Pollen Spread and CBD


Good Morning. My name is Leah Sandler with the Michael Fields
Agricultural Institute and I am here today to talk a little bit about male and female
plants, as well as pollen drift in CBD hemp production. We know that CBD hemp comes from the Genius
Cannabis species Sativa and that it is an annual plant. If it has 0.3% THC content or above it is
considered Marijuana and is used for medicinal or recreational purposes. But if it has 0.3% THC content or below it
is considered industrial hemp. It is grown for a wide variety of uses but
the three dominant ones being Seed, Fiber, and CBD which is what we are going to talk
more about today. So where does CBD come from? CBDA, which is the precursor for CBD and what
the plant secretes during the extraction process, when CBDA is heated it is turned to CBD. CBDA is produced by the trichomes on female
flowers, the surface of the female flowers. You can see on this left hand picture, the
female flower with lots of little white specs along the leaves and those are the trichomes. On the right we have the magnified version
and you can see these little glandular hairs, so these little hairs with this bolus, jelly
like pits – and that’s what’s making the majority of the chemicals that hemp is known for. So, we are talking about CBD but as well as
terpenes, flavonoids – most of these are produced from these glandular hairs called trichomes
on female plant. Important for this discussion, Cannabis is
also Dioecious. This means that male and female flowers are
on separate plants. So there are male plants and there are female
plants. Additionally, it is wind pollinated. So, male plants that contain male flowers
produce the pollen and this pollen is distributed via the wind to the female flowers that then
take the pollen, pollenate the flowers and go towards seed production. In CBD hemp production, we are trying not
to pollinate the female plants and I will explain more about this later. But, this is important because in terms of
differentiating the plants and the flowers. So Cannabis has pre-flowers which means that
their nodes, which is where the weed branches stem off of, come off of the main stem – there
will be little flowers that indicate whether it will be a male plant or a female plant. On the left hand side we have the male pre-flower
and it looks like a little bulb that will become the pollen sac and then on the right
hand side we have the female flower. You can see it will have this kind of bulb but it will have this pistil that is starting to come out, which will be
charactistic in the full plant as well. Excuse me, the full flowers. By the sixth week or so you should be able
to start seeing these pre-flowers and that can help determine which sex of the plant. And so one is able to remove the male plants,
thus removing the pollen. Here we have some pictures. On the left hand side we have the female pre-flower
and as I mentioned before you can see this little pistil structure coming out of the
bulb. And then on the right hand side we have the
male pre-flower and you have these little bulbs that are basically what the pollen sacs
will look like as they grow. That kind of translates to the full flowers,
which we see here. On the left hand side again we have the whole
female flower with all of these white little stems, being the pistils. And on the right hand side we have the male
flower and you can see all of these pollen bulb sacs. Some of these are open, so on the top here
we can see, on the top right hand picture, the sacs are starting to open and those anthers
are hanging down and that is what will release the pollen. Cannabis is an interesting plant in that it
is predominately dioecious, but there are also monecious varieties or partially monacious
plants. So what that means is that there are male
and female flowering parts on one plant. So here, what you can see is that kind of
on the left in the back there, we have a female flower. You can see those pistil structures again. But then in the forefront, on the right hand
top part of the picture we can see these male flowers and these pollen sacs. In so, when we producing for CBD hemp we want
to remove all of the monecious plants as well because again, they contain pollen. So why do we want to reduce the males and
thus the pollen? The main reason is that pollination of female
flowers reduces CBD content. What I have here is a graph to show this. So, on the left hand side on the Y axis we
have total CBD content. In so, the three different bars, blue, orange,
and grey are just talking about where the flowers are in relation to the stalk so that
is not so much important. What is important to notice is that on the
left hand side the pollinated flowers have significantly less CBD than on the right hand
side, those have not been pollinated. Basically showing that with pollination, CBD
content of that female flower goes down and thus when we are producing hemp for CBD we
want to make sure that pollination is not occurring and thus reducing the CBD content. Additionally to the fact that pollination
reduces CBD, CBD hemp or industrial hemp in general creates a lot of pollen. It is very prolific. So, some experts say
that within 10 miles of CBD hemp you don’t want any grain or fiber production, particularly
grain production because for grain hemp you actually want pollination to occur so that
a seed is produced. However, in Europe and Canada they reduced
that distance to 5 kilometers, which is just over 3 miles required for the highest class
of hemp seed. In so, this is a graph to show you why and
what that looks like. Up here, this graph basically shows research
that is done that shows how pollen moves over time, or over distance. You can see it is called a leptokurtic curve,
