Harvest Aid and Post-harvest Weed Control

Melissa Bartels Author

10/01/2020 Added

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How do you control weeds during and after harvest? Join Melissa and Dr. Jhala while they discuss harvest aid and tips for post-harvest weed control in your fields during this week’s podcast.

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[00:00:00.105](upbeat country music)
[00:00:02.900]Welcome to CropWatch Podcast,
[00:00:04.918]a production of Nebraska Extension.
[00:00:11.950]Welcome to the CropWatch Podcast.
[00:00:14.140]I am your host, Melissa Bartels,
[00:00:16.050]a Cropping Systems Educator in Nebraska Extension.
[00:00:19.150]And today I'll be joined by Dr. Ahmed Jaholla,
[00:00:22.710]and we will be talking about Harvest Aid
[00:00:24.800]and post-harvest weed control.
[00:00:26.500]Thank you for joining me today.
[00:00:28.098]How are you?
[00:00:28.931]Good to be here.
[00:00:29.764]I'm very well.
[00:00:30.597]How are you?
[00:00:31.430]Good.
[00:00:32.263]Can you tell us a little bit about your role in extension?
[00:00:35.200]so my role is,
[00:00:36.140]Nebraska extension weed management specialist.
[00:00:38.860]My office is in Lincoln.
[00:00:40.070]and I provide weed control,
[00:00:42.570]research and extension activities in corn,
[00:00:44.659]soybeans, sorghum, and popcorn.
[00:00:46.770]Those are four important crops in Eastern Nebraska.
[00:00:49.820]Thank you.
[00:00:50.653]So I've been hearing about Harvest Aid,
[00:00:53.070]and we're in harvest here in Nebraska.
[00:00:55.410]Can you tell us what is Harvest Aid?
[00:00:58.521]So Harvest Aid is a chemical,
[00:01:00.572]is like a herbicide which can be used to desiccate weeds
[00:01:04.490]as well as crop.
[00:01:05.880]For example ,in Nebraska,
[00:01:07.140]we grow some indeterminate soybean varieties.
[00:01:10.169]So sometimes when you go for harvest time,
[00:01:13.230]you will see some plants are green
[00:01:14.940]as well as weeds might be green at this time of the year.
[00:01:18.210]Particularly those weeds, they emerge late in the season.
[00:01:21.290]For example, waterhemp and Palmer Amaranth.
[00:01:23.830]So Harvest Aid herbicides can be used just to dry them out,
[00:01:28.420]to desiccate them.
[00:01:29.780]So harvest operation can be easily accomplished
[00:01:33.270]and there should not be any combined choke up
[00:01:35.980]and things like that.
[00:01:36.870]And second objective for Harvest Aid
[00:01:39.550]is just to make sure the crop is uniform
[00:01:42.149]and ready to harvest.
[00:01:43.940]So it makes harvesting much easier
[00:01:46.340]compared with when there are a lot of green weeds
[00:01:48.980]are interfering with a harvester person.
[00:01:51.700]Okay.
[00:01:52.533]Can this be used on both corn and soybeans?
[00:01:55.950]Yeah, right now there are some differences.
[00:01:59.430]There are some chemicals can be used in corn
[00:02:02.840]and there are some chemicals can be used in soybean.
[00:02:06.330]But generally in corn growers do not apply Harvest Aid
[00:02:10.740]because of the height of the corn.
[00:02:12.810]And it makes it very difficult to apply herbicide
[00:02:16.260]at this time or this growth stage of corn.
[00:02:19.390]You have to use drop nozzles and things like that.
[00:02:22.190]So harvest aid application in corn is very, very rare,
[00:02:26.660]unless some grower has some issues
[00:02:28.520]with like morning glories,
[00:02:29.830]are taking over on the corn stalk
[00:02:32.370]and if they want to kill them,
[00:02:34.540]then sometimes they use it.
[00:02:36.130]But otherwise Harvest Aid in Nebraska, in corn,
[00:02:39.700]I would say very rare.
[00:02:41.410]And even in soybean it's not very common,
[00:02:44.060]but some growers have started using it.
[00:02:46.530]And this year I received few phone calls
[00:02:48.740]about Harvest Aid herbicides
[00:02:51.221]which are labeled for use in soybean.
[00:02:53.530]So today's discussion we can focus more on soybean
[00:02:56.874]because more chances that Harvest Aid would be applied
[00:03:00.900]more commonly in soybean compared with corn.
