Risk assessment for Puccinia psidii becoming established in South Africa

Puccinia psidii, the causal agent of myrtle rust, was first recorded from Latin America more than 100 years ago. It occurs on many native species of Myrtaceae in Latin America and also infects non-native plantation-grown Eucalyptus species in the region. The pathogen has gradually spread to new areas including Australia and most recently South Africa. The aim of this study was to consider the susceptibility of selected Eucalyptus genotypes, particularly those of interest to South African forestry, to infection by P. psidii. In addition, risk maps were compiled based on suitable climatic conditions and the occurrence of potential susceptible tree species. This made it possible to identify the season when P. psidii would be most likely to infect and to define the geographic areas where the rust disease would be most likely to establish in South Africa. As expected, variation in susceptibility was observed between eucalypt genotypes tested. Importantly, species commonly planted in South Africa show good potential for yielding disease-tolerant material for future planting. Myrtle rust is predicted to be more common in spring and summer. Coastal areas, as well as areas in South Africa with subtropical climates, are more conducive to outbreaks of the pathogen.

New tools for management of phosphine resistance

Phosphine is the primary fumigant used to protect the majority of the world' s grain and a variety of other stored commodities from insect pests. Phosphine is playing an increasingly important role in the protection of commodities for two primary reasons. Firstly, use of the alternative fumigant, methyl bromide, has been sharply curtailed and is tightly regulated due to its role in ozone depletion, and secondly, consumers are becoming increasingly intolerant of contact pesticides. Niche alternatives to phosphine exist, but they suffer from a range of factors that limit their use, including: 1) Limited commercial adoption due to expense or slow mode of action; 2) Poor efficacy due to low toxicity, rapid sorption, limited volatility or high density; 3) Public health concerns due to toxicity to handlers or nearby residents, as well as risk of explosion; 4) Poor consumer acceptance due to toxic residues or smell. These same factors limit the prospects of quickly identifying and deploying a new fumigant. Given that resistance toward phosphine is increasing among insect pests, improved monitoring and management of resistance is a priority. Knowledge of the mode of action of phosphine as well as the mechanisms of resistance may also greatly reduce the effort and expense of identifying synergists or novel replacement compounds.

Co-evolution of wild rabbits (Oryctolagus cuniculus) and RHDV: resistance and virulence

Rabbit Haemorrhagic Disease Virus (RHDV) was introduced to Australia in 1995 for the control of wild rabbits. Initial outbreaks greatly reduced rabbit numbers and the virus has continued to control rabbits to varying degrees in different parts of Australia. However, recent field evidence suggests that the virus may be becoming less effective in those areas that have previously experienced repeated epizootics causing high mortality. There are also reports of rabbits returning to pre-1995 density levels, Virus and host can be expected to co-evolve. The host will develop resistance to the virus with the virus subsequently changing to overcome that resistance. It has been 12 years since the release of RHDV and it is an opportune time to examine where the dynamic currently stands between RHDV and rabbits. Laboratory challenge tests have indicated that resistance to RHDV has developed to different degrees in populations throughout Australia. In one population a low dose (1:25 dilution) of Czech strain RHDV failed to infect a single susceptible rabbit, yet infected a low to high (up to 73%) percentage across other populations tested. Different selection pressures are present in these populations and will be driving the level of resistance being seen. The mechanisms and genetics behind the development of resistance are also important as the on-going use of RHDV as a control tool in the management of rabbits relies on our understanding of factors influencing the efficacy of the virus. Understanding how resistance has developed may provide clues on how best to use the virus to circumvent these mechanisms. Similarly, it will help in managing populations that have yet to develop high levels of resistance.

