How To Protect Kale From Diseases And Pests

In spite of kale’s being considered to be an alkaline plant, hardy and healthy, it is often at risk of both pests and diseases under particular conditions.

Before taking any action, you should know the crops’ issue. The diseases that affect kale include a number of bacterial pathogens, together with several fungi that can affect kale.

Most kinds of insects can infect the plants, which range from flea beetles to thrips and cabbage butterflies. You can use floating row covers to protect kale.

The covers help avoid splashing water, which might have pathogens, from reaching the plants, and preventing bugs from laying eggs on the kale.

Additionally, working with heat-treated seed will protect against several diseases and specific bacterial pathogens.

With proper care, you can safeguard the plants from these threats and have healthy and tasty kale.

In this article, you’ll see the different pests and diseases you may get on your kale.

Pathogens and pests that attack kale

A range of pathogens will attack kale, which includes several fungal infections which are brought about by vicious nematode, water molds, and scaring kinds of bacteria.

Fungal infections that affect kale

Though rare, many fungi that attack this plant can be destructive pathogens.

  1. Colletotrichum Higginsianum (Anthracnose)

This fungus usually causes round, dry, lesions on your kale plant leaves; and puts them at risk of bacterial soft rot. Infection sources include fallen leaves, some kinds of weeds, and infected seeds.

Luckily, anthracnose is possibly to take place during warm moist conditions, not usual kale growing weather. You can use fungicides to control this infection.

  1. Alternaria leaf spot (Alternaria brassicae, A. Brassicicola)

Alternaria leaf spot is a condition popularly referred to as “black spot.” It causes the formation of dark spots on the kale leaves. The abrasions might appear like a mark that has coordinated rings.

This disease will probably be an issue in moist, warm conditions. Some of the ways to manage include cultural means, like keeping the best air circulation between plants, using free from disease seeds that are heated with water with 122 degrees Fareigheight for fifteen minutes.

This helps to kill cruciferous weeds and rotating crops. In addition, find ways of keeping the leaves of kale dry. This will help in preventing any fungi from obtaining a footing.

If you opt for irrigation, do that early morning and make sure the spray stays at the plant’s base, off the kale leaves. You also have the option of spraying biofungicides like B. subtilis (Serenade) or Bacillus amyloliquefaciens (Double Nickle). Another good option is liquid copper.

  1. Damping off (Rhizoctonia solani, Pythium SPP.)

This is the cause of the destruction when seeds flop to germinate, or worse, the seedlings wither and die.  It is good to note that there are ways of preventing the seedlings from getting affected. 

  1. Downy mildew

For ages, downy mildew has been know to be a fungus, and in fact when you look closely it actually appears like one. However, more research has resulted in its being given another classification as oomycete or water mold, something more similar to algae.

Downy mildew will cause issues under moist weather, like high humidity, fog, heavy dew, and drizzling rain. It’s easy to know if your kale is infected as the leaves’ bottom will have downy gray patches.

The upper surfaces of the leaves will show yellow patches, which later with take a light brown. The right way of managing this disease is by practicing prevention. This can be achived by crop rotation, which aren’t crucifiers. If the disease is severe, you might have to turn to fungicides.

Water mold diseases that affect the kale plant

Though these molds aren’t seen as fungi, they appear the same and cause destructing diseases on most plants.

Best products for controlling common pests on kale


No products found.

You can get a number of different Btk formulas for killing caterpillars. This product won’t harm birds or helpful to insects. You have the choices of liquid concentrates or spray-on Monterey Bt liquid.


Safe for bees and earthworms

When you follow instructions of use, this product doesn’t affect earthworms, birds, or helpful insects like ladybugs or honeybees.

Protects plants

This product is made for use on a range of foliage, which includes ornamentals, tomatoes plants, melons, mustard greens, cabbage, broccoli, shade trees, lettuce, cauliflower, turnip greens, celery and much more.

Kills insect

This insecticide is made to use on caterpillars and worm kind insects, like elm spanworm, gypsy moth, cabbage looper, fall cankerworm, bagworm, and much more

Ready for using

This insecticide is ready for you to use when it’s shipped. You should apply directly from the bottle that features a trigger sprayer.