[00:03:03.910]So if a grower has a soybean field
[00:03:06.310]and they're looking at using a Harvest Aid,
[00:03:08.320]what are some tips you would give them?
[00:03:11.020]So, first of all you have to select
[00:03:12.660]the right harvest aid herbicide.
[00:03:14.820]There are four herbicides are labeled to be used in soybean,
[00:03:19.130]as an harvest aid.
[00:03:20.568]Number one is Aim,
[00:03:22.380]which is a Carfentrazone-ethyl based herbicide.
[00:03:26.010]You can apply in range of one to 1.5 fluid ounces per acre.
[00:03:30.860]So it's a really low-rate herbicide.
[00:03:33.680]It can be used as a desiccant.
[00:03:35.380]And one important thing is you have to maintain
[00:03:38.210]certain pre-harvest interval.
[00:03:39.960]So for example, in case of Aim,
[00:03:42.350]you have to maintain three days of pre harvest interval.
[00:03:46.010]And there are some other chemicals as well,
[00:03:48.080]for example, Gramoxone, which is a Paraquat based herbicide.
[00:03:52.690]There's also a contact herbicide like Aim,
[00:03:56.010]but Paraquat can provide very quick activity
[00:03:59.419]as an harvest aid,
[00:04:00.840]because it's a contact herbicide
[00:04:02.380]and it goes in the plant very quickly.
[00:04:05.050]And you will see symptoms in just a few hours.
[00:04:08.470]So Paraquat is also commonly used as an harvest aid.
[00:04:12.260]Regarding Paraquat, one important thing is,
[00:04:14.740]there is a special training is required
[00:04:16.870]to apply Paraquat for the last couple of years.
[00:04:20.380]And when it comes to Gramoxone Paraquat,
[00:04:24.400]the pre-harvest interval is 15 days.
[00:04:26.980]If you compare with some other chemicals like Aim,
[00:04:30.550]you have to maintain three days of pre-harvest interval.
[00:04:33.510]And the third chemical is Sharpen
[00:04:35.910]which is Saflufenacil based herbicide,
[00:04:38.340]which can be used as an harvest aid
[00:04:40.300]mostly for broadleaf weeds and broadleaf crops.
[00:04:43.950]So there are three or four chemicals are labeled.
[00:04:47.070]The last one is Glyphosate
[00:04:48.650]can also be used as an harvest aid,
[00:04:50.800]but majority of soybean in Nebraska they are roundup ready,
[00:04:55.300]means they are glyphosate resistant.
[00:04:57.070]So Glyphosate will not have much activity
[00:05:00.100]on Glyphosate resistance soybeans.
[00:05:02.285]So if some growers also want to desiccate soybean,
[00:05:06.150]then they have to use some other chemicals
[00:05:08.490]like either Aim or Gramoxone or Sharpen.
[00:05:11.770]Okay. It sounds like this is something
[00:05:13.910]that if you wanna use it
[00:05:14.997]you really have to have a plan.
[00:05:17.427]Yes
[00:05:18.260]Because if you have those longer intervals
[00:05:19.840]it's not something that you can go out on a field.
[00:05:21.760]Okay, I'm gonna spray it,
[00:05:22.970]but I also wanna harvest in two days
[00:05:25.570]because it's gonna rain this weekend.
[00:05:27.360]Yes. And so, yeah.
[00:05:28.410]Pre-harvest interval is very important to maintain
[00:05:31.920]especially with Gramoxone.
[00:05:33.500]It requires 15 days of pre-harvest interval
[00:05:36.340]compared with Aim and Sharpen,
[00:05:38.050]that requires three days of pre harvest interval.
[00:05:41.000]And majority of them, I was reading the label
[00:05:43.210]and once you apply them
[00:05:44.451]you cannot use that for animal feed or forage.
[00:05:48.960]So that is something kind of a limitation.
[00:05:51.729]Some growers are planning to use the stalk
[00:05:54.690]for animal grazing
[00:05:55.790]or something that is the limitation of using Harvest Aid.
[00:05:59.610]Okay. So this gets back it's really important
[00:06:02.360]to check those labels.
[00:06:03.940]Yeah. Some of them there may update labels
[00:06:07.050]so it is always good to follow the latest label.
[00:06:10.056]Great.
[00:06:11.020]Let's talk a little bit about post-harvest weed control.
[00:06:15.010]Harvest has started here in Nebraska,
[00:06:17.290]and we know that we have some soybeans coming out.
