Katelyn Kesheimer – Insects of Industrial Hemp: Year One

Katelyn Kesheimer – Insects of Industrial Hemp: Year One


– [Katelyn] Hi everyone, my
name’s Katelyn Kesheimer, and I’m an Extension entomologist
with Auburn University and Alabama Cooperative Extension Service. Today I’ll be giving a brief overview of insects that attack industrial hemp. Many of you are aware that
this is the first year that industrial hemp can
legally be grown in Alabama thanks to the 2018 farm bill that classifies it as an
ordinary agricultural commodity. And a few states outside Alabama have been growing hemp since 2015 or so with the passage of the 2014 farm bill. But prior to that, hemp
has not really been grown in any major capacity since World War II. However, lots has changed
in the past 70 years, and now that we’re back to
growing industrial hemp again, there is much to be learned. So today I’m gonna give a
quick background on hemp, and so far what we learned this first year about pest management in Alabama. So when I talk about industrial hemp, I’m talking about the
plant Cannabis sativa. The genus Cannabis
includes multiple species that produce these unique
compounds that are not found in any other plants
that we know of so far. And cannabis can be broadly separated into two distinct groups, and these include marijuana
and industrial hemp. Now, we all know that marijuana is illegal to grow in Alabama, but while these two groups,
marijuana and industrial hemp are used for two very different purposes, they are impossible to distinguish
from each other visually, and they will interbreed out in the wild. So talking about marijuana that is bred and grown
for its THC content, which is a psychoactive compound. These plants are almost exclusively grown indoors in greenhouses and cultivated for that THC content. On the other hand, we
have industrial hemp, and the major difference
here is the low THC content, is less than .3% THC. And industrial hemp can be grown indoors similar to marijuana, but
it’s also grown outdoors like when you think of a typical row crop shown in this picture here. And it’s bred and grown
for a variety of end uses including fiber, seed and cannabidiol which is used as medicinal
compounds, also known as CBD. So I mentioned there’s a
lot of different end uses, it’s a very versatile plant, and it can be grown for
seed and fiber production, seed can be used for human consumption, and it’s similar to growing
small grains in the field. Hemp grown for fiber can be
used for a variety of things such as clothing, paper,
rope, or building materials. And that’s one of the
reasons it was so popular about 100 years ago. And then hemp grown for fiber and seed are usually grown from seed in the field and have a much higher plant density in the field than those grown for CBD. And so plants grown for CBD is really the majority of the plants grown in Alabama right now. These are much lower density
plantings in the field, and are typically started as transplants, shown here in the greenhouse, and then moved into the field. And these are primary female plants which are the desirable plants as opposed to the male
plants that are also created. And there’s also a lot of variation just in the way that hemp is grown, it’s a very new crop, there’s no real kind of standard protocol for growing it as we’re still kind of
figuring things out. It’s grown outdoors in
the field, on plastic, pots, high tunnels, greenhouses, so there’s lots of variation with it. And with that variation
of growing methods, indoors and outdoors,
comes a lot of pests. These weeds and diseases and insects aren’t really gonna wait
for us to figure out the agronomics of the
crops before they show up, so here we are, and we have to kind of figure it out as we go along. For the next few minutes, I’m gonna focus primarily on insects, but I do just wanna mention
that as you’re growing, it’s really important to have a solid integrated pest
management program, that should be in place
for any type of pest. Especially with hemp because
we know very little about it and you’re gonna get inundated with weeds and diseases and insects. Any of these can hinder the
production of your crop. A lot of the questions this year have focused on pesticide usage and what can we spray to kill the weeds to stop this disease from
spreading, to kill this insect, but there are several other
things that are part of a good IPM strategy that you can do before you wanna even think about spraying that will really help your crop. And so when it comes to pest management, there’s all these different strategies. People usually think about
pesticides or chemical control as their first line of defense, but really, as shown
in this triangle here, it should be your last resort, it should be the last thing you consider. Because there’s a variety of strategies, and if you employ all these strategies and create a healthy crop,
if you have a healthy plant, it is more resistant to
these pests and diseases, it’s able to fight off
