August 5, 2025 • 30 mins
Have you noticed a white, powdery coating on your cucumbers or yellow-spotted leaves on your tomatoes? Mid-summer fungal diseases like powdery mildew, blight, and leaf spots can devastate your garden if left unchecked.
Today on Just Grow Something, I break down commonsummer fungal diseases and why they appear in wet, humid conditions, organic treatment methods, including milk sprays and baking soda, store-bought organic fungicides like copper and sulfur sprays, prevention strategies, and how to rotate treatments to prevent fungal resistance.
Whether you’re dealing with relentless rain or high humidity, this episode arms you with practical, organic solutions to protect your garden and maximize harvests. Let’s dig in!
Save 20% on your new own-root rose plant at Heirloom Roses with code JUSTGROW at https://heirloomroses.com
Find full show notes at https://justgrowsomethingpodcast.com/episode/how-to-tackle-mid-summer-fungal-diseases-ep- 261
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
Have you ever strolled out into your garden, coffee in hand or
maybe cocktail, and suddenly noticed that your.
Beautiful cucumber plant looks. Like it was dusted in powdered
sugar. Yeah, that fluffy white coating
is powdery mildew. And it is the uninvited guest
that keeps showing up to the garden party.
So today we're driving into the sometimes mysterious but always
(00:23):
annoying world of fungal diseases, powdery mildew,
blight, leaf spots, all the fun things.
These issues are not just cosmetic, they can actually
seriously affect our plants productivity and the health of
the plant if we let them go unchecked.
So today on Just Grow Something,we are going to break down
exactly what causes these issues, how to prevent them, and
(00:44):
how to treat them organically and effectively using both
homemade and store bought options.
We're going to talk milk sprays,pruning for airflow, cultural
controls and more. Let's dig in.
Hey, I'm Karen and what started as a small backyard garden 20
years ago turned into a lifelongpassion for growing food.
Now as a market farmer and horticulturist, I want to help
(01:04):
you do the same. On this podcast I am your friend
in the garden, teaching evidencebased techniques to help you
grow your favourites and build confidence in your own garden
space. So grab your garden journal and
a cup of coffee and get ready tojust grow something.
So part of the reason that we'redoing this episode this time of
(01:25):
the year rather than in the spring is because it has been a
very, very rainy season, unusually so for a lot of us
here in the US And these fungal diseases in the Midsummer time
frame are not usual for us, especially here in West Central
Missouri. We are very used to having a
(01:46):
cool and wet spring and that's usually when these fungal
diseases are starting to try to run rampant and we really have
to keep an eye on them and keep them under control.
But in most instances, once we get to about the middle of July,
Mother Nature has turned the faucet off and the sun has come
out to try to cook us. And that means that the plants
(02:06):
have a chance to dry up. Even though we will still have a
high level of humidity throughout the the summer, we
still get those Suns rays to help sort of cook a lot of this
off. What we're experiencing this
year is very different from mostseasons.
We have had such a rainy July. I mean we had a very rainy
(02:27):
spring to begin with and then wecontinued into to June and now
all the way into the end of Julyand now into August.
It's just been insane the amountof rain that we have had.
So our usual humidity has been even higher.
The plants aren't really gettingmuch of a chance to dry out in
(02:49):
between these rainstorms. So if this is something that you
are experiencing, you very well may be finding that you are
having higher instances of thesefungal diseases in your garden
right now, which is not usual. So what are we up against here?
Fungal diseases come in a lot offorms, but some of the most
(03:10):
common and most troublesome onesfor us as home gardeners are
things like powdery mildew, leafspot diseases and blights.
So powdery mildew looks like a white powder on your leaves and
it thrives in warm, humid conditions with poor airflow.
(03:30):
The next one is those leaf spot diseases.
These show up has black, brown or yellow spots that can cause
premature leaf drops. So think Septoria leaf spot and
then blight. So tomato blight or potato late
blight. These are very serious and they
can actually wipe out plants in a matter of days.
(03:51):
Most fungal pathogens love wet leaves, so if your plants are
not getting the chance to dry out in between rainstorms, this
is the perfect place for these fungal pathogens to just latch
on and hold on. They also love very crowded
plants. So if you've made an attempt at
(04:11):
interplanting this year and there's not enough airflow in
between those plants right now, those plants may be experiencing
some sort of crowding conditionsfor air circulation that goes
along with the crowded plants. And then nitrogen overloaded
growth. So if you have been feeding your
(04:32):
plants, but what you're feeding them is high in nitrogen and
they're getting a lot of that really good green leafy growth,
that nitrogen overload can actually attract fungal
pathogens. Now a lot of these pathogens
will actually overwinter in plant disease or implant debris.
And so the diseases that are showing up actually mean that
(04:54):
last year's issues have become this year's issues, especially
if we're not careful and we don't pay attention to what's
going on. So one of the ways that we can
treat these fungal issues is just by essentially changing the
pH of the leaf surface. So one of the easiest ways to do
(05:20):
this with just stuff that you have in your house that is very
low cost and also impacts, you know, highly is milk spray.
Yes, milk like moo moo juice milk, cow's milk or goat's milk,
even whatever. Studies have shown that a very
simple 10% solution of milk and water, so it's one part milk to
(05:44):
9 parts water, can be just as effective as controlling or at
controlling powdery mildew as synthetic fungicides.
So I mean, you could make it higher than this.
Some gardeners go as high as 40%, but essentially, not only
are we kind of changing the pH of the leaf surface at this
(06:06):
point, but the proteins in milk react with sunlight.
So that creates compounds that basically fry the fungus.
It's like an organic little laser beam.
It's just, you know, burning it off.
So this is something that you could spray on your plants about
every, you know, week to two weeks or so during really humid
(06:26):
weather. You would want to do this either
at the very first sign of that powdery mildew coming on or even
beforehand if you know that thisis something that you're going
to end up dealing with, right? Whole, whole milk works best.
And you're going to want to apply it in the morning so the
(06:47):
leaves dry very quickly during the day.
Another homemade solution would be baking soda.
Now be careful with this becausetoo much baking soda can
actually cause leaf burn if it starts to get too hot outside.
So again, you can mix this, you mix the baking soda with the
water, but just start light and test it on a few leaves before
(07:12):
going wild over the entire thing.
