Welcome to the Urban Forestry Radio Show brought to you by
the Community Orchard Network.
In this monthly radio show and podcast, I'm going to take you on a journey.
We'll learn about fruit trees, permaculture, food
forests, and so much more.
So if you're a gardener and enjoy growing your own food, if you love trees and
especially fruit trees, Or if you're just interested in living a more sustainable
life, you've come to the right place.
I'm Susan Poizner, your host for today.
So get ready, roll up your sleeves, and let's dig in to today's episode.
Hello and welcome to the Urban
Forestry Radio Show with your host
Susan Poizner.
Right here on Reality Radio 101.
To contact Susan live right now, send her an email.
In Studio 101.
And now,
right to your host of the Urban Forestry Radio Show, Susan Poizner.
Hi everyone, and welcome to the show today.
You know, when you're growing fruit trees, harvest time is the
most exciting time of the year.
There is nothing like organic fruit picked fresh from the tree.
But what could be more disappointing than harvesting the fruit, only to discover
that someone else got there first?
Now I'm not talking about human bandits.
I'm talking about insect pests.
Those little bugs and moths that nibble on our tree's leaves and
fruit and lay eggs under the skin.
Now, fresh organic fruit just doesn't taste quite as good.
When there's a worm or a maggot hidden inside.
Now in the Ben Nobleman Park Community Orchard in Toronto our
approach is to use orchard socks.
Orchard socks are nylon sockettes that we slip onto the baby fruit and just when
the fruit is no larger than a nickel.
As the fruit grows the sock expands.
All the while protecting that little fruitlet from insect infestation.
Now that approach works if you have maybe ten fruit trees, or one
fruit tree, or twenty fruit trees.
But if you have a thousand trees, tying on orchard socks
will be quite time consuming.
So you may consider investigating other non chemical approaches.
Today, we'll talk about some of those approaches with my first guest, Dr.
Gary Judd, an entomologist who has spent a lot of time studying the sex lives of
insect pests and learning how to use this information to protect our fruit trees.
Then later in the show...
Is there a wrong way to water a fruit tree?
The answer, believe it or not, is yes.
In the second half of the program today, I'll talk to Chuck Engels, a
fruit tree expert from Sacramento, California, about the do's and don'ts.
of fruit tree watering.
And I think we'll all be pretty surprised at how little we know about this
seemingly simple fruit tree care task.
But first, the secret sex lives of the fruit tree insect pests.
Now on the line I have Dr.
Gary Judd, an entomologist from British Columbia's Summerland
Research and Development Center.
Dr.
Judd, welcome to the show.
Yes,
good afternoon.
Thank you for having
me.
Mm hmm.
It's a pleasure.
Can you tell me a little bit about your work?
What is it that you do?
Well, as you introduced me, I am an entomologist.
And my specialty is in chemical ecology.
And specifically in that, I examine the mating cycles of insects and
the chemical communication signals that they use to find each other.
And those signals, they come from plants that attract insects.
So, chemical ecology is what I
am.
Hmm, well let's start from the beginning.
Pests, what kind of damage can they do to our fruit trees?
Well, in True Fruits, we normally classify pests into two types, generally.
Direct pests and indirect pests.
Now, an example of a direct pest would be codling moth.
And direct because the caterpillar feeds its way into the centre
of the apple and destroys it.
Or in southern Ontario, Toronto area, you might have a pest like
apple maggot and the maggot...
crawls its way to the center.
And then we have pests that are indirect.
These could be things like leaf rollers that feed on the
leaves and surface of the fruit.
So the oblique banded leaf roller would be an example of an indirect pest.
So, okay, so we've got these kinds of pests, and they are ruining the harvest.
So what exactly was the typical, maybe a more, can I say, old fashioned approach
to preventing pest damage on fruit trees?
Well, ever since, since introduce Used apples, uh, came to Canada a
hundred years ago in the Okanagan.
Um, we've been controlling insects primarily with some sort of toxic spray.
And some spray that would either kill the eggs or the young caterpillars
before they entered or fed on the fruit.
And that's the classical way that we've controlled insects for a hundred years.
And, and what's the downside of that?
I mean, if it works, it works.
Well, it
works.
Yes, it works.
But, um, those toxins have indirect effects on a lot of other organisms
in the orchard environment.
They cause a number of secondary problems by, by killing beneficial insects that
help us control those indirect pests.
And generally they, um, they're just not good to consume in large quantities.
You have grower and worker exposure to these toxic materials as they apply them.
So, um, You know, environmental consciousness is given us a reason to
believe these chemicals are just better off not having them in the environment.
So if we can find alternatives, that's, that's
our aim.
So, okay, a different approach of actually looking at the
mating habits of these pests.
What's the history of that?
Um, you know, when did people start to consider?
Well, maybe there's a different way to do this.
Well, the first pheromones, uh, the sex pheromones for insects were discovered,
um, in, in about 1970 in the case of the codling moth, and so, um, we've
been considering, uh, this use of these, these chemical signals, these
sex pheromones, for at least, uh, a better part of 40 to 50 years now.
Okay, and what, what were they trying to do at that time, in those early years?
