Managing Ascochyta blight

The first outbreak of Ascocbyta blight in commercial chickpea crops in Western Australia was detected in July 1999. By the end of 1999, over 7C crops were found to be infected. Due to difficulty in detecting low levels of the disease, it is expected that many parts of the wheatbelt that now appear free of the disease may have a low level of infection. Ian Pritchard reports on the disease symptoms, its spread, and the management principles now in place to minimise the impact of Ascocbyta blight for the 2000 season

Automated Impact Crater Detection and Characterization Using Digital Elevation Data

Impact craters are used as subjects for the remote study of a wide variety of surface and subsurface processes throughout the solar system. Their populations and shape characteristics are collected, often manually, and analysed by a large community of planetary scientists. This research investigates the application of automated methods for both the detection and characterization of impact craters on the Moon and Mars, using machine learning techniques and digital elevation data collected by orbital spacecraft. We begin by first assessing the effect of lunar terrain type variation on automated crater detection results. Next, we develop a novel automated crater degradation classification system for martian complex craters using polynomial profile approximation. This work identifies that surface age estimations and crater statistics acquired through automatic crater detection are influenced by terrain type, with unique detection error responses. Additionally, we demonstrate an objective system that can be used to automate the classification of crater degradation states, and identify some potential areas of improvement for such a system

Successful field pea harvesting

Many thousands of hectares of field peas are harvested trouble free each year. Growers experience together with recent machinery innovations and modifications have solved the majority of harvesting difficulties. Optimum harvesting conditions are in a crop of uniform density on a level soil surface with the machine either working into or across the direction that the crop has been laid by the wind. To make harvest easier the receival standard for moisture in pulses has been lifted to 14 per cent, which allows harvest to begin sooner when the crop is the range of 14 to 15 per cent moisture. Harvesting at higher moisture levels has a wide range of advantages for growers, grain handlers (CBH), buyers and end users of our pulse crops.https://researchlibrary.agric.wa.gov.au/bulletins/1149/thumbnail.jp

Pulses : profitable new crops for the wheatbelt

Narrow-leafed lupins have beeb produced on sandy acid soils throughout the wheatbelt for more than two decades. However, the wheatbelt contains large areas ofsoilsnot suited to narrow-leafed lupins. For several years reasearchers have been examining alternatives to narrow-leafed lupins for these soils. Kadambot Siddique, Stephen Loss and Ian Prichard look at production of these new grain legumes, known as pulses

Field pea in the great southern

Semi-leafless field pea like Kaspa have lifted the benchmark set by the previous conventional varieties such as Parafield and Dunwa. Semi-leafless field pea have the same traits as conventional field pea: adaptation to a range of soil types; wide selection of weed control options (including crop topping); nitrogen input; disease break; and reduction in root lesion nematodes. Semi-leafless pea is easier to harvest and is less prone to pod shatter

The value of break crops in weed management

This publication discusses the effect on weed management of the inclusion of break crops (lupin, field pea, chickpea, faba bean, lentil and canola) in the cropping rotation compared to a rotation of continuous cereals. Including break crops in the cropping rotation allows weed management options unavailable or not suited in wheat. For example, growing field peas allows crop-topping/ desiccation for weed seed set control, crop topping cannot be used in wheat without severe yield loss. Problem weeds can be targeted through break crops, for example, grass weeds are generally more easily controlled in break crops than in cereals. Most weed management benefits attributed to break crops depend upon a well grown and well managed break crop.https://researchlibrary.agric.wa.gov.au/bulletins/1117/thumbnail.jp

Evolutionary relationships among bluetongue and related orbiviruses

Polymerase chain reaction (PCR) sequencing of specific viral gene segments was used to investigate the phylogenetic relationships among the orbiviruses. Sequence comparisons of the bluetongue virus (BTV) RNA3 from different regions of the world (North America, South Africa, India, Indonesian, Malaysia, Australia and the Caribbean region) showed that geographic separation had resulted in significant divergence, consistent with the evolution of distinct viral populations. There were at least 3 topotypes (Gould, 1987); the Australasian, African - American and another topotype represented by BTV 15 isolated in Australia in 1986. The topotypes of BTV had RNA3 nucleotide sequences that differed by approximately 20 per cent. Analysis of BTV-specific gene segments from animal and insect specimens showed that bluetongue viruses had entered northern Australia from South East Asia, possibly by wind-borne vectors. Nucleotide sequence comparisons were used to show the close genetic relationship between BTV 2 (Ona-A strain) from Florida and BTV 12 from Jamaica, and to investigate the reassortment of BTV genome segments in nature. The mutation rates of the BTV RNA2 and RNA3 segments were estimated to be of the order of 10(-4) nucleotide changes/site/year, similar in magnitude to that reported for other RNA viruses

