1 00:00:00,001 --> 00:00:03,920 Bethany Harris: And so I have the pleasure of introducing our next speaker. 2 00:00:03,920 --> 00:00:08,640 Bethany Harris: And today we're going to really focus on the speaker. We'll talk a little bit about disease management. 3 00:00:08,640 --> 00:00:08,960 Bethany Harris: Dr. 4 00:00:08,960 --> 00:00:10,080 Bethany Harris: Bikash 5 00:00:09,680 --> 00:00:20,080 Bethany Harris: Ghimire actually is our ornamental pathologist at the University of Georgia, and he works to support many different types of growers, from greenhouse and nursery growers to cut flower growers. 6 00:00:20,080 --> 00:00:20,320 Bethany Harris: So 7 00:00:20,200 --> 00:00:25,000 Bethany Harris: he's going to share a little bit more about disease management and cut flowers with us today. 8 00:00:25,000 --> 00:00:27,480 Bethany Harris: So I will turn over the floor to him. 9 00:00:27,960 --> 00:00:28,439 Bikash Ghimire: Awesome. 10 00:00:28,439 --> 00:00:34,280 Bikash Ghimire: Thank you so much, Bethany, and the team for this opportunity to talk about some of the disease in cut flowers. 11 00:00:34,280 --> 00:00:36,680 Bikash Ghimire: As Bethany mentioned, my name is Bikash Ghimire. 12 00:00:36,700 --> 00:00:42,620 Bikash Ghimire: I'm a new ornamental pathologist here in the Department of Plant Pathology at University of Georgia. 13 00:00:42,620 --> 00:00:45,500 Bikash Ghimire: And what a pleasure to be here and speak about the cut flower. 14 00:00:45,500 --> 00:00:48,540 Bikash Ghimire: And by the way, this is my first time attending the symposium. 15 00:00:48,540 --> 00:00:49,580 Bikash Ghimire: Here with me. 16 00:00:49,540 --> 00:00:54,739 Bikash Ghimire: I'm going to start with a couple of the production environment and what are the issues that you might be facing. 17 00:00:54,739 --> 00:00:57,220 Bikash Ghimire: One, starting with the open field production. 18 00:00:57,220 --> 00:01:00,420 Bikash Ghimire: If you have a field, then it is weather dependent. You 19 00:01:00,540 --> 00:01:06,860 Bikash Ghimire: might have conditions with drought, rain, storm, wind, and temperature extreme, which are some abiotic factors. 20 00:01:06,860 --> 00:01:08,940 Bikash Ghimire: And then you also have to deal with irrigation. 21 00:01:08,940 --> 00:01:13,340 Bikash Ghimire: Like you obviously will irrigate the field, but also you have no control because 22 00:01:13,260 --> 00:01:19,340 Bikash Ghimire: there will be rainfall, and that's where you will bring all the diseases and pathogens, so which I'll talk in a minute. 23 00:01:19,340 --> 00:01:28,060 Bikash Ghimire: And then if we have high tunnel production, oftentimes you have a reduced airflow, there is a high humidity condition and high temperature stress. 24 00:01:27,840 --> 00:01:33,920 Bikash Ghimire: And also you can control irrigation, so you have a better control compared to the in the field. 25 00:01:33,920 --> 00:01:37,280 Bikash Ghimire: And then you can also provide extended seasons, and then the 26 00:01:37,660 --> 00:01:41,180 Bikash Ghimire: plants are often longer and then are thicker stems and all that. 27 00:01:41,180 --> 00:01:44,940 Bikash Ghimire: So you have both pros and cons of both environments. 28 00:01:44,940 --> 00:01:49,740 Bikash Ghimire: But why I'm relating bringing this point is because you'll have cases where you have 29 00:01:49,740 --> 00:01:54,940 Bikash Ghimire: disease in one environment versus other, depending on what production system you are in. 30 00:01:54,940 --> 00:01:57,900 Bikash Ghimire: And also talking a little bit about the soil 31 00:01:57,660 --> 00:02:00,540 Bikash Ghimire: consideration, I know the other speaker already mentioned previously. 32 00:02:00,540 --> 00:02:12,140 Bikash Ghimire: So for the field production particularly, it matters because what crop you planted previous season is going to affect the way, because a lot of the pathogens, they reside, like, they will have 33 00:02:12,460 --> 00:02:17,340 Bikash Ghimire: They reside in the soil or in the debris of the plant, and then they will come back next year. 34 00:02:17,340 --> 00:02:25,980 Bikash Ghimire: So that's why in field production you might be seeing more diseases, and then there are survival structure of the pathogen that can survive for several years, like five years, 35 00:02:25,660 --> 00:02:29,500 Bikash Ghimire: even 10 years, and I'll talk about a couple of those in my slides later on. 36 00:02:29,500 --> 00:02:38,220 Bikash Ghimire: And in the raised bed condition you can have a combination of the field soil and the soilless mix, some kind of compost or organic amendments. 37 00:02:37,780 --> 00:02:46,500 Bikash Ghimire: And when we say organic amendment, it could be compost, composted bark, or some crop residue, the products, byproducts like peanut hulls and all that. 38 00:02:46,500 --> 00:02:46,819 Bikash Ghimire: So 39 00:02:47,040 --> 00:02:53,840 Bikash Ghimire: you can have those organic amendments, and then that is how easily we have this setup in the field. 40 00:02:53,840 --> 00:03:01,200 Bikash Ghimire: Now when it comes to disease management, we have certified organic growers, we have organic and non-organic production, depending on what 41 00:03:01,360 --> 00:03:14,000 Bikash Ghimire: group you belong to, we have different options. Again, like if you are organic growers, then you have very less options because you cannot do chemical fungicides and you have to go to biological agents or one of the plant extracts, and then 42 00:03:14,340 --> 00:03:24,100 Bikash Ghimire: For this biological product, it can only be applied preventatively because it does not have any curative activity as does with some of the other chemical fungicides. 