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Sigatoka symptoms on cassava

 

  • Organs attacked  :
Leaves

 

  • Symptoms :
    • Symptoms are visible on older leaves.
    • At the start of development, small round, brown spots with sharp edges, surrounded by a yellow halo, appear on the upper surface of the leaves (figure 1).
    • On the underside of the leaf, the spots appear brown-gray.
    • The necrotic spots gradually enlarge taking on an angular appearance (figure 2). Their center then becomes more shaded (figure 3).
    • Eventually, the infected leaves turn yellow and end up falling (figure 4).
  • Impact :
    • In wet conditions, the disease can lead to a yield loss of around 20%.
    • Although it is widespread in most cassava-producing countries, this disease is not of major economic importance and does not require specific interventions.
  • Signs  : presence on the lesions of a charcoal-black down consisting of conidiophores and conidia hyaline and slightly curved, cylindrical and unbranched, with 3 to 6 transverse partitions. Their end is rounded. When the pycnidia emerge, the conidia appear in clusters (figure 5).
  • Possible confusion : Periconia manihoticola because this fungus causes symptoms more typical of Sigatoka than Cercospora henningsii.
  • >>> More pictures

 

  • Affected production areas :
New Caledonia

  

  • Cercospora spp. reported on cassava : Mycosphaerella henningsii Sivan. (anamorphe: Cercospora henningsii Allesch., Cercosporidium henningsii (Allesch.) Deighton)
Last change : 05/05/22
Cercospora-Manioc4
Figure 1
Cercospora-Manioc2
Figure 2
Cercospora-Manioc3
Figure 3
Cercospora-Manioc5
Figure 4
Cercospora-Manioc1
Figure 5