Potential Human Exposure to Australian Bat Lyssavirus, Queensland, 1996-1999

Two human deaths caused by Australian bat lyssavirus (ABL) infection have been reported since 1996. Information was obtained from 205 persons (mostly adults from south Brisbane and the South Coast of Queensland), who reported potential ABL exposure to the Brisbane Southside Public Health Unit from November 1,1996, to January 31, 1999. Volunteer animal handlers accounted for 39% of potential exposures, their family members for 12%, professional animal handlers for 14%, community members who intentionally handled bats for 31%, and community members with contacts initiated by bats for 4%. The prevalence of Lyssavirus detected by fluorescent antibody test in 366 sick, injured, or orphaned bats from the area was 6%. Sequelae of exposure, including the requirement for expensive postexposure prophylaxis, may be reduced by educating bat handlers and the public of the risks involved in handling Australian bats.

Building better information products by assessing the information needs of growers of subtropical strawberries in Queensland

Timely access to effective technical information is a key ingredient of profitable strawberry production. Through the Better Berries Program, a joint RD&E initiative of government and industry, a number of information products and services have been provided in recent years to Australia's subtropical strawberry industry, centred in southern Queensland. However, there is a lack of knowledge of how well these are meeting the information needs of growers, both in content and delivery. To better understand grower information use and needs, a stratified sample of 25 growers was interviewed on-farm during the 2004 season. Growers were asked about how they currently accessed information, what they thought of a range of information products and ideas on show, and what advice they would provide for information development in the future. Results indicated that information sought by growers and the style in which it is best presented, varied considerably with grower experience, but little with farm size. New growers had a wide range of needs while the needs of experienced growers were focused mainly on problem identification and new production development. Interestingly, the overwhelming majority across all sectors still preferred paper-based information products despite their extensive use of computers for business purposes. The findings were used to develop a strategy for an improved range of technical information products and services that are more accessible, easier to use, more timely, and more relevant to the needs of growers.

Pest management in Queensland strawberries: Reality bites, and growers' perspectives change!

Prior to the 1980s, arthropod pest control in Queensland strawberries was based entirely on calendar sprays of insecticides (mainly endosulfan, triclorfon, dimethoate and carbaryl) and a miticide (dicofol). These chemicals were applied frequently and spider mite outbreaks occurred every season. The concept of integrated pest management (IPM) had not been introduced to growers, and the suggestion that an alternative to the standard chemical pest control recipe might be available, was ignored. Circumstances changed when the predatory mite, Phytoseiulus persimilis Athios-Henriot, became available commercially in Australia, providing the opportunity to manage spider mites, the major pests of strawberries, with an effective biological agent. Trials conducted on commercial farms in the early 1980s indicated that a revolution in strawberry pest management was at hand, but the industry generally remained sceptical and afraid to adopt the new strategy. Lessons are learnt from disasters and the consequent monetary loss that ensues, and in 1993, such an event relating to ineffective spider mite control, spawned the revolution we had to have. Farm-oriented research and evolving grower perspectives have resulted in the acceptance of biological control of spider mites using Phytoseiulus persimilis and the 'pest in first' technique, and it now forms the basis of an IPM system that is used on more than 80% of the Queensland strawberry crop.