43 00:03:24,100 --> 00:03:25,060 Bikash Ghimire: That's why 44 00:03:24,760 --> 00:03:36,360 Bikash Ghimire: it is very important, and that's why as a plant pathologist we always emphasize on cultural practice first, because a lot of times these diseases come due to improper cultural practice. 45 00:03:35,900 --> 00:03:41,180 Bikash Ghimire: So that's why we recommend cultural practice and also planting resistant cultivars whenever possible. 46 00:03:41,180 --> 00:03:50,700 Bikash Ghimire: But sanitation is very important, roguing infected plants, scouting early in the season, and then doing a crop rotation to avoid some of this inoculum buildup in the soil. 47 00:03:50,640 --> 00:03:57,840 Bikash Ghimire: And of course, there are irrigation management, because a lot of time due to overwatering, we'll have a problem of some of the root-borne issues. 48 00:03:57,840 --> 00:04:03,360 Bikash Ghimire: And then fertility management is other important aspects when it comes to disease management. 49 00:04:02,600 --> 00:04:15,240 Bikash Ghimire: So basically disease management, you are taking into account a number of factors, even the crop production as a whole, so that you don't have to apply fungicide, or if you have to, then apply at a minimum dose and rate. 50 00:04:15,240 --> 00:04:15,560 Bikash Ghimire: So 51 00:04:16,040 --> 00:04:20,360 Bikash Ghimire: When it comes to disease in specialty cut flowers, there are numbers of them. 52 00:04:20,360 --> 00:04:21,799 Bikash Ghimire: I have listed on the left. 53 00:04:21,799 --> 00:04:24,040 Bikash Ghimire: You can see root and stem diseases, 54 00:04:23,760 --> 00:04:27,280 Bikash Ghimire: and it has a mostly wide host range because they are in the soil. 55 00:04:27,280 --> 00:04:33,280 Bikash Ghimire: That's why they can infect different plant types, and then some of the common ones that we often identify 56 00:04:32,760 --> 00:04:43,800 Bikash Ghimire: are Phytophthora, Pythium, Rhizoctonia, also causing white mold, we have Sclerotium rolfsii causing southern blight, and we have Fusarium stem rot. 57 00:04:43,160 --> 00:04:53,800 Bikash Ghimire: On the foliar side, as on the right, mostly they are host specific, means they can only go and infect particular type of plant, or even sometimes particular cultivars. 58 00:04:53,200 --> 00:05:05,440 Bikash Ghimire: And then some of the common ones we see are leaf spot caused by bacteria, by fungi, leaf rust, powdery mildews, and we have Botrytis blight, which is also a big problem, and some virus diseases, 59 00:05:04,920 --> 00:05:08,440 Bikash Ghimire: which I'll talk about this one by one in my next slide. 60 00:05:08,440 --> 00:05:11,560 Bikash Ghimire: So where does this pathogen come from? 61 00:05:11,560 --> 00:05:14,760 Bikash Ghimire: What are the source for this pathogen in the coming in your 62 00:05:14,940 --> 00:05:15,580 Bikash Ghimire: facility. 63 00:05:15,580 --> 00:05:29,100 Bikash Ghimire: So a lot of time it comes from the infested seed, like for example for downy mildew, bacterial leaf spot, you might have that infection going on in the seed, or the seed lot is bad, and that's how you are getting this disease in your planting stock. 64 00:05:28,539 --> 00:05:37,099 Bikash Ghimire: And then also you might be bringing infected plants from outside, and that's where a lot of time you'll be starting getting those problems, and oftentimes 65 00:05:37,340 --> 00:05:39,900 Bikash Ghimire: you also see that the plant is asymptomatic. 66 00:05:39,900 --> 00:05:45,980 Bikash Ghimire: You don't see any symptom in the beginning, but over the time they might start producing symptoms and then become a problem. 67 00:05:45,960 --> 00:05:53,400 Bikash Ghimire: And then also contaminated trays, pots, tools and pruning equipment, benches, all this could be the source of inoculum. 68 00:05:53,400 --> 00:05:55,960 Bikash Ghimire: And then as I mentioned already, the crop residue from 69 00:05:56,240 --> 00:05:58,160 Bikash Ghimire: previous years could be a problem. 70 00:05:58,160 --> 00:06:04,320 Bikash Ghimire: When the previous speaker was talking about the crop residue, she was mentioning about how it should be non-disease or 71 00:06:04,379 --> 00:06:09,419 Bikash Ghimire: pathogen free, so that's why we have to be very careful when you do a crop rotation and all that thing. 72 00:06:09,419 --> 00:06:15,259 Bikash Ghimire: Wind-blown and rain-driven spores are also other source, and then you'll be surprised, like how many times there are 73 00:06:15,260 --> 00:06:22,700 Bikash Ghimire: There's no problem in the field and you overlook, and then over the years, if you come back after two, three, four years, then I'm sure you'll get a disease. 74 00:06:23,760 --> 00:06:32,800 Bikash Ghimire: It will be at the time, if you don't control or have an action in the bed from the very beginning, then by the time it might be too late, and you might see a big epidemics over there. 75 00:06:32,880 --> 00:06:34,080 Bikash Ghimire: Just keep that in mind. 76 00:06:34,620 --> 00:06:37,740 Bikash Ghimire: So now let me start with root and crown rot disease. 77 00:06:37,740 --> 00:06:45,180 Bikash Ghimire: So it's very confusing sometimes with this kind of symptom because you will not know if it is abiotic stress or it is due to the pathogen. 78 00:06:45,020 --> 00:06:53,180 Bikash Ghimire: And then oftentimes when you go out in your tunnel house and you see these patches like where plants are dying, and then you see these patches are even like a 79 00:06:53,160 --> 00:07:02,920 Bikash Ghimire: plants are chlorotic, they are yellowing, and then all that wilting sign, then you need to take a closer look and try to see the entire plant just to see what where the problem is. 80 00:07:02,920 --> 00:07:06,040 Bikash Ghimire: And a lot of time you'll see the problem is in the root and crown region. 