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White Blister

White blister on sprouts & close up of leaf symptoms (Photos R. Bradbury

Pathogen

Fungus

Hosts

Field brassicas

Symptoms

Pale leaf spots can be seen on the upper leaf surfaces with the associated and corresponding powdery white blisters developing on the undersides of the leaves, these can be up to 20 mm in diameter and can release large spore masses.

Development

Spores can be dispersed by insects, wind or rain splash. Leaf moisture is required for the spores to germinate and pass into the leaves via the stomata. As well as the leaves, this fungus can be found on the stems, pods and florets of host plants. White blister can survive in a dormant state as an oospore in soil or crop debris. Infected seed can also be a source of infection.

Favourable Factors

Warm, wet weather.

Importance

This disease can infect many members of the brassica vegetable family as well as cruciferous weeds such as shepherd's purse. Stems and leaves can be distorted and twisted and individual plants can show signs of reduced vigour. This disease can be directly responsible for economic loss by adversely affected crop quality, particularly on flower head and leafy brassicas such as broccoli, cauliflower, cabbage and brussel sprouts.

Control

Identification and Management of field brassica diseases

Find out more information on the key disease threats to your field brassica crop. For each disease you will find out the importance of the disease in terms of potential yield penalty, how to identify the disease in its early stages and our advice on the best control strategies.

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