Neem oil also helps in this instance, so same thing, though
too much of the oil in like the wrong weather can actually cause
leaf burns. So just know that you know
you're going to be putting this on in the early part of the day
and hoping that it is dry beforethat sun's rays start to get
strongest at between you know that like 10:00 AM and 4:00 PM
(07:35):
or or at least noon and two timeframe, right?
So always test these things very, you know, simply or very
minimally before you move on to spraying the entire plant.
Now there are store bought organic options for this because
honestly sometimes homemade justdoesn't cut it.
If you have a really really tough infection with any of
these things, you might want to look at organic fungicides.
(07:58):
So sulfur and copper based fungicides are approved for
organic use and they can both prevent and suppress a wide
range of fungal issues. My preference is for the copper
spray. I generally start spraying my
tomatoes early in the season, even in the spring.
(08:21):
So basically right as our springrains sort of start to die off
is when I normally start spraying for copper or spray the
copper spray once every week to 10 days depending on how humid
it's been and how much fungal pressure I am seeing.
Normally I will start to see that at the base of my tomato
(08:41):
plants. I'll start to see usually it's
the the blight or the satoria leaf spot.
You'll start to see yellowing leaves and the spots on the
leaves. That is a good indication that
I've got some fungal stuff goingon.
But if I start early enough, it prevents it from taking hold.
And if I continue to use it, then it's going to help suppress
those fungal issues. Now, this year has been a little
(09:04):
bit different because you're relying on that copper spray or
that sulfur spray to stay put, right?
But if it doesn't stop raining, then it can't really stay put.
So, you know, I have gone out twice this season earlier in
like the late spring, early summer when I would normal.
At first, I skipped the first application because it was still
(09:27):
raining. There was no sense in me going
out there and trying to spray anything.
But then the second time I went out, I thought I had timed it
pretty well. And I went out and I sprayed all
of my tomatoes and I pulled off the lower leaves to make sure
that, you know, that, that anything that was on those lower
leaves wasn't spreading. Sprayed everything down and
quite literally, I think it was 12 hours later, we had a
(09:49):
torrential downpour. And I know that all that copper
spray was just washed off. I, I have not gone back out and
used it again. What I am using is First
Saturday Lime and I've talked about this product before.
It is a really good filtered lime product that is not water
soluble. So that's good news.
(10:11):
Unlike like if we're using it for pest issues, people will use
like diatomaceous earth. But if you use the First
Saturday Lime number one, it's going to change that pH because
it is, it is a lime, right? So the pH is going to be much
higher than what the fungal diseases like to attach onto.
And you can do a coating of thisand you won't have to reapply it
(10:35):
as frequently if you get some rain.
Now if you are getting a deluge of rain like what I have been
getting, then it's nothing is going to hang on, right?
And you're still going to have to go back out there.
But I have found it to be a bit more effective this year just
based on the amount of rain thatwe've been getting.
So that is something that is another another option for you.
(10:58):
There is also potassium bicarbonate.
You can find this online. You can sometimes you can find
them in in the garden centers ormaybe in an AG store.
It is very similar to baking soda, but instead of being
sodium bicarbonate, it's potassium bicarbonate.
(11:19):
So it is formulated to be gentler on the plants and a bit
more effective. So this is something that you
would want to try. I will say always, always read
and follow the label for anything that it is that you're
using. The other thing you want to do
is rotate. What it is that?
You are using to prevent any kind of resistance from building
up because these fungi are theseare living organisms and they
(11:41):
can adapt the same way our insect pests can adapt to
something. So how that adaptation works is
if you're spraying something andit knocks down 90% of the
fungus, but then that 10% of thefungus starts to reproduce.
Well, the ones that are reproducing are the ones that
(12:02):
have shown themselves to alreadybe sort of resistant to the
fungicide that you are using, whether it's a store bought
version or it's milk or whatever.
And so when you come back through and you knock it down
again, then maybe it's only 80% effective and the 20% that
remains continues to reproduce. So that's that's how our
resistance gets built up. So if you can alternate what it
(12:24):
is that you're using, right? So go out there the first time
and use the milk spray and then the next time come back through
and use a copper spray. And the third time you come
through, you use say the the potassium bicarbonate or you do
a baking soda mixture, whatever.Change it up to where if it
wasn't 100% knocked down the first time, whatever was
(12:45):
remaining that was resistant to that first attempt is now being
knocked out by something completely different.
Or the third thing that you use knocks it out.
That's going to help to prevent resistance from building.
OK. You also want to apply them as a
preventative if you have had recurring issues, which once
again, is where your garden journal will come into play
(13:07):
here. OK, You're not going to know or
remember a lot of the time. Now, if you've been doing this
for years like I have and, you know, I mean, you've dealt with
it year after year after year, Yeah.
Then it's finally kind of drilled into your brain that,
oh, I really have to get out there and take care of this
before it becomes an issue. But if you are new to this or if
this is a new issue for you, make sure that you are taking
notes so that as you sit down and try to make your garden plan
(13:31):
in the offseason for next spring, you have these notes in
front of you. Which means you can put things
on the calendar to remind you, this is a time that I need to go
out and I need to start doing some preventative measures for
the fungal diseases. It's on my calendar for the
(13:51):
season at the date that I need to start.
And I just put spray copper. That's all it is.
Or spray tomatoes. I can't remember which one it
is. I think I've said spray tomatoes
and that tells me that, Oh yes, I have to get out there and
start doing it. And then make a note on your
calendar of when you did it so that seven to 10 days you can go
back out and do it again. 14 days.
Whatever it is, don't wait untilyou see that this is an issue
(14:15):
that has like latched on before you start doing anything about
it because these fungal diseaseswill spread super, super
quickly, especially in this typeof a, of an atmosphere where
we're constantly getting these rains and stuff.
So do your due diligence and usethem as a preventative or as
soon as you see the problems rearing their ugly head.
(14:37):
Roses love water. The correct amount of water
helps them grow and promotes large, long lasting flowers with
rich color and the thick, sturdypetals.
Water transports nutrients to the Rose through both the roots
and the leaves. When watering your rose plants,
remember these tips, especially in the summertime.
Water your roses early in the day, right at the soil level to
(15:00):
help prevent diseases like Blackspot.