81 00:07:06,060 --> 00:07:11,259 Bikash Ghimire: And then as I already mentioned, you can see this chlorotic, yellowing of the leaves, wilting and all that. 82 00:07:11,259 --> 00:07:15,259 Bikash Ghimire: So you have to carefully pull the entire plant, including the root system, 83 00:07:15,440 --> 00:07:23,280 Bikash Ghimire: and then in the root, then you'll be able to see some kind of this, you know, reddening or some kind of discoloration. 84 00:07:23,440 --> 00:07:26,160 Bikash Ghimire: And then you will also see the problem in the root system. 85 00:07:26,160 --> 00:07:38,160 Bikash Ghimire: And on your right you can see this pathogen, as you are seeing here in the little video, like here is a pathogen producing sporangia, and inside that sporangia, [VERIFY: "copseps"] sporangia, it has these zoospores, 86 00:07:38,020 --> 00:07:40,020 Bikash Ghimire: which are the motile spores. 87 00:07:40,020 --> 00:07:41,300 Bikash Ghimire: They need water. 88 00:07:41,700 --> 00:07:43,700 Bikash Ghimire: That's why they are called water mold. 89 00:07:43,700 --> 00:07:48,660 Bikash Ghimire: And these spores, when it gets water, then it can freely swim and then go to the 90 00:07:48,960 --> 00:07:51,919 Bikash Ghimire: healthy root system and then creates a problem. 91 00:07:51,919 --> 00:07:58,479 Bikash Ghimire: So that's why if you have overwatering condition, then that's where most likely you will see root and crown rot disease. 92 00:07:58,479 --> 00:08:03,759 Bikash Ghimire: And as I mentioned, the root system will be like soft, it will slough off, 93 00:08:02,860 --> 00:08:10,540 Bikash Ghimire: and you can also smell some bad odor, and that's how you can identify the pathogen and the disease behind the scene. 94 00:08:10,540 --> 00:08:13,020 Bikash Ghimire: What, how, when it comes to disease management 95 00:08:12,660 --> 00:08:13,780 Bikash Ghimire: for Phytophthora. 96 00:08:13,780 --> 00:08:24,260 Bikash Ghimire: So as I mentioned, water management is the key because if you have overwater condition with bad drainage, like a poor drainage condition, then that's where you will be seeing a lot of problem. 97 00:08:23,560 --> 00:08:31,800 Bikash Ghimire: That's why when you have a lowland, when you have areas where there is water stagnating, then that's where you'll see problem arising. 98 00:08:31,740 --> 00:08:38,140 Bikash Ghimire: And for the management side, you can incorporate organic material that can help the soil and also the drainage condition. 99 00:08:38,140 --> 00:08:44,540 Bikash Ghimire: So whenever you see the disease plant, then immediately you have to remove the infected plant as a whole, including the root system. 100 00:08:44,560 --> 00:08:54,240 Bikash Ghimire: And then you can do some kind of, you know, the treatment in the beginning when you start, even before planting, you can do some kind of the biological, apply some kind of biological products, you can do soil 101 00:08:54,280 --> 00:09:00,120 Bikash Ghimire: solarization, and all those things that will, even use the steam, that will help to inhibit the pathogen. 102 00:09:00,120 --> 00:09:06,680 Bikash Ghimire: And there are some fungicides that can be applied when it comes to transplanting some of these plants in the container. 103 00:09:06,820 --> 00:09:17,060 Bikash Ghimire: Now let me talk about this another important disease called white mold, which is also known as Sclerotinia stem rot caused by Sclerotinia sclero- 104 00:09:16,560 --> 00:09:17,600 Bikash Ghimire: -tiorum. 105 00:09:17,600 --> 00:09:21,200 Bikash Ghimire: So this is a lot of mouthful of scientific name here of the pathogen. 106 00:09:21,200 --> 00:09:31,200 Bikash Ghimire: But anyway, for this pathogen it loves cooler temperature, high humidity and a lot of moisture, as it does with the Phytophthora that we just talked about. 107 00:09:31,220 --> 00:09:39,460 Bikash Ghimire: So it can affect numerous crops and flower species, and especially the cool season crops are the ones that get infested. 108 00:09:39,339 --> 00:09:48,779 Bikash Ghimire: And then when you see that white fungal growth can be seen in the stem, and then you can see the stem lesion, which is like a tan color. 109 00:09:48,540 --> 00:09:57,580 Bikash Ghimire: And that's how you start the symptom, like with some kind of the lesion in the stem, and over the time that you can see this white fuzzy mycelial growth. 110 00:09:57,320 --> 00:10:03,400 Bikash Ghimire: So it can also produce the overwintering structure called sclerotia, which I'll show in the next slide. 111 00:10:03,400 --> 00:10:06,280 Bikash Ghimire: Oftentimes when it gets infected, then the 112 00:10:06,640 --> 00:10:11,120 Bikash Ghimire: the stem is soft, mushy, and then the entire plant kind of collapse. 113 00:10:11,120 --> 00:10:21,360 Bikash Ghimire: So when you see that, then first of the thing that you need to do is remove that infected plant and make sure that it does not go to the compost, but rather you safely dispose it out. 114 00:10:21,760 --> 00:10:26,320 Bikash Ghimire: And the overwintering structure that I was mentioning is called sclerotia. 115 00:10:26,320 --> 00:10:29,440 Bikash Ghimire: So this is a black structure that you can see over here. 116 00:10:29,459 --> 00:10:31,380 Bikash Ghimire: And then you can also see this structure. 