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Symptoms on potato


  • Organs attacked  :
Leaves Vessel Roots, tubers


  • Symptoms :
    • Leaf rollings (figures 1 and 2); f withering of the leaves of the apex occurring at the hottest times of the day which are often reversible during the night at first. they become permanent thereafter causing the yellowing and drying of the leaves of one or two stems (unilaterally), or even of entire plants at term. the leaves sometimes take on a slightly bronze hue.
    • Appearance of bacterial exudates in leaf axils or vascular tissues.
    • Superficial browning of the stem manifesting itself above the soil line, alteration of the vessels from which exude white bacterial masses once the stem is cut.
    • A section through the tubers reveals a reddish browning and necrosis of the vascular ring diffusing into the adjacent tissues (Figure 3), and subsequently the formation of creamy bacterial exudates (Figure 4). Exudates also visible at the level of the eyes and the areas where the stems join the tubers. Development of brown and necrotic lesions on the surface leading to their complete decomposition.
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  • Signs  : perform a "water glass test" to reveal the presence of bacteria in the vessels. To do this, take a stem fragment from the lower levels of the stem, immerse it in a glass of water: white mucous wisps made up of billions of bacteria appear within 5 minutes (figure 5). Similarly, presence of bacterial exudates in the axils of the leaves, at the level of the vascular ring of the tubers once cut, but also of the eyes and the heel, sometimes forming crusts after adhesion of soil particles.
  • Possible confusion :
  • Production areas affected :
New Caledonia
Last change : 07/04/22
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5