Sclerotinia rot

Sclerotinia rot
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The typical white mould visible on a carrot infected with sclerotinia rot (Sclerotinia sclerotiorum)
Scientific Classification
Kingdom:	Fungi
Phylum:	Ascomycota
Class:	Leotiomycetes
Subclass:	Leotiomycetidae
Order:	Helotiales
Family:	Sclerotiniaceae
Genus:	Sclerotinia
Species:	Sclerotinia sclerotiorum
Synonyms
Blossom blight Cottony rot Drop Pink rot Sclerotinia stem rot Water soft rot White mold Hymenoscyphus sclerotiorum (Lib.) W. Phillips, (1887) Peziza sclerotiorum Lib., (1837) Sclerotinia libertiana Fuckel, (1870) Sclerotium varium Pers., (1801) Whetzelinia sclerotiorum (Lib.) Korf & Dumont, (1972)

Sclerotinia rot (Sclerotinia spp.), also known as Blossom blight, Cottony rot, Crown rot, Drop, Pink rot, Water soft rot, White mold. And is very similar to Onion white rot or Mouldy nose (Sclerotium cepivorum) in alliums.

Symptoms

Symptoms can depend on the plant infected and the mechanism of infection. Common symptoms include water-soaked spots on fruits, stems, or leaves, petioles with altered morphology. The watery spots enlarge and develop a cottony white mass that converts the plant to a slimy, wet mass that produces abundant sclerotia. Symptoms appear like Pythium, but occur in dry weather.

In some plants, the symptoms are described as dry. The plant develops brown lesions that coalesce and circle the plant. Everything above the lesion wilts and dies.

Alliums

The first visible symptom is the wilting and yellowing of the foliage, most likely during dry weather. If the weather is wetter the foliage may not wilt, but the plant will become loose in the soil. Under the soil a white, fluffy fungus grows on the base of and invades the bulb. Later this mould becomes covered in small, round, black structures.

Treatment

If attacks are seen in the garden, water healthy plants with Cheshunt Compound after removing diseased plants immediately.

There are some fungi that are parasitic on Sclerotinia and that can be used to control it. The most effective of these is Coniothyrium minitans, but none have been turned into a practical treatment.

Chemical control can include soil fumigation, which is considered an effective control method. Some fungicides, including benomyl, are effective in some crops, but not all.

Prevention

Good cultural practices are necessary to avoid attacks such as taking care to avoid planting susceptible crops in poorly drained soils, low planting densities and weeding between crop rows. Infected fields should be planted with non-susceptible crops, such as cereals for at least three years.

Hosts

Potential hosts of sclerotinia rot include:

• Alliums
• Aubergine
• Beans
• Cabbage
• Carrot
• Citrus fruit
• Celery
• Coriander
• Cucumber
• Lettuce
• Melon
• Squash
• Soybean
• Sunflower
• Tomato

Examples

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  Broccoli

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  Cabbage

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  Chrysanthemum

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  Courgette

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  Lettuce

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  Runner bean

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  Sweet pepper

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  Turnip