117 00:10:31,380 --> 00:10:42,899 Bikash Ghimire: This is just like a black, the mycelia that are clustered together, that hyphae, and forming this pigmented structure so that it can thrive harsh condition and can remain in the soil for several years, and some of the 118 00:10:43,040 --> 00:10:47,839 Bikash Ghimire: papers and literatures have mentioned that it can survive for five years or even more in the soil. 119 00:10:47,839 --> 00:10:52,560 Bikash Ghimire: So that's how it can be a problem even after several years of crop rotation, 120 00:10:51,980 --> 00:10:58,860 Bikash Ghimire: if you are planting the susceptible cultivar, and the environmental condition is favorable for the pathogen. 121 00:10:58,860 --> 00:11:02,540 Bikash Ghimire: So the next disease that we have in the list is 122 00:11:02,459 --> 00:11:08,540 Bikash Ghimire: southern blight, which is caused by Agroathelia rolfsii. It used to be called as Sclerotium rolfsii. 123 00:11:08,540 --> 00:11:10,700 Bikash Ghimire: So compared to the white mold, it 124 00:11:11,180 --> 00:11:14,060 Bikash Ghimire: favors warm condition instead of the cool condition. 125 00:11:14,060 --> 00:11:16,620 Bikash Ghimire: But the other environmental condition are pretty much similar. 126 00:11:16,620 --> 00:11:22,220 Bikash Ghimire: It loves humid condition, a lot of moisture and all that, which is perfect now in the summertime. 127 00:11:22,220 --> 00:11:22,540 Bikash Ghimire: So 128 00:11:22,560 --> 00:11:29,040 Bikash Ghimire: that's where you see more of the problem of this southern blight, and it can affect different kind of ornamental and flowering crops. 129 00:11:29,040 --> 00:11:30,320 Bikash Ghimire: So it produces this 130 00:11:30,259 --> 00:11:38,180 Bikash Ghimire: when you see on the crown region that you can see the hyphae, that white radiating hyphae, and also you can see this brown color mustard-like 131 00:11:38,540 --> 00:11:47,500 Bikash Ghimire: must-, it looks like a seed of the mustard, and then that is the sclerotia of the pathogen. That is again the overwintering structure that can remain in the soil for years. 132 00:11:47,339 --> 00:11:59,100 Bikash Ghimire: For the management practice for the southern blight, so all you have to do is you dig there and remove the infected, the disease plant, and then what you can do is you can dig soil eight centimeters deep and then you can 133 00:11:59,440 --> 00:12:04,800 Bikash Ghimire: flip the soil and bury that sclerotia deep enough that it cannot come out. 134 00:12:04,800 --> 00:12:06,960 Bikash Ghimire: But again it can remain but cannot 135 00:12:07,040 --> 00:12:08,880 Bikash Ghimire: come out and be a problem. 136 00:12:08,880 --> 00:12:19,760 Bikash Ghimire: And do not add infected plant to the compost pile, because that could again, like when you use the compost next year, then that overwintering structure likely come back and start the infection. 137 00:12:19,240 --> 00:12:25,480 Bikash Ghimire: So some of the fungicides are there which can be effective, but it does not help the disease plant. 138 00:12:25,480 --> 00:12:31,560 Bikash Ghimire: It can only help the non-infected plant or the new growth that it can cure. 139 00:12:31,560 --> 00:12:33,960 Bikash Ghimire: It does not cure basically. 140 00:12:33,360 --> 00:12:35,200 Bikash Ghimire: It has to be applied preventatively. 141 00:12:35,200 --> 00:12:36,400 Bikash Ghimire: That's what I mean to say. 142 00:12:36,400 --> 00:12:43,840 Bikash Ghimire: And then when you do the plant propagation, you bring tubers or corms in your greenhouse or in your tunnel house, then 143 00:12:43,759 --> 00:12:50,079 Bikash Ghimire: you need to be very careful, like you don't introduce those pathogens in your planting materials to your facility. 144 00:12:50,079 --> 00:12:52,880 Bikash Ghimire: So that's how you control this disease. 145 00:12:52,560 --> 00:13:03,440 Bikash Ghimire: So the next root-borne issue that we have is with Fusarium causing stem rot and wilting, so which is one of the biggest problem I would say that has been reported out in lisianthus. 146 00:13:03,560 --> 00:13:12,280 Bikash Ghimire: And then you can see how in the stem, with the stem rot, you can see some kind of the lesion in the stem, in the crown region, and then you see wilting of the plant. 147 00:13:12,280 --> 00:13:17,080 Bikash Ghimire: So when you see those stress, like a wilted plant, this kind of the problematic, the 148 00:13:17,240 --> 00:13:29,160 Bikash Ghimire: plant in the bed, then all you have to do is remove that as early as possible, because you can spot in the early stage when you do a scouting, and then that will help to disseminate the pathogen to the next healthy plant. 149 00:13:30,020 --> 00:13:33,060 Bikash Ghimire: So I think that's pretty much I have for Fusarium. 150 00:13:33,060 --> 00:13:36,500 Bikash Ghimire: So the next one I have in the list, and let me check my time. 151 00:13:36,500 --> 00:13:39,460 Bikash Ghimire: So the next one I have in my list is Botrytis. 152 00:13:39,160 --> 00:13:47,400 Bikash Ghimire: So which is which cause gray mold, so which is a big problem, especially it can be in the standing plant, and also it can be in the harvested 153 00:13:47,560 --> 00:13:57,240 Bikash Ghimire: flower, once the flower is harvested, and then it can also be a big problem if it does not get the proper storage facility, then you can have that problem of gray mold. 154 00:13:57,100 --> 00:13:59,100 Bikash Ghimire: So it can affect numerous plant species. 155 00:13:59,100 --> 00:14:08,860 Bikash Ghimire: Again, it loves wet, humid and moderate temperature, and it can colonize the succulent plant part, like a flower part or the young shoots on the top. 156 00:14:08,459 --> 00:14:18,300 Bikash Ghimire: And then in the beginning it starts with a leaf spot and some kind of the blighting in the flower, and it can cause stem canker, it can cause crown rot and all these different kind of the issue. 