Pests and diseases of Asian vegetables

Asian vegetables – an overview:

This page provides an overview of the key pests and diseases of Asian 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.

Vegetables originating in the East and Southeast Asian countries are called Asian vegetables. Many Asian vegetables are from the Brassica and Cucurbit families and therefore may be impacted by key insect pests and diseases of Brassica and Cucurbit vegetables. Asian vegetables include the Asian leafy brassicas (e.g. buk choy, choy sum), melons (e.g. hairy melon), and luffas. Key insect pests of the Asian leafy vegetables include Diamondback Moth, Aphids, Thrips, Leafminer, Cabbage white butterfly, and Rutherglen bug.

Asian leafy vegetables can also be affected by bacterial and fungal diseases and viruses such as turnip mosaic virus and cauliflower mosaic virus can affect some Asian vegetables. These viruses are transmitted by insect pests such as aphids. Snails and slugs can also be a problem for Asian vegetables.

Key pests of Asian vegetables

Crop	Insect pests	Diseases
Bok choy/Buk choy and Pak choy	Diamondback moth; Aphids; Caterpillars; Onion thrips; Rutherglen bug; Brassica flea beetle; Silverleaf whitefly.	White leaf spot; White blister; Downy mildew; Alternaria leaf spots; Damping-off; Black leg; Phoma leaf spot; Clubroot; Root rot; Mosaic virus;Bacterial leaf spots; Bacterial soft rot; Black rot.
Chi qua – Hairy melon	Onion thrips; Cocksfoot thrips.	Anthracnose.
Choy sum – Chinese flowering cabbage)	Diamondback moth; Looper caterpillar; Aphids; Cabbage white butterfly; Western flower thrips; Onion thrips; Plague thrips.	White leaf spot; White blister; Downy mildew; Phoma leaf spot; Damping-off; Alternaria leaf spots; Black leg; Clubroot; Root rot; Mosaic virus; Bacterial leaf spots; Black rot; Bacterial soft rot.
Daikon – White radish		Leaf spot; White blister; Clubroot; Root rot; Mosaic virus.
Fu qua – Bitter melon	Western flower thrips; Plague thrips; Onion thrips; Banded thrips.	Gummy stem blight; Powdery mildew; Mosaic; Bacterial leaf spot.
Gai choy – Chinese mustard	Aphids; Diamondback moth.	Downy mildew; White blister; Alternaria leaf spot; Damping-off; Clubroot; Phoma leaf spot; Mosaic virus; White leaf spot; Bacterial soft rot; Bacterial leaf spot; Black rot.
Gai lan – Chinese broccoli	Diamondback moth; Cabbage white butterfly; Looper caterpillar; Cabbage aphid; Cabbage moth; Plague thrips; Onion thrips; Striped flea beetle or Brassica flea beetle.	Downy mildew; White blister; Clubroot; Damping-off; Alternaria leaf spot; Phoma leaf spot; Mosaic virus; White leaf spot; Bacterial soft rot; Bacterial leaf spot; Black rot.
Kangkong – Water spinach	Leaf beetle; Wireworm; Aphids.	Stem rot; Root rot; Leaf spot; Mosaic virus.
Okra	Coon bug.
Luffas – Angled luffa (Sin qua) and Smooth, sponge luffa (Shui qua)		Anthracnose; Root rot.
Seng qua – Long melon and Chinese winter melon	Onion thrips.	Root rot; Gummy stem blight; Powdery mildew; Mosaic virus; Anthracnose.
Snake bean	Cabbage aphid; Onion thrips; Cocksfoot thrips; Whitefly; Bean flies;Cutworms; Mites.	Root rot; Leaf spot; Wilt and stem rot; Mosaic virus; Rusts; Mildews.
Wombok – Chinese cabbage	Aphids; Caterpillars.	White leaf spot; White blister; Downy mildew; Black leg; Alternaria leaf spots; Clubroot; Mosaic virus; Bacterial leaf spot; Bacterial soft rot.
Wasabi		Leaf spot.

Pest management

The impact on Asian vegetables from insect pests and diseases can vary according to the type of crop being grown, the cultivar selected, the method of production, as well as factors such as weather, climate, geographical location of the crop, and the time of the year. IPM methods discourage the use of broad-spectrum chemical pesticides, and instead, recommend growers to employ a combination of plant protection strategies, such as best-practice farm hygiene, biological controls, and a targeted application of selective chemicals.

Insect pests

Frequent scouting for insects pests; timely release of biological controls (beneficial insects) in protected cropping environments; trap crop planting, designed to attract pests away from the commercial crop, while potentially being a breeding ground for beneficial insects.

Foliar diseases

New disease forecasting models can improve management of foliar diseases; new management strategies incorporating weather-based disease prediction, spray scheduling, and irrigation.

Root diseases

Hydroponic systems are a good way of combating Clubroot in leafy brassicas, as is crop rotation and applying lime where suitable.

Viruses

It is imperative for growers to understand the importance of weed management, whole farm, and crop hygiene as preventive measures against mosaic viruses.

Regular surveillance of crops

An effective way of monitoring the presence of beneficial insects – such as natural predators – within the crop and can help determine that an IPM program is working effectively.

Chemical usage

Misuse of broad-spectrum chemical properties is a major concern to industry as it may lead to increased resistance in insect pests, crop residues, and broader implications on the surrounding environment. Chemicals should only be applied in response to the actual need rather than according to a fixed calendar schedule.

Beneficials

Some key beneficials or biocontrol agents for use in Asian vegetables include Wasps; Spiders; Lacewings; Hover fly; and Lady beetles. In addition some minor beneficials include Pirate bugs; Soldier beetle; Tachinid flies; Rove beetle; Soldier beetle; Red and blue beetle; Assassin bug; Damsel bug; and Big eyed bug.