Agggghhh... cabbage worms! There are my nefarious, sworn enemy, one of my very worst pests
that I deal with in the garden every year! Now this year was weird because for
whatever reason, the weather maybe- we had a very late cold snap, they actually
didn't show up until just recently, so within like the last two weeks and it's
July. And that's very rare, usually they are out and active the time that I put
all of my Brassica transplants out, so like early early April usually, and
usually they're eating up my tiny little transplants. This year I was actually
able to get most of my crops harvested before they became a problem. But you can
see in this late season stuff that's still left they are making up for lost
time. There are four main caterpillar pests of the Brassica family- so the most
common ones include the imported cabbage worm, the cross striped cabbage worm, the
diamondback moth larvae, and the cabbage looper. So the most common that I deal
with here are the imported cabbage worm and the cross striped cabbage worm and I
will show you examples of both and kind of the damage that they do. Now it's
pretty obvious once your plants get to this point that you have a problem but
you really want to catch these guys much earlier in the process. Here we've got
imported cabbage worm. A pretty heavy population on these collards and you can
see when there is enough feeding damage going on that they almost skeletonize
the entire leaf- so basically just leaving the mid ribs on these leaves and
eating all of the tender green parts.
And then we have the cross striped cabbage worm on these kohlrabi leaves
and here you can see how the damage starts which is you start to see these
holes kind of eaten through the middle of the leaves. Now one of the two signs
that you can look for to identify cabbage worms of any type early on is
the chewing holes in the leaves and piles of frass at the base of the plant.
Now frass is just a fancy word for bug poop basically, but with cabbage worms it
is really obvious because, because of their diet their frass tends to be like
a dark green little speckles and it's easy to see, sometimes in the beginning
easier to, easier to spot than the actual worms themselves. Fortunately there are
several very effective methods to keep cabbage worms from inflicting this much
damage on your crops. The first is the use of row covers. You can use a
lightweight row cover, there are a lot of different options out there, but the key
with row covers is timing. As I mentioned in a typical year for me the cabbage
whites, which are the adult imported cabbage worm butterflies, are out and
active very early in the spring you want to get those row covers on as soon as
you set your transplants out or as soon as seedlings emerge from the ground to
prevent the adults from laying any eggs on the plants. The other key is to keep
them securely fastened to the ground so that there aren't any big holes or gaps
where the adults can fly in under the covers. Another tactic is to encourage
the natural predators of the cabbage worms. One of the most effective and
lethal is the parasitic wasps. Now you can encourage their presence in the
garden by planting plenty of things that they feed on. So they prefer the nectar
from small flowers- so think cilantro, parsley, dill when it
bolts and goes to flower, things like that. Other natural predators include
shield bugs, ambush bugs and birds. And in general you can encourage these species
just by keeping your plantings mixed and providing a little bit of something for
everything, rather than planting say, entire blocks
of just broccoli. If you mix it up with other with other species, with herbs, with
flowers, that's a good way to bring in a lot of diversity to your garden.
The next tactic is the use of trap crops. So you may have noticed in gardening
that with certain pests there is always a crop that they seem to prefer the most.
And this is the case with cabbage worms as well. One of the most highly
recommended trap crops for cabbage worms is collards. Now the idea of trap crops
is that you plant a block of the pests that you're dealing with most preferred
food source in the hopes that you will lure them to eat that trap crop rather
than the crop that you're trying to grow for food. So if I'm trying to go broccoli,
but I plant a trap crop of collards, the idea is that the cabbage worms will go
to the collards rather than feasting on the broccoli. Now with trap crops you can
either just let the crop grow and let the pests eat that crop and and just
stay on that crop, sometimes people will actually prefer to let the crop get
highly infested and then do something like use a flame weeder to burn the
whole thing down, sometimes use a BT spray which will kill caterpillars or
other methods to destroy that crop and all of the caterpillars that are on it.