Originally, the first, uh, the first sex pheromones that were
identified, these, um, let's take, for example, the codling moth.
They're shown to attract the male codling moth in very large numbers, in
very small amounts of these chemicals.
I mean, uh, hundreds or thousands of a gram is all you need.
And they attract lots of males, and so we put them in traps, and our
intention was to try and trap the males.
And we thought, naively, that we might be able to control the
insect populations by reme...
Removing the male insects, so male removal was sort of, or mass trapping
of males was our target of using
these pheromones.
Well, that makes a lot of sense, doesn't it?
If the males are dead, then the females have nobody to mate with
and your fruit trees are protected.
Yes, that,
that was the supposition and that was the hypothesis we were trying to test, but
as we stood, studied the insects and we realized that a male insect might mate
with several females, um, it takes a very few males to mate with a large number
of females to cause damage to your crop.
So it's very difficult to control 100% of the males and remove them
before they mate with a female.
So that approach was somewhat naive and really hasn't been that effective.
Hmm.
So, uh, what happened next?
I mean, I know that if anybody has, uh, you know, gone to a Yupik
orchard and wandered around, you do see these pheromone traps.
Are they the yellow sticky paper?
Is that what the pheromone, or what do the pheromone traps look like?
Entomologists have employed lots of different traps.
Some of them are based on chemicals like sex pheromones, these signals,
and others might be based on color.
So you might have a yellow trap that attracts certain flies like
apple maggot or cherry fruit fly.
So entomologists have tried a variety of different traps, but let's specifically
talk about the sex pheromone traps.
Now the original, one of the most consistent uses of them, and you
still see it and it's still used to a large extent, is to tell the grower
Uh, that the insect is active in his orchard, when they're there, what
numbers, and where they might be.
If you have, if you could well imagine, if you had a hundred acre orchard, the
insects are not necessarily everywhere.
So the traps could tell you what part of the orchard they were in,
and when they were most abundant.
And so that knowledge of the seasonal life cycle, the ups
and downs of the population.
gives growers a good idea of when they might spray their insecticide.
So, if they had to use insecticide, they could use much less, and it
would be properly timed and properly
targeted.
Hmm.
So, in fact, if they only have the pests in one part of the orchard, they may
not need to spray the other part of the
orchard.
That's exactly right.
And that those are the kinds of techniques we call are generally called integrated
pest management techniques, and they became very popular after Rachel Carson's
book Silent Spring and into the early seventies, we started to develop these
IPM techniques, and they still are being developed and refined consistently.
And is there evidence that they work?
Well, there's very good evidence that they work.
We have minimized the use of pesticides and allowed greater protection of
crops with far less insecticides than we were using 25, 30, 40 years ago.
But we as entomologists want to keep pushing the boundaries and so we've
tried to use non chemical approaches to remove all chemicals from the orchard.
And we've been somewhat successful with that in British Columbia in particular.
So tell me a little bit about where, where you went from there.
You weren't happy with just this idea of putting out the pheromone traps
and, uh, in order to discover where the pests are and then spray them.
Uh, where did you take it from there?
What, what year was this?
Yeah, the, um, well, my career started in tree fruits, uh, in, in 1989 here at
Summerland after moving from southern Ontario, um, and That was the time,
um, we were starting to investigate the possibility that we could use
these sex pheromones not to trap the males, but to simply confuse the males.
Okay, and so I'll give you a little descriptor.
Um, we can synthesize the natural pheromone in the laboratory.
That synthetic pheromone then can be put in a small device that can be hung in
the tree and it can release sex pheromone over the course of an entire season.
And if you have one of those, it works quite well to attract...
The insects to that one lure, but if you put a hundred of these or several hundred
of these lures throughout the orchard, what it does is it creates a fog is the
best way to try and describe it to the average person is we create this fog of
pheromone throughout the orchard canopy.
That then confuses the male moth, so they don't know where to search for the female.
So the, the natural signal becomes camouflaged, if you like, and the
synthetic signal is very prominent.
They respond to that, and that, that camouflaging effect or confusion effect
is something we collectively call mating.
disruption.
I have this image of the male insects flying around back and forth looking,
you know, going towards, I guess it's the smell or is it a smell based thing?
They're going towards the smell and it's like, Hey, where are the girls?
I can't find any girls around here.
And then they fly somewhere else.
So is that it?
They're just flying back and forth wasting their time.
That's
precisely how the mechanism starts, and again, in our early days,
we thought that they would just fly themselves to exhaustion.
But you're right, we create this synthetic female.
It is a chemical signal.
It's a signal they detect with their noses, which is really
their antenna on their head.
And they smell the signal, and then they follow it to its source.
But as you can well imagine, after doing that several times during a
single night, the male becomes fatigued.
And he does eventually become what we in sensory physiology call habituation.
So he becomes habituated to the signal, and so he no longer smells the
signal, not even the natural signal.
And at that point, he would become sedentary and stop flying and
simply sit on the leaves or branches of a tree and become inactive.
So he just gives up.
He simply gives up.
He will then probably start the next night again.
The process will start again.