[00:06:20.470]There's also some corn fields that are coming out already,
[00:06:23.520]but we still have some nice weather
[00:06:26.250]that would allow some of our pesky weeds
[00:06:28.560]to take hold in our fields from now till winter.
[00:06:31.670]What are your recommendations for post-harvest weed control
[00:06:35.020]to set us up for success next spring?
[00:06:38.210]So, first of all, growers should take notes
[00:06:40.640]when they go for harvesting their corn and soybean
[00:06:43.680]that can help them to see which weeds
[00:06:47.260]were present at the time of harvest and that can help them
[00:06:50.690]to develop their herbicide program next year.
[00:06:53.210]And even after post-harvest,
[00:06:55.325]they can scout the field
[00:06:57.480]and if they see more winter annual weeds,
[00:07:00.190]for example, maresteil, henbit,
[00:07:01.590]field pennycress,
[00:07:03.470]tansy mustard,
[00:07:04.760]and some grass-weed species such as,
[00:07:06.940]cheatgrass or brome grass.
[00:07:08.670]Those are two very commonly found grass-weed species
[00:07:12.490]in corn and soybean fields in Nebraska.
[00:07:14.800]So they have to scout the fields
[00:07:16.780]and if they see the infestation of weeds is much more then
[00:07:20.900]they may to consider applying some herbicides in the fall.
[00:07:26.040]Okay. We've talked a little bit about Palmer.
[00:07:28.860]Is there anything we can do,
[00:07:29.980]if we have a field that had a lot of Palmer this year?
[00:07:32.840]Is there any control measures that can be taken this fall?
[00:07:36.020]Or is that something we, to really target next spring?
[00:07:39.930]Right. Palmer is summer annual weed
[00:07:42.490]and so Palmer Amaranth do not emerge until May next year.
[00:07:47.310]So if we do something in the fall like applying herbicides
[00:07:51.690]that generally do not help much
[00:07:54.150]because it's typical summer annual broadleaf weed,
[00:07:57.130]and you have to rely mostly on pre-emergence herbicides
[00:08:01.680]applied at planting
[00:08:03.670]corn or soybean,
[00:08:04.680]and that's would be the best strategy
[00:08:07.550]for managing waterhemp or Palmer Amaranth type of weeds.
[00:08:11.028]And if you have some other weeds like winter annual weeds
[00:08:15.070]such as Maresteil,
[00:08:16.640]which is a very widespread,
[00:08:19.140]another issue of Maresteil is,
[00:08:20.920]majority of Maresteil populations in Nebraska
[00:08:24.080]that have evolved resistance to Glyphosate
[00:08:26.500]as well as some ALS-inhibiting herbicide.
[00:08:29.320]So those herbicides would not work to kill Maresteil.
[00:08:33.452]Especially Maresteil can emerge in the fall.
[00:08:36.885]So once you harvest your corn and soybean,
[00:08:39.110]and if you go to the field sometime in October,
[00:08:42.311]you will see some small Maresteil will start emerging.
[00:08:46.610]And when they are small,
[00:08:48.600]it is better to apply some herbicides.
[00:08:51.391]Typically 2,4-D Dicamba based herbicides
[00:08:53.940]have provided very good control of Maresteil population.
[00:08:58.010]Although they are resistant to Glyphosate and ALS chemistry
[00:09:01.093]because those 2,4-D Dicamba are Phenoxy group herbicides
[00:09:05.380]and can still be very effective
[00:09:07.460]on controlling Glyphosate resistant Maresteil.
[00:09:10.260]If you have a lot of Maresteil ,
[00:09:11.870]I definitely recommend to apply those types of herbicides
[00:09:15.830]in the fall when Maresteil is less than two inch tall,
[00:09:19.735]compared to when they will grow
[00:09:22.940]and they can, over winter actually,
[00:09:25.760]in a (indistinct) stage.
[00:09:27.100]And once weather is good,
[00:09:29.270]early spring they will start growing up.
[00:09:31.200]And so by the time you go for planting your corn or soybean,
[00:09:34.440]those Maresteil will be really too tall
[00:09:36.310]and it will be less effective to control
[00:09:39.690]by using post-emergence herbicides.
[00:09:41.653]Okay. So it sounds like
[00:09:43.680]it is really important to check on those fields
[00:09:47.020]and know what you have in your field.
[00:09:49.690]So you can make a plan
[00:09:51.350]on how to control those throughout the season,
[00:09:53.900]even when we're not in the active growing season.
