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Sclerotinia disease is a fungal infection of many vegetables and ornamental plants. The fungus lives for long periods in the soil. When infected, plants rot at the base and a white fluffy mould may grow on affected parts.
Sclerotinia disease is caused by the fungus Sclerotinia sclerotiorum. This fungus produces black, seed-like structures (sclerotia) that can live for long periods in the soil and cause disease in a very wide range of plants. Damage is seen in summer and early autumn.
S. sclerotiorum attacks a wide range of plants including vegetables: lettuce, beans, celery, chicory, cucumbers, tomatoes and peas; and many ornamentals, especially plants with hollow stems such as Delphinium, Dahlia and Helianthus (sunflower) and related yellow daisies.
In commercial agriculture and horticulture S. sclerotiorum is a major problem in lettuce, oilseed rape and sunflower production.
Other very similar Sclerotinia or related species attack gladioli (Stromatinia gladioli) and bulbs (Sclerotinia bulborum). In addition to Sclerotinia sclerotiorum, lettuce can also be affected by Sclerotinia minor.
You may see the following symptoms:
There are no chemical treatments available to UK gardeners.
When plants infected with sclerotinia die, the black sclerotia fall to the soil, where they can remain viable for several years. It is these sclerotia that spread the disease. They can infect plants in two ways:
There is no secondary spread by spores produced on the first infections, unlike with other diseases such as rusts and powdery mildews. However, each apothecium can produce many thousands of spores, and if weather conditions are suitable outbreaks can be serious, especially in commercial crops.
Delphinium black blotchDisposing of diseased materialLeek rustLettuce downy mildewOnion white rotSmuts
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