157 00:14:18,300 --> 00:14:21,899 Bikash Ghimire: And then this is the beginning, this will become a big problem. 158 00:14:21,360 --> 00:14:28,720 Bikash Ghimire: And then as I said, like you can see over the time then the entire flower will be covered with this mycelial mass. 159 00:14:28,720 --> 00:14:34,000 Bikash Ghimire: And then also it produces spores very quickly, and that spores is windblown. 160 00:14:33,280 --> 00:14:41,760 Bikash Ghimire: So this is the spores that is in a cluster that is oval shaped, and that spores are when the humidity is high above 85%, 161 00:14:41,380 --> 00:14:56,180 Bikash Ghimire: that spores can be windblown, or it can be splashed with the overhead irrigation or whatever the irrigation, like or the rain, even the rain event, and that can be disseminated to the next healthy plant or next field, and then that how the infection is starts actually. 162 00:14:56,420 --> 00:15:01,699 Bikash Ghimire: And you can see the fuzzy growth on the tissue and all that, and you can easily identify for Botrytis. 163 00:15:01,699 --> 00:15:06,660 Bikash Ghimire: This is one of the easy diseases to identify in the field. 164 00:15:06,140 --> 00:15:16,380 Bikash Ghimire: And as I said, it is a problem in the post-harvest and storage as well, that causes a lot of economic issue if you don't properly store the harvested flowers and bloom. 165 00:15:16,140 --> 00:15:25,420 Bikash Ghimire: You need to remove the infected plants in terms of the management, and then also the stem that has this deadhead, whenever you see some of the flowers are dying or decaying, then 166 00:15:25,540 --> 00:15:30,980 Bikash Ghimire: you want to better remove that because that could be the source for pathogen, an entry point. 167 00:15:30,980 --> 00:15:40,180 Bikash Ghimire: So providing good air circulation is very important, and again proper spacing, as speakers previously mentioned about how spacing is important. 168 00:15:39,700 --> 00:15:42,100 Bikash Ghimire: So it is also related to disease management. 169 00:15:42,100 --> 00:15:49,300 Bikash Ghimire: So you need to provide proper spacing so that we have a good air circulation and avoid that high humidity accumulating in the leaf surface. 170 00:15:49,300 --> 00:15:54,660 Bikash Ghimire: And then there are some fungicides that could be applied for reducing the infection and the growth of the pathogen. 171 00:15:54,640 --> 00:16:03,680 Bikash Ghimire: Next one in the list is powdery mildew, that requires warmer, humid but dry condition, and it can affect a lot of different plants, but different species might be 172 00:16:03,860 --> 00:16:12,420 Bikash Ghimire: you might be seeing the same powdery mass on the top of this leaf, but there might be different kind of species of the pathogen for each individual host type. 173 00:16:12,420 --> 00:16:15,380 Bikash Ghimire: So they are very much host specific, that's why. 174 00:16:14,959 --> 00:16:23,600 Bikash Ghimire: So the pathogen that is in sunflower might not be the same in zinnia, though the symptoms and the signs of the pathogen look very much similar. 175 00:16:23,339 --> 00:16:31,899 Bikash Ghimire: And then as with other disease, then if you spot this in the early stage, you remove the infected plant, but at the same time you can apply fungicides. 176 00:16:31,580 --> 00:16:39,340 Bikash Ghimire: Some of the fungicide that we can apply for powdery mildew and even leaf spot that I'll talk in a minute, like some fungicides on FRAC code 3, 177 00:16:39,280 --> 00:16:48,080 Bikash Ghimire: DMI fungicide, QoI fungicide, azoxystrobin in group 11, or some of the group 7 fungicides are very effective for controlling this disease. 178 00:16:47,400 --> 00:16:54,760 Bikash Ghimire: And then there are some biorational products like MilStop is found to be effective in powdery mildew to stop the spreading of the disease. 179 00:16:54,760 --> 00:16:57,480 Bikash Ghimire: So the next one is downy mildew. 180 00:16:56,600 --> 00:17:04,839 Bikash Ghimire: So with the downy mildew you can see that you see some kind of stunting, flower distortion and some on the top, on the above surface of the leaf. 181 00:17:04,839 --> 00:17:08,520 Bikash Ghimire: But if you flip the leaf and look underside, you can see the white spore 182 00:17:08,839 --> 00:17:17,480 Bikash Ghimire: production underneath, and that's how you identify this disease, and it's a problem in a lot of ornamentals, especially sunflower or [VERIFY: "bacia"], that you can see a lot of 183 00:17:17,640 --> 00:17:28,440 Bikash Ghimire: issue with the downy mildew. And this is a systemic disease that goes from the vascular region, that flow, that kind of pass in the vascular region and cause the infection. 184 00:17:28,460 --> 00:17:31,580 Bikash Ghimire: So the next one I have in the list is leaf rust. 185 00:17:31,580 --> 00:17:34,460 Bikash Ghimire: And one of the common ones that I see is in the snapdragon. 186 00:17:34,460 --> 00:17:36,460 Bikash Ghimire: As you can see, snapdragon, you can see 187 00:17:36,440 --> 00:17:48,679 Bikash Ghimire: this yellowish discolored patchiness on the top, and when you flip the leaf again on the underside, you can see a lot of this kind of, you know, pustules that has a tons of these spores, if you see under the microscope. 188 00:17:48,100 --> 00:17:56,980 Bikash Ghimire: So these spores are windblown, that can easily be blown by air, wind, and can go from several kilometers and then miles and can cause disease. 