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Sullivan P.R.,Tamworth Agricultural Institute | Postle L.A.,Industry and Investment NSW | Julien M.,CSIRO
Biological Control | Year: 2011

A three year study of the interaction of salvinia weevil, Cyrtobagous salviniae, with Salvinia molesta was undertaken in temperate Eastern Australia. Releases of C. salviniae were made on rivers, creeks and dams from spring to mid summer of the first year and 12 sites were monitored. Eight sites were controlled by C. salviniae within 12. months, however the weevil failed to persist long term at some sites in still water habitats of creeks and dams. Better control was achieved at sites with higher temperatures and higher salvinia nitrogen levels. Biological control is an important salvinia management option in temperate regions and is now being used by weed management organisations. © 2011 Elsevier Inc. Source

Nicholas A.H.,Tamworth Agricultural Institute
Irrigation Science | Year: 2010

Holes in sub-surface drip irrigation systems under lucerne are costly to the grower in terms of repairs and yield loss and are an impediment to future investment in this technology. The activity of whitefringed weevil Naupactus leucoloma larvae in relation to sub-soil drip irrigation tape (pipe) was monitored using glass plate observation chambers. Larvae were observed attacking the irrigation tape, and the resulting damage, in the form of grooves and holes, was comparable with the damage seen on tapes collected from the field. The grooves were measured and compared with the size and shape of the mouthparts of the larvae. This work positively identifies whitefringed weevil larvae as a cause of significant damage to 0.34-mm-walled sub-soil irrigation tape in Australian lucerne crops. © 2009 Springer-Verlag. Source

Timms W.A.,University of New South Wales | Young R.R.,Tamworth Agricultural Institute | Huth N.,CSIRO
Hydrology and Earth System Sciences | Year: 2012

The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr-1 rainfall, potential evapotranspiration >2000 mm yr-1) such as parts of Australia's Murray-Darling Basin (MDB). In this rare study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8-1.2 m depth under perennial vegetation and at 2.0-2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91-229 t ha-1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ≥ 10 m depth that was not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m-1 at 21 to 37 m depth (N Combining double low line 5), whereas deeper groundwater was less saline (290 mS m-1) with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM) software package predicted deep drainage of 3.3-9.5 mm yr-1 (0.7-2.1% rainfall) based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent soil water content, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total), and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge appears to be negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditions after changes in land use and a thick clay dominated vadose zone.

This is in contrast to regional groundwater modelling that assumes annual recharge of 0.5% of rainfall. Importantly, it was found that leaching from episodic deep drainage could not cause discharge of saline groundwater in the area, since the water table was several meters below the incised river bed. © Author(s) 2012. Source

Gunning R.V.,Tamworth Agricultural Institute | Moores G.D.,Rothamsted Research
Pesticide Biochemistry and Physiology | Year: 2010

The effects of raw or heat-denatured soybean flour in an artificial diet on the detection of Cry1Ac resistance in Helicoverpa armigera were examined. Resistant neonate larvae reared on denatured soybean flour diet showed resistance factors of 7980 and 16,901 at the LC 50 and LC 99.9 levels, respectively. By comparison, resistance could not be detected in neonate larvae reared on raw flour diet. Third instar larvae reared on denatured flour diet showed resistance factors of 322 and 21,190 at the LC 50 and LC 99.9 levels. Resistance was not detected in third instar larvae reared on raw flour diet. There was 68% survival of resistant neonate larvae on Bollgard II cotton leaf feeding assays, compared to 100% mortality in a susceptible strain. We conclude that detection of CRY1Ac resistance in H. armigera from Australia can be masked, if an artificial diet gives chronic exposure to potent, protease inhibitors present in raw soy flour. © 2009 Elsevier Inc. Source

Wood J.A.,Tamworth Agricultural Institute | Knights E.J.,Tamworth Agricultural Institute | Chocty M.,University of New South Wales
International Journal of Plant Sciences | Year: 2011

The morphology and composition of seeds of desi and kabuli chickpea (Cicer arietinum L.) genotypes were studied using light microscopy with differential staining for protein, starch, b-glucans, and nonfluorescing compounds. Kabuli seeds had a thinner seedcoat due to thinner palisade and parenchyma layers which contained fewer pectic polysaccharides and less protein. The outer palisade layer varied in thickness from one to two cells, leading to a textured and sometimes wrinkled appearance of the seed surface. In contrast, the desi palisade layers were rigid and extensively thickened. Hourglass cells were homogeneous for both seed types, but not in an interspecific desi line (containing Cicer echinospermum parentage), which had heterogeneous cells. The inner surface of the seedcoat contained both pectic and proteinaceous materials. The cotyledon comprised a single outer epidermal layer of protein-filled cells devoid of starch, with thickened outer cell walls; cell size and shape differed on abaxial and adaxial faces. Subepidermal cells on the abaxial face were similar to epidermal cells. These findings help explain differences in the processing behavior between the major chickpea seed types. © 2011 by The University of Chicago. All rights reserved. Source

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