Final diagnosis


Lettuce ring necrosis agent (LRNA)

On the underside of the leaf blade, these changes are greasy to moist and orange in color. <b> Lettuce ring necrosis agent </i>, LRNA)
On the underside of the leaf blade, the rings are more fatty. <b> Lettuce ring necrosis agent </i>, LRNA)
Under the limbus, the more advanced alterations take on a very characteristic orange color, at the origin of the French name of this affection: "disease of orange spots". <b> Lettuce ring necrosis agent </i>, LRNA)
LRNA3
LRNA2
Many translucent rings are visible on the upper side of this lettuce leaf. Some are starting to take on an orange tint. <b> Lettuce ring necrosis agent </i>, LRNA)
Subsequently, the rings visible on the limbus take on a brown tint. <b> Lettuce ring necrosis agent </i>, LRNA)
We find the same type of alterations at the base of the blade and the main vein of this lettuce leaf <b> Agent of the necrotic rings of lettuce </b> (<i> Lettuce ring necrosis agent </i>, LRNA)
Small spots and a few chlorotic rings are visible on the lower or middle leaves of this lettuce. <b> Lettuce ring necrosis agent </i>, LRNA)
LRNA4
LRNA5
LRNA6
Wet to greasy changes, orange to brown in color, are clearly visible on the periphery of the chlorotic blade of this lettuce. <b> Lettuce ring necrosis agent </i>, LRNA)
Some lower leaves are covered with small lesions both chlorotic and necrotic. <b> Lettuce ring necrosis agent </i>, LRNA)
Eventually, whole leaves are affected; they can then present on butter lettuce a rather intense yellow color. <b> Lettuce ring necrosis agent </i>, LRNA)
LRNA1
Numerous chlorotic and necrotic rings gradually cover the limbus; eventually, several leaves of this lettuce end up turning yellow and more or less completely necrotic. <b> Lettuce ring necrosis agent </i>, LRNA)
It does not take long for diseased tissue to necrode and dry out. <b> Lettuce ring necrosis agent </i>, LRNA)
Within these healthy salads, a lettuce shows several yellow, necrotic leaves; the leaves of the heart are blocked and deformed. <b> Lettuce ring necrosis agent </i>, LRNA)
These alterations can affect many leaves and more or less generalize to the entire blade. Affected leaf portions quickly necrosis and dry out <b> Lettuce ring necrosis agent </b> (<i> Lettuce ring necrosis agent </i>, LRNA)
Batavias are particularly sensitive; it is not uncommon to observe completely necrotic lettuce. <b> Lettuce ring necrosis agent </i>, LRNA)
In the cells of the root cortex of diseased plants, one can easily observe the presence of sporangia and resting spores of the vector fungus: <i> Olpidium brassicae </i>. <b> Lettuce ring necrosis agent </i>, LRNA)