Now I planted a trap crop of collards this year and while the cabbage worms
definitely seem to prefer the collards, they're eating them down to
just the the stems basically, I still have a lot of worms on my other
brassicas, so I'm finding that in and of itself trap cropping is not entirely
effective but when combined with other methods it's definitely useful.
Another thing that you'll want to do is make sure to eliminate weeds around your
garden that may serve as host plants for these pests. So that would typically be
things like wild mustards and wild rockets, kind of again, anything in that
Brassica family, because if the cabbage worms have a large population of host
plants, even if they are weeds, that's just going to encourage their
populations to grow and when you finally do put out your garden transplants guess
where they're gonna go? Now related to the idea of diversifying your plantings
is the concept of crop confusion. So as I mentioned- not planning huge blocks of
one single crop, breaking them up with other crops of other species helps cut
down on the pests ability to just have one giant smorgasbord.
So think if you plant a cabbage here and a cabbage there and a collard over here
but in between those plantings you have things like cilantro or dill or wormwood
or just basically anything that is not in the same Brassica family. It won't
stop the pests but it will slow down their progress. And along with that you
can incorporate known plants that will repel pests- so things that the pests
don't necessarily like and this includes things like wormwood, thyme, marigolds,
tansy and peppermint. So if you notice in that list it's a lot of very strong
smelling herbs, but breaking up your plantings with these kinds of things
again, in and of itself won't get rid of your cabbage worm problem, but all of
these things together will help to organically cut down on the pest
populations that you're seeing in your garden. A relatively easy form of cabbage
worm control is hand picking. So if your population is small enough and
you just want to go out and check your plants every day or every other day and
you can squish the cabbage worms that you find, you can pick them off and throw
them in soapy water, you can feed them to your chickens, anything to dispose of
them. Now the internet is full of wacky ideas, we all know this. One that I came
across earlier this year was the idea of using decoys.
The claim was that with imported cabbage worms- or the cabbage white butterflies
that they are territorial and they don't, they won't come and lay eggs on a plant
where they already see an adult butterfly working. So you make these little decoys
that look like cabbage butterflies and put them near your brassicas to prevent
infestation from real cabbage butterflies. Well I made a bunch of these
and put them out early the spring but since my cabbage whites didn't actually
show up till almost July I really didn't get an accurate reading on whether this
was effective or not. Now it's, I mean it's an easy thing to do, it was worth a
shot. If anyone has tried this and had it work for them I would love to hear from
you because if it works it's such a simple solution! But I'm kind of dubious
as to whether it will actually work. And the final kind of last resort tactic
that I will take if I really can't get my populations under control and they're
destroying my Brassica crops is the organic sprays. Now there are several
different products that will work on cabbage worms. My go-to is bt spray. So bt
is a bacterium that is naturally occurring in many soils around the world
and you will spray your Brassica crops with this the caterpillars will ingest
this and it kills them. In general it's regarded as environmentally safe and it
has no effect on non-target species. The thing to keep in mind with bt is that it
is effective on all Lepidoptera, so it will also kill things like swallowtail
butterfly caterpillars, monarch butterfly caterpillars, so you really want to be
careful where you're spraying it. Now typically, like a Swallowtail is not
going to feed on the same crops as a Brassica pest, so in general if you're
keeping the spray targeted to just your brassicas you're not going to be killing
off caterpillars that you want to be keeping in your garden.
Spinosad is another naturally occurring substance from soil bacterium and it's
typically effective within one to two days of spraying. Now spinosad is toxic to
honeybees until it is dry so you absolutely want to avoid spraying when
honeybees are active. Again with the Brassica crops because they're typically
not blooming when you're spraying I don't see a lot of honeybee activity on
or near the crops that I'm spraying it's just something that you want to be very
careful with. I've also heard that diatomaceous earth and neem oil will be
effective against cabbage worms I've not personally tried these but if
you have a lot of problems with cabbage worms they may be products that are
worth looking into. So if you are battling cabbage worms of any type in
your garden I wish you best of luck and I hope that some of these tips help! And
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channel Growfully with Jenna. Thanks for watching and I'll see you next time!