Holes In Kale Leaves – Common Causes & Solutions

When you notice holes in your kale leaves, there can often be a number of factors behind what’s causing it. And knowing the cause is vital for treating it as well as preventing it from happening again in the future. In this article, not only are you going to find out all the things that can cause holes in kale leaves, but you’ll also learn the treatment and prevention methods!

So keep reading to find out everything you need to know!

What’s Causing Holes In Your Kale Leaves?

There are going to be two main causes of holes in your kale leaves. The first cause is pests and the second cause is diseases. And as a heads up, generally speaking pests are going to be much easier to treat and prevent compared to disease.

What Pests Cause Holes In Kale Leaves?

There are a number of different pests that can cause holes in your kale leaves, and most of them you will have probably heard of before. So let’s start with one of the most common ones.


Aphids are extremely common pests and if you’re growing plants outdoors, then the chances are at some point you’re going to come into contact with them.

They damage plants by biting a hole into them and sucking the nutrients out. When they do this, not only are you going to notice small holes in your kale, but you’ll also notice that the leaves become discolored and may even become fuzzy.

They also leave behind honey dew. A sticky substance which increases the chance of fungus and bacteria growing on your kale.

And of course, the most clear sign that aphids are on your kale is when you actually see them. If you’re lucky, there’ll only be one or two, but if you’re not then there could be a whole a bunch of them.

How Do You Treat Kale Infested With Aphids

Fortunately, if your kale is infested with aphids there are a few things you can do to remove them. The easiest method is just to remove them manually. You can either do this by picking them off with your hands or spraying them with a hose.

If the problem is more severe then you may also need to introduce a predator such as ladybugs or parasitic wasps to remove them.

And lastly, you can try using pesticides. If you’re not too thrilled about the idea of non-organic pesticides, then neem oil can be a great choice. Just be aware it’s dangerous to bees, and you’ll need to wait a day after spraying your kale with neem oil before you can eat it.

If you don’t mind using stronger pesticides, then insecticidal soap can greatly reduce the number of aphids attacking your kale. Just make sure you’re using soap safe for edible crops, and that you’re reading the instructions carefully.

How Do You Prevent Aphids Eating Your Kale

Fortunately, there are a number of ways you can prevent aphids from infecting your kale and eating it.

One of the first and easiest ways is to place catnip around your kale. Aphids are repelled by catnip, however, of course, you may end up attracting cats (so you’ll need a repellent for them too.)

You could also try planting plants such as mustard and nasturtium close to your kale. Both of these plants are particularly attractive to aphids and they’ll choose to eat them over your kale.

Just like you can use certain insects such as ladybugs to treats aphids, they’re also a great method to prevent them as well!

Flea Beetles

Flea beetles are tiny, so you wouldn’t expect them to do much damage to your kale. However, the sheer number of them is the reason they can be so damaging to kale. While one flea beetle will only leave a couple of tiny holes in your kale. The amount they normally turn up in can completely ruin your kales leaves!

How Do You Deal With Flea Beetles?

When you’re dealing with flea beetles there are a couple of different treatment options available.

The easiest method is to sprinkle your kale with Diatomaceous Earth. If you don’t know, fossilized micro-organisms make Diatomaceous Earth, and on a microscopic level, they’re extremely sharp and damaging.

When the flea beetles inhale the DE it’s going to damage their respiratory systems, eventually killing them. And the best part is, it only harms small insects and animals. It has no effect on larger animals like us (although you should still give your kale a wash).

Spinosad which is made up of bacteria harmful to flea beetles is another product you can choose to spray on your kale as well. While contact will kill the flea beetles, ingesting it is much more effective, so make sure you’re giving it a few days before you start looking for any changes.

And once again, using Neem oil is another effective method for removing flea beetles. Just make sure you’re washing it off and waiting a day before eating your kale.

How Do You Prevent Flea Beetles?

Here are some great ways you can prevent flea beetles from attacking your kale in the first place. So if they’ve been a problem in the past, then you’re definitely going to want to prevent them!

One great natural way to prevent them is with beneficial nematodes. When nematodes are added to the soil they’re going to kill the flea beetles larvae which greatly reduces the number of adult flea beetles as well as reducing root feeding as well!

As well as adding nematodes you can also use yellow sticky traps to capture the adults as they’re migrating from plant to plant.

And of course, once again using crops like mustard and radishes are another great way to divert the pests away from your kale.

Harlequin Bug

Just like aphids, harlequin bugs suck the sap from your kale leaves creating holes, as well as causing the kale to brown and wilt. You’ll be able to tell harlequin bugs from other insects due to their shield shaped bodies which are either black and red or yellow.

How To Treat Harlequin Bugs

If you only notice a few harlequin bugs on your kale, then once again, the easiest thing you can do is remove them from the leaves by hand or spray them off.

However, if they’re more of a problem then using neem oil and spinosad is an effective measure for removing them

You can also release parasitic wasps into your garden to help keep the numbers low, and if you’re feeling like taking on another project, guinea fowl love eating garden pests like harlequin bugs.

Row covers are another effective measure against harlequin bugs as well! Just make sure you string them up over your kale, and weigh them down thoroughly so that no harlequin bugs can get underneath.

How Can You Prevent Harlequin Bugs

One of the simplest ways you can prevent harlequin bugs from infesting your kale is by making sure you’re keeping your kale weeded and clean. If there’s lots of places harlequin bugs can hide then you’re not going to be able to remove all of them as easily.

