Amit Jhala – Early Post or Late Post Herbicides, 2020 Virtual Field Day for Management of Atrazine, Glyphosate, and ALS Inhibitors-resistant Palmer amaranth in Corn

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07/13/2020 Added

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2020 Virtual Field Day for Management of Atrazine, Glyphosate, and ALS Inhibitors-resistant Palmer amaranth in Corn – Early Post or Late Post Herbicides

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[00:00:00.467](upbeat music)
[00:00:06.180]I'm going to discuss a project
[00:00:08.300]where we want to control this Palmer amaranth,
[00:00:11.160]which is resistant to atrazine, glyphosate
[00:00:11.993]and ALS inhibiting herbicides,
[00:00:16.560]just by using a post emergent herbicides,
[00:00:19.660]applied early post or late post.
[00:00:22.580]And this is not under ideal condition,
[00:00:24.630]but under worst case scenario,
[00:00:26.560]for example if some grower was not able
[00:00:28.860]to apply pre-emergence herbicide,
[00:00:31.340]then what are the options for controlling
[00:00:33.890]this resistant Palmer in corn?
[00:00:37.270]So that was the main objective here.
[00:00:39.310]We selected few herbicides applied early post-emergence
[00:00:42.850]and then in other set of treatments,
[00:00:45.340]they were applied late post-emergence.
[00:00:47.880]We planted this corn on May 12th,
[00:00:51.750]early post-emergence herbicides were applied on June 19th
[00:00:56.020]and late post-emergence herbicides
[00:00:57.830]were applied on June 23rd.
[00:01:00.250]So just to clarify, early post and late post herbicides
[00:01:04.170]were applied in different plots.
[00:01:05.720]We would want it to see how best a post-emergence herbicides
[00:01:11.180]can control when Palmer amaranth
[00:01:13.160]is somewhere less than six inches tall
[00:01:16.670]in early post-emergency application
[00:01:18.810]versus when they are applied late post-emergence herbicides
[00:01:23.340]were applied when Palmer amaranth
[00:01:25.420]was somewhere between eight to 12 inch tall.
[00:01:31.260]So that was the main objective of this project
[00:01:34.120]to evaluate the efficacy
[00:01:36.054]of post-emergence herbicides applied early post-emergence,
[00:01:39.610]or late post-emergence.
[00:01:41.720]So for example, this is untreated check means no herbicides
[00:01:45.750]were applied and naturally it is a full off Palmer amaranth
[00:01:50.340]as well as we also have some foxtail,
[00:01:53.480]it's like yellow foxtail and giant foxtail at this site.
[00:01:56.900]So you are seeing a combination of Palmer amaranth
[00:01:59.230]and foxtail species when you don't control
[00:02:02.330]these weeds at all.
[00:02:03.750]This is our weed-free plot means we want to keep
[00:02:06.660]this plot without any weed species.
[00:02:10.160]We also applied herbicides Acuron was applied pre-emergence,
[00:02:14.310]and then it was followed by DiFlexx
[00:02:18.310]in a tank mixture with a Liberty.
[00:02:20.690]DiFlexx is Dicamba-Based herbicides
[00:02:22.610]and it has great efficacy
[00:02:24.260]for controlling glyphosate resistant weeds
[00:02:26.570]like Palmer amaranth or waterhemp.
[00:02:28.620]So this plot is really very good looking
[00:02:31.670]because there was no early season competition.
[00:02:34.330]And if you will see this plot versus this plot,
[00:02:37.750]you will find a pretty great difference in corn height,
[00:02:42.010]because Pre-emergence herbicides was applied here
[00:02:45.040]and no herbicide was applied in this plot.
[00:02:49.960]In this plot, no pre-emergence herbicide was applied
[00:02:52.560]and only glyphosate was applied when corn was about five
[00:02:57.564]to six inch tall.
[00:02:58.420]And as I mentioned earlier,
[00:03:00.200]this Palmer amaranth at this period
[00:03:02.930]is very highly resistant to glyphosate.
[00:03:05.720]So even higher rate of glyphosate
[00:03:08.810]would not control this Palmer.
[00:03:11.000]And in fact of some of Palmer has just started flowering
[00:03:11.833]in this field because this population
[00:03:18.520]is very highly resistant
[00:03:20.250]to glyphosate up to like 37 X means,
[00:03:23.990]even if you will apply 37 times more rate
[00:03:26.890]than label rate, you will get some level of control.
[00:03:32.970]In this plot Liberty,
[00:03:34.510]which is a contact herbicide was applied
[00:03:36.630]there early post-emergence
[00:03:38.530]and there was no any pre-emergence herbicide was applied.
[00:03:41.710]So it has provided some level of control,
[00:03:44.260]but Liberty has no any residual activity.
[00:03:48.230]So you are now seeing some Palmer amaranth
[00:03:51.190]has started emerging now.
[00:03:52.880]And that is because --
[00:04:00.640]And this is why Palmer amaranth is difficult to control
[00:04:04.480]because it can emerge throughout the growing season.
[00:04:08.140]For example, this Palmer amaranth may
[00:04:10.130]have started emerging before the month,
[00:04:12.380]and this is a new little seedling of Palmer amaranth
[00:04:16.760]that just may have emerged before a couple of days.
[00:04:20.430]So that's why Palmer amaranth is difficult to control
[00:04:22.880]because it can emerge throughout the growing season.
[00:04:26.730]And in this plot particularly,
[00:04:28.630]we applied Liberty before about couple of weeks,
[00:04:31.120]so it has provided good control,
[00:04:32.710]but now Liberty has no any residual activity.
[00:04:36.130]So now it is a, some new Palmer amaranth is coming up.