  1. Bonide (BND255) – Captain Jack’s Dead Bug Brew
Bonide Captain Jack's Deadbug Brew, 32 oz Ready-to-Spray Outdoor Insecticide and Mite Killer for Organic Gardening
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Bonide Captain Jack's Deadbug Brew, 32 oz Ready-to-Spray Outdoor Insecticide and Mite Killer for Organic Gardening
  • INSECT KILLER - This pest control is great for use on bagworms, borers, beetles,...
  • VARIETY OF FOLIAGE - Protects a wide variety of plants including fruiting...
  • TARGETS PROBLEM INSECTS - Product is intended for control of listed insects. It...

This is the best organic pesticide/ insecticide for bagworms. Bonide is a certified organic pesticide for organic gardeners. It features spinosad, and you are aware that spinosad is an organic bug killer, which originates from soil bacteria.

Bonide is an effective product for controlling leaf miners, loopers, moth, caterpillars, bagworms, thrips, spider mites, borers, beetles, and other garden bugs. It’s also a contact pesticide, which means it will only work when the bugs come into contact with the spinosad formula.

The product is available in a hose-end sprayer container and is ready to spray solution. To treat the plants affected by bagworms, just attach a garden hose with a hose-end sprayer, and begin to spray on your plants until the leaves lower and upper surface wet entirely.


Organic gardening

The active ingredient in Captain Jack’s Dead Bug Brew is a natural bacteria referred to as Spinosad, which is a top pesticide used globally. 

It will target problem bugs

Bonide is meant to control listed bugs. It doesn’t greatly affect spiders, predatory mites, and helpful predatory insects while it controls target insects.

Plant variety

It will help protect an array of foliage, which includes pome fruits, stone fruits, leafy veggies, cucurbits, fruiting veggies, bushberries, tuberous veggies, and cole crops.

Kills insects

This product is perfect to use on thrips, leaf miners, spider mites, gypsy moth, beetles, bagworms, codling moth, tent caterpillars, loopers, borers, caterpillars, and many more.

Ready for spraying

Bonide is shipped in a container with a connected hose-end sprayer. Just attach a garden hose to the sprayer and start applying the insecticide.

Bacterial diseases that infect kale

These are popularly found in your kale plants:

  • BLACK ROT (Xanthomonas Campestris PV. Campestris)

It aquires its name as infected leaves take a black colour wither and die in the last phases of the disease, which leaves the entire plant decayed. Symptoms that manifest in the first stages of the disease are V-shaped abrasions on the leaves’ margins.

The disease often spreads through infected seeds, which are unintentionally harvested and put on the market. Most companies that sell seeds always test for this bacterial pathogen, given its harshness.

As with this disease, the ideal way of saving your plants from this deadly disease is prevention.

  • Bacterial leaf spot (Pseudomonas syringae PV. maculicola; Xanthomonas campestris PV. Amoracia)

The severe diseases brought about by these two pathogens are easily spread by splashing irrigation or rainwater. You can prevent these diseases with floating row covers. Symptoms include leaves becoming yellow, and in worse cases, leave might die. The best way of controlling this disease is prevention.

Insect pests that attack the kale plant

Unluckily, a huge number of insect pests like feeding on kale. But luckily, most of these insects have treatments available.

Beet Armyworm (Spodoptera Exigua)

You will probably find that you’re battling this caterpillar when you see skeletonized leaves; caused by heavy feeding by the larvae. You will notice unevenly or round-shaped holes. Older caterpillars are darker gree, and young ones are pale gree to yellow.

The caterpillars feature pink or yellow undersides and distinctive light and dark lines along their bodies’ sides. The chemicals offered for controlling these caterpillars aren’t often very effective; however, Bt (Bacillus thuringiensis) is an effective choice for controlling beet armyworm.

Cabbage Aphid (Brevicoryne Brassicaea)

These can be disastrous to kale and other crops. Cabbage aphids are easy to identify as they have a white, waxy coating. If a few cabbage aphids are visible, prune the infected leaves.

