Sigatoka symptoms on cassava

• Organs attacked  :

• 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 :

• Cercospora spp. reported on cassava : Mycosphaerella henningsii Sivan. (anamorphe: Cercospora henningsii Allesch., Cercosporidium henningsii (Allesch.) Deighton)