But, um, we also know that if the female doesn't mate within the first
48 to 72 hours of her emergence, her ability to lay eggs actually decreases.
So, even if he eventually finds a female, if it takes him two or three
days, and she's been waiting two or three days, She is going to lay far
fewer eggs than she would normally, and so there'd be far fewer caterpillars.
So we get this dual pronged approach of reducing mating and then actually
reducing egg laying in those that might actually escape our system.
Okay, so while the guy pests are flying around getting
confused, where are the females?
Like, have you managed to, I don't know, put them somewhere all by
themselves?
Yeah, well, we have done many studies, um, to, we've released
insects and studied where they are.
We've gone into orchards and collected insects.
So we, we have...
We understand where the female actually resides when she is, when she is naturally
emitting her pheromone, something we call, uh, the term calling behavior.
When she's calling the male with her pheromone, most insects, especially
codling moth, will climb to the tops of the trees or fly to the tops of
the trees and sit there and wait.
But she won't chase the male.
She sits and waits and she calls and leaves her signal and she won't go
in search of him if she doesn't mate.
She just, she's persistent.
Um, and so the males and females don't find each other.
It's not like she goes in search of them.
Hmm.
Uh, just, what, what does the pheromone lure look like?
Again, I have an image of, you know how in public washrooms they have these
things that automatically exude a smell so that it doesn't smell bad in there.
Is that what it is?
Well, as you can well imagine, entomologists are quite innovative,
and in this area, there's one different lure for every entomologist.
It's kind of like everybody wants to create a new mousetrap.
So, for example, the average lure, That releases pheromone in a trap that
you might see hanging in an orchard is, uh, usually just a little rubber,
piece of rubber, a little, what we call a rubber septum, that they use to
close bottles off, and, and so it's a piece of rubber that you, you put the
pheromone in, but it could be a plastic device that might be several inches long
and a hollow tube sealed at each end.
So, the lures can be all sorts of types, much science has gone into.
developing these and finding, making them inexpensive, making them robust,
making them protect the pheromone because many of these pheromones
are sensitive to ultraviolet light and so we have to protect them.
So there's lots of different lures and, uh, that you
might see.
Okay, so is each pheromone designed for a different type of insect or
is there a general all encompassing pheromone for all of them?
Yeah,
that's the beauty of the pheromones.
That was our original, um, thinking.
And that's why they work so well, is they are very often species specific.
Okay, so for example, codling moth uses a particular chemical for its
pheromone that we have since found.
There's no other insect that uses anything like that.
And it's just a one.
What we call a one component sex pheromone.
Now, that won't, that pheromone will not be detected or smelled or used by
any other insects or beneficial insects.
So it's, it only affects codling moths.
Hmm.
But as the science of pheromones evolved and as we learned more, we
learned that there were some insects, let's say, uh, like the oblique banded
leaf roller or oriental fruit moth.
Now they use something we call multi component pheromones.
So they might have...
Two pheromones, two chemicals that make up the complete pheromone signal.
And it turns out that some insects might share in common one of those components,
but not both of the components.
So what makes it specific is when two are together.
So we have learned that we can control, in some cases, several insects
with one component of pheromone.
Well, how did the test look out there in BC?
What kind of results have you got?
So what are the side effects?
If there are any,
I'm going to have to apologize, Susan.
My cell phone's gone very quiet, so I didn't quite hear that
last question.
Um, my question is in where you guys are in British Columbia.
So how is it all working?
And, uh, you know, how big a test have you done of this particular
technique?
Uh, in the Okanagan Valley, we have tested several thousand
acres of mating disruption.
Uh, at, at different times.
It, it has, um, these kinds of technologies have led to the,
to the growth of the largest organic apple industry in Canada.
Um, one of our valleys called the Simokin Valley is, they, they call
themselves the organic capital of Canada.
So it's, it's been highly successful for the, for the organic apple
growers.
Hmm.
And side effects?
Any negative side effects?
Well,
as you can well imagine, um, the negative side effects, um, it's hard to call them
negative, but they are, they have had effects, is that when you stop spraying
conventional insecticides, which are very broad spectrum, that protect your orchards
against all kinds of pests, we have seen a growth over the last 25 years of invasive
species that, Um, are having an impact on our organic systems and our pheromones
are not controlling those new pests.
So we have, we have made ourselves vulnerable.
Uh, by not spraying to these invasive incursions.
And, uh, they may have come anyways, but, uh, the chemicals
would have kept them under control.
So now we're having to deal with a number of invasive species, um,
as, as a somewhat as a indirect fact, effect of using pheromones.
Are you talking about species like Japanese beetles that...
that are, you know, affecting fruit trees?
Well, certainly the Japanese beetle is an invasive species.
Uh, but not a, not a pest of apples in British Columbia.
Um, but we have a pest from Europe called the apple clearwing
moth that's become a pest.
Um, brown marmorated stink bug.
And in British Columbia, we would consider apple maggot an
invasive species and a pest.
And we haven't yet discovered it here in the Okanagan.
Oh, really?
Wow.
Amazing.
Well, let's hope you don't get it.
We do certainly have it here.
Um, so that's very interesting.
