Report on maize streak virus in the South African sugar industry

Symptoms caused by Maize Streak Virus (MSV) were first observed in the Lower South Coast region of the South African sugarcane industry in 2007 on variety N44. Identical symptoms were subsequently observed on varieties N44 and N36 in the Midlands North and South Coast areas and on N36 in Mpumalanga. Phylogenetic analysis determined that the virus closely resembled the South African maize-adapted MSV strain, MSV-A, subtype MSV-A4. In a pot trial MSV infection resulted in an average yield loss of 31% in infected N44 plants. A colony of Cicadulina mbila was established at SASRI to screen commercial sugarcane cultivars for their susceptibility to MSV. Cytochrome oxidase C subunit primers were used to sequence genomic DNA from C. mbila for molecular identification of the leafhopper. A PCR protocol was established for the detection of MSV in the leafhopper C. mbila. The diversity and distribution of leafhopper species in the sugarcane industry is currently being monitored. Thirteen species of leafhoppers (Cicadellidae) were collected during the first season of monitoring: Gambialoa sp., Afrosteles sp., Aconurella prolixa (Lethierry), Exitianus frontalis (Distant), Exitianus taeniaticeps (Kirchbaum), Empoascanara ethiopica Dworakowska, Molopopterus spp., Maiestas dolabra (Kramer), Balclutha rosea Scott, Balclutha incisa Matsumura, Afrosus unimaculatus (Naude), Cicadulina anestae van Rensburg and C. mbila(Naude).