If it's been exceptionally dry and dusty, you can spray your
rosebush with water once per week if needed.
On a sunny day, a spray nozzle will provide enough force to
clear the leaves of dust and dirt and spider mites and other
insects, especially if your areahasn't seen any recent rainfall.
Avoid routinely wetting the foliage though, especially when
(15:23):
it's overcast, because this could encourage and spread
disease. Of course, the best roses start
with the best roots and HeirloomRoses sells only healthy virus
free own root roses and they guarantee your success in the
first year. They are a family owned company
that invests in not just their roses and their employees but
also in us the customer. Their friendly rose experts are
(15:44):
available year round to answer questions and there are guides
and tutorials on their website in case you ever or get lost
about what you should be doing with your roses and the
different stages of growth and different times of the year.
Get your own beautiful healthy rose from heirloomroses.com.
I'm using code Just GROW to save20% on your purchase.
(16:05):
heirloomroses.com use code just grow.
The link is in the show notes. Now let's also not forget the
basics, right? Fungus loves moisture and
congestion, so we want to worry about our airflow, our spacing,
our cultural control. So here's what you can do.
The first thing is to prune. OK if even if you're not
(16:27):
somebody who prunes on a regularbasis like me, I've I make no
bones about the fact that I generally don't really prune my
tomatoes very heavily. I only prune like the bottom 12
inches or so only because I knowthat I have these fungal issues
that come up every single year. And so keeping those that that
(16:49):
air flow going at the bottom of the plant, number one, it's
reducing the ability for any of the soil to splash up on those
lower leaves. And that can transfer disease.
Even with a heavy layer of mulchthat can still happen.
So I make sure that I'm pruning all of that off.
But it also keeps anything from,you know, it keeps the airflow
going. And that is going to increase
the airflow all the way through all the plants.
(17:11):
And that helps. You can do this with most of
your plants, your cucumbers, your zucchini plants, the lower
leaves often times are going to start dying off anyway as the
production of your plant continues.
So if you're paying really closeattention and you're looking at
like say your zucchini plants, right, you will see where the
(17:32):
current fruiting point is. So as because essentially, you
know, squashes, even your, your Bush varieties of squashes are
still essentially a vine. And so as the fruiting point
sort of moves up that plant, theleaves underneath those fruiting
points start to die off. They will yellow.
(17:52):
I get messages all the time frompeople going, Oh my gosh, what
is wrong with my plant? These lower leaves are turning
yellow. Yes, they're turning yellow
because the plant doesn't need them anymore.
So as soon as you see that startto happen, you can start to pull
all of that foliage off of thoseplants.
This goes for your cucumbers, your squashes, your tomatoes,
lesser extent. I mean, yeah, you can do this
(18:14):
with Peppers, too. I haven't had too much of a
problem with these foliar diseases in my Peppers.
But if you do have this problem and you see that the lower
leaves are starting to die off again, any time we see the 3DS
disease dead or dying, OK, we want to get it out of the out of
the out of the garden so that pruning from the bottom is your
first step. Staking or trellising to lift
(18:36):
your plants up off the ground isalso a really good idea here.
The first few years that I gardened, I didn't intentionally
trellis my cucumbers. They happen to be planted near
something that they use as a trellis.
So that very first garden in my suburban backyard, I had put up
a a piece of lattice to sort of block off that back corner and
(18:58):
the cucumbers naturally gravitated towards that and
climbed up and through and over and intertwined in and around
that lattice. And that wasn't something that I
had planned. The next few years when we moved
to the five acre homestead, I had planted them along a chain
link fence that was up against where we were housing our
(19:20):
chickens. And again, they naturally
climbed up, but they also naturally climbed or grew out
away from the base of that fenceas well.
And that I think was when I first started to notice that the
plants that were up on the fenceessentially trellised, were
(19:40):
seemed to do better. I had less instances of diseases
in those fruits and in those plants than I did the ones that
were crawling across the ground.Now that I know better,
obviously it makes sense becausethere's better airflow around
those plants that are up off of the ground.
You also don't have the fruit incontact with the ground because
any anywhere that fruit is contacting the soil, it's going
(20:04):
to cause some soft spots. You have more of a possibility
of a transfer of fungal pathogens and stuff and that of
course can lead to it getting onto the plant and then it
continues on and on and up. This is not to say that you
can't grow cucumbers and squashes and everything else
just sort of on the ground. I would prefer if you had a
really heavy layer of like strawmulch or something in between
there. But even in that instance, if
(20:26):
it's raining constantly, your mulch is going to be wet.
So those plants are going to be in contact with that moisture.
So if you are seeing that you are having issues with fungal
diseases, this might be your opportunity to say, OK, I should
be staking these things up or I should be doing some sort of a
trellis to help lift those plants up off the ground and
further increase that airflow tomake them just a healthier
(20:49):
plant. The other thing when it comes to
airflow is spacing your plants properly so that they're not
kind of elbowing each other for room.
Now, this sounds a little counter to what I normally
preach in terms of interplanting.
But I will say there is a littlebit of a line that we walk where
(21:10):
we have we have intercropped allof our plants to take the most
advantage of the space that we have and to allow those plants
to sort of support each other and, you know, feed off of each
other for for lack of a better term.
And placing them too closely together to where they just
don't have enough room and they don't have enough airflow.
(21:33):
And you know, this is another case for keeping a garden
journal where, OK, maybe you tried inter planting for the
first time this year, or maybe you got a little bit more
aggressive about it and you put more plants into your same
space. How are those plants faring
right now? What do they look like?
Do they seem like they're struggling?
Are you having more instances offungal diseases?
(21:57):
Is that because it is super rainy in your area right now?
Or are you having your normal weather conditions and you're
seeing more fungal diseases? These are things that you put
into your garden journal so thatyou can go back in the offseason
and look at that and understand when you start to plan next
year. Or even if you don't plan at
all, at least when you go to plant next year you can go and
(22:20):
back and look at your notes and go, OK, maybe they were a little
too close together. Let's maybe give them an extra
inch all the way around this season and see how they go.
