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.
Gold-labelled antibody decoration (GLAD) in the diagnosis of plant viruses by immuno-electron microscopy.
Abstract The diagnostic capabilities of immuno-electron microscopy have been developed by using antibodies labelled with colloidal gold-protein A. A method termed gold-labelled antibody decoration (GLAD) is described and results using the technique on a number of strains of tobacco mosaic virus are given.
Effect of Soybean Cyst Nematode (Heterodera glycines) on Yield of Resistant and Susceptible Soybean Cultivars Grown in Ohio.
Soybean (Glycine max) producers in Ohio rarely use soybean cyst nematode (Heterodera glycines, SCN)-resistant cultivars because of concerns over limited yield potential and lack of resistance to Phytophthora sojae. A two-year study was initiated to determine grain yield and nematode population increase on soybean cyst nematode-resistant cultivars in maturity groups II and III in production fields. Sites differed in soil texture, nematode densities, and P. sojae infestation at a number of locations in Ohio. Soil was assayed for nematode densities before planting and at harvest. Yields of resistant cultivars averaged 0% to 18% higher than those of susceptible cultivars in fine-textured soils with average preplant populations ranging from 463 to 14,330 SCN eggs/100 cm(3) soil. In coarse-textured soils, yields of susceptible cultivars were 21% to 56% less than the resistant cultivars with average preplant densities ranging from 1,661 to 15,558 SCN eggs/100 cm(3) soil. The reproductive index ranged from 0.1 to 5.5 for resistant cultivars and 0.4 to 112 for susceptible cultivars. In 1993, yield of P. sojae-susceptible, nematode-resistant 'Asgrow A 3431' was as high as yield of the P. sojae-resistant, nematode-susceptible cultivar 'Resnik' in a Phytophthora-infested field. The nematode-resistant cultivars Madison Experimental 131527 and Asgrow A3431 had higher yields than AgVenture AV1341 and susceptible cultivars Resnik and Kenwood when compared over five nematode-infested sites. Nematode-resistant cultivars were found to be excellent alternatives to currently grown susceptible cultivars for managing SCN where group III cultivars are used. However, better cultivar alternatives may be needed for sites with combined Phytophthora root rot and cyst nematode problems.