more of these problems and can maybe sustain some damage that isn’t going to be economical. And so starting with
cultural and sanitation, cultural control and sanitation, keeping your plants healthy, starting with good, clean seed, starting with a good
clean soil, clean field, making that environment
less hospitable for pests, making sure you’re not going into a field that’s already filled with
weeds or filled with pests that have overwintered and have
just a leg up on your crop. Another often overlooked
method is mechanical control. Just getting out there,
scouting for your pests and hand removing those insects,
creating physical barriers. Sticky traps are really good if you’re growing indoors
in the greenhouse. And then thinking about what are our free options for biological control? What are our natural enemies
that are gonna be out there that can help reduce some
of the pest populations? And so I mentioned pesticides
should be your last resort. If you end up spraying your hemp, it should be used as a
sensible control option. And most importantly, in
accordance with label directions. The label is the law, and so you have to make
sure to follow that label. And so I realized as
we’re in this first year, there’s a lot of confusion, a lot of misinformation
about what we can use in terms of chemicals on hemp. And so just a few things to think about before you put any chemical on your hemp. The number one thing to know is all pesticides used on
hemp have to be registered with the Alabama Department
of Agriculture and Industries. It’s the responsibility of the producer to make sure that the
pesticide can be used legally. And so this goes back to reading the label because that label is the law. And additionally, we have these rules that are put in place
by the state of Alabama, but then if you’re gonna take your hemp to a processor or a buyer, they may have a separate
set of regulations. And so I implore you before
applying any chemical to give your processor
or your buyer a call to make sure that they will still accept the product after the
chemical has been applied. Having this information
beforehand is crucial to ensure that you will pass, because a lot of these
processors have lists of chemicals that they
will and will not accept. They’ll also do residue tests for a lot of different substances and give the product a pass or fail, and so you wanna make sure
that if you put all this time and money into growing the
crop, that it’s going to pass. And finally, be very cautious of any lists that are not released by
the Alabama Department of Ag or Alabama Cooperative Extension. These have not been approved by the Department of Ag
in the state of Alabama. There’s some other lists going around that are approved by other states. And if you apply a product
that is on another state’s list but is not registered with the
Department of Ag in Alabama, it will result in your
crop being destroyed. If you have any questions
or are confused about this, feel free to give me a call, my contact information
will be at the end of this, or call the Alabama Department of Ag to verify the acceptability
of this chemical. Okay, now I’m just
gonna briefly go through what we have seen as some of
the major economical pests so far that are likely going to be major problems moving
forward with industrial hemp. This is not a comprehensive
list and it will likely change. I mentioned this is the first year, and so things may be very
different a year from now, but I imagine that these will
continue to be a problem. And so the first one is fire ants. These have been a major pest of hemp across the entire state of Alabama. Whether it’s grown in
open field conditions, in plastic, in pots, in
high tunnels, et cetera. What they’ll do is they’ll build mounds near the base of the plant underneath the pots,
underneath the plastic, and then they’ll tunnel into the stem as you can see in some
of the pictures here. Chewing and killing the seedlings, especially really young
plants are very vulnerable, and then after they kill a plant, they will quickly move to nearby plants. And then in many cases, it’s been so dry that you don’t see those stereotypical fire ant mounds that
you’re used to seeing, ’cause the ants get so
deep into the ground because it’s so hot. And so the picture on the bottom left here shows the yellowing and wilting
of a plant from ant damage, and you can see some of the tunneling and stripping of the bark that they’ve been doing
in fields this year. So recently we put out a pest alert about some of the products
that were approved through the Department of
Ag for fire ant control. These are all contact insecticides, which means they have to
find the fire ant mound and apply the chemical on
the mound to kill the ants. There is one bait in there, and that’s Extinguish Professional. And the bait means you put out the food, the ants go get it, and they
bring it back to the nest and feed it to all the
workers and the queen. The bait will obviously
be the most effective for long term control. But before applying, again,