189 00:17:56,980 --> 00:18:00,179 Bikash Ghimire: So rusts are very host specific, and some require 190 00:18:00,700 --> 00:18:15,260 Bikash Ghimire: multiple host type, like two, at least two host type, to complete its life cycle, but some of them only require one, like in the rust in sunflower or snapdragon, they don't require another host type to complete the life cycle. 191 00:18:14,760 --> 00:18:24,280 Bikash Ghimire: But anyway, so when you see those plants, again, like removing the infected plant, and you'll hear again and again from me talking about the same management practice 192 00:18:24,040 --> 00:18:29,720 Bikash Ghimire: of early scouting and removing the infected plant, because that's the first step of disease management. 193 00:18:29,720 --> 00:18:34,680 Bikash Ghimire: And then of course we have fungicide that can be applied preventatively to control disease. 194 00:18:34,519 --> 00:18:37,320 Bikash Ghimire: So the next one is fungal leaf spot. 195 00:18:37,320 --> 00:18:43,320 Bikash Ghimire: So which is, there are so many leaf spots that it's not convenient to list all of them here, but 196 00:18:43,100 --> 00:18:49,260 Bikash Ghimire: just as an example, in zinnia, whenever I go out in the field I see a lot of problem with Cercospora leaf spot. 197 00:18:49,340 --> 00:18:58,059 Bikash Ghimire: So that's a big problem in zinnias, and you can easily identify because you can see this tan center and then this is surrounded by this purple margin or border. 198 00:18:58,060 --> 00:19:01,340 Bikash Ghimire: And then you can also see the fungal fruiting structure of the pathogen. 199 00:19:01,340 --> 00:19:07,820 Bikash Ghimire: So for the leaf spot management, again, infection and spread is favored by leaf wetness, high humidity, 200 00:19:07,560 --> 00:19:12,200 Bikash Ghimire: poor air circulation, and then the fungi can overwinter in the plant residue. 201 00:19:12,200 --> 00:19:18,280 Bikash Ghimire: So that's why it's very important to remove that extra debris, and then the diseased or the 202 00:19:18,540 --> 00:19:25,660 Bikash Ghimire: dead stem and leaves that need to be taken out from the field so that it does not be a source of inoculum. 203 00:19:25,660 --> 00:19:31,820 Bikash Ghimire: And then also important point is to keep the foliage as dry as possible so that 204 00:19:31,660 --> 00:19:33,740 Bikash Ghimire: you don't have that extra leaf wetness. 205 00:19:34,300 --> 00:19:43,820 Bikash Ghimire: And spores are water splashed, so that's why if you are doing overhead irrigation, you might want to cut off that and go to the manual irrigation so that you don't help in the dissemination. 206 00:19:43,519 --> 00:19:47,039 Bikash Ghimire: So again, the pathogen is host specific. 207 00:19:47,039 --> 00:19:52,799 Bikash Ghimire: That's why rotating crops one after another year might be helpful in terms of controlling the disease. 208 00:19:52,799 --> 00:19:58,159 Bikash Ghimire: And then we recommend applying some of the biological and chemical fungicides that I mentioned. 209 00:19:58,120 --> 00:20:02,040 Bikash Ghimire: So that was the fungal leaf spot that I just mentioned. 210 00:20:02,040 --> 00:20:06,360 Bikash Ghimire: And then we have bacterial leaf spot, which is different from fungus because 211 00:20:06,460 --> 00:20:15,740 Bikash Ghimire: for bacteria it produced this angular leaf spot, which is compared to fungus, they produced in the concentric ring or around the structure. 212 00:20:15,740 --> 00:20:20,300 Bikash Ghimire: Here it is angular and it is in the vein region, it is like going in the vein. 213 00:20:19,940 --> 00:20:26,019 Bikash Ghimire: And then you can see a halo, which is called the yellowing around that leaf patch or that spot. 214 00:20:26,019 --> 00:20:30,100 Bikash Ghimire: So that's how you identify fungus versus bacterial leaf spot, because 215 00:20:30,060 --> 00:20:35,820 Bikash Ghimire: the management for bacteria versus fungus is a little bit different in terms of applying fungicides. 216 00:20:35,820 --> 00:20:41,100 Bikash Ghimire: So for bacteria, mostly we recommend copper-based fungicides like mancozeb. 217 00:20:41,100 --> 00:20:44,780 Bikash Ghimire: Those could be very effective in terms of controlling this pathogen. 218 00:20:44,900 --> 00:20:53,220 Bikash Ghimire: So again, water management is very important because if you have too much leaf wetness on the foliage, then that is when the bacteria starts infection. 219 00:20:53,060 --> 00:20:59,060 Bikash Ghimire: So removing the infected plant, and then also one thing to note is the bacterial pathogen are seed-borne. 220 00:20:59,060 --> 00:21:03,380 Bikash Ghimire: They can be in the seed and can go pass to the next generation. 221 00:21:03,380 --> 00:21:07,860 Bikash Ghimire: That's why it is important to make sure that you do not save the seed from the infected 222 00:21:07,940 --> 00:21:10,019 Bikash Ghimire: plants for the next year. 223 00:21:10,019 --> 00:21:13,460 Bikash Ghimire: So the next one that I want to quickly touch is virus disease. 224 00:21:13,460 --> 00:21:20,340 Bikash Ghimire: So there are several virus, plant virus diseases that are a problem, and just to list a few of those, we have this INSV, Impatiens 225 00:21:20,360 --> 00:21:28,840 Bikash Ghimire: Necrotic Spot Virus in snapdragon, we have Tomato spotted wilt virus in zinnia, and these are just like some of the common virus that we often identify. 226 00:21:28,840 --> 00:21:32,360 Bikash Ghimire: And virus are spread by insects like thrips, aphids, 227 00:21:32,540 --> 00:21:35,820 Bikash Ghimire: mites, and it also is spread by grafting and propagation. 228 00:21:35,820 --> 00:21:42,620 Bikash Ghimire: That's why the only way to control or manage this disease is by either applying 229 00:21:42,640 --> 00:21:48,880 Bikash Ghimire: insecticides to control insect, or just avoid propagating the infected plant. 