Brachiaria piligera and Sorghum verticilliflorum are natural hosts of two different strains of sugarcane mosaic virus in Australia
In 1985 and 1986, during an outbreak of mosaic in sugarcane in the lsis district of Queensland, Brachiaria piligera (hairy arm grass) with mosaic symptoms was found infected with the sugarcane strain of sugarcane mosaic virus (SCMV-SC). This is the first report of SCMV-SC naturally infecting a host other than sugarcane in Australia. Sorghum verticilliflorum (wild sorghum) with mosaic symptoms in the lsis and nearby coastal districts was always infected by Johnsongrass mosaic virus (JGMV), except at one site in Bundaberg where the sabigrass strain of SCMV (SCMV-Sabi), which does not infect sugarcane, was found. This is the first report of SCMV-Sabi occurring in wild sorghum and in a district distant from Gatton where infected sabigrass occurs normally.
Reaction of Different Maize Genotypes to Infection by Maize Lethal Necrosis Disease and Transmission of Viruses Causing the Disease From Soil and Plant Debris
A greenhouse study was conducted to determine the reaction of five different genotypes of maize to infection by Sugarcane mosaic virus (SCMV), Maize chlorotic mosaic virus (MCMV) and the synergistic interaction of the two viruses which results in maize lethal necrosis (MLN) disease. The genotypes included H614, H513, Duma 43, Kikamba and Kinyanya. Their selection was based on the Agro-ecological Zones (AEZ) where they are grown in addition to whether they are hybrids or landraces. The treatments included SCMV and MCMV each inoculated separately and in combination (SCMV+MCMV) and with inoculum obtained from MLN infected plants. The plants were mechanically inoculated at four leaf stage. The plants were assessed for disease severity using a scale of 1-5 and area under disease progress curve (AUDPC) and percent disease incidence determined starting from week 1 post inoculation to week 6. Leaf samples were collected and analyzed for the presence of the viruses using Double Antibody Sandwich Enzyme Linked Immuno-sorbent Assay (DAS-ELISA). All the genotypes had >90% incidence recorded with significant differences among genotypes only for the co-infection (SCMV+MCMV) at P=0.05 while on disease severity, the SCMV+MCMV had the highest AUDPC. The landraces recorded higher disease severity with Kinyanya having an average of 4.9 and Kikamba 4.5 on the SCMV+MCMV treatment. In general, landraces showed more severity to the different viral infections. When the plants were co-infected with both SCMV and MCMV, the disease severity was quite high with more than 80% crop loss whereas the plants inoculated with MLN extracted
The detection by serological methods of viruses infecting the rose
SUMMARY 
 
Homogenates of herbaceous test plants infected with arabis mosaic virus (AMV), prunus necrotic ringspot virus (PNRSV), or strawberry latent ringspot virus (SLRV), and purified virus preparations were used to assess the sensitivities of four serological methods (the enzyme-linked immunosorbent assay - ELISA, immunodiffusion in gels, the latex flocculation assay, and serologically specific electron microscopy -SSEM) for the detection of these viruses. The latex test was up to 250 times more sensitive than gel immunodiffusion, but SSEM and ELISA were respectively up to 1000 and 200 times more sensitive than the latex test. 
 
 
 
Gel immunodiffusion and latex tests failed to detect any of the viruses in infected roses. Although ELISA reliably detected PNRSV and SLRV when leaves from infected roses were homogenised in a leaf: buffer ratio of 1 g:10 ml, AMV was occasionally undetected. However, when a modified ELISA technique, which reduced non-specific reactions, was used some PNRSV-infected roses were also not detected. Detection by SSEM was c. twice as sensitive as ELISA for all three viruses in rose extracts. The relative advantages of ELISA and SSEM for the detection of plant viruses are discussed.