Now, are these, uh, pheromone lures available to home growers
or community orchardists or people who grow fewer trees?
You could, you could
certainly buy pheromones and you can buy pheromone traps, but, um,
and so you could, there's a number of outlets in, in, uh, in Southern
Ontario or various parts of the U.
S.
that could.
There was just someone knocking on my car door as I was talking to you.
Okay.
Um, so yes, you could buy these, uh, these materials from a number of supply houses.
Um, now the traps, the pheromone traps work very well for the backyard gardener
or the small, or who might have 20 trees.
But pheromones...
that we use for mating disruption, unfortunately, work
best in very large acreages.
We, we tend to think of the minimum acreage that mating disruption
might work to control calling mouth.
We might think that there's something around two to three
acres of apples is necessary for mating disruption to be effective.
Okay, interesting.
Well, Dr.
Judd, in just a moment we're going to hear a few words from our sponsors,
but after that I want to talk to you about your other project, I think your
newest project, and that is to breed sterile pests to release in orchards.
Are you okay holding on the line for a few minutes?
I am.
Great.
And to the listeners, please do send in your questions or comments for Dr.
Judd.
Anything about fruit tree pests.
And past prevention, pheromones, all that good stuff, and I'll
ask those questions to Dr.
Judd for you.
Just send an email to us now to Intu 1 0 1 gmail.com.
You're listening to the Urban Forestry Radio Show on Reality Radio 1 0 1.
I'm Susan Poisoner and we'll be back after the short break.
I'm Susan Poisoner and in today's show we're pulling back the curtains on the
Sex Lives of Fruit Tree Insect Pest.
You'll never look at an apple maggot or codling moth again without blushing.
My guest today is Dr.
Gary Judd, an entomologist from British Columbia's Summerland
Research and Development Centre.
So Dr.
Judd, you're still on the line, right?
Yes I am.
So we've been talking about the historic approaches of using the knowledge of
insect pest mating habits as a way to stop pests from ruining our fruit crops.
Now so far we've chatted about pheromone traps, we've chatted about
other techniques, but I understand that you've developed an approach that
involves breeding sterile insect pests and then bringing them into orchards.
Can you tell me a little bit about that?
Yes, I certainly can.
Now, I want to be very honest.
This technique was developed by an entomologist who has since retired from
the Summerland Research Centre, Dr.
Jinx Proverbs.
And, um, he worked, his career spanned somewhere between 1950 to 1985.
So it's a fairly old technique.
But he was working on codling moth, which was the key pest
of apples here in the Okanagan.
And the understanding and belief was, if you could remove codling
moth from the orchard, then you really could grow organically.
And that's pretty much the case today.
So he, he was studying, um, a technique called sterile insect technique.
And in that technique, what you do is you sterilize the male moths with, um,
could be x rays or chemical sterilant.
And those sterile moths are then bred up in the laboratory
and released into orchards.
Those sterile males then mate with the wild female codling moth.
And, as it turns out, in codling moth, the female only mates once in
her life, and if, if she mates with a sterile male, she's fully satisfied
and will then begin to lay eggs, and those eggs will not hatch, they will
be in fact sterile, and you won't get any, uh, caterpillars forming, and you
won't get any damage in your fruit.
Hm,
quite amazing.
I'm just trying to imagine what this would look like, like, where
do you get all these male insects, what happens if there's like, Female
insects in the bunch and you put them in an x ray machine or something.
It's just
yes.
Yes.
Well, dr Dr.
Proverbs developed a technique for for raising these these insects in
trays of diet and Those the rearing system he designed is housed in a in
a Several thousand foot, uh, Griffith facility in the Soyuz, British Columbia.
That's right on the border to the United States and the
southern end of the Okanagan.
So that, that was a several million dollar facility.
That really is, um, it, it, it produces millions of moths
per week in a closed facility.
And, it produces, as it turns out, it produces males and females on that diet.
But, the males and females are both, uh, irrate, what we call, they're,
they're, they're exposed to, to, uh, irradiation, a gamma radiation, very
similar to x rays, in a machine.
And so, both the males and females are sterilized.
So, in fact, When what you release into the orchard are
sterile males and sterile females.
The sterile females just lay sterile eggs and the sterile males go in
search of, of the wild females, and that causes them to lay sterile eggs.
So this, so
that's how the technique works.
So this is amazing.
So this has been, been in existence for many years.
Is it only now being brought into, uh, orchards or, or
No, as I say, Dr.
Proverbs career spanned the 1950s to the mid 1980s and then another entomologist
took over his program on his retirement.
And it took, um, from 1985 to about 1992 to get the program that
we have fully functioning here in British Columbia in operation.
It was a joint venture of regional governments, provincial governments, and
federal governments to build the facility.
And in 1994 they made the first releases of sterile codling moths.
And ever since 1994, um, they have been controlling codling moth in
the Okanagan Valley, uh, uh, with the sterile insect technique.
So ever since the beginning of my career when I was working on pheromones, the
two programs were running parallel.
Hmm.
So do you need both programs now or, or is one being phased out?
Well,
um, the sterile insect program is, it's a good question.
Um, it's a very expensive program.