230 00:21:48,880 --> 00:21:55,280 Bikash Ghimire: But there is no other cure method for this virus diseases, that's why whenever you see the plant, spot the plant 231 00:21:55,540 --> 00:22:10,260 Bikash Ghimire: getting this virus, then you just have to uproot the entire plant and safely dispose them, and then also control, the monitor the insect population, and apply some kind of insecticides to control this vector that transmit this virus. 232 00:22:09,400 --> 00:22:23,320 Bikash Ghimire: So that's the only way you can see, and as you see the virus diseases are very easy to spot, because you will see some kind of the ring spot, like a mottling, yellowing of the leaves, and this unusual pattern, when you see, then you are mostly likely dealing with virus diseases. 233 00:22:23,140 --> 00:22:30,980 Bikash Ghimire: So luckily we have this ImmunoStrip that is from Agdia that we can test, and the result can come as quick as five minutes. 234 00:22:31,140 --> 00:22:38,420 Bikash Ghimire: And then all you have to do is take that infected leaves, macerate it, and then throw it at the ImmunoStrip in the buffer bag. 235 00:22:38,420 --> 00:22:42,420 Bikash Ghimire: And this is just like a pregnancy test kit where we have two control, two lines. 236 00:22:42,260 --> 00:22:45,380 Bikash Ghimire: When you see both line, then that is positive. 237 00:22:45,380 --> 00:22:47,140 Bikash Ghimire: When you see only one, that is negative. 238 00:22:47,140 --> 00:22:54,660 Bikash Ghimire: For example, here in this case with this plant, zinnia, sorry, we have this TSWV positive for 239 00:22:54,660 --> 00:22:58,660 Bikash Ghimire: zinnia, whereas INSV is negative because there is only one band. 240 00:22:58,660 --> 00:23:02,180 Bikash Ghimire: So that's how we identify the disease right away. 241 00:23:02,200 --> 00:23:11,639 Bikash Ghimire: And there are other ImmunoStrip that is out from Agdia, which is for TMV, CMV, and then we have for Xanthomonas, Phytophthora, and Rhizoctonia, which are also 242 00:23:11,640 --> 00:23:24,520 Bikash Ghimire: very helpful in terms of quickly identifying the pathogen, and then it can also be taken to the field, so we can do either in-house testing or in the field, and then it does not cost that much, like a six to eight dollar per ImmunoStrip, so 243 00:23:24,560 --> 00:23:27,120 Bikash Ghimire: it could be very handy resources for growers. 244 00:23:27,120 --> 00:23:30,160 Bikash Ghimire: So this is, I think, I'm towards the end now. 245 00:23:30,160 --> 00:23:36,160 Bikash Ghimire: So I know I'm rushing a little bit, but just to wrap up my, or cover all of my content, I was 246 00:23:36,220 --> 00:23:37,180 Bikash Ghimire: a little bit faster. 247 00:23:37,180 --> 00:23:42,140 Bikash Ghimire: But these are the list of some of the biological control as, and that could be applied. 248 00:23:42,140 --> 00:23:45,580 Bikash Ghimire: It is listed for edible greenhouse, but it can be applied for 249 00:23:45,560 --> 00:23:53,960 Bikash Ghimire: ornamental plants, and I have tested or I'm about to test some of those, like I have tested some in the turfgrass, but I'm about to test this in the ornamental, so 250 00:23:53,800 --> 00:24:01,320 Bikash Ghimire: some of the Bacillus products are very effective in controlling a lot of different diseases, foliar and also the root and crown rot disease. 251 00:24:01,320 --> 00:24:05,320 Bikash Ghimire: We have some Trichoderma products that is also very effective in terms of controlling, 252 00:24:05,260 --> 00:24:09,260 Bikash Ghimire: you know, Fusarium, Pythium, Phytophthora, and all that root and crown rot. 253 00:24:09,260 --> 00:24:15,740 Bikash Ghimire: And of course we have neem oil, we have some Pseudomonas, and then plant extract, so that can be applied. 254 00:24:15,740 --> 00:24:16,059 Bikash Ghimire: So 255 00:24:16,440 --> 00:24:20,200 Bikash Ghimire: With that, just I want to leave you with this resource. 256 00:24:20,200 --> 00:24:26,840 Bikash Ghimire: e-GRO is out there, which is an online platform where it gives you a lot about disease, insects, 257 00:24:26,440 --> 00:24:29,559 Bikash Ghimire: environmental and physiological and nutritional disorders and all that. 258 00:24:29,559 --> 00:24:31,480 Bikash Ghimire: So you can utilize these resources. 259 00:24:31,480 --> 00:24:32,919 Bikash Ghimire: The link for the website. 260 00:24:32,919 --> 00:24:36,440 Bikash Ghimire: Just if you have not gone through this, this could be a useful resource 261 00:24:36,160 --> 00:24:36,880 Bikash Ghimire: for the growers. 262 00:24:36,880 --> 00:24:46,080 Bikash Ghimire: And then we have Georgia Pest Management Handbook that has a very comprehensive list of fungicides and application amount and dose and intervals and all that you can find. 263 00:24:46,080 --> 00:24:48,560 Bikash Ghimire: So we always recommend referring to this 264 00:24:48,360 --> 00:24:50,919 Bikash Ghimire: handbook whenever you have to apply any fungicide. 265 00:24:50,919 --> 00:24:53,399 Bikash Ghimire: So with that, that should be all for me. 266 00:24:53,399 --> 00:24:59,240 Bikash Ghimire: Thank you so much for patience and listening to me, and then I'll be happy to take any questions either now or in the future. 267 00:24:59,240 --> 00:25:01,159 Bikash Ghimire: So here's my contact information. 268 00:25:01,159 --> 00:25:01,960 Bikash Ghimire: Thank you. 269 00:25:02,240 --> 00:25:07,920 Bethany Harris: Bikash, thank you so much for sharing with us a little bit about disease management strategies this morning. 270 00:25:07,920 --> 00:25:14,720 Bethany Harris: We do have a couple questions from the audience, and the first one is, can you speak on aster yellows and prevention? 