The performance of strawberry plugs in Queensland

Plugs or containerized plants can offer several advantages over traditional bare-rooted runner plants for strawberry (Fragaria x ananassa) production. Some of these benefits include easier planting, better establishment, fewer pests and diseases, and lower water use during plant establishment resulting in less leaching of applied fertilizers. Plugs also offer the potential for mechanical planting. In some areas of Europe and North America, plugs provide earlier production, greater productivity and larger fruit than runners. Research has also shown that the plants can be grown under short days and low temperatures to manipulate flower initiation and fruiting. Plugs are more expensive to buy compared with runner plants, and will only be adopted by industry if the extra costs are matched by convenience, resource conservation, increased fruiting and returns to producers. We investigated the productivity of 'Festival' and 'Sugarbaby' propagated as plugs (75 cm3 containers) and runners from Stanthorpe in southern Queensland (elevation of 872 m), and grown at Nambour on the Sunshine Coast (elevation 29 m). At planting, the plug plants weighed 0.8 ± 0.1 g DW compared with 53 ± 0.5 g DW for the runner plants. 'Sugarbaby' plugs were larger than 'Festival' plugs (33 ± 0.6 g versus 2.9 ± 0.6 g). The differences in growth at planting were maintained until the third week of July (day 94), with the plug plants weighing 17.8 ± 2.2 g, and the runner plants 21.4 ± 23 g. The proportion of plant dry matter allocated to the leaves increased over time from 59 to 70%, while the proportion allocated to the roots decreased from 21 to 10%. Harvest commenced after 60 days, with the plug plants yielding only 60% of the yields of the runner plants up until 8 August or day 109 (14.2 ± 1.4 g plant -1 week-1 versus 23.6 ± 1.9 g plant-1 week-1). 'Festival' (22.2 ± 2.0 g plant-1 week -1) had higher yields than 'Sugarbaby' (15.5 ± 1.5 g plant-1 week-1), even though plants of the latter were larger. Average fruit weight was 15.6 ± 0.3 g, with no effect of cultivar, plant type or harvest time. In other words, the differences in yield between the various treatments were due to differences in fruit set The lower yields of the plug plants probably reflect their small size at planting. Future research should determine whether plugs grown in larger cells (150 to 300 cm3 as in the USA and Europe) are more productive. Tips to be grown in larger containers should be harvested earlier than those for small cells to maximize root growth of the plug plant. This will probably extend the time required from harvest of the tips and potting them from the current four to five weeks, to eight to ten weeks.

Effect of micro-propagation on the health status of strawberry planting material for commercial production of strawberry runners for Queensland

Plant tissue culture has been used for a number of years to produce micropropagated strawberry plants for planting into runner growing beds in the Stanthorpe (Queensland) and Bothwell (Tasmania) regions. This process has allowed the rapid release of new cultivars from the LAWS (Late Autumn, Winter, Spring) breeding program into the current runner production system. Micro-propagation in vitro allows plants to be produced during the autumn and winter months, when mother plants would normally be in a fruit production phase in the field in Queensland. The plants produced are of a high health status when they are planted. The subsequent arrival and build up of various diseases in the runner fields are closely monitored. Using tissue culture for the first generation reduces the time the plants spend in the field by twelve months, reducing disease incidence. To date, any disease outbreak has been successfully managed using early detection and rapid response methods.

Strawberry breeding in a subtropical environment

Strawberry breeding aims to provide cultivars that maximise consumer satisfaction and producer profitability in a changing environment. In this paper some concepts of profitability, consumer satisfaction and sustainability are explored for a subtropical climate using Queensland Australia, and Florida USA, as examples. The typical production environment is annual autumn planting of bare rooted runners into polythene covered raised beds at about 40000 plants/ha. Harvesting is late autumn to early spring, with fruit arriving at the major markets up to 2000km away from the production area within 1-4 days of harvest. The basic premise in the breed-big work is that consumers must enjoy the experience of eating strawberries, and that perceived flavour, sweetness, and juiciness are the major contributors to this experience. Using market chain information, we developed a basic value model comprised of costs, returns, and sustainability of market. To this basic outline are applied operational descriptors, such as 'speed of harvest', and associated plant characteristics, such as 'fruit display'. The expression of each plant characteristic is ascribed a value or level and together numerically describe the phenotype. This description is mathematically manipulated to provide a 'value index' for the cultivar. Nine cultivars including 'Strawberry Festival', 'Kabarla', 'DPI Rubygem' and 'Sweet Charlie' are described, and environmental issues that may impact on the subtropical strawberry breeding objectives are discussed. Product differentiation and the use of exotic germplasm as a new source of genes for flavour and resistance to disease and environmental stress will likely be the cornerstones of future progress in subtropical strawberry breeding. This approach should satisfy both consumers and producers.

