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Brassicas

Brassicas – an overview:

This page provides an overview of the key pests and diseases of Brassica vegetables in Australia. The related tools provided at the end of the page can be used by growers and crop consultants to assist in the identification of insect pests, mites, diseases, beneficials, and disorders. They include photographs and detailed information about specific pests. For unknown pests, it is important to have an expert identify them so that they can be managed appropriately.

Brassicas, also known as ‘cruciferous vegetables’, ‘cabbages’, or ‘cole crops’ include broccoli, cabbage, cauliflower, Brussels sprouts, kale, Chinese cabbage (wombok) and the Asian leafy brassicas such as buk choy, choy sum and gai lan. For more information on Asian leafy brassicas, see Asian vegetables.

Key pests of brassicas include caterpillars, aphids, slugs, snails, weeds, and a range of fungal, bacterial and virus diseases such as clubroot, downy mildew and white blister/rust. A range of beneficials are available to assist in the management of these pests, for example parasitoids of caterpillars.

Key pests of Brassicas:

Crop

Insect pests

Diseases
Broccoli Diamondback cabbage moth; Heliothis caterpillars (particularly on paddock straight from pasture); other caterpillars. Fungal diseases: Black leg, Clubroot, Downy mildew, Ringspot, Light-leaf spot, Damping-off Bacterial diseases: Black rot; Broccoli headrot; Head-stem rot.
Cabbage Aphids; Cabbage white butterfly; Diamondback moth; other caterpillars. Black rot and other leaf spots; Blackleg; Downy mildew; Sclerotinia; Ring spot; Clubroot.
Cauliflower Weeds; Aphids; Cabbage white butterfly; Diamondback moth; other caterpillars. Black rot and other leaf spots; Blackleg; Downy mildew; Sclerotinia; Ring spot; Clubroot.
Brussels sprouts Diamondback moth; other caterpillars. Clubroot; Downy mildew; Root-knot nematodes.
Chinese cabbage Aphids; Caterpillars. Clubroot; Downy mildew; White rust or White blister.
Radish Aphids; Diamondback moth. Black rot; White blister (rust); Clubroot
Swedes Aphids; Diamondback moth; Red-legged earth mite; Vegetable weevil. Black rot; Clubroot; White rust; Sclerotinia rot
Turnips Aphids; Diamondback moth; Red-legged earth mite; Vegetable weevil. Black rot; Clubroot; White rust; Sclerotinia rot
Kale Cabbage worms, Diamondback moth, and Looper caterpillars; Aphids. Head rot; Downy mildew
Rocket Cabbage white butterfly; Green caterpillar. Leaf spot; Clubroot

Pest management:

Integrated pest management (IPM) is an approach to improve management and profitability using regular crop monitoring to determine if, when and what treatments are needed for effective control of pests. Effective IPM employs a combination of chemical, cultural, and biological strategies to keep weeds, insect pests, mites, diseases, and other crop production problems low enough to minimise economic crop loss.

Good farm hygiene is critical for minimising insect pest and mite damage to crops. Regular crop monitoring will also solve the problems to be identified early. Beneficials should be encouraged and used. Parasitoids, predatory wasps, spiders, lacewings, damsel bugs, and ladybird beetles may feed on moth eggs and caterpillars and may also provide some relief against aphids and thrips. Learn about beneficials that help control the insect pests most common on your farm. Disease management strategies could include the following steps:

  • Exclusion or avoidance – quarantine, grow crops in regions where diseases seldom occur or during periods when the virus or the vector are at a low level, and use of virus-free and seedling transplants.
  • Reduction of virus spreading sources and improvement of hygiene – Spores of diseases can be transmitted by anything carrying soil or water, including machinery, shared/contract labour and equipment, boots, livestock, pallets, transplants and dams receiving run-off from affected areas.
  • Protection of the host plant – plant resistant varieties, use barrier crops to reduce activity, use insecticides to protect plants, and use highly effective mulches and oil sprays to deter pests.
  • Modify the soil: Environmental factors to create soil conditions that restrict disease development.
  • Rotate crops – Increase the duration between successive brassica crops to allow the natural decay of the spores. Rotate with non-brassica crops and maintain crops free of brassica crops.
  • Use fungicides wisely – Application of fungicide may be necessary in paddocks with previously high levels of disease. However, it is important to evenly distribute fungicides around the transplant root zone. This is best achieved by incorporating the fungicide into the transplant row at planting.
  • Know the disease risk – Effective on-farm application of integrated management techniques will require some estimation of disease risk and depend on sowing time, soil type, drainage, soil pH, and brassica weed hosts.

Source of information and related tools: