Latex spots

Salad producers, especially chicory, are sporadically confronted with a new syndrome, the cause of which is not yet known.

Damage is mainly to the nearby ribs and / or limb. There are a few small, orange to light brown lesions (Figures 1 and 2). In fact, these are latex accumulation pockets that eventually burst (Figures 3 and 4). This, when oxidized, takes on a rusty brown coloration as it spots the surrounding leaf tissues (Figure 5) (see also Figures 6-8).

The etiology of the disease focused mainly on the possibility of phytoplasmosis. Indeed, a phytoplasma belonging to the group of aster yellows ("Aster Yellows") is reported in the literature as responsible for latex spots on the veins of leaves. This symptom frequently accompanies others, such as yellowing and reduction in leaf size and plant dwarfism. None of them have been observed in French cultural contexts. The laboratory investigations carried out to highlight a phytoplasma were unsuccessful, ruling out the possibility of late attacks generating only latex spots.

Further etiological studies, integrating field surveys, should be carried out to better understand and possibly identify a factor explaining this syndrome.