Diseases of Cassava

BACTERIAL DISEASES

CASSAVA PHYTOPLASMA/YELLOWS/WITCHES’ BROOM DISEASE caused by Candidatus ‘Phytoplasma’

Cassava phytoplasma disease is one of the most destructive diseases of cassava. Symptoms on infected plants are yellowing and purpling of leaves, shortening of the internodes resulting to bunchy top appearance of the plant. The disease reduces root yield and starch content significantly. Total yield loss may occur if the symptoms appear on the onset of crop establishment.

CASSAVA BACTERIAL BLIGHT caused by Xanthomonas campestris (Pammel) Dowson pv. manihotis (Arthaud-Berthet) Star

Cassava bacterial blight is now recognized as one of the most important factors limiting cassava production in the country. Symptoms include angular leaf spots that appear water-soaked. These spots exude a yellowish sticky gum that dries up to form glistening scabs. Gms also exude from cracks that develop on young infected stems and petioles. Severe infection results to defoliation, wilting, dieback and death of plant.

FUNGAL DISEASES

BROWN LEAF SPOT caused by Cercosporidium henningsii Allesch.

Cercospora brown leaf spot is the most important cassava fungal disease in the field. Severe infection can cause heavy defoliation in susceptible varieties and can reduce yield up to 20%.

BLIGHT LEAF SPOT caused by Cercospora vicosae A.S. Mull. & Chupp

Blight leaf spot occurs during rainy season in warm cassava-growing areas where brown leaf spot is also prevalent. The disease is not usually serious and is confined to the older leaves.

BUD NECROSIS caused by complex of Basidiomycetes

Bud necrosis usually occurs in humid cassava growing areas. Infection starts with the spongy material covering the buds and progresses to the internodes. Infected stakes fail to germinate.