This is especially important once you’re done growing kale for the year (if you’re growing outside). This way you’re going to make it much harder for them to survive the winter, and you’ll likely massively reduce the population in your garden.

Imported Cabbageworm

You’ve probably seen a cabbage white butterfly in your garden at some point. And if you notice them in your garden, then you may want to double check your kale, as they may have been infested with imported cabbageworms.

Unlike their adult form, imported cabbageworms are green in color, and if they’ve infested your kale then you’ll notice large holes on your kale as well as the edges of your kale leaves missing.

And if left untreated, they can cause massive amounts of damage to all your plants.

How Do You Treat Imported Cabbageworm?

There are a few different ways you can treat imported cabbageworms, so make sure you pick the one that seems best for your crop. A lot of cabbageworm will require different treatments when compared to kale that is only suffering from a few.

The first and easiest way to remove imported cabbageworms is picking them off by hand. Not only should you pick the cabbageworms off, but you should also pick off their eggs as well. Once you’ve picked them off, add them to a container of soapy water to kill them.

If you don’t mind using insecticides, then bacterial insecticides can be an effective way of controlling and removing imported cabbageworms. Baccilus Thuringiensis Kurstaki is the standard insecticide to use, and in most cases, you can still eat your kale the day after spraying it. (Just make sure you check the label first.)

How Do You Prevent Imported Cabbage Worm?

If you’re wondering how to prevent imported cabbage worms then they’re actually a lot easier to prevent than other pests on this list

The first way to prevent imported cabbage worms is to cover your plants with row covers to prevent the imported cabbage worms. These are going to stop the adult butterflies being able to lay their eggs on your kale.

Once again, another great way is to grow other plants around your kale that attracts cabbageworms. Mustard is a great choice as it attracts pests, however, thyme can also be used to repel them too!

And lastly, another great choice is using parasitic wasps which will eat the cabbageworms on your kale as well as laying eggs inside of them.

Diseases That Can Affect Your Kale

As well as pests, there are also a few diseases that can also affect your kale. So it’s important that you’re able to differentiate between the different diseases.

Leaf Spot

Leaf spot is a common blight that affects kale and you can read more about it here.

If you’re kale is suffering from leaf spot you’ll notice black holes beginning to cover it. There are two causes of black leaf spot, it can either be fungal or bacterial.

When your kale is suffering from either leaf spot you’ll notice that they’ll have holes which are yellow, brown or black on the outside with concentric rings going around them.

The spots can range in size from 3/16 of an inch all the way up to 1/2 an inch.

How Do You Treat Leaf Spot

The best ways to treat leaf spot are removing the infected leaves as well as using baking soda and spraying them with neem oil.

However, it’s important to note, once leaf spot sets in, it can take over kale and there’s not much that can be done to prevent it.

How Do You Prevent Leaf Spot

Leaf spot is much easier to prevent than treat. If you’re going to try and prevent leaf spot, make sure that you do the following.

  • Buy Disease Free Seeds
  • Add Mulch
  • Keep Good Airflow
  • Remove Cruciferous Weeds
  • Rotate Your Crops
  • Keep The Soil Clean
  • Avoid Cross Contamination

If you want to know everything there is to know about leaf spot then make sure you check out this article.

Black Rot

Another disease that your kale could suffer from is black rot. This is most likely to happen in warm damp conditions, so if you’re growing your kale outside especially you need to be aware of this.

If your kale begins to suffer from black rot then you’ll notice the following.

At first there’ll be a v shaped patch on the leaves that’s either yellow or brown. The V itself points inward and as the black rot becomes worse it slowly expands turning the whole leaf yellow and the veins inside the leaf to brown and then black.

As it goes from leaf to leaf the whole plant will begin to look lopsided and it some cases it will look completely burned.

How Do You Treat Black Rot?

The most effective way to treat black rot is to prune your kale, removing any leaves that have been infected. With each new leaf you cut, however, make sure that you’re thoroughly disinfecting your tools, otherwise, you risk infecting other plants.

As well as this, you should also try giving each of your kale plants more space. This way you’re going to help improve air circulation which will reduce the spread of black rot to other leaves.

If you’re growing your kale outside then you’ll need to remove any weeds that are surrounding your kale. Not only are they going to house black rot spores, but they’re also going to affect air circulation.

And if you’re really desperate you’ll need to use a fungicide to treat black rot in kale. Captan is the most widely available and common fungicide to use.

If you catch it early enough, it may also be a good idea to remove the plants completely from your hydroponic system or garden to prevent it spreading to other plants.

How Do You Prevent Black Rot?

The first thing you can do to prevent black rot in your kale is buy disease free seeds. While they may be a little bit more expensive in the beginning. In the long run they’ll end up becoming much cheaper.

You should also rotate where you’re growing your kale every year if you’re growing them in soil. This way the black rot wont’ have time to build up. While black rot can infect many different plants. It tends to specialise on one type over time.

And of course, grow kale hydroponically! When you grow kale hydroponically the chances of disease and pests is going to be much less likely as you control all the conditions!


Now you know all the different reasons that your kale could have holes in it. Prevention is always going to be better than treating your kale, but if you do have to treat it, fortunately, there are many treatments available.

If you liked this article check out the rest of the website! Otherwise have a great day!

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