Brassica campestris White Cottony Spots - Causes & Fixes

Jump to cause: Powdery Mildew Cottony Aphid Colonies Sclerotinia Sclerotiorum (White Mold)

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Powdery Mildew

This fungal disease, caused by species like Erysiphe cruciferarum, manifests as white, flour-like patches on the leaves of Brassica campestris. It thrives in high humidity and moderate temperatures, eventually causing leaves to yellow and wilt.

Very Common

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How to confirm: Check if the white spots can be rubbed off with your finger, leaving a dusty residue behind.

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shopping_cart Recommended Products

1 Apply an organic fungicide to eliminate existing fungal spores and prevent the spread to healthy leaves.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

$12

In Stock

2 Improve air circulation around the plant and reduce humidity by pruning heavily infected foliage.

3 Ensure the plant is in a well-draining environment to prevent the damp conditions that favor mildew growth.

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Cottony Aphid Colonies

Certain aphid species or heavy infestations of related pests can produce white, waxy, or cottony secretions (honeydew and wax) on the undersides of cabbage leaves. This often leads to leaf curling and stunted growth in mustard greens.

Common

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How to confirm: Inspect the undersides of the leaves for small, soft-bodied insects moving near the white patches.

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shopping_cart Recommended Products

1 Apply an organic insecticide spray to the undersides of the leaves to eliminate the aphid colonies and their waxy secretions.

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

In Stock

2 Use yellow sticky traps near the plant to capture adult aphids and prevent further infestation of your mustard greens.

Super Ninja Fungus Gnat Traps - 30 Pack

30 pcs

$7

In Stock

3 Prune and dispose of heavily infested or curled leaves to reduce the pest population and improve airflow.

Fiskars 5/8" Bypass Pruning Shears

Cutting Tools

$13

In Stock

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Sclerotinia Sclerotiorum (White Mold)

This soil-borne pathogen produces a dense, white, cottony mycelium that can envelop the base of the cabbage plant or its leaves. It leads to rapid tissue decay and eventual collapse of the mustard stalks.

Common

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How to confirm: Look for small, hard, black structures (sclerotia) at the base of the stem or within the white mass.

build How to fix it

shopping_cart Recommended Products

1 Immediately remove and destroy all infected plant material and debris to prevent the spread of fungal spores through the soil.

2 Apply an organic fungicide to protect healthy tissues and manage existing fungal growth.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

$12

In Stock

3 Improve air circulation and reduce moisture around the base of the plant by using well-draining substrates like perlite or horticultural grit.