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African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730
EISSN: 2072-6589
Vol. 2, No. 4, 1994, pp. 511-517
Bioline Code: cs94061
Full paper language: English
Document type: Research Article
Document available free of charge

African Crop Science Journal, Vol. 2, No. 4, 1994, pp. 511-517

 en The fungal Disease of Cassava in the Republic of Congo, Central Africa
Makambila, C.

Abstract

The main fungal diseases of cassava are listed. They include leaf spot disease of minor importance caused by Cercospora henningsii check for this species in other resources Allesher, C. caribaea Chupp. et Cifferi and C. vicosae. They also include stem diseases represented by anthracnose of cassava whose symptoms are formed in two stages: (i) wounding by the bug Pseudotheraptus devastans check for this species in other resources (Distant) Het., Coreidae in aprts of the stem that are not yet fully lignified. Wounding activity of P.devastans is influenced by numerous factors related to the genotype of the insect, the diurnal cycle and environment. Analysis of the results also shows that the saliva of P. devastans has a toxic or enzymatic effect on the cytoplasm and cell walls of cassava tissues, causing cell degradation; (ii) the wounds are infected by conidia of the fungus Colletotrichum gloeosporioides check for this species in other resources Penz. Among environmental factors, relative humidity plays a major role. Infection of cassava stems under experimental conditions is only successful with high relative humidity close to saturation and at temperatures of 24-28°C. Finally, there are two groups of root diseases referred to as root rots: (i) soft rots caused by Phytophthora drechsleri check for this species in other resources Tuck., Pythium check for this species in other resources spp,. Fusarium solani check for this species in other resources Mart. and Sphaerostilbe repens check for this species in other resources B. et Br. The latter is the most widespread in the Congo; (ii) dry roots rots caused by Rigidoporus lignosus check for this species in other resources (Klot.) Imazeki, Rosellinia necatrix check for this species in other resources (Hart.) Berk., Botriodiplodia theobromae check for this species in other resources Pat., Armillaria mellea check for this species in other resources (Vahn: Fr.) P. Kumm., Armillaria heimii check for this species in other resources and Phaeolus manihotis check for this species in other resources Heim. Rot caused by A. heimii is a problem that must be solved in the tropics.

Keywords
Cercospora henningsii, Colletotricum gleosporioides, soft rots, wounding, Manihot esculenta

 
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