check with your processor before to make sure that
they allow it even though this one has been approved
by the Department of Ag. And just one thing, when
using these products, especially the oils and the pyrethrins, these are all natural products and they’ll break down with UV exposure. And so you want to make sure you’re not applying them in full sun. Also, fire ants, they don’t wanna be out in the heat of the day,
they’re not gonna be foraging, they’re not gonna be at
the top of their mounds, they’re gonna be deep down in the deep part of the ground when it’s really hot in their tunnels. And so the best time to
apply these mound treatments is first thing in the morning
before it gets too hot or late in the day when it cools off. The other thing to think about is, these do need a lot of water to get into their
extensive tunneling system, so don’t cut back on water when you’re applying
some of these products. Our fire ant pest alert can be found at the URL at the bottom of this slide. The next major pest
that’s gonna be causing economic damage both indoors and outdoors are the hemp russet mites. These are a special type of
mites that’s very, very small. And what we know so far, these are a specialist on cannabis plants, and so they’re only gonna be
found on hemp or marijuana. When you’re getting plants
or scouting for them, I would highly recommend
investing in a hand lens or a magnifying glass if you have one, because you won’t see these mites without magnification
because they are so tiny on the plant unless
you’re looking for them, but you will see their
characteristic damage. So these pictures show characteristic hemp russet mite damage
with this upward curling of the leaves, yellowing, brittle leaves that can break off. And you can tell these are
different from spider mites if you’re familiar with
spider mite damage, because hemp mites do not produce the characteristic webbing
that spider mites do. However, they are similar to other mites in that
they are very prolific and they can explode in
populations if left unchecked. So you can see in this picture, it’s really bad mite damage, there’s thousands if not millions
of mites on these plants, and the bud’s already
starting to turn brown. So hemp mites can also
infest the flower tops and feed on the pistils, which will render the
female flower sterile. In the picture on the left, you can see the pistil is
healthy and white or green and hasn’t been damaged by mites. To contrast, the pistil on the right is turning brown from a
severe mite infestation. Unfortunately, we don’t
have a lot of information on the life history of hemp mites. Since they’re a specialist
on cannabis like I mentioned, there just hasn’t been a lot
of research done on them. For plants grown outdoors, they may overwinter on infested seeds. For indoor plants, they can
remain on plants year round. Anyone who’s grown plants
in a greenhouse or inside knows just how difficult it is and how much a pain in the butt mites are. And as the mite population increases and starts to kill the plant, they will crawl to the top of the plant to be dispersed naturally
by wind or water. And this is why early control and sanitation are so important. If you are receiving
transplants from a greenhouse, this is where you need
to get out your hand lens and inspect your plants very carefully. This is likely one of the main sources of hemp mites as they’re moving
around through the state. In terms of control, we don’t know a lot about biological control agents yet. That isn’t to say some
generalist predators won’t work, we just don’t know what they are yet. We have some data on what won’t work, but this is a very specific,
unique type of mite, and it behaves differently
than other mites that we have more experience with. And so it’s gonna take a
lot of time and research just to figure out what are the best
biological control agents. And there is some information about using oils like horticultural oils, and they are effective
against some russet mites like tomato russet mites, but they may or may not be effective against the hemp russet mites. Again, we just don’t have this research, and so the best option is to
scout your plants regularly and inspect anything coming from an indoor growing situation, because that’s really where you can have year-round mite infestations. Okay, and finally, there’s a whole host of caterpillars that are known to infest hemp and that we’ve already started to see around the state of Alabama. Historically, European corn
borer was the most destructive, but that really hasn’t materialized yet. But that’s not to say it isn’t a problem or won’t be in the future. There are defoliating caterpillars that we don’t think is gonna
cause a lot of problems, a lot of economical damage
as they chew the leaves. There’s also a hemp borer that hasn’t shown up yet in Alabama. It may be here, I just
haven’t found it personally. One of the main problems
we’re dealing with right now at the end of the season, it’s mid-September right