But big populations will stunt the plant’s growth or kill it as well. Try to spray using canola oil, neem oil, or use insecticidal soaps to destroy an infestation.

Thrips (Frankliniella Occidentalis; Thrips Tabaci)

Not only will these pests cause destruction, but they will also spread viruses. Thrips are hard to identify, as they are tiny, with a length of just around 1.5 millimeters. The nymphs have a lighter color, and the adults light brown to pale yellow.

But the damage done by these pests is anything but minimal. Destroyed leaves might be deformed and will have a silver color. You can use reflective mulch early in the season to prevent thrips.

Do not plant alongside crops that often appeal to huge populations. These include growing garlic, onions or cereals. If your vegetable patch population becomes very big to manage and there’s major crop damage, you can use insecticidal soaps or neem oil to control them.

Pieres Rapae (Large cabbage white) and Evergestis Rimosalis (cross-striped cabbageworm) 

It may appear like the butterfly is nice-looking, the hairy, green caterpillars will fast cause far-reaching damage to the plants.

A telltale sign of the caterpillars is that they seem to be gliding very slowly, causing the leaves to have big, ragged holes. If you anticipate an infestation since you have had issues previously, set up floating row covers before the butterflies begin to fly around to lay eggs.

If the infestation starts, you can use your hands to pick them off the crops and eliminate them. In case you see them early, use Bt. Later on, use spinosad or pyrethrin to control them, though such organic compounds can harm helpful insects.

Root-Knot Nematode (Meloidogyne SPP.)

At first, your kale plants may get infested with these roundworms when they wilt in the noon sunshine. The plants might be stunted and grow unevenly as well. You should unearth a plant and look; the roots can have distinctive galls.

Unluckily, kale is sensitive to all species in this big genus. The good thing is, these roundworms are most active during the summer season when kale is hardly ever grown. Sandy, well-drained soils are often prone to nematodes.

You can prevent their infestation by rotating the land with a grass crop for at least 24 months. Make sure you avoid broadleaf crops, as most are hosts for the insects.

You can get nematicides for killing nematodes; however, they can be created with compounds such as chloropicrin.  There aren’t any chemical choices for home gardeners for controlling nematodes.

Now that you are more knowledgeable about protecting the plants from garden pests and diseases affecting kale, you will be able to enjoy a new crop yearly without any concerns.

Flea Beetles (Phytlotreta SPP.)

If the kale leaves have several small holes in them, It’s most likely flea beetle infestation. The glittery black insects jump when distraught. Younger plants are more prone to damage, but big plants will stand an infestation.

If you are aware that these pests will probably be an issue in your region, you can install floating row covers to help keep them off the crops. Another choice is using trap plants of some other kind of crucifier, like a radish.

Additionally, you can mulch your soil to ensure they don’t come out of the ground during spring. Effective choices for controlling these insects are applications of diatomaceous earth or sprays of neem oil.

Diamondback Moth (Plutella xylostella)

These moths’ larvae are unique as both ends are tapered. The rear end of diamondback moths features V-shapes prolegs. You will often notice larvae in between the leaves’ upper and lower surfaces.

These pests will create tiny holes on the leaves’ bottom and can be noticeable coming through the top. Helpful bugs can help in controlling these larvae. 

In roughly 14 days, the larvae mature and spin cocoon-like fog on the leaves and stem to pupate. You can use Enthrust or Bt to control these insects. One benefit of using Bt is that it cannot affect the helpful pests.


These are very destructive, as they lie in wait in the soil. It will also take a while to see the damage caused.

Cabbage Looper (Trichoplusia NI)

You can recognize these caterpillars by the way they are moving. Cabbage looper caterpillars drag their legs back toward the front legs. This forms a nearly round loop before extending their bodies once more.

These pests have a length of between 1.5 and 2 inches and chew up big, unusual-shaped holes in the plants.

Natural enemies, which include wasps, pirate bugs, ladybugs, and spiders, will eat the larvae and eggs and often keep the cabbage looper caterpillars in check. But if you want to, you can use pyrethrins or Bt to control these pests.

Last update on 2023-03-31 / Affiliate links / Images from Amazon Product Advertising API