ABSTRACT
There is a considerable deficit in the annual production of cassava in Cameroon of about 31 million tons, and this has been mainly due to constraints related to pest attacks and most especially diseases like the African Cassava Mosaic Disease (ACMD). This study was therefore undertaken on three sites in the locality of Bityili (South Region of Cameroon), to determine amongst improved and local cassava cultivars those that provide resistance to the development of the ACMD. The severity and incidence of this disease was evaluated and its impact on cassava yield. In each site, cassava was grown in a randomized complete block design. The local cultivars (Ekobele and Ngon kribi) showed higher severity (76-100%) and incidence of ACMD compared to the improved cultivars (TMS 92/0326 and TMS 96/1414) of 0-25% and 0-10%, respectively. Strong inverse correlations were observed between ACMD severity and yield performance, measured in terms of number of tubers/plant and weight of fresh tubers. The improved cultivars, TMS 92/0326 and TMS 96/1414, could, therefore, be recommended for large-scale planting in a bid to promote cassava production in the South Region of Cameroon.
ABSTRACT
Cassava is a basic staple in Cameroon whose industrialization faces major constraints especially those related to the management of whiteflies (Bemisia tabaci), a vector of the African cassava mosaic virus (ACMV). This work has as main objective to identify the tolerance of some cassava genotypes to whiteflies and to undertake an agro-morphological characterization of infected cultivars to the ACMV. Data were collected from September to November 2015 on six cultivars: Five improved (TMS92/0057, TMS92/0067, TMS92/0326, TMS96/1414 and TME419) and one local (NTOLO), on a young plot (three months old) and mature plot (six months age). Adult whiteflies were counted on the underside of the last leaves of one apex and for nymphs; they were counted randomly between the ninth and fourteenth leaves. Three cultivars (TMS96/1414; TMS92/0057 and TMS92/0067) ramified early with a large number of apices. For the younger plants (three months old), three cultivars (NTOLO, TMS96/1414 and TMS92/0326) harbored the largest number of adult whiteflies, whereas two others (TMS92/0326 and TME 419) were the most attacked by the ACMD. Younger plants (3 Months old) were most vulnerable to ACMV attack (r = 0,307** with whiteflies population), while the older ones (at 6 Months), represent early senescence period for short-cycle genotypes.