[00:04:42.180]DiFlexx DUO in this plot
[00:04:43.500]was applied early post-emergence when Palmer amaranth
[00:04:46.340]was less than six inches tall,
[00:04:48.590]and it has provided a decent level of control.
[00:04:51.520]And DiFlexx DUO is actually a good combination
[00:04:54.040]of a Dicamba with one more herbicide,
[00:04:57.430]so it can provide broad spectrum weed control.
[00:05:00.460]You are seeing a good level of control of Palmer amaranth
[00:05:03.610]as well as a foxtail grass species.
[00:05:18.309]And these are some good symptoms of DiFlexx DUO
[00:05:22.230]because it is a Dicamba-Based herbicide
[00:05:24.760]as well as you are also seeing some bleaching
[00:05:27.240]on the top of Palmer.
[00:05:30.810]Status is one more Dicamba-Based herbicides
[00:05:34.220]that can be applied in corn.
[00:05:37.770]It was applied early post-emergence when a Palmer amaranth
[00:05:41.440]was less than six inches tall,
[00:05:43.010]and it has provided a decent level of control --
[00:05:50.725](clears throat)
[00:05:51.558]This are some typical symptoms
[00:05:53.210]of Dicamba-Based herbicides on Palmer amaranth.
[00:05:57.080]They are twisting, and this mainstem is also twisting.
[00:06:00.520]The leaves are also twisting,
[00:06:02.290]and this plant will die maybe after about a couple of weeks
[00:06:05.800]because Dicamba is a systemic herbicide
[00:06:07.950]and it takes time for the susceptible broadleaf weed species
[00:06:12.650]to completely kill.
[00:06:16.390]Treatments I'm going to discuss now
[00:06:18.200]were applied only late post-emergence
[00:06:20.590]under worst case scenario,
[00:06:21.840]what will happen or what kind of control we can achieve,
[00:06:27.080]if we use only post-emergence herbicides very late
[00:06:30.650]in the season, so which is not very ideal,
[00:06:33.400]but under rescue conditions is there any herbicides
[00:06:37.370]that can provide effective control of Palmer amaranth,
[00:06:40.110]which is resistant to atrazine, glyphosate
[00:06:42.980]and ALS inhibiting herbicides?
[00:06:45.490]So now when all the herbicides were applied
[00:06:48.110]when Palmer amaranth was somewhere
[00:06:50.440]between eight to 12 inches tall.
[00:06:53.250]For example, Liberty, which is a good contact herbicide,
[00:06:56.430]it was applied at the maximum label rate
[00:07:00.070]of 43 ounces per acre,
[00:07:01.830]and it has provided a decent level of control.
[00:07:05.450]And just to clarify there was no any pre-emergence herbicide
[00:07:08.380]was applied in this plot.
[00:07:10.280]And because Liberty is a broad spectrum herbicide,
[00:07:12.960]it has also provided a good level of control of foxtail.
[00:07:17.540]For example, yellow in a giant foxtail
[00:07:21.630]that we do have in this plot.
[00:07:25.190]DiFlexx was applied the late post-emergence
[00:07:27.410]when Palmer amaranth
[00:07:28.450]were somewhere between eight to 12 inch tall,
[00:07:32.220]and it has provided good level of control
[00:07:34.410]of Palmer amaranth
[00:07:36.780]although it was applied relatively late in the season.
[00:07:41.960]The only thing because, DiFlexx
[00:07:43.690]is a Dicamba-Based herbicide.
[00:07:45.100]So we are seeing some grass weeds,
[00:07:47.610]and it can be controlled by applying glyphosate type
[00:07:51.990]of grass killing herbicides.
[00:07:54.730]But this is also one of the best herbicides to apply,
[00:07:58.680]if you want to consider any rescue herbicide,
[00:08:02.670]pour controlling Palmer amaranth late in the season.
[00:08:06.850]Armazon PRO was applied late post-emergence
[00:08:09.760]in this plot, when Palmer amaranth
[00:08:12.110]was somewhere between eight to 12 inch tall.
[00:08:14.760]And it has provided some level of control,
[00:08:17.190]but Palmer amaranth was too tall
[00:08:18.910]to be effectively controlled.
[00:08:20.750]You can still see some symptoms of this herbicide,
[00:08:24.680]for example, this is HPPD inhibiting herbicides.
[00:08:28.010]So this type of bleaching,
[00:08:29.310]you can see white color on Palmer amaranth.
[00:08:32.420]These are typical symptoms of a herbicide
[00:08:35.690]like Armezon PRO,
[00:08:36.920]which has Topramezone,
[00:08:39.240]an HPPD inhibiting herbicide.
[00:08:41.490]So not only on broadleaf weed species,
[00:08:43.540]but it can also provide a control of grass weeds,
[00:08:47.250]for example, here this foxtail species,
[00:08:50.680]it was too tall to be effectively controlled
[00:08:53.410]at the time of application,
[00:08:54.890]but are seeing some symptoms of this herbicide
[00:08:57.880]on this grass species.
[00:09:01.530]So the take home message from this project is number one,
[00:09:05.510]we can not achieve a very high level of control
[00:09:08.260]by using only early post or late post-emergence herbicides
[00:09:12.180]and the best thing we can do is under rescue condition,
[00:09:16.060]you can use certain herbicides such as Liberty
[00:09:19.830]or Dicamba-Based herbicides,
[00:09:21.480]such as DiFlexx or DiFlexx DUO,
[00:09:23.490]that can provide decent level of control
[00:09:25.640]of Palmer amaranth,
[00:09:27.630]which is resistant to atrazine, glyphosate,
[00:09:30.380]and ALS inhibiting herbicides.

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Amit Jhala – Early Post or Late Post Herbicides, 2020 Virtual Field Day for Management of Atrazine, Glyphosate, and ALS Inhibitors-resistant Palmer amaranth in Corn

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