Abstract
Lethal Yellowing Disease (LYD) is globally recognized as a serious threat to the cultivation of coconut. Planting of resistant varieties is the only practical solution for the management of this disease. The reaction to LYD in five coconut varieties, viz., West African Tall (WAT), Malayan Yellow Dwarf (MYD), Malayan Orange Dwarf (MOD), Chowghat Green Dwarf (CGD), and Malayan Green Dwarf (MGD) planted in the isolated coconut seed garden in NIFOR, Benin City, Nigeria, were evaluated under natural field conditions where the disease occurs in epidemic proportions. Observations on the incidence and intensity of LYD were recorded in April and November 2003. West African Tall had 86.0% disease incidence, followed by MYD (71.8%) and MOD (64.3%) during November 2003. All the palms of CGD and MGD were free from the disease, indicating that these two green dwarf varieties are highly resistant to the disease. Observations on the progression of disease during the interval of six months indicated that the disease progressed rapidly in all the susceptible varieties. Identification of the high resistance of CGD and MGD paves the way for the rehabilitation of the coconut industry in the disease-prevalent tracts of Nigeria, by undertaking large-scale replanting programmes using these green dwarf varieties of coconut. Resistance of green dwarf varieties of coconut to LYD in Nigeria is reported for the first time in this paper.