Once you have a couple of years of notes, then you can start to
develop a plan that says, OK, I know exactly how far I can push
the envelope with these plants. Now if you also are doing this
(22:44):
and you know that this year is different for you and it is more
rainy than it normally is and you have done your normal
interplanting, I tell you I packmy, especially my raised
planters. I pack them very, very tightly.
There is no shame in going aheadand removing some plants so that
all of the plants can benefit. OK, so if you have a bed where
(23:07):
you've interplanted a bunch of different things and the stuff
that normally would be thriving at this point is starting to get
a lot in terms of diseases, see what you can remove around the
base of that plant to give it more airflow or consider just
removing that plant. So you have to make the decision
as to whether or not your cucumbers are more important to
(23:28):
you or your kale is more important to you or whatever it
is that you have planted them with, right?
That's where it's up to the gardener to decide whether or
not, you know, you have to sacrifice one plant for the
health or the benefit of the other.
So, but space, you know, plant spacing is absolutely, you know,
one of the factors here when it comes to a lot of these fungal
(23:49):
diseases. And despite the rain in a lot of
these areas, you know, some folks aren't getting that type
of rain and you are having to water quite a bit.
So a way to prevent these fungaldiseases from happening is to
use drip irrigation or soaker hoses to just keep that foliage
(24:09):
dry. Even if you know, you're in an
area where you're getting a ton of rain and then all of a sudden
stops, right, OK, you're going to have to water.
So make sure that you're doing it at the soil level.
And then of course, we also wantto water early in the morning if
we can, so that any water that splashes can dry quickly.
There's always that mulch too. Using mulch is going to help
(24:32):
prevent that soil splash. And so that's another thing to
do. And once again, we don't want to
overfeed the nitrogen. That lush green flush of growth
is super tasty to fungus. They love that aphids too.
By the way, Aphids are also veryattracted to over fertilized
plants. So if you know, if you've been
(24:55):
feeding quite frequently with something that is high in
nitrogen and you're starting to see a lot of fungal diseases,
then we want to just go ahead and back off of that a little
bit. And then once we get towards the
end of the season, let's just make sure that we are cleaning
up our garden beds, we're removing and destroying any
diseased plant material. First of all, this also means
(25:15):
during the season 2, if you havediseased material, I am a, I'm a
proponent of the sort of chop and drop or, you know, prune and
just kind of drop it onto the soil because again, that's just
plant material. It's going to break down.
But we don't want to do this if the plant material is diseased
because all that's doing is justharboring that pathogen and they
(25:35):
can stick around not only in that plant debris but also in
the soil, just waiting for the ideal circumstances.
So not just at the end of the season should we be removing
this, but we should also be doing it during the season as we
are pruning for that airflow or as we are removing that disease
tissue to make sure that it's not sticking around.
(25:57):
Whether you are growing in the ground or in raised beds or
containers, be generous with your spacing if you have the
space to do it in ground. OK, if, if fungal diseases
really are a problem, then this means as we're doing our
interplanting, we really want topay attention to that high, low,
(26:18):
fast, slow mentality. You know, if you if you are
planting things together, make sure that the taller ones have
enough room around them to be able to get that air flow even
if the shorter ones are there. And if not, we can just space
them out just a little bit more.Interplanting doesn't
necessarily mean crowding. OK, So be generous with the
spacing, prune regularly and stay on top of your irrigation
(26:41):
and doing it properly. If you're not in an area that's
getting a ton of of rain right now, if you are growing in a
raised bed, airflow is very mucha key here because you have to
think you might be dealing with a little bit more humidity as
those plants are kind of tucked into a container, especially if
(27:03):
you your soil doesn't go all theway to the top right.
It's it's stopping a few inches shy of the top, which means the
plants are sort of settled down in there.
You probably need to focus a little bit more on some airflow.
So just don't skimp on that, that spacing.
And then if you're growing in containers that you can move
around, move them right even, you know, just to give yourself
(27:25):
some more air flow, separate those pots a little bit.
Powdery mildew can can sneak up really quickly on like potted
squashes or cucumbers. So make sure that you have
really good drainage in your pots.
If you have them on a porch or something where you can run a
fan out there in the afternoon when it's just super stagnant
(27:46):
and there's no airflow and it's just humid and ucky and gross.
If a fan would feel good on you,trust me, the fan is going to
feel good on your plants too. They're going to be very happy
about it. So if you can move your
containers around a little bit and give them more space to
increase that airflow, great. And and if you need to add a fan
for the health of your plants, then hey, I'm not going to make
(28:08):
fun of you. I think that's a fantastic idea,
and what it boils down to is start early.
So start applying those milk sprays or those other treatments
before the fungal problems start.
You want to stay ahead of the game.
So if that means writing it on your calendar to say that every
seven to 10 days or 14 days you're going out there and
(28:30):
you're repeating it, or more frequently if you need to, then
do that. But just make sure that if you
are having to treat very frequently that you are rotating
what you're using. Try to improve your airflow.
So prune and steak and space your plants really well.
Water smartly, so drip or soakerhoses, morning irrigation,
(28:52):
please make sure that you are cleaning up sanitizer tools.
Remove those disease plants. Rotate your crops around as
needed at the end of the season.Treat what you can and support
that plant health through the soil like we talked about last
week, instead of relying on, youknow, those synthetic sources to
to feed the plant. We want to support that plant
(29:13):
health by feeding the soil and we don't want to over fertilize
and we absolutely want to use mulch.
So if you have been dealing withpowdery mildew or leaf spots or
blight, don't panic, OK? You have the tools that you
need. You've got the knowledge now
that you need and I'm hoping this episode will give you the
(29:35):
confidence to kind of fight backagainst these fungal diseases.
It is not all is not lost when you walk out there and you see
these things occurring in the garden, but you need to jump on
the problem immediately and takeaction right away in order to be
able to sort of beat back these fungal diseases and keep them
under control until either the weather conditions change or you
(29:59):
get your first frost and then we're just done with the garden,
right? I hope this episode will help
you feel more prepared. If you know somebody who is
dealing with fungal issues, thenI would love for you to share
this episode with them. If you have tried milk sprays or
if you are having, you know, really good luck using something
specific, I would love to hear how it went for you.
(30:20):
You can shoot me a message. You can leave a comment under
Spotify or in YouTube. Just send me an e-mail reply to
this week's e-mail. I would love to hear how it's
going for you. Until next time, my gardening
friends, keep on cultivating that dream garden, and we'll
talk again soon.
