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Downy Mildew

Peronospora farinosa

Pathogen

Fungus

Hosts

Sugar Beet, beetroot.

Symptoms

Heart leaves are light green, thickened, distorted and develop a purplish downy growth. Older leaves may turn yellow similar to the symptoms of virus yellows.

Development

The disease is spread by air-borne spores from infected beet seed crops, mangold seed crops, groundkeepers, old camps, cleaner-loading sites or wild beet. Infection can also arise from resting spores (oospores) in the soil.

Favourable Factors

Cool, humid weather following crop emergence.

Importance

Infection in June can seriously affect root yield, whereas infection in July will reduce sugar content. Heavy losses due to downy mildew have been reported in seed crops grown on the continent. Whilst it can be a serious problem in some countries, it has not been a major problem in the UK as damage is usually restricted to odd plants in fields.

Control

Identification and Management of sugar beet diseases

Find out more information on the key disease threats to your sugar beet 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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