Emerging aspects of oesophageal and gastro-oesophageal junction cancer histopathology – an update for the surgical oncologist

Adenocarcinoma of the oesophagus and gastro-oesophageal junction are rapidly increasing in incidence and have a well described sequence of carcinogenesis: the Barrett's metaplasia-dysplasia-adenocarcinoma sequence. During recent years there have been changes in the knowledge surrounding disease progression, cancer management and histopathology specimen reporting. Tumours around the gastro-oesophageal junction (GOJ) pose several specific challenges. Numerous difficulties arise when the existing TNM staging systems for gastric and oesophageal cancers are applied to GOJ tumours. The issues facing the current TNM staging and GOJ tumour classification systems are reviewed in this article. Recent evidence regarding the importance of several histopathologically derived prognostic factors, such as circumferential resection margin status and lymph node metastases, have implications for specimen reporting. With the rising use of multimodal treatments for oesophageal cancer it is important that the response of the tumour to this therapy is carefully documented pathologically. In addition, several controversial and novel areas such as endoscopic mucosal resection, lymph node micrometastases and the sentinel node concept are being studied. We aim to review these aspects, with special relevance to oesophageal and gastro-oesophageal cancer specimen reporting, to update the surgical oncologist with an interest in upper gastrointestinal cancer

Calibrated BOLD using direct measurement of changes in venous oxygenation

Calibration of the BOLD signal is potentially of great value in providing a closer measure of the underlying changes in brain function related to neuronal activity than the BOLD signal alone, but current approaches rely on an assumed relationship between cerebral blood volume (CBV) and cerebral blood flow (CBF). This is poorly characterised in humans and does not reflect the predominantly venous nature of BOLD contrast, whilst this relationship may vary across brain regions and depend on the structure of the local vascular bed. This work demonstrates a new approach to BOLD calibration which does not require an assumption about the relationship between cerebral blood volume and cerebral blood flow. This method involves repeating the same stimulus both at normoxia and hyperoxia, using hyperoxic BOLD contrast to estimate the relative changes in venous blood oxygenation and venous CBV. To do this the effect of hyperoxia on venous blood oxygenation has to be calculated, which requires an estimate of basal oxygen extraction fraction, and this can be estimated from the phase as an alternative to using a literature estimate. Additional measurement of the relative change in CBF, combined with the blood oxygenation change can be used to calculate the relative change in CMRO2 due to the stimulus. CMRO2 changes of 18 ± 8% in response to a motor task were measured without requiring the assumption of a CBV/CBF coupling relationship, and are in agreement with previous approaches

Genome-Wide Analysis of the Response of Dickeya dadantii 3937 to Plant Antimicrobial Peptides

Antimicrobial peptides constitute an important factor in the defense of plants against pathogens, and bacterial resistance to these peptides have previously been shown to be an important virulence factor in Dickeya dadantii, the causal agent of soft-rot disease of vegetables. In order to understand the bacterial response to antimicrobial pep- tides, a transcriptional microarray analysis was performed upon treatment with sub-lethal concentration of thionins, a widespread plant peptide. In all, 36 genes were found to be overexpressed, and were classified according to their deduced function as i) transcriptional regulators, ii) transport, and iii) modification of the bacterial membrane. One gene encoding a uricase was found to be repressed. The majority of these genes are known to be under the control of the PhoP/PhoQ system. Five genes representing the different functions induced were selected for further analysis. The results obtained indicate that the presence of antimicrobial peptides induces a complex response which includes peptide-specific elements and general stress-response elements contributing differentially to the virulence in different hosts