Have you ever strolled out into your garden, coffee in hand or
maybe cocktail, and suddenly noticed that your.
Beautiful cucumber plant looks. Like it was dusted in powdered
sugar. Yeah, that fluffy white coating
is powdery mildew. And it is the uninvited guest
that keeps showing up to the garden party.
So today we're driving into the sometimes mysterious but always
(00:23):
annoying world of fungal diseases, powdery mildew,
blight, leaf spots, all the fun things.
These issues are not just cosmetic, they can actually
seriously affect our plants productivity and the health of
the plant if we let them go unchecked.
So today on Just Grow Something,we are going to break down
exactly what causes these issues, how to prevent them, and
(00:44):
how to treat them organically and effectively using both
homemade and store bought options.
We're going to talk milk sprays,pruning for airflow, cultural
controls and more. Let's dig in.
Hey, I'm Karen and what started as a small backyard garden 20
years ago turned into a lifelongpassion for growing food.
Now as a market farmer and horticulturist, I want to help
(01:04):
you do the same. On this podcast I am your friend
in the garden, teaching evidencebased techniques to help you
grow your favourites and build confidence in your own garden
space. So grab your garden journal and
a cup of coffee and get ready tojust grow something.
So part of the reason that we'redoing this episode this time of
(01:25):
the year rather than in the spring is because it has been a
very, very rainy season, unusually so for a lot of us
here in the US And these fungal diseases in the Midsummer time
frame are not usual for us, especially here in West Central
Missouri. We are very used to having a
(01:46):
cool and wet spring and that's usually when these fungal
diseases are starting to try to run rampant and we really have
to keep an eye on them and keep them under control.
But in most instances, once we get to about the middle of July,
Mother Nature has turned the faucet off and the sun has come
out to try to cook us. And that means that the plants
(02:06):
have a chance to dry up. Even though we will still have a
high level of humidity throughout the the summer, we
still get those Suns rays to help sort of cook a lot of this
off. What we're experiencing this
year is very different from mostseasons.
We have had such a rainy July. I mean we had a very rainy
(02:27):
spring to begin with and then wecontinued into to June and now
all the way into the end of Julyand now into August.
It's just been insane the amountof rain that we have had.
So our usual humidity has been even higher.
The plants aren't really gettingmuch of a chance to dry out in
(02:49):
between these rainstorms. So if this is something that you
are experiencing, you very well may be finding that you are
having higher instances of thesefungal diseases in your garden
right now, which is not usual. So what are we up against here?
Fungal diseases come in a lot offorms, but some of the most
(03:10):
common and most troublesome onesfor us as home gardeners are
things like powdery mildew, leafspot diseases and blights.
So powdery mildew looks like a white powder on your leaves and
it thrives in warm, humid conditions with poor airflow.
(03:30):
The next one is those leaf spot diseases.
These show up has black, brown or yellow spots that can cause
premature leaf drops. So think Septoria leaf spot and
then blight. So tomato blight or potato late
blight. These are very serious and they
can actually wipe out plants in a matter of days.
(03:51):
Most fungal pathogens love wet leaves, so if your plants are
not getting the chance to dry out in between rainstorms, this
is the perfect place for these fungal pathogens to just latch
on and hold on. They also love very crowded
plants. So if you've made an attempt at
(04:11):
interplanting this year and there's not enough airflow in
between those plants right now, those plants may be experiencing
some sort of crowding conditionsfor air circulation that goes
along with the crowded plants. And then nitrogen overloaded
growth. So if you have been feeding your
(04:32):
plants, but what you're feeding them is high in nitrogen and
they're getting a lot of that really good green leafy growth,
that nitrogen overload can actually attract fungal
pathogens. Now a lot of these pathogens
will actually overwinter in plant disease or implant debris.
And so the diseases that are showing up actually mean that
(04:54):
last year's issues have become this year's issues, especially
if we're not careful and we don't pay attention to what's
going on. So one of the ways that we can
treat these fungal issues is just by essentially changing the
pH of the leaf surface. So one of the easiest ways to do
(05:20):
this with just stuff that you have in your house that is very
low cost and also impacts, you know, highly is milk spray.
Yes, milk like moo moo juice milk, cow's milk or goat's milk,
even whatever. Studies have shown that a very
simple 10% solution of milk and water, so it's one part milk to
(05:44):
9 parts water, can be just as effective as controlling or at
controlling powdery mildew as synthetic fungicides.
So I mean, you could make it higher than this.
Some gardeners go as high as 40%, but essentially, not only
are we kind of changing the pH of the leaf surface at this
(06:06):
point, but the proteins in milk react with sunlight.
So that creates compounds that basically fry the fungus.
It's like an organic little laser beam.
It's just, you know, burning it off.
So this is something that you could spray on your plants about
every, you know, week to two weeks or so during really humid
(06:26):
weather. You would want to do this either
at the very first sign of that powdery mildew coming on or even
beforehand if you know that thisis something that you're going
to end up dealing with, right? Whole, whole milk works best.
And you're going to want to apply it in the morning so the
(06:47):
leaves dry very quickly during the day.
Another homemade solution would be baking soda.
Now be careful with this becausetoo much baking soda can
actually cause leaf burn if it starts to get too hot outside.
So again, you can mix this, you mix the baking soda with the
water, but just start light and test it on a few leaves before
(07:12):
going wild over the entire thing.
Neem oil also helps in this instance, so same thing, though
too much of the oil in like the wrong weather can actually cause
leaf burns. So just know that you know
you're going to be putting this on in the early part of the day
and hoping that it is dry beforethat sun's rays start to get
strongest at between you know that like 10:00 AM and 4:00 PM
(07:35):
or or at least noon and two timeframe, right?
So always test these things very, you know, simply or very
minimally before you move on to spraying the entire plant.
Now there are store bought organic options for this because
honestly sometimes homemade justdoesn't cut it.
If you have a really really tough infection with any of
these things, you might want to look at organic fungicides.
(07:58):
So sulfur and copper based fungicides are approved for
organic use and they can both prevent and suppress a wide
range of fungal issues. My preference is for the copper
spray. I generally start spraying my
tomatoes early in the season, even in the spring.