Um, and...
We, um, it is very specific to codling moth, and it's the only pest that we can
currently control here in BC with it.
Now, we have a number of other indirect pests, as I said to you earlier, we
get a number of, uh, secondary pests.
And so my work, uh, for the last 30 years has been in controlling
those other pests with pheromones.
Now, we know full well we can also control codling moth with pheromones.
And so we can quote and quote codding moth and several other insects
if we just use pheromones, but it's a very long running program.
It's very successful and it's done area wide.
Everybody, everybody must participate in it.
It's legislated.
And so you can well understand that even if we had an alternative
technology like pheromones.
Um, it's a very difficult, uh, step to take to, to reverse that
program that's been so successful for our control of codling moth.
Wow, so basically it looks like the two are working hand in hand.
You've got the sterile, uh, insect program for codling moth, and then you've got the
pheromones working for the other insects.
That's correct.
Do you need to spray anymore?
Are these spray free orchards?
Well,
most of our growers rarely spray except, as I said, for
these, these invasive species.
We, we, um, not all, not all growers make use of the pheromones.
So those that don't use pheromones, um, the pheromones are primarily
used by organic growers.
We still have conventional growers who would have to spray for
some of these secondary pests.
And more recently, since 2006, we've had this invasive pest, the apple clearing
moth, that is causing us some concern because our organic growers are now
having to spray to control that insect.
And, unfortunately, we have a pheromone for it, we have identified
the pheromone, and we've tried mating disruption, but we are dealing with
a pest that's in very large numbers.
Uh, and we, we need to get populations down under, uh, lower levels before
pheromones are really going to be
effective.
Mm hmm.
Well, so what, what does the future look like?
What is your goal for the future?
Well,
the, the goal is to, uh, minimize pesticides wherever we can, to
use, um, the, this information on chemical ecology and mating
systems to control as many insects.
The most exciting part of my work right now is that we have only just
in the last two years discovered a group of chemicals, natural chemicals,
that attract the female insects.
Many female insects.
And so we do think if we can trap enough female insects, And hopefully I'm not
being naive like my predecessors, but we believe if we can trap the female
insects, then we could, uh, control those populations without pesticides.
So, my work and that of others will continue on into the future after
I'm retired, but, uh, this whole area of chemical ecology and using
natural chemicals, I think is, is, uh, going to be around for some time
and, and only get more interesting.
That is interesting.
Is it happening anywhere else, or is this just a BC program?
Am I going to see it here in Ontario?
We've got listeners in all over the United States.
The sterile insect program for codling moth in British
Columbia is a unique program.
It's the only one of its kind in the world.
We, we have other sterile insect programs in the world, but mainly
in the tropics and they're used to control tropical fruit flies.
There's one in Arizona that controls a pest of cotton pink molar, but the
codling moth program in BC is unique.
It is, um, being tested.
The technique is being tested, uh, by people in South Africa, in
South America, and in New Zealand.
And the way it's being tested is they are buying moths from our facility to release
and, uh, during their season, because being Southern Hemisphere countries,
they grow in the opposite season to us.
So when our facility is, uh, down in the, in the winter, we can
produce moths and sell them south.
Uh, and, and there are, so there are other countries and industries trying
to use this technique for cotton.
Hmm.
I'm very curious to see how it develops, because I know that there are a lot
of people out there that would love to know that the apples and, and
pears and all the fruit that they're buying doesn't have toxic chemicals
on it, so it's a hopeful development.
It very much is, but um, I will say that there's a very large industry
outside of British Columbia, the Washington State industry for example.
Almost 80% of its industry uses mating disruption to control condom moths.
There are other industries that are very progressive in southern Ontario.
I know you have a group of pests that have not, um, have not been able
to be controlled with pheromones.
Something like apple maggot.
And that does pose a problem to entomologists and growers.
And so we're having to develop different techniques to control pests
like that.
Hm, quite amazing.
Well, Dr.
Judd, it's been really great to talk to you.
And I appreciate you coming on the show today.
Well, thank you so much for having me.
I was glad to be
here.
Oh, great.
Okay, goodbye for now.
Hopefully we'll talk again someday.
Goodbye, Susan.
Thanks.
Well, if you missed the beginning of this interview, or if you would
like to listen to it again, you can of course download the podcast.
Just go to orchardpeople.
com slash network.
And while you're there, you can sign up for our iTunes podcast feed so that
you can catch up on previous episodes and so that you don't miss future ones.
But wait!
Don't go anywhere yet, because coming up after a word from our sponsors, we
will explore fruit tree irrigation.
Is it, is there a right way?
Is there a wrong way?
Is this a hard thing to do?
Apparently it is.
And we're going to find out more from Sacramento based
fruit tree expert Chuck Ingalls.
You're listening to the Urban Forestry Radio Show on Reality Radio 101.
I'm Susan Poizner, and we'll be back after this short break.
I'm Susan Poizner, and you're listening to the Urban Forestry Radio Show, a program
where we learn about fruit trees, food forests, permaculture, and lots more.
Thanks for tuning in.
In the first half of the show, we spoke to Dr.
