Everything You Need To Know On Broccoli Early Blight (And Other Pests…)

broccoli disease

Have you noticed that your broccoli plant is suffering from blight? You are not alone! Perhaps you are asking yourself what causes early blight on broccoli.

What Is Early Blight On Broccoli?

Broccoli’s early blight is due to a fungal pathogen named Alternaria Solani. It consists of a form of chlorosis (some sort of leaf anemia) that rapidly develops a browning of the plant tissue, such as leaves, branches, or floral organs. Eventually it will lead to death.

Despite being relatively easy to grow, broccoli can suffer from numerous diseases. In this article, I want to share with you the most common pests and diseases that attack our beloved plants. Broccoli is undoubtedly one of the most cultivated vegetables in our gardens. With its inviting flower and foliage, it is a delight for the eyes and the symbol of a prosperous garden. Packed with minerals and vitamins, broccoli is a constant presence on our tables, and we’ve learned to appreciate them both raw and cooked.

Broccoli is relatively easy to grow with the right conditions, and healthy plants usually could resist a light infestation without our intervention. However, several diseases and pests frequently infest our beloved plants. In this article, I prepared a list (with recipes when needed) with the most common diseases and fungi infestation that broccoli suffers from.

First Signs Of Early Blight Infestation

Early blight fungus will appear first in the form of small dark spots on the leaves with a distinctive “bullseye” pattern. These leaf spots will then turn from brown to gray and eventually develop into lesions. These lesions may form concentric rings and usually crack in the center. Infected leaves soon turn yellow and drop. This disease occurs when conditions are moist, for instance, if it has been hot and rainy weather.

How to minimize the damage:

  • Utilize a fungicide at the first sign of the disease
  • Try not to spread the infestation to other crops or other parts of the garden. Clear infected debris (foliage, dead plants). Clean your boots and garden tools to prevent the spores from falling into other parts of the garden.
  • Avoid watering in the evening. Water your broccoli crop in the morning to expose the plants to a wet environment for the shortest amount of time.
  • Use a drip irrigation system if possible. This should minimize leaf wetness
  • Rotate your crops. Don’t put any plants from the cabbage family (Coneflower, Broccoli, Cabbage, Kale) on that part of the land for at least three years.
  • Closely monitor your crops, especially in warm damp weather when it grows fastest, and spray with an organic fungicide if necessary.
  • Plant resistant cultivars.
  • Plant your seedlings further apart. By doing this, it will increase air circulation between your broccoli rows. The lack of air circulation and moisture are the optimal conditions for the growth and spread of early blight.

How to make organic fungicide to use against early blight on broccoli:

you can prepare at home a powerful organic fungicide at home. Avoid using chemicals on your veggies. Here is the recipe:Mix in a bowl the following ingredients:

  • 1 ½ cup of water
  • 1 tbs of baking soda
  • 1 tsp of vegetable oil or Neem oil
  • 1 tsp of Castile soap or any other eco-friendly organic dish soap.
  • Pour the mixture into a spray bottle and apply directly on the leaves.

Other Fungus-Like Diseases Of Broccoli

Clubroot (Plasmodiophora brassicae)Clubroot is quite a common disease in broccoli plants. It is caused by a fungus-like micro-organism named Plasmodiophora Brassicae. Once infected with the crops, the fungus can survive in the soil for many years. This disease spreads in moist acidic soil conditions deforming the roots of the plant, which develops clubs. When the fungus attacks the seedling, they will die. If the plants are mature, the disease rarely kills, but the roots will be severely distorted. They will have a reduced capacity to absorb nutrients from the soil. Downy mildew (Hyaloperonospora parasitica)

The fungus Peronospora Parasitica causes downy mildew. This disease thrives in moist, growing conditions. Usually, it attacks crops that don’t get enough air circulation. The signs of infestation are gray mold on the leaves with black spots on the surface. The disease can survive in the soil for many months, even in the absence of a host.

Disease Control:

  • Plant a more robust broccoli cultivar, resistant to the fungus disease such as Green Magic or Windson.
  • Plant your seedlings further apart. This will increase air circulation between your broccoli rows.
  • Water in the mornings. Install an irrigation system so as not to wet the leaves.
  • Remove all plant debris after harvest as well as from your boots and gardening tools, to prevent spreading the disease in other parts of your garden.
  • Regularly rotate crops.
  • Apply organic fungicides.

Blackleg : Blackleg disease in broccoli is caused by the fungus Phoma Lingam, which overwinters in soil, on crop debris, and in infected seeds. Blackleg usually starts on seedlings two to three weeks from transplantation. The disease develops in moist and windy conditions, and it is easily spread by irrigation and water splashes. Blackleg symptoms are small brown lesions that expand into circular areas with gray centers covered in black dots. Disease control: There is no effective treatment against Blackleg. The best cure is prevention. The rotation of crops every three or four years is the best way to treat this disease.

Which Other Pests Attack The Broccoli Plant?

Here is a list of the most common ones:

1. Aphids: Turnip aphids and cabbage aphids, usually appear green or gray and are the two most commonly found on broccoli plants. These are small sap-sucking soft-bodied insects and could be lethal for our broccoli if the infestation is not stopped in time. If you suspect your plant is suffering from them, it is relatively easy to spot them by looking under the broccoli leaves.

Pest Control: You can kill them quickly with either garlic spray or soapy water spray. Here you can find the recipe on how to prepare these organic pesticides.


2. Cabbage Loopers: Cabbage loopers are the larvae of the cabbage moth. They are small green caterpillars that love to feast on broccoli leaves. This critter is not significantly destructive; however, it can become challenging to manage, depending on the size of the infestation.
Pest Control: Handpicking would be a solution; however, it is time-consuming. Release of Bacillus Thuringiensis (Bt). Bt is also valid on several other pests common to the brassica family, such as the imported cabbageworm and the cabbage webworm. You can read more about the Bacillus Thuringiensis here.

3. Cutworms: Cutworms are dark moth larvae. They are soft-bodied caterpillars, 1-2 inches long with colors that range from grey to black. These larvae feed on plant stems at or below ground, eventually cutting them down. They are very active during the night and hide under the ground during the day.
Pest control:*

  • Handpick them at night.
  • Spread some Diatomaceous Earth on the base of the plants
  • Make plant collars when planting broccoli seedlings
  • Release Beneficial Nematodes
  • Release Trichogramma Wasps around the time the dark moths lay their eggs in your garden.
  • Sprinkle a mix of coffee grounds and eggshells around the plants
  • Apply some B.T. (Bacillus Thuringiensis), which is organic insecticide.
  • Grow tansy close to your crops

*For further information on how to get rid of cutworms, I wrote an article that you can read here.

4. Harlequin Bug The harlequin bug is a sap-sucking insect with orange and black colors. It is one of the most feared cabbage pests. This critter can destroy the entire crop where it is not controlled. The signs of Harlequin bug infestation are crops with dead brown leaves which are caused by bug’s saliva injected into them. Pest Control:

  • Neem Oil Spray. To know how to make this spray read here.
  • Handpick the bugs
  • Plant a trap crop of mustard or kale to attract the insects away from the broccoli crop

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Anat Goldberg

Hi! My name is Anat and I have lived all my life in the countryside. I grew on a farm in Northern Italy and from an early age, I took care of the animals on the farm and the family garden. Over the years I have developed a growing passion for organic cultivation and pest control.

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