[00:09:56.870]Especially if they can over winter,
[00:09:58.600]you might already be behind the game
[00:10:00.820]if we wait until the spring
[00:10:02.060]and you roll up on your field and realize,
[00:10:04.650]you have something growing
[00:10:05.700]but it's not a crop that you want.
[00:10:07.500]Right. And another weed to watch is Henbit.
[00:10:10.870]Especially if you have a lot of infestation of Henbit,
[00:10:15.000]then you can consider applying herbicide in the fall
[00:10:18.640]or maybe in early spring.
[00:10:20.640]Because Henbit is a weed where Soybean Cyst Nematode
[00:10:24.856]can survive on Henbit.
[00:10:27.510]And then next year when you go for planting your soybean,
[00:10:30.870]they can,
[00:10:31.703]henbit can become a host for Soybean Cyst Nematode,
[00:10:34.980]and then it can transmit to soybean.
[00:10:39.300]So if an infestation of henbit is too much,
[00:10:42.660]then I would consider to spray those fields.
[00:10:45.641]Just to avoid that Green Beech.
[00:10:48.190]Right. And that's important to know,
[00:10:50.860]Soybean Cyst Nematode can be in pockets
[00:10:53.970]and that henbit might allow it,
[00:10:56.070]to spread from yes.
[00:10:57.200]those isolated pockets.
[00:10:59.260]Henbit seems to grow very well here in Nebraska.
[00:11:02.080]Yes
[00:11:02.913]It could easily take over
[00:11:04.410]and spread throughout your field.
[00:11:06.400]Is there anything else you want our producers to know
[00:11:09.460]you know, during harvest time
[00:11:10.930]or weed control things to look for?
[00:11:13.760]And every year I get questioned
[00:11:15.550]about including residual herbicide
[00:11:18.250]with polyreactive herbicide in the fall can help or no?
[00:11:23.000]And we generally, typically
[00:11:25.720]do not recommend to use residue herbicide in the fall.
[00:11:29.220]But if you have a lot of infestation of Maresteil,
[00:11:32.374]and if you have a history of Maresteil
[00:11:34.190]growing in the same field every year,
[00:11:36.795]and if it is resistant to Glyphosate and ALS chemistry
[00:11:41.590]then it is advisable to add some residual herbicides.
[00:11:46.270]There are a number of residual herbicides
[00:11:48.260]can also be applied in the fall.
[00:11:50.640]For example, those Authority Brand Herbicides,
[00:11:53.700]Whaler Brand Herbicides can also be considered
[00:11:57.370]and it can provide some more residual activity
[00:12:00.150]along with polyreactivity from 2,4-D Dicamba,
[00:12:03.850]and then it can prevent the further germination.
[00:12:07.750]And if with some reason,
[00:12:09.420]if growers are not able to control those Maresteil or Henbit
[00:12:13.340]in the fall,
[00:12:14.330]then they can still consider
[00:12:15.830]applying appropriate herbicide early spring.
[00:12:19.166]When I say early spring,
[00:12:20.630]it has to be sometime in March
[00:12:22.870]when weather is favorable to apply herbicide
[00:12:25.300]because if you will be too late,
[00:12:26.800]then,
[00:12:27.730]particularly Maresteil can grow very tall.
[00:12:31.650]And then it can interfere with emerging corn and soybean.
[00:12:36.350]And we have very limited herbicides
[00:12:38.440]labeled in crop
[00:12:40.330]for controlling those Glyphosates Maresteil
[00:12:43.950]with post emergence herbicides.
[00:12:45.710]So yeah, using those herbicides
[00:12:48.240]at right time is very, very important,
[00:12:50.600]particularly for Maresteil
[00:12:52.720]Okay.
[00:12:53.553]So it sounds like weeds are becoming a challenge and an art.
[00:12:57.840]You have to have a plan
[00:12:59.620]and make sure you
[00:13:02.730]do that plan
[00:13:03.600]as needed to make sure you meet all the criteria
[00:13:06.410]on those labels
[00:13:07.410]and our resistance Yes.
[00:13:08.590]Weeds we're Absolutely.
[00:13:10.050]dealing with.
[00:13:11.230]And particularly in soybean,
[00:13:12.720]a survey we conducted last year says,
[00:13:15.390]weight management is number one challenge
[00:13:17.820]for soybean producers.