(08:21):
So basically right as our springrains sort of start to die off
is when I normally start spraying for copper or spray the
copper spray once every week to 10 days depending on how humid
it's been and how much fungal pressure I am seeing.
Normally I will start to see that at the base of my tomato
(08:41):
plants. I'll start to see usually it's
the the blight or the satoria leaf spot.
You'll start to see yellowing leaves and the spots on the
leaves. That is a good indication that
I've got some fungal stuff goingon.
But if I start early enough, it prevents it from taking hold.
And if I continue to use it, then it's going to help suppress
those fungal issues. Now, this year has been a little
(09:04):
bit different because you're relying on that copper spray or
that sulfur spray to stay put, right?
But if it doesn't stop raining, then it can't really stay put.
So, you know, I have gone out twice this season earlier in
like the late spring, early summer when I would normal.
At first, I skipped the first application because it was still
(09:27):
raining. There was no sense in me going
out there and trying to spray anything.
But then the second time I went out, I thought I had timed it
pretty well. And I went out and I sprayed all
of my tomatoes and I pulled off the lower leaves to make sure
that, you know, that, that anything that was on those lower
leaves wasn't spreading. Sprayed everything down and
quite literally, I think it was 12 hours later, we had a
(09:49):
torrential downpour. And I know that all that copper
spray was just washed off. I, I have not gone back out and
used it again. What I am using is First
Saturday Lime and I've talked about this product before.
It is a really good filtered lime product that is not water
soluble. So that's good news.
(10:11):
Unlike like if we're using it for pest issues, people will use
like diatomaceous earth. But if you use the First
Saturday Lime number one, it's going to change that pH because
it is, it is a lime, right? So the pH is going to be much
higher than what the fungal diseases like to attach onto.
And you can do a coating of thisand you won't have to reapply it
(10:35):
as frequently if you get some rain.
Now if you are getting a deluge of rain like what I have been
getting, then it's nothing is going to hang on, right?
And you're still going to have to go back out there.
But I have found it to be a bit more effective this year just
based on the amount of rain thatwe've been getting.
So that is something that is another another option for you.
(10:58):
There is also potassium bicarbonate.
You can find this online. You can sometimes you can find
them in in the garden centers ormaybe in an AG store.
It is very similar to baking soda, but instead of being
sodium bicarbonate, it's potassium bicarbonate.
(11:19):
So it is formulated to be gentler on the plants and a bit
more effective. So this is something that you
would want to try. I will say always, always read
and follow the label for anything that it is that you're
using. The other thing you want to do
is rotate. What it is that?
You are using to prevent any kind of resistance from building
up because these fungi are theseare living organisms and they
(11:41):
can adapt the same way our insect pests can adapt to
something. So how that adaptation works is
if you're spraying something andit knocks down 90% of the
fungus, but then that 10% of thefungus starts to reproduce.
Well, the ones that are reproducing are the ones that
(12:02):
have shown themselves to alreadybe sort of resistant to the
fungicide that you are using, whether it's a store bought
version or it's milk or whatever.
And so when you come back through and you knock it down
again, then maybe it's only 80% effective and the 20% that
remains continues to reproduce. So that's that's how our
resistance gets built up. So if you can alternate what it
(12:24):
is that you're using, right? So go out there the first time
and use the milk spray and then the next time come back through
and use a copper spray. And the third time you come
through, you use say the the potassium bicarbonate or you do
a baking soda mixture, whatever.Change it up to where if it
wasn't 100% knocked down the first time, whatever was
(12:45):
remaining that was resistant to that first attempt is now being
knocked out by something completely different.
Or the third thing that you use knocks it out.
That's going to help to prevent resistance from building.
OK. You also want to apply them as a
preventative if you have had recurring issues, which once
again, is where your garden journal will come into play
(13:07):
here. OK, You're not going to know or
remember a lot of the time. Now, if you've been doing this
for years like I have and, you know, I mean, you've dealt with
it year after year after year, Yeah.
Then it's finally kind of drilled into your brain that,
oh, I really have to get out there and take care of this
before it becomes an issue. But if you are new to this or if
this is a new issue for you, make sure that you are taking
notes so that as you sit down and try to make your garden plan
(13:31):
in the offseason for next spring, you have these notes in
front of you. Which means you can put things
on the calendar to remind you, this is a time that I need to go
out and I need to start doing some preventative measures for
the fungal diseases. It's on my calendar for the
(13:51):
season at the date that I need to start.
And I just put spray copper. That's all it is.
Or spray tomatoes. I can't remember which one it
is. I think I've said spray tomatoes
and that tells me that, Oh yes, I have to get out there and
start doing it. And then make a note on your
calendar of when you did it so that seven to 10 days you can go
back out and do it again. 14 days.
Whatever it is, don't wait untilyou see that this is an issue
(14:15):
that has like latched on before you start doing anything about
it because these fungal diseaseswill spread super, super
quickly, especially in this typeof a, of an atmosphere where
we're constantly getting these rains and stuff.
So do your due diligence and usethem as a preventative or as
soon as you see the problems rearing their ugly head.
(14:37):
Roses love water. The correct amount of water
helps them grow and promotes large, long lasting flowers with
rich color and the thick, sturdypetals.
Water transports nutrients to the Rose through both the roots
and the leaves. When watering your rose plants,
remember these tips, especially in the summertime.
Water your roses early in the day, right at the soil level to
(15:00):
help prevent diseases like Blackspot.
If it's been exceptionally dry and dusty, you can spray your
rosebush with water once per week if needed.
On a sunny day, a spray nozzle will provide enough force to
clear the leaves of dust and dirt and spider mites and other
insects, especially if your areahasn't seen any recent rainfall.
Avoid routinely wetting the foliage though, especially when
(15:23):
it's overcast, because this could encourage and spread
disease. Of course, the best roses start
with the best roots and HeirloomRoses sells only healthy virus
free own root roses and they guarantee your success in the
first year. They are a family owned company
that invests in not just their roses and their employees but
also in us the customer. Their friendly rose experts are
(15:44):
available year round to answer questions and there are guides
and tutorials on their website in case you ever or get lost
about what you should be doing with your roses and the
different stages of growth and different times of the year.
Get your own beautiful healthy rose from heirloomroses.com.