now, are the bud feeders. And these are feeding on the buds of the more mature hemp plants, both causing economic yield loss and then opening that bud up to infection which can cause bud rot, which will also lead to more yield loss. One of the other more abundant
caterpillars we’ve seen is the yellow-striped armyworm. Corn earworm is also really common. In a lot of instances,
proximity to other crops has determined both the abundance and severity of damage
by some of these pests, and so kind of look at your landscape and see what’s around you, is
there a lot of corn nearby, and use that to gauge
what the threat might be in terms of the caterpillar pests. But the point of this
slide is just to show that there’s a lot of different
species of caterpillars that may feed on hemp at
any given growth stage, and so it’s vulnerable to attack, and we’re still trying to figure out what is gonna be the most damaging, but right now it looks
like these bud feeders are having the biggest impact in terms of economic yield loss. So what can you do? The best thing really is just to be out there scouting your crops to control the caterpillars early. You’ll likely see the feeding damage or frass, which is insect poop, before you see the worms
because they’re really small, they can be cryptic, they
might hide under the leaves in the heat of the day. And sometimes even giving the lack of chemical control options
that we have right now, hand removal may be your best option. But keep in mind that as we get into these later growth stages of these caterpillars, they become increasingly difficult to kill. Bigger caterpillars do more damage, they feed more, and
they’re harder to kill, even if we had all the
chemical options available, a lot of them don’t even
touch these late instar fourth, fifth instar caterpillars. And so the best thing you can do is find them when they’re really young, when they’re only 1/4
inch or smaller at most. And so you really need to be
out there inspecting your crop to make sure that you don’t
have these caterpillars. And so I mentioned it a minute ago, but one of the biggest
problems we’re seeing right now is with corn earworm. They’re still around, the corn
either has been harvested, or even some of the late planted corn is past that silking stage, and so the corn eraworm moths do not want to lay eggs
in the more mature corn, and so the most attractive
crop to them right now is all the hemp that’s around. The hemp has these beautiful flowers and it’s just really attractive
for these moths to lay eggs, for them to hatch and have these nice buds for them to feed on. And once that bud gets a wound
from caterpillar feeding, it now becomes vulnerable
to infection from pathogens, and so this is where we’re
seeing a lot of bud rot in the last couple weeks
with this more mature hemp. So looking ahead, we are seeing some pests that are
causing economic damage, fire ants, mites, caterpillars,
namely yellow-stripe armyworm and corn earworm. But there’s a lot of information gaps. We don’t know what the
relationship between these insects and yield loss is quite yet, and as a result, we haven’t
developed economic thresholds. Just because we have
some insects on the plant doesn’t necessarily mean it’s a problem, it doesn’t mean it’s gonna
lead to economic yield loss. But hopefully some of these questions we can answer moving forward. We expect very much so in 2020, and in coming years
there will be an increase in the acreage of hemp grown
in Alabama and other states, and this will likely lead to an increase in the number and diversity of insects, weeds, and diseases that
can move into the crop. And so it’s important
just to stay vigilant. In 2019, we had approximately 10,000 acres approved for
growing hemp in Alabama, and I imagine that will
go much higher in 2020. And so just stay on top of your scouting and proper identification of
any pest we see in the field. And I understand that we have a lot of legal uncertainties
regarding pesticide usage between the state and federal government, the USDA is hopefully getting ready to release some rules in the coming weeks, and so hopefully that’ll add some clarity to this issue with pesticide usage. But if you have any questions or are confused about what product to use, if you can use it, please
get in touch with me. Please get in touch with someone from the Alabama Cooperative
Extension Hemp Action Team. We are happy to answer your questions. We’d much rather answer your questions than you apply something you can’t then have to deal with
your crop being destroyed. But right now we just have more questions than we do answers, and so as
a researcher, this is great, but there’s just a lot of information gaps that we need to fill moving forward. I hope this was helpful,
here’s my contact information. Please don’t hesitate
to get in touch with me. And hopefully we can get your questions on industrial hemp answered
moving forward, thanks.

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