Field evaluation of spinosad as a grain protectant for stored wheat in Australia: efficacy against Rhyzopertha dominica (F.) and fate of residues in whole wheat and milling fractions

The potential of spinosad as a grain protectant for the lesser grain borer, Rhyzopertha dominica, was investigated in a silo-scale trial on wheat stored in Victoria, Australia. Rhyzopertha dominica is a serious pest of stored grain, and its resistance to protectants and the fumigant phosphine is becoming more common. This trial follows earlier laboratory research showing that spinosad may be a useful pest management option for this species. Wheat (300 t) from the 2005 harvest was treated with spinosad 0.96 mg/kg plus chlorpyrifos-methyl 10 mg/kg in March 2006, and samples were collected at intervals during 7.5 month storage to determine efficacy and residues in wheat and milling fractions. Chlorpyrifos-methyl is already registered in Australia for control of several other pest species, and its low potency against R. dominica was confirmed in laboratory-treated wheat. Grain moisture content was stable at about 10%, but grain temperature ranged from 29.3°C in March to 14.0°C in August. Bioassays of all treated wheat samples over 7.5 months resulted in 100% adult mortality after 2 weeks exposure and no live progeny were produced. In addition, no live grain insects were detected during outload sampling after a 9 month storage. Spinosad and chlorpyrifos-methyl residues tended to decline during storage, and residues were higher in the bran layer than in either wholemeal or white flour. This field trial confirmed that spinosad was effective as a grain protectant targeting R. dominica.

The performance of irrigated mixtures of tall fescue, ryegrass and white clover in subtropical Australia. 1. The effects of sowing mixture combinations, nitrogen and oversowing on establishment, productivity, botanical composition and persistence.

In the subtropics of Australia, the ryegrass component of irrigated perennial ryegrass (Lolium perenne) - white clover (Trifolium repens) pastures declines by approximately 40% in the summer following establishment, being replaced by summer-active C4 grasses. Tall fescue (Festuca arundinacea) is more persistent than perennial ryegrass and might resist this invasion, although tall fescue does not compete vigorously as a seedling. This series of experiments investigated the influence of ryegrass and tall fescue genotype, sowing time and sowing mixture as a means of improving tall fescue establishment and the productivity and persistence of tall fescue, ryegrass and white clover-based mixtures in a subtropical environment. Tall fescue frequency at the end of the establishment year decreased as the number of companion species sown in the mixture increased. Neither sowing mixture combinations nor sowing rates influenced overall pasture yield (of around 14 t/ha) in the establishment year but had a significant effect on botanical composition and component yields. Perennial ryegrass was less competitive than short-rotation ryegrass, increasing first-year yields of tall fescue by 40% in one experiment and by 10% in another but total yield was unaffected. The higher establishment-year yield (3.5 t/ha) allowed Dovey tall fescue to compete more successfully with the remaining pasture components than Vulcan (1.4 t/ha). Sowing 2 ryegrass cultivars in the mixture reduced tall fescue yields by 30% compared with a single ryegrass (1.6 t/ha), although tall fescue alone achieved higher yields (7.1 t/ha). Component sowing rate had little influence on composition or yield. Oversowing the ryegrass component into a 6-week-old sward of tall fescue and white clover improved tall fescue, white clover and overall yields in the establishment year by 83, 17 and 11%, respectively, but reduced ryegrass yields by 40%. The inclusion of red (T. pratense) and Persian (T. resupinatum) clovers and chicory (Cichorium intybus) increased first-year yields by 25% but suppressed perennial grass and clover components. Yields were generally maintained at around 12 t/ha/yr in the second and third years, with tall fescue becoming dominant in all 3 experiments. The lower tall fescue seeding rate used in the first experiment resulted in tall fescue dominance in the second year following establishment, whereas in Experiments 2 and 3 dominance occurred by the end of the first year. Invasion by the C4 grasses was relatively minor (<10%) even in the third year. As ryegrass plants died, tall fescue and, to a lesser extent, white clover increased as a proportion of the total sward. Treatment effects continued into the second, but rarely the third, year and mostly affected the yield of one of the components rather than total cumulative yield. Once tall fescue became dominant, it was difficult to re-introduce other pasture components, even following removal of foliage and moderate renovation. Severe renovation (reducing the tall fescue population by at least 30%) seems a possible option for redressing this situation.

Premature fruit softening, a major physiological problem of persimmon in subtropical Australia.