271 00:25:14,660 --> 00:25:18,340 Bethany Harris: This grower noticed their first coneflower infection this week. 272 00:25:18,340 --> 00:25:21,060 Bethany Harris: So do you mind sharing a little bit more about that? 273 00:25:21,300 --> 00:25:25,860 Bikash Ghimire: So aster yellows, I think we got an email about aster yellows, I remember. 274 00:25:25,860 --> 00:25:29,380 Bikash Ghimire: So it's a bacterial kind of disease caused by phytoplasma. 275 00:25:29,160 --> 00:25:32,600 Bikash Ghimire: And then so phytoplasma is similar to bacteria. 276 00:25:32,600 --> 00:25:41,800 Bikash Ghimire: So again, with this kind of pathogen disease, it's very, sometime it is confusing with, I remember I had an email where sometimes it is confusing with the 277 00:25:41,940 --> 00:25:55,059 Bikash Ghimire: herbicide injury that it produced this, you know, witches' broom kind of symptom and all that, that is very confusing, but, but this, whenever you see this disease, all you have to do is just uproot the plant and then safely dispose, 278 00:25:55,140 --> 00:25:59,860 Bikash Ghimire: because it can be trans-, I believe it is transmitted by some kind of hoppers. 279 00:25:59,860 --> 00:26:05,140 Bikash Ghimire: I forgot what exactly that is, but that's why you safely dispose the plant, and then 280 00:26:05,260 --> 00:26:12,780 Bikash Ghimire: just make sure that it does not go out and spread on the healthy plant, and also you can apply some kind of insecticide to control. 281 00:26:12,780 --> 00:26:13,419 Bethany Harris: Perfect. 282 00:26:13,419 --> 00:26:15,900 Bethany Harris: And I think we have one more for you too. 283 00:26:15,900 --> 00:26:16,299 Bethany Harris: If 284 00:26:16,460 --> 00:26:20,380 Bethany Harris: there is a widespread of Botrytis infection in tulips. 285 00:26:20,380 --> 00:26:23,100 Bethany Harris: Will it remain in the soil until the next spring? 286 00:26:23,100 --> 00:26:29,900 Bethany Harris: And what can be done to prevent it from infecting tulips the following spring that are planted in the same area? 287 00:26:29,919 --> 00:26:31,200 Bikash Ghimire: That's a very good question. 288 00:26:31,200 --> 00:26:33,760 Bikash Ghimire: Yes, the pathogen can reside. 289 00:26:33,760 --> 00:26:41,840 Bikash Ghimire: The picture, if you remember I showed, so it was, so it produced a lot of conidia in the finger-like appearance, and then that remained in the 290 00:26:42,040 --> 00:26:47,480 Bikash Ghimire: in the soil debris, or in the, not necessarily in the soil, but in any kind of plant debris. 291 00:26:47,480 --> 00:26:52,920 Bikash Ghimire: And then it can come back next year depending on what type of plant you are planting. 292 00:26:52,920 --> 00:26:55,720 Bikash Ghimire: If you are planting the same host or same plant or 293 00:26:55,660 --> 00:26:59,660 Bikash Ghimire: cultivars, then that could come back again and then start infection. 294 00:26:59,660 --> 00:27:06,780 Bikash Ghimire: So I would suggest if you see those in the early stage, make sure that you scout that all the plant in the early stage. 295 00:27:06,340 --> 00:27:14,500 Bikash Ghimire: And then for the next season, you might want to start with some kind of the application in the beginning if you are planting in the same bed. 296 00:27:14,260 --> 00:27:19,220 Bikash Ghimire: So I would suggest going and applying any kind of, you know, systemic product. 297 00:27:19,220 --> 00:27:26,820 Bikash Ghimire: You can start with some kind of contact fungicide first, like chlorothalonil, fludioxonil, and all those are contact fungicide that is 298 00:27:26,660 --> 00:27:29,540 Bikash Ghimire: it can, that has a preventative action, mode of action. 299 00:27:29,540 --> 00:27:34,660 Bikash Ghimire: And then you can also apply some kind of, you know, the systemic fungicides like DMI fungicide like 300 00:27:34,480 --> 00:27:38,720 Bikash Ghimire: tebuconazole, azoxystrobin, and boscalid, those could be applied. 301 00:27:38,720 --> 00:27:46,560 Bikash Ghimire: So you can do one early stage application as a contact and the next one as a systemic, depending on how severe you will see the symptom. 302 00:27:46,320 --> 00:27:46,960 Bethany Harris: Perfect. 303 00:27:46,960 --> 00:27:49,600 Bethany Harris: And then I think we've got one more last question here. 304 00:27:49,600 --> 00:27:54,160 Bethany Harris: And it's, do you have any recommendations for bacterial stem rot? 305 00:27:54,760 --> 00:27:55,880 Bikash Ghimire: Okay. 306 00:27:55,880 --> 00:28:00,919 Bikash Ghimire: So for the bacterial stem rot, I know somebody's asking about the Pectobacterium. 307 00:28:00,919 --> 00:28:02,519 Bikash Ghimire: James is asking about Pectobacterium. 308 00:28:02,519 --> 00:28:09,159 Bikash Ghimire: So for the Pectobacterium, I would suggest going with, for the bacterial disease, I would suggest going with copper-based 309 00:28:08,779 --> 00:28:12,700 Bikash Ghimire: product. Mancozeb could be one of the effective ones to start with. 310 00:28:12,700 --> 00:28:20,620 Bikash Ghimire: They have a better control compared to other the regular fungicides for fungal leaf spot, fungal, for example Fusarium stem rot, 311 00:28:20,060 --> 00:28:22,940 Bikash Ghimire: which is also a big problem in a lot of other ornamentals. 312 00:28:22,940 --> 00:28:24,860 Bikash Ghimire: So I would start with the copper-based fungicides. 313 00:28:24,860 --> 00:28:26,460 Bikash Ghimire: So that could be the best bet. 314 00:28:26,540 --> 00:28:27,500 Bethany Harris: Thank you very much. 315 00:28:27,500 --> 00:28:31,580 Bethany Harris: And thank you all for being here today, joining us this morning.