Abstract:
Citrus tristeza virus (CTV) is one of the most important causal agents of citrus diseases and has varying strains of the tristeza virus. Production of sweet orange in Abura-AsebuKwamankese District is highly constrained by quick decline and stem-pitting variants of the Tristeza virus. For better cognition of CTV prevalence, a survey on incidence and severity of CTV was conducted between May 2012 and February 2013 in the six major citrus growing communities in Abura-Asebu-Kwamankese District, Ghana. A total of 4200 sweet orange trees from 60 farms in six communities, were systematically observed for CTV disease incidence and severity during the survey. Symptoms such as stunted growth, leaf cupping, vein clearing, leaf curling, leaf chlorosis, twig die-back, leaf defoliation, reduced fruit size and stem back breaks were used at assessing incidence. Rough lemon were the most preferred rootstock used by farmers in all the locations in establishing sweet orange farm. A severity scale of 1–5 was used. The analysis of variance for both incidence and severity showed a significant difference at across all locations. Disease incidence was highest in Asebu, Amoanda and Edumifa at 75%, 73.5% and 74.6% respectively. There was a significant difference in the severity index between and across four locations; Asebu (3.5), Amoanda (2.7), Abakrampa (3.1) and Nsanfo (2.8) with the exception of Edumifa (2.1) and Bantanya (2.0). The use of CTV free (clean) bud-wood and resistant rootstocks in establishing Citrus farms will help the management of the disease