which means that as we move away from the center of the field where that hemp is, at
first it rapidly reduces. Early distance we see a great reduction in
pollen. Within that first couple of meters, we see
50% of the pollen. However, that drop off starts to slow. So there is still pollen quite far out from
that plant, initial plant. What the research has kind of determined is
that pollen was reduced greatly at first but as we moved farther away there was still pollen
in the air. In particular, that wind movement really impacted
it. Basically, pollen was distributed downwind
six times more than it was distributed upwind – which makes sense. But, that isolation distance of 5 kilometers
on the downwind side was equivalent to an isolation of less than 1 kilometer on the upwind side. If we are looking at wind movement patterns,
that isolation area of 5 kilometers could actually be greatly reduced. So you would not need to be isolated 5 kilometers
on all sides in hemp production that was for grain. So that is an interesting thing to take of
note. However, we still in our own fields we still want to
manage males. If we are not able to control growers around
us we can definitely control our own fields. There is non-feminized seed and there is feminized
seed. Non-feminized see is about a 50/50 mix of
male and female plants. But feminized seed is trying to get 100% female
plants. So basically, you don’t have to worry about
male plants being in that mixture. However, I would like to reiterate strongly
here that is not a guarantee, if you buy feminized seed it is not a guarantee that there will
be no male plants in it. The difference is that in terms of seed is
located mainly in seed cost. Feminized seed is significantly more expensive
than non-feminized seed, however the idea that you need less of it because if you are
buying non-feminized seed you have to immediately get rid of 50% of those plants. Whereas feminized seed hopefully you are not
having to remove any or if you are it is only a few. Regardless of whether you use feminized or
non-feminized seed, you need to be scouting your fields and once it gets to the flowering,
almost every day, and removing male plants so there is no pollen among your field. Additionally, you should be scouting nearby
ditches, fence lines for feral hemp, considered “ditch weed,” that could also be introducing
pollen into your field. And then the idea that the minute you see
a male plant or a male pre-flower as we discussed earlier, you are removing those. Another way we can reduce pollen in our fields,
outside of managing plants in our own fields, is to block pollen from neighboring fields. There is a couple of ways of doing that. The first is indoor growth. So either using high tunnels, hoop houses,
greenhouses, so if that’s plastic, if that’s glass, so basically you are producing the
plants inside and so pollen is not able to enter into your production. However, that is highly resource intensive
if you have high tunnels, as well as space intensive. A lot of the production in Wisconsin is going
to be happening in open fields. So, if we are in open fields what are ways
we can block pollen? Wind breaks or tree lines can be really useful. They are really good at blocking pollen, as
well as blocking wind. Or looking at the topography of your land. Is there hills? Are there valley’s? Knowing how the wind moves through your land
and putting that hemp in areas with low wind movement. However, it is also if you don’t have wind
breaks for tree lines, and don’t want to wait 10 or 15 years to plant Hemp, as well as have
flat land, you can also plant annual species to help block the pollen movement. A lot of growers will plant corn around their
hemp fields and corn will grow significantly taller than the hemp which should be able
to block a lot of that pollen flow. As well as, as I spoke earlier about downwind
vs. upwind, knowing how wind is generally moving across your land, and making sure that
if you’re downwind of other hemp fields you are really protecting those sides. So what you can see here is hemp planted in
a alcove of a tree line. That tree line is gonna really help block
pollen movement and wind movement. So, in conclusion there are a couple of things
for CBD hemp production that are really important. The first is to manage males in your own field. This is because, as we have talked throughout,
male plants are what create the pollen and pollination of female flowers really drastically
reduce the CBD content in those flowers. Managing the males in your own field, whether
that is from non-feminized or feminized seed, as well as then planting in either naturally
occurring wind breaks or planting annuals around your fields to help in reducing that
pollen movement through your field. And being aware of how wind moves across your
land. Finally, I believe what you are here today
to talk about after this presentation, is who is growing what kind of hemp where in
different counties. Trying to work together to make sure if grain
hemp is being produced with CBD hemp that it is outside of that isolation area of 5
kilometers, depending on upwind or downwind and what that looks like. In so, just trying to come together as a group
of farmers to determine who is growing what where and how to reduce that pollen drift
with the wind. So I will leave it there and just wanted to
say thank you very much and if you have any questions, feel free to contact me. I have my email address here and if you do
have questions and I don’t know the answer I will be happy to find them out for you. So thanks so much.

One thought on “Pollen Spread and CBD

  1. You can have tree lines or plant corn around but you can’t control natural bees pollinating. Correct?

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