able to find bleach pretty regularly in the stores. But there are some other options and we do have a good publication that we put out earlier on during the COVID outbreak to give some good options to producers and homeowners that include things like pine salt and a few others that can do really well at getting rid of viruses, fungi and bacteria. So try and fertilize in the fall instead of the spring, as I mentioned, the disease is most common, you know, when the plants are flowering during humid wet conditions that are hot. So if you apply those fertilizers you're going to increase succulent growth so that's more growth that the pathogen can then infect so really try and fertilize in the fall. For homeowners, we don't really recommend fungicide applications, but there are some options for commercial producers we have seen some success in using copper applications in the dormant period followed up by streptomycin applications in the spring seem to do pretty decent at controlling the disease. So the next one I'm going to talk about is probably one of the most difficult out of the three to control. And there's no fungicide options for this disease. It's called bacterial wilt. It's caused by a soil borne bacterial pathogen Ralstonia cilinacerum as a very wide host range of 450 plant species and 54 different families. These include geranium, zinnias, marigolds, as well as some of your common commercial vegetable production, including tomatoes, eggplant, potatoes and pepper. This disease you may have heard about it recently. If you signed up for USDA pest alerts or on our aces webpage. Ralstonia is classically classified into five different races and biovars. We always have race one that's endemic to the US. You know, it's just something that we have to kind of live with the one that we're most worried about is race three bio of our two. It's not endemic to the US. But it is very aggressive on geraniums, tomatoes and potatoes. So this is something we don't want to have become common in our bacterial wilt pathogen population. It is on the select agent list for the USDA athis. We've had several outbreaks over the last few decades. The most recent one being in April of this year. The most common control practices is once we know that it's here it came in on geranium cuttings that were shipped from other countries into the US, which is the most common way and route this pathogen comes in. We do quarantines and eradication and they work with local governments to remove all diseased material. So as of June 11 we dodged a bullet we no longer have race three bio of our two in our geranium greenhouses in the US. In terms of race one it's still a problem and overall this pathogen is very difficult to manage as it can survive in contaminated soil and irrigation water for several years. You could put this in tap water on a lab bench in the tube and it will survive for at least seven years without any nutrients or plant materials. So this pathogen is very durable and could be a big problem for producers. So in terms of symptoms on if you're familiar with the disease on tomatoes and other vegetables. You'll see there's very many listed common symptoms here but on geraniums and other ornamentals you'll get this initial symptoms with chlorosis and wilting of the lower leaves at this stage. The plants may appear to recover at night when the temperatures are cooler just to wilt again the following afternoon or a couple days later. Eventually this wilting will spread from the older to newer leaves and in geranium the wilted leaves will become necrotic and wedge shaped patterns as pictured here on the right that expand towards the leaf margins. You may also see stem collapse especially with race three bio of our two because it's the most aggressive one out of the ones we have. And you may also see stem and root tissue discoloration that will eventually become necrotic. The pathogen lives in the soil it's up taken by the roots and then gets into the vascular tissue and basically blocks transport of water and nutrients, which gives the wilting symptoms. Eventually the whole plant will wither and die. So this is definitely one that you want to prevent from coming into your greenhouse production. In control this disease cannot be cared so once the plants infected really the only thing you can do is remove that plant and prevent the spread to your healthy plants. But most of the control practices revolve around quarantines eradication and prevention. So what we want to do is you want to isolate any new shipments of geraniums from the rest of your crops when they come in and spec those thoroughly keep batches from different propagators and different cultivars separate from each other. You want to sanitize your pruning shears just as I recommended with fire blight. You also want to sanitize your trays and plots I know many commercial producers reuse those, especially in vegetable production. As I mentioned this pathogen very durable and can survive in soil so you just want to make sure that those trays and pots are thoroughly sanitized, sanitized before reusing them. You also don't want to grow ID baskets over seed or zonal geraniums, especially in the spring. If you're growing both vegetable seedlings and ornamental plants to sell to the public in your nurseries, you want to try and keep ornamentals away from vegetables. There's other diseases, including bacterial well that can spread from ornamentals to vegetables. When you're going between greenhouses you also want to wash and change your gloves often. This will prevent in case you have an outbreak in one greenhouse it will prevent it from going to the other greenhouse. So now I'll move on to the last bacterial disease that I'll talk about today. This is bacterial leaf scorch. As I mentioned, Dr. Connors said that she's seen this disease become more common in recent years. Like I mentioned, likely due to the warmer winter temperatures that we've seen the last couple years. This one is caused by a xylem limited bacterium called xylelifastidiosa. This one does not survive outside of host tissue. We actually can't grow it really easily or not well at all in laboratory conditions. It does have a wide host range that includes ornamental landscape trees such as maple, oaks, flowering dogwood and sweet gum. All of these are common shade trees in Alabama, especially the maples around Auburn. People love the fall color. But as I mentioned, this disease can infect those. One of the issues with this one that we have is that there's several alternative hosts that might be in the landscape that are asymptomatic or have very little discernible symptoms. So they kind of serve as a reservoir for this pathogen. It's transmitted from tree to tree and from plant to plant by xylem feeding insects such as leaf hoppers and sharpshooters. So it can feed on those alternative hosts and then transmit it to your landscape trees. In terms of symptoms, it will first appear in the later part of the summer and then progress through the fall. So in terms of symptoms, they vary by tree hosts, trees with determinate growth such as oaks, the scorching will appear on all leaves at any age at the same time. Trees with indeterminate growth such as sycamore and elms, it will progress from older to younger leaves. These disease symptoms can also be easily confused with abiotic stresses. You can get some leaf scorching for nutrient issues or also water stress. But one of the biggest things with bacterial leaf scorch is that you have this yellow or red band between the scorched tissue and the green tissue. And that's characteristic that it's bacterial leaf scorch. Your abiotic issues typically won't have this margin there. So that's one of the characteristic symptoms that we look for with this disease. So in terms of control, this one's also very difficult to control like bacterial wilt. And once a tree gets the disease, there's not much we can do. You cannot cure. It's very difficult to cure plant diseases. One of the biggest things you can do is if you do have a tree that does become infected, symptoms are going to be very mild at first. It's a very slow progressing disease. So you may be able to extend the life of that tree by avoiding stress to the trees and maintaining trees and optimal health. So avoiding water stress, you know, watering during drought periods are very hot periods during the summer. Like we just went through a couple of weeks ago, you can also mulch trees that will help keep soil moisture there. Also ensure adequate nutrient uptake and maintain proper soil pH. You should also prune out dead wood like you should with or infected wood like you should with fire blight. But like I said, sanitize those pruning tools. And then once disease trees become very symptomatic with extensive dieback, you should remove those trees like they're pictured here. That's basically just going to be a hazard, especially as you can see in this picture houses are very close to this huge oak. So you want to try and remove those trees once they become heavily symptomatic. So with that that ends my presentation. You are more than welcome to ask questions if you can't think of anything now. Don't worry I put my contact information up there. Feel free to email me or call me and if you're in the Auburn area. I'm in the Alpha Services building with the plant diagnostic clinic.