Gary Judd about understanding the sex lives of insect pests, and
how that can help us protect our trees from insect infestations.
Now we love it when you reach out and contact us and we've got an email here
from Chase who says, Wow, what a show.
Very interesting.
Good luck with the continued research.
So I wish that Dr.
Judd was still on the line so we can hear that encouraging comment.
Now protecting your fruit trees from insect infestation is really
important but one of the key ways that you can do this is to actually just
care for your trees properly in the first place, especially when they're
young and establishing themselves.
Now, there are various tasks involved in fruit tree care, including annual
pruning, fertility management, and more, but one of the key jobs
is correct fruit tree irrigation.
Now why is that so important?
Well, fruit trees can only take in nutrients from the soil in liquid form.
So, a dehydrated fruit tree is actually a malnourished fruit tree.
And when a fruit tree is malnourished, it is weaker.
And of course, more vulnerable to pests and disease.
So, I wanted to talk to Chuck Ingles.
An expert in palmology, viticulture, environmental horticulture, and
more from the UC Cooperative Extension in Sacramento, California.
We're going to be talking in a minute.
Now if you have questions and anything related to fruit tree
irrigation, do send your email to us now in studio 101 at gmail.
com.
Now I understand that Chuck is on the line.
So Chuck, are you there with me?
Yes.
Hi, good to be here.
Good to have you.
How's the how's the weather over there in California this year?
Is it as dry as it has been in years past?
The summers are definitely typically dry, and right now we're going through a heat
wave, as I think much of the country is.
We're supposed to reach about 104, 105
today.
Oh my goodness.
Oh, that doesn't sound very pleasant.
And all week.
Oh my goodness, I've been complaining here in Toronto, it's hot too.
So, if irrigation is important anywhere, it must be in California,
where your heat is just...
so extreme.
Um, well, tell me a little bit first about California.
Why is proper irrigation essential in in your part of the world?
Well, fruit trees won't grow in a desert without water and we basically
are in a desert in the Central Valley.
Uh, and so Irrigation is mandatory every year.
In some parts of the country, it's not, but here we definitely
have to water and water a correct amount to keep the trees healthy.
Well, it's interesting because I know here in Ontario, there are some
orchards, organic orchards, that don't even have irrigation systems.
Yeah, and that can work where you don't have really hot conditions and maybe get
some summer rainfall, which we don't.
And the roots are.
Deeper because they have to grow deeper because that's where the moisture is.
So that builds their drought tolerance.
Yeah,
and yet it can also lead to trouble.
This year we had such a dry spring.
We have a we're having a very dry summer.
I don't know what what would that do to those fruit trees.
These are beautiful orchards that haven't had, you know,
hardly a drop of water in months.
Well, we
get that problem when we don't have enough winter rainfall.
And so often, not often, but sometimes when that happens, growers and
individuals need to water their trees late in the winter to start the soil,
to start the season out with a full profile of moisture in the soil.
Uh, so when you don't start the season, Enough, then you're going to with enough
moisture, then you're going to go through the summer with stress of some kind.
And in your case, it may not kill the trees, but the trees.
will probably be stunted, and they'll have smaller fruit.
Hmm.
Yeah, who knows if they even have fruit at all.
I looked at our trees in our orchard park, and we spend hours out there on
the weekends just with hoses watering and watering because it's been such a
dry year, and I just think, you know, whatever fruit is on those trees, if
I was the fruit tree, I would drop it.
Because that fruit, you know, it takes up a lot of energy.
So, um, yeah.
So, I mean, is that the case?
Does it drop the fruit as well when it's dry?
Yeah.
If there's not enough fruit, uh, enough moisture in the soil, then they
may not set as well to start with.
But yes, if they're, if they go through the season with insufficient water,
then they will drop some of that fruit,
no doubt.
So, so whether it's in California, what do the irrigation
systems look like in orchards?
What, what kind of irrigation do you guys do?
Well, uh, originally there used to be a lot of flooding, and there still is
some, uh, there was furrow irrigation, and more and more, uh, orchards are,
then became sprinkler irrigated, and now drip irrigation and micro
sprinklers are probably at least as prominent as sprinkler irrigation.
What are
the, what, mm hmm,
sorry.
Drip lines, uh, you know, a single drip line going down the center,
or usually one on either side.
If there's micro sprinklers, there'd be a single line with, you know,
a micro sprinkler between each
tree.
What are the pros and cons of the different approaches?
Um, the pros of using drip and micro sprinkler is that it uses less
water, especially drip irrigation, as long as it's managed correctly.
Uh, the con for drip irrigation is that...
You don't wet the entire soil surface, and that's true with
micro sprinklers, too, usually, but you wet a bigger area with micro
sprinklers than with drip irrigation.
But you can still do it.
For instance, all of our grape growers here use, those that use drip irrigation,
it's right down the row, so the middles between the vines are not getting
any water, which you can still do it.
Uh, it's just...
Um, for fruit trees, we'd like to have a little wider coverage because the
trees are bigger.
Yeah, I'm just kind of imagining how in the ground as the roots are spread out,
they, they kind of probably congregate those underground roots towards
where that drip system is, and then everywhere else, either the roots are
dead or they're just not very active.