[00:13:19.420]So yeah, paying some more attention on scouting fields
[00:13:23.030]and what you have in the field,
[00:13:24.187]and then deciding your herbicide program
[00:13:27.430]based on which weed can grow at what time,
[00:13:31.090]because as we discussed,
[00:13:32.240]if you will try to apply some herbicide
[00:13:34.870]for controlling Palmer Amaranth in the fall,
[00:13:37.150]that is not going to help.
[00:13:38.750]And if you have Maresteil, then yes.
[00:13:41.110]If you have waterhemp or Palmer Amaranth
[00:13:43.880]are your major weeds,
[00:13:44.940]then you don't need to apply herbicides in the fall.
[00:13:47.780]And one more thing is using cover crops.
[00:13:50.290]Particularly cereal rye,
[00:13:51.800]can provide very good suppression of Maresteil.
[00:13:54.890]Because Maresteil typically starts emerging in the fall
[00:13:57.870]in Nebraska.
[00:13:58.930]Some of them they can also emerge early spring
[00:14:01.250]but if you already have a good stand up cereal rye
[00:14:03.990]it can provide very good suppression of Maresteil.
[00:14:07.810]Particularly.
[00:14:09.290]Nowadays planting green is also becoming a good concept
[00:14:13.120]by some growers,
[00:14:14.480]especially when they want to see some good suppression
[00:14:17.970]of your cereal rye cover crop
[00:14:20.750]in crop.
[00:14:21.583]Then they just plant corn and soybean
[00:14:24.330]when cereal rye is still green.
[00:14:26.360]And then they terminate after a couple of weeks
[00:14:28.690]of planting corn and soybean next year.
[00:14:31.050]So the idea is,
[00:14:31.990]it can provide good suppression of early emerging waterhemp
[00:14:35.440]and Palmer Amaranth.
[00:14:36.760]And in that case yeah, you can consider planting cereal rye
[00:14:41.140]in the fall after corn and soybean harvest,
[00:14:43.547]and then let them to grow.
[00:14:45.580]And if you have a good stand,
[00:14:47.410]it can suppress early emergence of waterhemp
[00:14:50.122]and Palmer Amaranth type of summer annual weeds as well.
[00:14:53.160]Mhm.
[00:14:53.993]And using something like that
[00:14:55.570]probably helps us too,
[00:14:57.110]to make sure we're not pushing those weeds into resistance
[00:15:00.370]faster to some of these modes of actions.
[00:15:03.813]Yes. And that's what we recommend
[00:15:05.830]to have Integrated Weed Management program ,
[00:15:09.230]that do not only include herbicides
[00:15:11.530]but also some of this type of cultural techniques,
[00:15:14.220]like using cereal rye cover crop,
[00:15:16.990]has some good benefit overall to suppress weeds,
[00:15:20.589]depending on situation.
[00:15:22.610]As well as using some other cultural practices
[00:15:26.360]like a narrow row spacing can also provide some benefit.
[00:15:30.210]Some of the studies we did,
[00:15:31.750]where we compared 15 inch row spacing in soybean
[00:15:35.048]versus 30 inch row spacing.
[00:15:37.140]And in both the situations
[00:15:39.070]you still have to consider using pre-emergence herbicides
[00:15:42.260]at planting was still the key factor.
[00:15:44.871]Even if you have narrow row soybean row spacing.
[00:15:47.770]Integration of all these techniques can provide
[00:15:51.350]good weed management practice.
[00:15:53.740]Great. Do you have any programs
[00:15:56.190]or articles coming out
[00:15:57.690]that are related to this topic,
[00:15:59.480]that you'd like our listeners to know about?
[00:16:02.960]Yeah. And probably after a couple of weeks
[00:16:05.150]there will be an article
[00:16:06.290]about Palmer Amaranth seeds in manure.
[00:16:09.630]And what can we do about this?
[00:16:11.620]Because several growers they apply manure in their field
[00:16:14.860]and that manure contains Palmer Amaranth seeds.
[00:16:18.100]And that is how the seeds are getting disseminated
[00:16:21.470]from one field to another field.
[00:16:22.793]And whenever you apply those manure.
[00:16:25.970]So that will be a good article,
[00:16:27.650]we are writing right now ,to watch for.
[00:16:30.410]It should be on CropWatch in couple of weeks.
[00:16:33.300]Okay great. Well thank you for joining me today
[00:16:36.200]and I hope everyone has a safe harvest.
[00:16:39.220]Thank you.
[00:16:40.053](upbeat music)

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Harvest Aid and Post-harvest Weed Control

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