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.
Mosaic diseases in sugarcane
Mosaic symptoms in sugarcane are associated with four diseases that are caused by several viruses: mild mosaic caused by the Sugarcane mild mosaic virus (SCMMV), mosaic caused by the Sugarcane mosaic virus (SCMV) and the Sorghum mosaic virus (SrMV), streak mosaic caused by the Sugarcane streak mosaic virus (SCSMV) and striate mosaic caused by the Sugarcane striate mosaic-associated virus (SCSMaV). Among those, mosaic is the most known and world wide spread disease. A number of techniques based on the detection of virus nucleic acids are available for diagnosis of sugarcane mosaic diseases. Several reverse-transcription polymerase chain reaction (RT-PCR) protocols were developed for molecular diagnosis of SCMV, SrMV, SCSMV and SCSMaV. These protocols are generally based on the virus coat protein sequence. Because this sequence is often variable, the effectiveness of the RT-PCR assays to diagnose all isolates/strains of the pathogen needs to be tested. No molecular assay is yet available to diagnose SCMMV. (Resume d'auteur)
Hill country sheep production. I. The influence of age, flock, and year on some components of reproduction rate in Romney and Border Leicester × Romney ewes.
Data from 7,091 straightbred Romney and Border Leicester × Romney ewes grazed at the Whatawhata Hill Country Research Station over the period 1959 to 1967 have been used to obtain estimates of flock and age-of-ewe effects on reproduction rate and its components and of year-to-year variation. The ewes were from six groups: a Romney control (RCR) flock, a Romney flock in which ewes were mated either to Romney (RER) or to Border Leicester rams (REB), and flocks of first-cross (F1), second-cross (F2), and third-cross (F3) Border Leicester × Romney ewes mated to first-cross Border Leicester × Romney rams. The ewes' ages at lambing varied from 2 to 5 years and no selection was practised. The ratio of number of lambs weaned per ewe present at lambing increased from the RCR (0.84) to the F1 (1.07), then declined with interbreeding to the F2 (0.92) and further to the F3 (0.87) ewes. Similar changes were evident for the percentage of ewes lambing, of multiple births, and of lambs surviving to weaning. Over...