In Côte d'Ivoire, cassava is an important source of food and income for the population. However, its development is confronted with the attack of numerous pathogens such as phytoplasmas as observed in several countries in recent years. The main aim of this study is to diagnose cassava leaf infection in Côte d'Ivoire in order to contribute to sustainable production. Thus, cassava leaf samples were collected from nine growing localities. Molecular analyses required the use of the universal primer pairs for the direct PCR and specific primers for Nested PCR in order to detect the presence of phytoplasmas in the DNA extracted from the samples. Mosaic, vein banding, chlorosis, shoestring and witches' broom symptoms were observed, sometimes alone and other times in complex symptoms. The prevalence of leaf infections was over 70%, with average severity scores ranging from 4.29 to 4.74 depending on the cassava variety. Of the samples tested, 42 (19.44%) were positive with the specific primer (AkwaSR/GH813f) and 32 (18.39%) with the universal primer (R16mF2n/R16mR2), thus demonstrating the presence of phytoplasmas in both symptomatic and non-symptomatic cassava leaves. The amplicons obtained with the specific primer pair allowed the detection of the phytoplasma "Candidatus Phytoplasma palmicola" of subgroup XXII-B associated with the coconut lethal yellowing disease in Côte d'Ivoire in cassava grown in the different collection localities.

The cocoa tree, the mainexport crop in Côte d'Ivoire is frequently attacked by a disease: brown pod rot, caused by Phytophthora spp. which causes a considerable drop in production. This soil-borne pathogen attacks on so-called weeds when environmental conditions are favourable. The presence of these susceptible weed hosts can amplify this scourge of brown rot by transmitting the pathogen to the crop plant. In order to improve the yield of this crop, a study was conducted in the Nawa region to identify the weed hosts through the characterization of the pathogen. This study consisted first in the inventory of susceptible host weeds of Phytophthora spp. and second in the morphological characterization of the pathogen. Concerning the host weeds inventory we procceeded determining all symptomatic weeds located within 3 m of the cocoa plants affected by brown rot. We identified 48 susceptible host species, divided into 41 genera and 22 families and we observed brown spots on the leaves of Oplismenus burmannii and Laportea aestuans; on the leaves of Clerodendrum splendens and Xanthosoma mafaffa, brown necroses surrounded by a yellow halo were noticed. Oily brown spots were examined on the leaves of Ageratum conyzoides. On the proximal, lateral and distal parts of the pods symptoms of brown spots covered with whitish mycelia were observed. Phytophthora strains obtained from the pods and weeds on PDA culture medium were characterized by matted, white mycelial colonies with a cottony appearance. Microscopic features revealed the presence of sporocysts, oospores and chlamydospores of different shapes.