Optical peanut yield monitor: Development and testing

An optical peanut yield monitor was developed, fabricated, and field-tested. The overall system includes an optical mass-flow sensor, a GPS receiver, and a data acquisition system. The concept for the mass-flow sensor is based on that of the cotton yield-monitor sensor developed previously by Thomasson and Sui (2000). A modified version of the sensor was designed to be specific to peanut mass-flow measurement. Field testing of the peanut yield monitor was conducted in Australia during the May 2003 harvest. After subsequent minor modifications, the system was more extensively tested in Mississippi in October of 2003 and November of 2004. Test results showed that the output of the peanut mass-flow sensor was very strongly correlated with the harvested load weight, and the system's performance was stable and reliable during the tests.

New insights into the altered adhesive and mechanical properties of red blood cells parasitized by Babesia bovis

Sequestration of parasite-infected red blood cells (RBCs) in the microvasculature is an important pathological feature of both bovine babesiosis caused by Babesia bovis and human malaria caused by Plasmodium falciparum. Surprisingly, when compared with malaria, the cellular and molecular mechanisms that underlie this abnormal circulatory behaviour for RBCs infected with B. bovis have been relatively ignored. Here, we present some novel insights into the adhesive and mechanical changes that occur in B. bovis-infected bovine RBCs and compare them with the alterations that occur in human RBCs infected with P. falciparum. After infection with B. bovis, bovine RBCs become rigid and adhere to vascular endothelial cells under conditions of physiologically relevant flow. These alterations are accompanied by the appearance of ridge-like structures on the RBC surface that are analogous, but morphologically and biochemically different, to the knob-like structures on the surface of human RBCs infected with P. falciparum. Importantly, albeit for a limited number of parasite lines examined here, the extent of these cellular and rheological changes appear to be related to parasite virulence. Future investigations to identify the precise molecular composition of ridges and the proteins that mediate adhesion will provide important insight into the pathogenesis of both babesiosis and malaria.

Use of optical density as a measure of Claviceps africana conidial suspension concentration

Sorghum ergot, caused by Claviceps africana, has remained a major disease problem in Australia since it was first recorded in 1996, and is the focus of a range of biological and integrated management research. Artificial inoculation using conidial suspensions is an important tool in this research. Ergot infection is greatly influenced by environmental factors, so it is important to reduce controllable sources of variation such as inoculum concentration. The use of optical density was tested as a method of quantifying conidial suspensions of C. africana, as an alternative to haemocytometer counts. This method was found to be accurate and time efficient, with possible applications in other disease systems.

Growth of koster’s curse (Clidemia hirta) from seedlings to reproductive maturity and following mechanical damage

Koster´s curse is a highly invasive, perennial shrub with potential to become a major weed in many parts of Queensland and elsewhere in Australia. Presently, there is one infestation discovered in Australia and the species is a Class 1 weed. It grows to 5 m and can produce over 500 berries annually which are dispersed by birds and water. This study quantified growth and the effects of damage on survival and time to reproduction under both field and shade house conditions in the Wet Tropics of north Queensland. Plants recovered to their original size and were capable of setting seed in as few as 86 days and 194 days after being cut back to 10 cm and 0 cm respectively.

Pond apple (Annona glabra L.) - Investigating novel mechanical control options

Pond apple usually occurs in swampy areas, but mechanical control may be a viable option in some locations during drier periods. Two machines, the Positrack™ and the Tracksaw™, have been trialled for initial kill rate, amount of follow-up control required, safety to field operators, cost-efficiency and selectivity (effect on native vegetation), compared to other control options. The Positrack™ is a tracked bobcat with a slasher-type attachment that cuts individual trees off near ground level and mulches them. It has no on-board herbicide application capability and requires an additional on-ground operator to apply herbicide by hand. The Tracksaw™ is a tracked mini-excavator with a chainsaw bar and spray applicator on the boom that cuts individual trees off near ground level and applies chemical immediately to the cut stump, requiring only a single operator. Initial trials were done in infestations of similar sizes and densities at the Daintree (Positrack™) and in Innisfail (Tracksaw™) in late 2009. Kill rates to date are 83% for Positrack™ mechanical, 95% for Positrack™ mechanical plus herbicide, and 78% for the Tracksaw™ combined treatment. If ongoing comparison proves either of these machines to be more cost effective, selective, and safer than traditional control methods, mechanical control methods may become more widely used.