Incidence of sweet potato viruses in the coastal savannah agro-ecological zone of Ghana

Abstract

An experiment was conducted under field conditions to assess the incidence of viral diseases in 20 accessions of sweet potato [Ipomoea batatas (L.) Lam.]. Using symptomatology, biological indexing, nitrocellulose membrane ELISA (NCM-ELISA) and PCR, the accessions were assessed for disease incidence and symptom severity. Symptom expression varied among the accessions with severity index ranging from 2.24 in UK/BNARI at eight weeks after planting (wap) to 3.63 in US029 at 12 wap. Mean disease incidence varied significantly among the accessions, ranging from 43.2% to 96.3%. Using NCM-ELISA, 85% of the sweet potato plants tested positive to Sweet potato feathery mottle virus (SPFMV), Sweet potato mild speckling virus (SPMSV, 55%), Sweet potato collusive virus (SPCV, 45%), Sweet potato chlorotic fleck virus (SPCFV, 30%), Sweet potato virus G (SPVG, 20%), Sweet potato mild mottle virus (SPMMV, 5%), Sweet potato chlorotic stunt virus (SPCSV, 1.67%) and Cucumber mosaic virus (CMV, 1.67%). PCR detected Sweet potato leaf curl virus (SPLCV) in accessions UK/BNARI and CRI054. Biological indexing resulted in characteristic symptoms, commonly vein-clearing with eventual death of plants grafted with scions mix-infected with SPCSV and SPFMV. This work provides the first detailed report on sweet potato virus diseases in Ghana correlating symptoms, grafting, serology as well as PCR. It emphasizes the importance of selecting resistant cultivars as planting materials and the enforcement of quarantine measures to minimise the introduction of viruses into Ghana and their subsequent spread. © 2015, Journal of Plant Pathology. All rights reserved.