Final diagnosis


Sclerotinia sclerotiorum, Sclerotinia minor (Watery soft rot)

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That girdle-necked lettuce suddenly collapsed. The fungus has now invaded a significant part of the apple and some leaves are totally liquefied. We can distinguish mycelial masses and rather sparse white mycelium. <b> <i> Sclerotinia minor </i> </b> ("<i> Sclerotinia </i> drop")
<b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop") settled on the leaf in contact with the now decomposed soil. Subsequently, it invaded several leaves and the crown. We distinguish the characteristic cottony mycelium of white color.
The altered tissues are initially moist to translucent; they break down fairly quickly. <b> <i> Sclerotinia minor </i> </b> ("Sclerotinia drop")
Plant tissue is now completely decomposed. Only a few main veins of the leaves and the scattered sclerotia of the fungus can be distinguished. <b> <i> Sclerotinia minor </i> </b> ("<i> Sclerotinia </i> drop")
Lettuce plant attacked by <b> <i> Sclerotinia </i> spp. </b> (sclerotinioses, <i> sclerotinia </i> drop)
This batavia also presents a rot located at the neck; a prominent white cottony mycelium partially covers it. <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop")
The ascospores produced by apothecia can be at the origin of airborne contaminations leading, as is the case with this chicory, to a wet and brown rot of the heart. <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop")
Numerous small black sclerotia more or less aggregated, from 0.5 to 2 mm, materialize the presence of <b> <i> Sclerotinia minor </i> </b> ("<i> Sclerotinia </i> drop" ).
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The outer leaves of this salad wilt due to the invasion of the petioles and the main veins by the fungus. <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop")
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A white, dense mycelium gradually covers the partially decomposed tissue. <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop")
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Rather large structures, initially white, are formed on the most formerly colonized parts. <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop")
These are forming sclerotia which quickly become melanized. They are hard in consistency. <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop")
The sclerotia of <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop") are also black but they are much larger (2.5 to 20 mm) and irregularly shaped.
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The perfect form of <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop") is materialized by the production of apothecia on the sclerotia. Their color is variable (yellowish white, light brown to slightly brown).
Small and fragile trumpets, beige to brown, form in clusters on the surface of the soil; these are the apothecia of <b> <i> Sclerotinia sclerotiorum </i> </b> ("<i> Sclerotinia </i> drop").
A few apothecia of <i> <b> Sclerotinia sclerotiorum </b> </i> have formed on sclerotia of this fungus present on the soil surface. (sclerotiniosis) (Thibaut CHESNEAU)
Often confused, <i> <b> Sclerotinia minor </b> </i> ("<i> Sclerotinia </i> drop"), as <b> <i> Sclerotinia sclerotiorum </i> </b> , attacks low leaves and the neck of salads. It causes wet, brown rot. This is surmounted by a rather sparse white mycelium.
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Unlike <i> Sclerotinia sclerotiorum </i>, sclerotia are irregular in shape and small in size. <b> <i> Sclerotinia minor </i> </b> ("<i> Sclerotinia </i> drop")
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<b> <i> Sclerotinia minor </i> </b> ("<i> Sclerotinia </i> drop") forms small, often aggregated black sclerotia measuring 0.5 to 2 mm in diameter.