I'm using code Just GROW to save20% on your purchase.
(16:05):
heirloomroses.com use code just grow.
The link is in the show notes. Now let's also not forget the
basics, right? Fungus loves moisture and
congestion, so we want to worry about our airflow, our spacing,
our cultural control. So here's what you can do.
The first thing is to prune. OK if even if you're not
(16:27):
somebody who prunes on a regularbasis like me, I've I make no
bones about the fact that I generally don't really prune my
tomatoes very heavily. I only prune like the bottom 12
inches or so only because I knowthat I have these fungal issues
that come up every single year. And so keeping those that that
(16:49):
air flow going at the bottom of the plant, number one, it's
reducing the ability for any of the soil to splash up on those
lower leaves. And that can transfer disease.
Even with a heavy layer of mulchthat can still happen.
So I make sure that I'm pruning all of that off.
But it also keeps anything from,you know, it keeps the airflow
going. And that is going to increase
the airflow all the way through all the plants.
(17:11):
And that helps. You can do this with most of
your plants, your cucumbers, your zucchini plants, the lower
leaves often times are going to start dying off anyway as the
production of your plant continues.
So if you're paying really closeattention and you're looking at
like say your zucchini plants, right, you will see where the
(17:32):
current fruiting point is. So as because essentially, you
know, squashes, even your, your Bush varieties of squashes are
still essentially a vine. And so as the fruiting point
sort of moves up that plant, theleaves underneath those fruiting
points start to die off. They will yellow.
(17:52):
I get messages all the time frompeople going, Oh my gosh, what
is wrong with my plant? These lower leaves are turning
yellow. Yes, they're turning yellow
because the plant doesn't need them anymore.
So as soon as you see that startto happen, you can start to pull
all of that foliage off of thoseplants.
This goes for your cucumbers, your squashes, your tomatoes,
lesser extent. I mean, yeah, you can do this
(18:14):
with Peppers, too. I haven't had too much of a
problem with these foliar diseases in my Peppers.
But if you do have this problem and you see that the lower
leaves are starting to die off again, any time we see the 3DS
disease dead or dying, OK, we want to get it out of the out of
the out of the garden so that pruning from the bottom is your
first step. Staking or trellising to lift
(18:36):
your plants up off the ground isalso a really good idea here.
The first few years that I gardened, I didn't intentionally
trellis my cucumbers. They happen to be planted near
something that they use as a trellis.
So that very first garden in my suburban backyard, I had put up
a a piece of lattice to sort of block off that back corner and
(18:58):
the cucumbers naturally gravitated towards that and
climbed up and through and over and intertwined in and around
that lattice. And that wasn't something that I
had planned. The next few years when we moved
to the five acre homestead, I had planted them along a chain
link fence that was up against where we were housing our
(19:20):
chickens. And again, they naturally
climbed up, but they also naturally climbed or grew out
away from the base of that fenceas well.
And that I think was when I first started to notice that the
plants that were up on the fenceessentially trellised, were
(19:40):
seemed to do better. I had less instances of diseases
in those fruits and in those plants than I did the ones that
were crawling across the ground.Now that I know better,
obviously it makes sense becausethere's better airflow around
those plants that are up off of the ground.
You also don't have the fruit incontact with the ground because
any anywhere that fruit is contacting the soil, it's going
(20:04):
to cause some soft spots. You have more of a possibility
of a transfer of fungal pathogens and stuff and that of
course can lead to it getting onto the plant and then it
continues on and on and up. This is not to say that you
can't grow cucumbers and squashes and everything else
just sort of on the ground. I would prefer if you had a
really heavy layer of like strawmulch or something in between
there. But even in that instance, if
(20:26):
it's raining constantly, your mulch is going to be wet.
So those plants are going to be in contact with that moisture.
So if you are seeing that you are having issues with fungal
diseases, this might be your opportunity to say, OK, I should
be staking these things up or I should be doing some sort of a
trellis to help lift those plants up off the ground and
further increase that airflow tomake them just a healthier
(20:49):
plant. The other thing when it comes to
airflow is spacing your plants properly so that they're not
kind of elbowing each other for room.
Now, this sounds a little counter to what I normally
preach in terms of interplanting.
But I will say there is a littlebit of a line that we walk where
(21:10):
we have we have intercropped allof our plants to take the most
advantage of the space that we have and to allow those plants
to sort of support each other and, you know, feed off of each
other for for lack of a better term.
And placing them too closely together to where they just
don't have enough room and they don't have enough airflow.
(21:33):
And you know, this is another case for keeping a garden
journal where, OK, maybe you tried inter planting for the
first time this year, or maybe you got a little bit more
aggressive about it and you put more plants into your same
space. How are those plants faring
right now? What do they look like?
Do they seem like they're struggling?
Are you having more instances offungal diseases?
(21:57):
Is that because it is super rainy in your area right now?
Or are you having your normal weather conditions and you're
seeing more fungal diseases? These are things that you put
into your garden journal so thatyou can go back in the offseason
and look at that and understand when you start to plan next
year. Or even if you don't plan at
all, at least when you go to plant next year you can go and
(22:20):
back and look at your notes and go, OK, maybe they were a little
too close together. Let's maybe give them an extra
inch all the way around this season and see how they go.
Once you have a couple of years of notes, then you can start to
develop a plan that says, OK, I know exactly how far I can push
the envelope with these plants. Now if you also are doing this
(22:44):
and you know that this year is different for you and it is more
rainy than it normally is and you have done your normal
interplanting, I tell you I packmy, especially my raised
planters. I pack them very, very tightly.
There is no shame in going aheadand removing some plants so that
all of the plants can benefit. OK, so if you have a bed where
(23:07):
you've interplanted a bunch of different things and the stuff
that normally would be thriving at this point is starting to get
a lot in terms of diseases, see what you can remove around the
base of that plant to give it more airflow or consider just
removing that plant. So you have to make the decision
as to whether or not your cucumbers are more important to
(23:28):
you or your kale is more important to you or whatever it
is that you have planted them with, right?
That's where it's up to the gardener to decide whether or
not, you know, you have to sacrifice one plant for the
health or the benefit of the other.