Is that what I might see if I could go and look into the soil?
That's exactly right.
Uh, if you start the spring with a full profile of soil, Uh, uh,
I'm sorry, water in the soil.
Then the roots can continue to grow out into that below the, you know,
well below the surface through the season, cuz there'll be some moisture.
As long as there's not a lot of weeds, which take a lot of that soil moisture
away, then they can continue to grow.
But they will dry out eventually and more and more of the water will
be taken up from where the soil is moist, uh, from drip irrigation.
Hmm.
Interesting.
So thinking in terms of home growers, people in their backyard, uh, so you
say micro sprinklers, I mean, I know people who put a regular, you know,
grass sprinkler or whatever on their tree and they just leave it for a few
hours and water their tree that way.
Is that a good way to water your tree or if you're doing a backyard orchardist?
It
certainly can
work as long as you, uh, water more when it's warm and water less when it's cooler.
Uh, but nowadays, especially in California with the drought,
we've had a four year drought.
And some people say we're not in a drought, but we still are
and we almost always will be.
Uh, we're going to need to pay really close attention to
how much water we're using.
In many water districts in urban areas, people were given last year
one or two days a week to water, which really isn't enough for some things,
including lawns and fruit trees, too, if you have drip irrigation.
Uh, so, um, uh, I forgot where I was leading with that, but, uh, but it
is important, really important to water, uh, Enough and not water too
much.
Yeah, that's the other problem.
That's the other problem that you get.
You know, um, we have, uh, little espalier, lovely little espalier fruit
trees in our backyard and there's the temptation to water them every day
because, you know, we have the water.
Why not?
It's good for them, right?
But could that be a problem as well?
Right.
Watering every day could work if you're under really, uh, severe
heat and you have drip irrigation.
You may need to water every day because you have few points, sources
where that water is available for the trees and it dries out quickly.
Uh, but generally, sprinkling, uh, and watering every day otherwise.
Is not a good idea because you want to let the roots go deeper.
You want to let the soil not dry out, but become less saturated.
So the air comes back into the soil because when you water, especially flutter
for irrigation or sprinklers, you drive a lot of that moisture out of the soil,
especially under clay soil conditions.
So you need to let it dry out a little.
And the other thing is there are diseases that Occur when the soil is wet all
the time, especially in clay soil.
So, you want to not have the soil.
Wet all the time or anaerobic.
Oh, well, that's an interesting point.
So if you water too much you can be incurring Inadvertently encouraging
disease so we wouldn't want to do that and we definitely have clay heavy clay
soil Here in in Toronto at least so I have two questions here that just came in from
Clifford now He says his first question.
What is the best type of emitter to use for fruit trees?
And where can I get them?
Now let's see, he has another question, so take note of question number one.
Does chlorination affect fruit trees?
Um, we use city water at home from Clifford, so what,
what do you have to say?
Okay, first on the drip emitters, uh, my preference, and I think a really
good strategy, is to use Inline drip tubing, which has the drip
emitters built into the drip tubing.
Uh, that way you just run it, uh, in a circle around the tree
or in rows alongside the tree.
Uh, and you don't have to worry about an emitter getting, uh,
kicked off when you walk around.
Uh, so it's, it's just a, it looks like drip tubing, but it
has the emitters built into it.
And
where would you be able to get something like that?
Yeah.
Uh, big box stores, Terriot, um, and, uh, irrigation supply stores.
You have a better line of them usually, and they'll help.
They usually work with commercial, um, landscape people, but
they'll work with homeowners too.
Uh, so there are definitely places to buy it.
Hardware stores too will often have it.
Uh, the problem is, and we often recommend using wood chip mulch.
So you never see the drip tubing, which can be a problem because you never
know if it's clogged and not working.
That's why micro sprinklers are often good, uh, because You can
turn it on and look down the row and see, oh yeah, they're all working.
Uh, unlike drip irrigation, you can't see if they're working
at all.
And what about that question about chlorination?
We are indeed using city water to water these trees and, uh, I can sometimes
even smell the chlorine in our tap water.
How does that affect the
fruit trees?
Yeah, chlorination is fine.
It doesn't hurt anything.
Oh, good.
Yeah, no problem at all.
It's only when you try to use something that's like, uh, Bt or some other
organism that you're spraying for pest control, there's some of them
that you need to have non chlorinated water because it kills the organism.
Uh huh.
Spraying
on the tree.
That would not be helpful then.
No.
You're trying to put something good on and it's dead by the
time it gets on your tree.
Exactly.
Well, okay, so we've talked about emitters and a little bit about frequency.
There would be, it would be so good to know how much is enough.
Like is there a way to test, is my fruit tree getting
enough water or too much water?
Well there certainly...
It are several ways.
Uh, one way is to dig in the soil and see how deep the water,
the moisture in the soil is.
And that's a really good strategy, but there's better ways than digging a hole.
And one includes using a soil sampling tube to pull a core of soil out of the,
you know, out, and you can look at it and see how dry it is on the top versus.
How deep do you want it to be watering?
Like, do you want it to, the soil to be damp 2 inches down, 6 inches down?
