 Hey, I would like to welcome everyone to the extension agronomy team October webinar This is Steve Lee extension weed scientist of Auburn University. I would like to talk about using sequential application of synthetic oxygen herbicide and gophosinate for pomegranate control This is my PhD student Francis Brown's Project and I'm gonna briefly talk about some of the main findings from last two years So we conducted field projects in 2017 and 2018 in Henry County and also We had a location this year in Henry County as well in 2019. So most of the data you see are actually from the 2018 and 2019 field trials We have four applications small plot research It's a randomized complete blood design We apply the different treatments to pomegranates that we are artificially seeded we We used CO2 backpack and TTI or TT nozzles Calibrated for 20 gallon per acre because we're spring to pretty dense vegetation Depends on if we're spring Liberty or bicamba or 240 we'll choose to use either TT nozzles or TTI nozzles we rated visual injury and also Francis measured the pigwee height two and four weeks after initial treatment she also Collected pigwee bomb as at five weeks after initial treatment So if you look at a table right here the major difference between 2018 and 2019 experiment is the average height of the pomegranates and they differ Quite a bit between the two years. So we were spraying at a much larger pomegranates in 2019. So in Production we don't recommend people spray anything above six inches, you know below six inches is always the best The smaller the better. So these are really The salvage situation that we're looking for rescue treatment to Save a crop or save a field from getting ate up by pigweed So we don't recommend people use these treatment on a regular basis We used five different chemicals in our treatment. They were used in different combinations or different sequence So we use that camber well, which was extending max in terms of formulation I was running power max Liberty do magnum in this one. All right, you can see the use rate we We included in the experiment for the last few years and we didn't use any other rates during the experiment we added 1% of class act read on which is a yes and DRA at a half percent to all the dicamba treatment to satisfy label requirements So in terms of our of our treatment structure, we do have a few one-time applications such as extending max was roundup Liberty with do magnum and also we had illegal treatment of Extended max with roundup with Liberty with do magnum. This treatment is totally legal label doesn't allow it So we just included for Experiment purpose. Also, we have in this one with Liberty with do magnum So these are all the one-time application and we also have a few sequential application program So you can see what we spray in the initial application and then these are what we spray in the follow-up application The timing between the two application were either three days, but mostly seven days after initial treatment So we had some treatment used two shots of dicamba like this one We have dicamba first followed by Liberty at a three or seven days after We have the list one with Liberty with do magnum followed by a list do or the same treatment again Or Liberty was do magnum. We also had a Liberty with do magnum first followed by extending max with roundup Or Liberty with do magnum and they should not really check So if we talk about extending max programs, all right, this gives you an idea how much pressure with pressure. We're We were working on these fields are very very weedy. They're traditionally wheat science research area So we got a lot of pressure there Looking at the Palmer Emirates visual injury at four weeks after the initial treatment There are a few treatment That gave us more than 80% of damage, but most of the treatment Did not produce satisfactory control which is well expected because we spray on Palmer that are way too big. All right We couldn't combine the two-year data because year was significant during Data analysis so we have to present the data by year. All right So visual injury doesn't really show much even though you can have you know over 80% injury But we all know Palmer Emirates has amazing ability to recover from injury and Then this will give you some idea five weeks after initial treatment We certainly have seen pigweat start to recover, you know, like those healthy pigweats in both years Trial All right. One shot is not definitely not gonna do it. Liberty with dual magnum looks even worse Just because Liberty is contact herbicide. It doesn't penetrate the canopy very well round up with Extended max with Liberty with dual magnum, you know the illegal treatment. It doesn't look impressive at all so We scientists always talk about tank mixes tank mixes But it's not always true that the more you mix the better control you get that is wrong All right, look at the biomass five weeks after initial treatment We do have a significant year effect. So we have to present the data by year But if you look at 2018 data, which were represented by the blue bars, we have some pretty short ones, you know say round up with extended max dual magnum followed by extended max and Roundup or even two shots of Liberty gave us pretty short bar, you know in 2018 and then we have Some really good treatment down here that can but with roundup followed by Liberty and do my whether it's the three days or seven days after We had almost no Palmer survived after those program. But if you look at 2019 Treatment results. They were not looking good, you know, we don't have very short bars no more just because the pigweats were Much bigger in 2019 experiment All right another Interesting finding is the grass control this is nothing new but 2018 was a wet summer most, you know, mostly in the first part But 2019 was dry throughout the summer from the start to the end All right. So this program was a Liberty do followed by Liberty do Magnum All right Liberty has never worked great on grasses. But in 2018, we still get some okay grass control It's not good, but it's at least not too terrible versus 2019 Treatment, I mean pig. We didn't get control much in either year, but grasses were disaster You know, they were they were looking like disaster in 