So, but space, you know, plant spacing is absolutely, you know,
one of the factors here when it comes to a lot of these fungal
(23:49):
diseases. And despite the rain in a lot of
these areas, you know, some folks aren't getting that type
of rain and you are having to water quite a bit.
So a way to prevent these fungaldiseases from happening is to
use drip irrigation or soaker hoses to just keep that foliage
(24:09):
dry. Even if you know, you're in an
area where you're getting a ton of rain and then all of a sudden
stops, right, OK, you're going to have to water.
So make sure that you're doing it at the soil level.
And then of course, we also wantto water early in the morning if
we can, so that any water that splashes can dry quickly.
There's always that mulch too. Using mulch is going to help
(24:32):
prevent that soil splash. And so that's another thing to
do. And once again, we don't want to
overfeed the nitrogen. That lush green flush of growth
is super tasty to fungus. They love that aphids too.
By the way, Aphids are also veryattracted to over fertilized
plants. So if you know, if you've been
(24:55):
feeding quite frequently with something that is high in
nitrogen and you're starting to see a lot of fungal diseases,
then we want to just go ahead and back off of that a little
bit. And then once we get towards the
end of the season, let's just make sure that we are cleaning
up our garden beds, we're removing and destroying any
diseased plant material. First of all, this also means
(25:15):
during the season 2, if you havediseased material, I am a, I'm a
proponent of the sort of chop and drop or, you know, prune and
just kind of drop it onto the soil because again, that's just
plant material. It's going to break down.
But we don't want to do this if the plant material is diseased
because all that's doing is justharboring that pathogen and they
(25:35):
can stick around not only in that plant debris but also in
the soil, just waiting for the ideal circumstances.
So not just at the end of the season should we be removing
this, but we should also be doing it during the season as we
are pruning for that airflow or as we are removing that disease
tissue to make sure that it's not sticking around.
(25:57):
Whether you are growing in the ground or in raised beds or
containers, be generous with your spacing if you have the
space to do it in ground. OK, if, if fungal diseases
really are a problem, then this means as we're doing our
interplanting, we really want topay attention to that high, low,
(26:18):
fast, slow mentality. You know, if you if you are
planting things together, make sure that the taller ones have
enough room around them to be able to get that air flow even
if the shorter ones are there. And if not, we can just space
them out just a little bit more.Interplanting doesn't
necessarily mean crowding. OK, So be generous with the
spacing, prune regularly and stay on top of your irrigation
(26:41):
and doing it properly. If you're not in an area that's
getting a ton of of rain right now, if you are growing in a
raised bed, airflow is very mucha key here because you have to
think you might be dealing with a little bit more humidity as
those plants are kind of tucked into a container, especially if
(27:03):
you your soil doesn't go all theway to the top right.
It's it's stopping a few inches shy of the top, which means the
plants are sort of settled down in there.
You probably need to focus a little bit more on some airflow.
So just don't skimp on that, that spacing.
And then if you're growing in containers that you can move
around, move them right even, you know, just to give yourself
(27:25):
some more air flow, separate those pots a little bit.
Powdery mildew can can sneak up really quickly on like potted
squashes or cucumbers. So make sure that you have
really good drainage in your pots.
If you have them on a porch or something where you can run a
fan out there in the afternoon when it's just super stagnant
(27:46):
and there's no airflow and it's just humid and ucky and gross.
If a fan would feel good on you,trust me, the fan is going to
feel good on your plants too. They're going to be very happy
about it. So if you can move your
containers around a little bit and give them more space to
increase that airflow, great. And and if you need to add a fan
for the health of your plants, then hey, I'm not going to make
(28:08):
fun of you. I think that's a fantastic idea,
and what it boils down to is start early.
So start applying those milk sprays or those other treatments
before the fungal problems start.
You want to stay ahead of the game.
So if that means writing it on your calendar to say that every
seven to 10 days or 14 days you're going out there and
(28:30):
you're repeating it, or more frequently if you need to, then
do that. But just make sure that if you
are having to treat very frequently that you are rotating
what you're using. Try to improve your airflow.
So prune and steak and space your plants really well.
Water smartly, so drip or soakerhoses, morning irrigation,
(28:52):
please make sure that you are cleaning up sanitizer tools.
Remove those disease plants. Rotate your crops around as
needed at the end of the season.Treat what you can and support
that plant health through the soil like we talked about last
week, instead of relying on, youknow, those synthetic sources to
to feed the plant. We want to support that plant
(29:13):
health by feeding the soil and we don't want to over fertilize
and we absolutely want to use mulch.
So if you have been dealing withpowdery mildew or leaf spots or
blight, don't panic, OK? You have the tools that you
need. You've got the knowledge now
that you need and I'm hoping this episode will give you the
(29:35):
confidence to kind of fight backagainst these fungal diseases.
It is not all is not lost when you walk out there and you see
these things occurring in the garden, but you need to jump on
the problem immediately and takeaction right away in order to be
able to sort of beat back these fungal diseases and keep them
under control until either the weather conditions change or you
(29:59):
get your first frost and then we're just done with the garden,
right? I hope this episode will help
you feel more prepared. If you know somebody who is
dealing with fungal issues, thenI would love for you to share
this episode with them. If you have tried milk sprays or
if you are having, you know, really good luck using something
specific, I would love to hear how it went for you.
(30:20):
You can shoot me a message. You can leave a comment under
Spotify or in YouTube. Just send me an e-mail reply to
this week's e-mail. I would love to hear how it's
going for you. Until next time, my gardening
friends, keep on cultivating that dream garden, and we'll
talk again soon.
Popular Podcasts
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com
On Purpose with Jay Shetty
I’m Jay Shetty host of On Purpose the worlds #1 Mental Health podcast and I’m so grateful you found us. I started this podcast 5 years ago to invite you into conversations and workshops that are designed to help make you happier, healthier and more healed. I believe that when you (yes you) feel seen, heard and understood you’re able to deal with relationship struggles, work challenges and life’s ups and downs with more ease and grace. I interview experts, celebrities, thought leaders and athletes so that we can grow our mindset, build better habits and uncover a side of them we’ve never seen before. New episodes every Monday and Friday. Your support means the world to me and I don’t take it for granted — click the follow button and leave a review to help us spread the love with On Purpose. I can’t wait for you to listen to your first or 500th episode!