Well,
the majority of the fruit tree roots of almost all fruit trees in most conditions
are down to about 18 inches to 2 feet.
The majority of...
Tree roots are in the top two feet on large trees in the top three feet.
So you may have a taproot initially when you plant the tree, but that taproot.
Basically goes away and the roots move out laterally, so all your roots
are moving out and even beyond the drip line or the edge of the canopy.
They're going outward.
So you want to water that deep.
So you want to somehow check the soil that deep if possible.
Hmm.
And if it's...
But there's other ways.
Okay, yeah.
Yeah, there's other ways you can, you can, um, you can keep track
of evapotranspiration, which is a mouthful, I understand.
Evapotranspiration is a combination of evaporation of water from the
soil and transpiration of water through the leaves of a tree.
So, there are...
Sites and I looked on online to see if Toronto has sites that list
the daily evapotranspiration rates.
Uh, but I couldn't find any.
I don't know if you have them available, But basically the warmer
it is, the more water you're applying.
The cooler it is, the less water you're applying.
Hmm.
Somebody's got to figure out an easy way to do this.
I've got at home, uh, a little self watering pot.
And, uh, it's for little seedlings that I'm growing for the garden.
And you can see a red line on this sort of, it, it looks like a
thermometer in the, in the soil.
And it tells you, okay, uh, you need to add more water.
Somebody needs to invent that for homegrowers because, you know, and
also it's like the soil is moist today.
So do you want to wait until it's dry, dry, dry until you water again?
I don't know.
Your thoughts on my meandering thoughts?
Well, there are soil moisture testers, but they usually
don't go very deep in the soil.
And...
And, and there are various sensors.
I use certain types of sensors that are a little complicated,
but not that complicated.
They go deep into the soil.
So you can basically have eyes in the soil and see how dry the
soil is without having to dig.
But those are a little complicated.
And, and, uh, the other thing is, if your trees are healthy.
And they're growing well, they set a lot of fruit and produce a lot of good fruit.
You're probably doing something right.
Uh, but if you, a lot of times you'll have small fruit or you'll have, which
could be related to several things, or you'll have stunted trees, which
could also be related to other things.
Uh, but, uh, but tree health and production.
are a good indication that you might be doing something
right.
Hmm, well that's a good way to think about it.
I so appreciate you coming on the show.
I feel like we could continue talking for quite a while, and it's
amazing, because again, you think, irrigation, oh isn't it basic?
And it's kind of complicated.
If I could just say one other thing, this is really common where people think you
need to set the hose right by the trunk.
That's where all the roots are.
You don't want to water by the trunk.
Unless it's a really young tree, the roots are moving outward.
You've got to move that water out and keep the trunk dry
below ground.
That's a really good point because, of course, uh, you know, they say you
really want the, under the canopy of the tree, the farthest canopy, so it's
actually quite far from the trunk.
Right, exactly.
Roots are near the trunk too, but we want to keep the trunk dry to
keep, uh, to keep it from dying.
Some diseases love that moisture around the trunk, so keep that area dry.
I have another, Clifford has sent us another email.
He's obviously very interested in this topic.
Now he says, and this is interesting actually, Is it, is it best to water
a fruit tree once during the day?
Or multiple times during the day, morning or evening?
Well, the multiple times would only be if there was a slope and
you don't want it to run off.
So you water a little, let it sit, water a little, let it sit.
Uh, generally water all at once to get it down to the 18 inches, of
course, unless you have the slope.
But regarding his other question about emitters, if he's gonna use
punch in emitters on the drip tubing, then use pressure compensating Emitt.
Generally, one gallon per hour or thereabouts is
best.
Wow.
Fantastic.
Oh, thank you so much for coming on the show today.
Oh, you're welcome.
My pleasure.
Hopefully, you'll come back and I know you, there's lots of
things that you can talk about.
So maybe we'll get you back another day.
We'll talk about something else.
Yep.
Okay.
Thank you so much.
Goodbye.
Bye.
Okay, well, that was fast.
That's all for the show today.
And it was really nice to speak to my special guests, Chuck Ingalls,
Palmology, Viticulture, Environmental Horticulture, and Master Gardener
Advisor at the University of California Cooperative Extension.
And earlier in the show, I spoke to Dr.
Gary Judd, an entomologist from British Columbia's Summerland
Research and Development Center.
So if you missed part of the show and you want to listen
again, just go to orchardpeople.
com slash network where you can access this episode and all the other episodes
that we've done about fruit trees, food forests, and permaculture gardens.
And while you're on the site, do sign up for my monthly
newsletter at orchardpeople.
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And I'll remind you about upcoming podcasts, and you'll get
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Tune in to the show again next month, and we will have more great guests.
You're listening to the Urban Forestry Radio Show.
I'm Susan Poizner from the fruit tree care training website, OrchardPeople.
com, and I look forward to seeing you next month.
If you want to learn more about the Community Orchard Network.
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I'm Susan Poizner.
Thanks for tuning in and I'll see you next time.
Thank you for listening to the Urban Forestry
Radio Show with your host,
Susan Poizner, right here on Reality Radio 101.