 The topic of this present webinar is cotton blue disease and new virus disease in Alabama cotton up until really last two or three years given the long history of cotton production in Alabama and other southeastern states. We've never really had an issue with a virus disease in cotton. Now in Arizona there is a white-white transmitted virus but surprisingly here we've not run into problems with this type of disease in this area in the past. The symptom patterns showed up about two or three years ago, maybe longer than that according to the comments from some crop consultants but certainly in 2016 some unique symptoms were noticed in cotton in either Barbara County or Talapusa County. The symptoms showed up again the following year in those two areas. Samples were collected and the resulting disease was identified as being caused by the cotton leaf roll dwarf virus which is the causation of cotton blue disease. Since we were alerted to the fact that that the virus was present the more vigorous survey of cotton in Alabama was done in 2018 and we'll talk about the distribution in a moment but again more samples were collected some genomics work sequencing was done and again the virus was identified as either cotton leaf roll dwarf virus or a very close relative and there are always some differences among strains and that's where the issue showed up and then for 2019 since we had a number of good samples collected some additional gene sequencing was done and it turns out that the Alabama isolates were confirmed as a strain of the cotton leaf dwarf virus. You know right now as I said we did some surveying in 2018 and cotton blue disease was identified in 24 Alabama counties most of the symptoms were collected in between September which is really when the disease was first observed in cotton until the first hard frost but however some of the positive samples also come out of defoliated stalks were collected in cotton fields in in South Alabama in January February and March. The once the disease was recognized as having shown up last fall some sampling was done in Georgia as well as Mississippi and there were a number of counties in both of those states and cotton producing areas where the virus was confirmed and then in February some samples were collected in South Carolina from fields that had the accentuated accentuated verticality symptom pattern that we've associated with blue disease in the United States and they also tested positive so and also some samples were also taken last fall from several counties in the Florida Panhandle so right now we have five states where this particular disease has been identified. The cotton leaf dwarf virus is transmitted by the cotton aphid there may be some other aphids involved in the spread of this virus that's the only means of transmission. It's first was identified in Africa in the late 40s but had a much greater impact on cotton production when it showed up in Brazil in Argentina in the late 1880s early 1990s where yield losses up to 80% were reported. Other countries where the virus has been identified in cotton include India, Thailand and the island of Timor which is in the Indian Indonesian archipelago. In addition there's a very closely related aphid transmitted virus called cotton bungee top in Australia and it turns out the resistance that was identified for cotton bungee top in Australia has also been used as the basis of our resistant varieties in South America so these viruses are very closely related and the mechanisms for resistance appear to be identical. As I mentioned before we do have an aphid vector the main aphid vector is the cotton aphid but as I said there may be some other aphids involved. Usually aphids are not considered a major pest in cotton they kind of show up in June and populations will increase slowly over time then a typically a fungal disease shows up in July and thins out the population to the point that they don't cause damage but there is a possibility that the you know the several aphids are involved in virus transmission and the other point where the arrow is pointing in the B image is that there are some symptoms associated just with the aphid aphids feeding on cotton they will roll the leaves that's also a symptom pattern that we associate with the virus but there are some subtle differences in the symptoms and at this point in time we've we've not identified the virus in cotton in June. The SIPCA patterns vary greatly by the cotton variety the time of year probably also growth stage the most notable symptoms up close are as the is the puckering and rugosity of the leaves in the top of the plant which so far is generally shown up in September in some cases as in B and C images they the leaves may roll down or roll up but I already mentioned that in association with the with the aphid but the look is a little bit different another symptom is the deep vein vanation color in this case of phytogen variety is kind of a maroon color and then in the final image E just some subtle rugosity in the leaves but that particular plant tested positive for the virus so it so the symptoms are not real severe at least in the sometimes in the terminals of the plant it the disease is rather deceptive in comparison with some other virus diseases that I've that I'm familiar with some advanced symptoms that show up in September and October was as in image A a distinctive maroon coloration of the upper stems and also the pedioles I mentioned the accentuated verticality these plants tend to stretch out and continue to grow they do shed set squares in the terminals but those squares never develop into blooms and of course never develop into bowls so the plants keep on growing as you can see in image C where you have a a normal crop down in the canopy then the plants began to grow off and did not produce any bowls so you get a very unusual growth pattern one of the other issues you run into with virus diseases particularly in what in essence is an annual crop is there there has to be some other reservoir hosts out there where the virus can survive between growing seasons at least for the cotton and some survey work this winter and early spring showed that some weeds are potential reservoirs of this virus now one of them is hen bet we did find a virus in in a resident virus in hen bet however that play it does it persist very long and other we've got positives in white clover and also evening evening primrose and those plants are either perennials or maybe biennials so there's a possibility that that there is some carry over the virus in in some of the weed populations we have in the field the other possible potential source is cotton regrowth out of stalks and this year particularly in Georgia where Hurricane Michael destroyed a lot of cotton the plants were left in the field they began to sprout in late March and early April and and they tested positive for the virus the only situation was we may not have had any aphids there and we so we really don't know what impact that might have on the early season spread of this virus either in the cotton or perhaps some other weed hosts but all of the images in all the plants in these images that are shown did test positive for the virus and in the image on the right hand side you can see the early season regrowth on a cotton stalk as far as management of cotton blue disease things are very fluid at this point in time as you can imagine this is a new disease in cotton we really don't have any established procedures in place for managing this disease we could only look at some of the sources of virus that we've identified up until this point and perhaps manage those sources of virus as a means of maybe slowing or interrupting the spread of this disease into into cotton and one of which would be stalk destruction as I've already discussed and we do have cotton can over winter here it will sprout in late winter early spring if we got aphids onto plants that were infected with the virus we could see some spread from that point I mentioned the winter weeds and some of the perennial weed issues essentially there the growers can either go in and burn down their winter weeds to keep the fields clean the other option is to come in with deep tillage and particularly in the fall and plant a winter cover crop and that way the overseasing of the cotton stalks is taken care of and then one other point that showed up last year is that the the disease was more prominent more damaging in June than in May planted cotton so there's the possibility that getting in with a little earlier planting day particularly in southwest Alabama where the disease was more prevalent and more damaging might be an effective means of avoiding some damage from the virus as a result of the appearance of this disease in Alabama cotton as well as in our neighboring states we do have a regional project in place to try and begin to address some questions with respect to the distribution of the disease in the southeast as well as the progression of the disease in cotton we're trying to determine whether or not it has an impact on yield now it seemed like in some of the fields involved when county there certainly was a lot of damage and very poor ball set in some situations but that still needs to be confirmed right now more than likely the most effective means of managing a virus disease like this will be through breeding we do have some sources of resistant germplasm from South America and which actually originated in Australia hopefully the strain of the virus we have here can be managed with the resistance that we already have in the cotton gene pool hopefully we won't have to go out and find a new source of resistance there's a possibility of managing the aphid vector or manipulating the crop to manage the aphid vector there's still some questions about basic biology questions about the transmission of the causal virus and then we need a faster diagnostic procedures because the current PCR procedure is a two-day procedure and it takes or costs about $30 per sample so it's kind of costly as well so we're looking for a rapid diagnostic program to simplify the diagnosis of this disease so that that kind of covers the topics that I wanted to mention with respect with respect to cotton blue disease as I said there's a fairly extensive program ongoing in Mississippi in Georgia and in Alabama to try and address the distribution and control of this disease and hopefully we'll have some information in the fall at least with respect to the resistance of some of the varieties we have out there as well as some maybe some input on the impact of this disease on cotton yield thank you