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Sclerotinia

Pathogen

Fungus

Hosts

Carrots, oilseed rape, peas, potatoes, lettuce, beans and other vegetable crops

Symptoms

The characteristic Sclerotinia white mycelium containing large black sclerotia resting bodies can be found on the foliage, stems and the roots. In severe infestations the foliage collapses into a slimy mass.

Development

Sclerotinia overwinters in sclerotia resting bodies in soil and crop debris. These germinate in favourable conditions to form apothecia (trumpet-like structures) which release wind-borne ascospores. In wet conditions these invade crop debris or diseased, senescing or decaying plant tissue. The roots are infected via the leaf petioles and the crown. A few weeks after disease establishment sclerotia, 5 – 15 mm in diameter, can easily be found within the white `cotton wool` mycelium. Infection occurs from June to October.

Favourable factors

Warm (above 10 degree C) and moist soils.

Importance

A very important economic disease of carrots which can cause huge losses in stores especially where Sclerotinia and secondary bacterial pathogens are active. Losses as much as 50 % of stored produce have been recorded. Other host plants include oilseed rape, lettuce, beans, brassicas, peas, potatoes, other vegetable crops as well as a range of weeds including mayweed, deadnettle, cleavers, chickweed, fat-hen and field pansy.

Control

Identification and Management of carrot diseases

Find out more information on the key disease threats to your carrot 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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