2019 just because it was too dry and Liberty don't like dry condition It just doesn't work well So this is the round up fall roundup that can follow by roundup that camber program So in both years, so I was able to kill most of the grasses even Considering 2019 being a fairly a dry year But on pig weed, you're not gonna expect too much out of this that camber followed by that camber procedure Which I don't really recommend to most of the growers anyway that puts too much pressure on that camber and Three sets three shots of that camber is a even worse idea. Don't even try it Liberty we still follow by that camber plus roundup in 2018 grass control. It was great Palmer not so much in 2019 Palmer control was still pretty mediocre But I got plenty grass left In the plot. All right, so grass control has been a struggle in 2019 This was a good program back in 2018, you know that camber was around that followed by Liberty with stew and also If you wait seven days after initial treatment put out your Liberty do Magnum in 2018, I got All the pig we kill pretty much, but in 2019 I have plenty survivors, you know from this two programs that That was simply because The pig we size was way too big in 2019 versus 2018 there's no way you can kill two-foot tall pigweed Consistently at all. So this is a general rule of thumb on large pigweed Occasionally you may kill a few but consistently that never happened All right, so looking at the percentage non-treaty check I mean looking at the upon-memory as biomass as converted by percentage non-treaty check in 2018 we had some really good control with Dicamba was around the first followed by Liberty and do Magnum in 2019 None of those programs were very effective. All right So that just tell us the value of spring on time spring early when the weeds are small All right again much bigger pigweed in 2018 2019. All right. Once you have pigweed being knee-high It's gonna be impossible to kill them all so hand-weeding will be needed. I if you still want to save your crop Well, we saw in our research plus kind of match what I saw in growers field in 2019 You know all these pictures were taken in 2019 a few trips that I made throughout the state Are in many grass escapes many pigweed escapes pre-emergence didn't work out too well because These are mostly dry land and we don't get rain No, those didn't get activated and it's just hard to kill weeds particular grass weeds when they're You know in that terrible drought stress. It's just hard to kill them with herbicides All right for in this cooling for 240 cooling, which is in this one We saw some pretty decent injury in 2018 which were Represented by the blue bar, but if you look at the orange bars 2019 data We certainly had a drop of visual injury, which was caused by the increased size of pigweed We were able to combine 2018 2019 biomass data and we do have a few pretty short bars right here like in this one With liberty we still follow by the same treatment seven days again or followed by liberty We still magnum seven days after treatment, you know or followed by in this do seven days after initial treatment This all seemed to be working fairly well However, this little amount biomass of pigweed can still bounce back and occupy a lot more area We know that because the tolerance of pigweed in the field is zero All right looking at the biomass five weeks after initial treatment combined 2018 2019 data We do have some program work fairly well, you know these three with letter C after the number These work really well on pigweed control, but still not a hundred percent There's no way you can kill large pigweed a hundred percent You're always gonna have some leftover that need to be cleaned up by hand or by whole All right plot pictures in this one plus liberty followed by this do in 2019 it looked pretty good to me in 2019. I got plenty escapes of grasses and Pigweed so the grass escapes match the extent program Fairly well, you know, you're just gonna gonna get it kill you either one of the system It is one plus liberty plus do magnum followed by the same treatment again Really really good-looking plots 2018, but not so good-looking plots in 2019 All right, so environmental stress can put a big effect on we control and a lot of other things as well You this one liberty was do Mac followed by liberty was do max seven days later 2018 very good pigweed controls not a hundred percent, but pretty decent in 2019. It's a full of pigweed plus grass All right So we saw lots of similar story happened over and over again I just tell us we want to spray weeds particularly pigweed when they are small and also When it hasn't rain for a long time, you know, the field is bone dry It's just gonna be very hard to kill weeds But the good thing is it won't take much water or rain to make those weeds active again So if you just rain a little bit to moisture the weeds you probably can get a better control with post-emergent herbicides We also did a greenhouse study to measure the physiological response of Palmer to four different treatment That's actually three different treatment as shown right here in this table Extending max with round up with liberty was due which is illegal treatment and also extending max with round up followed by liberty and do seven days later or Liberty was do magnum first followed by extend extending max and round up later All right, so we spray those greenhouse plants in with TDI nozzle or TT nozzles Same output 20 gallon per acre when the pigweed were 12 to 18 inches tall So we still spread a fairly tall plants and we only spread one third of the food library because these are greenhouse plants They are more sensitive to herbicide. We don't want to have You know this treatment kill them completely. All right, we measured a few things Related to their physiology response such as CO2 assimilation, stomata conductance, dark respiration, PSD efficiencies All right, these pictures give you some idea about how these plants look like seven days after initial treatment All right, so we do so some differences there All right All right looking at the photosynthetic assimilation Following the herbicide treatment. All right, this tells us how well photosynthesis is running in terms of fixing CO2 for for Hydrocarbons or You know stuff