Successful management of colletotrichum crown and stolon rot in runner production in sub-tropical Australia

Crown, stolon, and petiole rots caused by Colletotrichum gloeosporioides (C.g.) were first identified in runner beds of the Queensland Approved Runner Scheme (QARS) in February 1989. The outbreaks occurred annually from 1990 to 1994. Minor losses in subsequent fruit crops occurred from 1990 to 1993, with 50% post-establishment losses occurring on fruit farms in southeast Queensland in 1994. The objective of this work was to provide a control strategy for the disease that would give stability to the QARS. Runner-bed trials in 1993-1994 showed that Octave® (462 g/kg prochloraz as the MnCl2 complex) was highly effective in reducing the incidence field symptoms and laboratory recovery of C.g. from symptomless petioles. A simple detached petiole laboratory test for measuring fungicide efficacy in runner bed trials and for laboratory screening of fungicides, is described. Scheme protocols were changed to require that only foundation plants from tissue culture were allowed onto QARS sites. These were to be symptomless and to have tested negative for the presence of C.g. The application of Octave® at fortnightly intervals in all QARS nurseries has reduced the level of visible symptoms and the laboratory recovery of C.g. from symptomless petioles to almost zero.

Swan’s Lagoon Celebrating 50 years

Swan’s Lagoon, which is 125 km south-south-west of Townsville, was purchased by the Queensland Government as a beef cattle research station in 1961. It is situated within the seasonally-dry tropical spear grass region of North Queensland. The station was expanded from 80 km2 to 340 km2 by purchase of the adjoining Expedition block in 1978. The first advisory committee formed and initiated research in 1961. The median annual rainfall of 708 mm (28 inches) is highly variable, with over 80% usually falling in December–April. Annual evaporation is 2.03 metres. The 60% of useable area is mostly flat with low fertility duplex soils, of which more than 50% is phosphorus deficient. Natural spear grass-based pastures predominate over the station. Swan’s Lagoon research has contributed to understanding the biology of many aspects of beef production for northern Australia. Research outcomes have provided options to deal with the region’s primary challenges of weaning rates averaging less than 60%, annual growth rates averaging as little as 100 kg, high mortality rates and high management costs. All these relate to the region’s variable and highly seasonal rainfall—challenges that add to insect-borne viruses, ticks, buffalo fly and internal parasites. As well as the vast amount of practical beef production science produced at Swan’s Lagoon, generations of staff have been trained there to support beef producers throughout Queensland and northern Australia to increase their business efficiency. The Queensland Government has provided most of the funds for staffing and operations. Strong beef industry support is reflected in project funding from meat industry levies, managed by Meat and Livestock Australia (MLA) and its predecessors. MLA has consistently provided the majority of operational research funding since the first grant for ‘Studies of management practices, adaption of different breeds and strains to tropical environments, and studies on tick survival and resistance’ in 1962–63. A large number of other agencies and commercial companies have also supported research.

Inactivation of Aspergillus flavus spores by curcumin-mediated photosensitization

Minimizing fungal infection is essential to the control of mycotoxin contamination of foods and feeds but many potential control methods are not without their own safety concerns for the consumers. Photodynamic inactivation is a novel light-based approach which offers a promising alternative to conventional methods for the control of mycotoxigenic fungi. This study describes the use of curcumin to inactivate spores of Aspergillus flavus, one of the major aflatoxin producing fungi in foods and feeds. Curcumin is a natural polyphenolic compound from the spice turmeric (Curcuma longa). In this study the plant has shown to be an effective photosensitiser when combined with visible light (420 nm). The experiment was conducted in in vitro and in vivo where A. flavus spores were treated with different photosensitiser concentration and light dose both in buffer solution and on maize kernels. Comparison of fungal load from treated and untreated samples was determined, and reductions of fungal spore counts of up to 3 log CFU ml−1 in suspension and 2 log CFU g−1 in maize kernels were obtained using optimal dye concentrations and light dose combinations. The results in this study indicate that curcumin-mediated photosensitization is a potentially effective method to decontaminate A. flavus spores in foods and feeds.