Premature or abnormal softening of persimmon fruit within 3-7 days after harvest is a major physiological problem of non-astringent persimmon cultivars grown in subtropical regions of Australia. Up to 30% of consignments may soften rapidly frequently overnight, often resulting in the flesh becoming very soft, completely translucent, and impossible to handle. Incidence of premature soft fruit can vary with season and production location. To study the incidence of this problem, we conducted surveys of fruit harvested from five environmentally-diverse regions of Australia over a two-year period. We found wide variation in the rate of both premature softening and normal softening with differences of up 37 days between orchards in percentage of fruit reaching 50% soft. We found that the rate of fruit softening was exacerbated by lower calcium concentrations at fruit set, shorter fruit development periods and heavier rainfall during the fruit development period. The implications of our findings, in terms of orchard management, export and domestic marketing strategies are discussed.

Duckweed-based Wastewater Treatment Systems: Design Aspects and Integrated Reuse Options for Queensland Conditions

Point sources of wastewater pollution, including effluent from municipal sewage treatment plants and intensive livestock and processing industries, can contribute significantly to the degradation of receiving waters (Chambers et al. 1997; Productivity Commission 2004). This has led to increasingly stringent local wastewater discharge quotas (particularly regarding Nitrogen, Phosphorous and suspended solids), and many municipal authorities and industry managers are now faced with upgrading their existing treatment facilities in order to comply. However, with high construction, energy and maintenance expenses and increasing labour costs, traditional wastewater treatment systems are becoming an escalating financial burden for the communities and industries that operate them. This report was generated, in the first instance, for the Burdekin Shire Council to provide information on design aspects and parameters critical for developing duckweed-based wastewater treatment (DWT) in the Burdekin region. However, the information will be relevant to a range of wastewater sources throughout Queensland. This information has been collated from published literature and both overseas and local studies of pilot and full-scale DWT systems. This report also considers options to generate revenue from duckweed production (a significant feature of DWT), and provides specifications and component cost information (current at the time of publication) for a large-scale demonstration of an integrated DWT and fish production system.

Archaeaphage therapy to control rumen methanogens

Phage therapy is becoming increasingly important as a means of eradicating or controlling microbial populations and has been raised as a potential strategy to reduce methane emissions from ruminants. To date, very little is currently known about phages which may infect the methane-producing archaeal strains (methanogens) dominant within the rumen of Australian cattle, such as the Methanobrevibacter ruminantium. This project aimed to assemble a collection of phages to be employed in phage therapy. A range of animal-derived and environmental source samples were tested using culture-based methodology, however no lytic phages of methanogens were isolated. Given the dearth of knowledge regarding phages of rumen methanogens, this project established that these naturally-occurring phages may be present in very low concentrations within the rumen and this will need to be considered in future methanogen-phage isolation investigations. The project has begun the process of developing and adapting new methodologies for detecting and examining these phages

DAQ00129 Improving the Integration of Legumes in Grain and Sugarcane Farming Systems in Southern Queensland

The farming systems and agribusinesses of the inland Burnett and southern coastal cropping regions of Queensland are becoming increasingly interlinked as grain legume crops, a key component of dryland cropping systems, become more firmly entrenched in the coastal sugarcane cropping areas. Soybeans, peanuts and possibly winter cereals like barley have a real and demonstrated role in sugarcane rotations, and assistance with the integration of those crops into viable and sustainable cropping systems with sugarcane will be critical to the futuer development of these industries.

The DOOR manual for plant nurseries

In the nursery industry, generic research conducted by government institutions is often not specific enough to be highly valued and adopted by the individual operator. Operators need practical solutions to their particular problems. Such problems almost invariably involve sets of conditions common to few other enterprises. This uniqueness reflects the almost infinite variation of options available in terms of species grown, media used, fertiliser, amendments and chemicals applied and the way water is supplied. The DOOR (Do Our Own Research) method advocates a relatively unexplored way of generating new, statistically sound research information in the nursery industry. The manual aims to enhance nursery operators' understanding and skills development in the following areas: critially evaluating opportunities and problems in the nursery environment, gathering relevant information, deriving and prioritising potential solutions to problems and opportunities, becoming familiar with the scientific method employed in testing potential solutions, carrying out statistically sound aand rigorous research, and developing recommendations that flow from the research information generated. The DOOR approach has application in a number of other industries and may provide important support at a time of declining research, development and extension investment by the public sector.