like sugar, starch, cellulose and all those things. All right, so this lie on the top in yellow Is non-treaty check. All right, and then the orange line represents Extending Max with Roundup followed by Liberty with still Magnum. All right and This one doesn't show much of difference early on as compared to the non-treaty check This sharp drop here was caused by the Liberty and Applied a seven days after initial treatment. So Liberty was put on on these plants on the seventh day So you can see a big drop of CO2 assimilation caused by Liberty and then the plants start to roll out of the Liberty injury and by the 14th day After the initial treatment in terms of CO2 assimilation We don't see a difference between this treatment and a non-treaty check All right for this two program down here One is Liberty with due followed by Extending Max and Roundup. The other one was Roundup with It was Extending Max with Liberty with due Magnum with Roundup. So both had the Liberty applied Upfront that's why the CO2 simulation started at a very low point and slowly work its way up All right Dicamba and Roundup was sprayed a seven days after initial treatment for this gray line right here But Dicamba has no effect almost no effect on CO2 assimilation for this pigweed and plus all these pigweed are Roundup resistant. So Roundup don't do anything but something we learned from these results is Dicamba doesn't really slow down CO2 assimilation much compared to the non-treaty plant But Liberty does Liberty cause a lot of problem for CO2 assimilation All right PS2 efficiency as measured by quantum yield or fluorescence yield We saw similar trend all right the The yellow line represents non-treaty check the orange line represents Extending Max plus Roundup followed by Liberty and due Magnum All right, you can see similar trend as the last in as in the last figure This treatment didn't show a much difference Until the seventh day when it got sprayed on with Liberty Liberty was sprayed on and then a sharp drop of quantum yield which represents the healthiness of PS2 system in photosynthesis I've read you know in in the whole photosynthesis process and Then slowly recover as time goes by so Liberty cause problem for photosynthesis System 2 as well for these two treatment. They got sprayed with Liberty first and Dicamba later. That's why we saw quantum yield started low and start to go higher and higher Until it has no difference with a non-treaty check So conclusion we can make is Dicamba doesn't hit photosynthesis very hard, but Liberty does That's a difference. That's why I say Dicamba. That's why I usually say that's what I usually say in the Extension meeting Dicamba will freeze the plant, but Liberty is the hammer drop on top of the pigweed You know that actually killed it or severe severely damaged it All right So after we measure all the physiological response All right, we pull all the leaves off at a 35 days after the treatment and You can see all three treatments see significantly reduced the Leaf biomass as compared to the non-treaty check. All right So we pull all the leaves off. It's almost like we artificially defoliate all these pigweed plant Because in production one thing we saw many many times is Liberty Defoliate pigweed leaves and burn the pigweed into a bare stem But if that bare stem remains alive It's gonna grow back and regenerate all those leaves Although the new leaves can look smaller and a little bit funky compared to the original leaves So we simulate this process. We pull all the leaves off left all the bear stem to regrow and Then something interesting is for this two treatments, you know for the four-way mix illegal four-way mix or the Liberty followed by Dicamba program We saw no difference of the regrowth in terms of Leaf biomass that were generated during the regrowth. We let all the bare stem regrow for three weeks However for the Dicamba first followed by Liberty program We saw less regrowth leaf biomass as compared to the non-treaty check So the implication of these data is if we do Dicamba first followed by Liberty later We probably can hold off this pigweed a little bit longer and they don't generate As much new leaves as compared to some other programs So that somehow explain why this treatment was the best treatment in 2018 Study which resulted almost hundred percent fatality on those pigwee All right conclusions We still recommend sequential application That's absolutely the best thing if you have a few larger pigwee, you know, larger than six or even 12 inches You need to spray Dicamba first followed by Liberty and that's still the best thing to control those big Palmer and reduce leaf regrowth The bigger Palmer gets harder It's gonna be to kill you saw from the contrast between 2018 and 2019 experiment In this one plus Liberty seems to be a little bit more effective on large pigweed It's not because Dicamba is more effective on on it's not because 240 is more effective than Dicamba It's probably probably because you can combine Liberty with 240 and that caused more damage on large pigweed Then Dicamba alone because you can't do Dicamba with Liberty mix yet. You know, we don't have to label yet throughout stress severely impacted grass control For both Liberty and Roundup as you saw from 2018 and 2019 plot pictures You know spray with the same treatment So in our physiological study We saw Dicamba had a little effect on photosynthesis And and you know, whether it's a co2 assimilation or stomata conductance or It's a quantum yield. You know, I didn't show the stomata conductance data, but it has almost no effect on it Liberty greatly reduced the photosynthesis rate and ps2 efficiency though and The concern on spraying sequential treatment on large Palmer is those is because those severely damaged Palmer Still can come back and they pose serious concern for herbicide resistance because if we do this year after year try to kill large pigweed But don't completely kill them and don't spend time or labor or money to pull them out Some of those some of those severely damaged plants still produce seeds and maybe one of those seeds carry the mutation and Next you're gonna have a whole lot of resistant plants to Dicamba that you have to deal with So that's definitely something we don't want to see