Mile-a-minute (Mikania micrantha): its distribution, growth and physical and socio-economic impacts in Papua New Guinea

Mikania micrantha, Kunth. H.B.K (Asteraceae) or mile-a-minute is a weed of Neotropical origin in 17 Pacific Island countries. It is becoming increasingly regarded as an invasive weed in Papua New Guinea and is now the focus of an Australian Government-funded biological control program. As part of the program, growth rates, distribution and physical and socia-economic impacts were studied to obtain baseline data and to assist with the field release of biological control agents. Through public awareness campaigns and dedicated surveys, mikania has been reported in most lowland provinces. It is particularly widespread in East New Britain and West New Britain Province. In field trials, mikania grew more than 1 metre per month in open sunny areas but slightly slower when growing under cocoa. The weed invades a wide range of land types, impacting on plantations and food gardens, smothering pawpaw, young cocoa, banana, taro, young oil palms and ornamental plants. In socia-economic surveys, mikania was found to have severe impacts on crop production and income generated through reduced yields and high weeding costs. These studies suggest that there would be substantial benefits to the community if biological control of mikania is successful.

Improvement of hardwood drying schedules.

Drying regrowth native hardwoods to satisfactory moisture levels is a significant challenge for the processing industry. Dried quality is becoming increasingly important as sawn hardwood continues to move away from structural markets into appearance applications, but more difficult to achieve as the resource mix being processed becomes younger. An accurate, predictive drying model is a powerful tool in schedule development, decreasing the reliance on expensive, repetitive drying trials. This project updates the KilnSched drying model to allow the drying behaviour of regrowth blackbutt, jarrah, messmate, spotted gum and Victorian ash to be modeled more accurately. The effect of high temperature drying and humidity treatments on spotted gum were also investigated, as was the economics of various drying methods on spotted gum and blackbutt.

Growing organic prawns - in inland saline waters

This report details the results of research into organic production of prawns in Australia. This has involved activities and experiments over two years at several sites and using a multidisciplinary approach. This includes farm trials at an inland demonstration prawn farm which solely utilises saline bore water, sample collection from two commercial prawn farms in coastal regions of south-eastern Queensland, replicated feed trials at one of DPI&F’s aquaculture research stations, specified feed manufacture at the laboratories of University of Queensland, and packaging and product storage trials and food analyses at two of DPI&F’s food technology laboratories. This work was designed to investigate and assist in the possible adoption of organic procedures by the Australian prawn farming industry. The import from Asia of cheaply produced prawns has forced all Australian prawn farmers to review their marketing procedures. Additionally investors are becoming increasingly concerned at the prospects for the expansion of this industry in Australia. Since the competition of seafood products in the marketplace is increasing on a global basis, alternate products are being investigated by those wishing to maintain and/or grow their market share. The premium paid for organic food products would hopefully provide an economic incentive for farmers to convert to organic production systems, with an added advantage that the standards that apply have beneficial implications also for the social and environmental practices of industry.

Burning, then resting, reduces wiregrass (Aristida spp.) in black speargrass pastures

Wiregrasses (Aristida spp.) are becoming more prevalent, causing reduced productivity, in the black speargrass (Heterpogon contortus) pastures of south-east Queensland. Burning a native pasture of poor botanical composition (with a high proportion of wiregrass) in spring, and resting a heavily-grazed pasture also of poor composition, both improved the condition of these pastures. However, burning in late summer did not. Three months after burning in spring, relative density of wiregrass had decreased and that of a desirable species, black speargrass, had increased. However, this effect did not persist under continuous and heavy grazing. Resting increased threefold both the yield of pasture and the proportion of black speargrass, and decreased the proportion of wiregrass by two-thirds. Burning in late summer had no effect on the relative density of black speargrass but relative density of wiregrass increased. Selective grazing after burning in late summer kept this pasture in very poor condition for 14 months. These results suggest that the best way to increase the proportion of black speargrass and reduce the proportion of wiregrass in a pasture would be to burn in spring and then rest the pasture

Vegetables containing phytochemicals with potential anti-obesity properties: A review

The incidence of obesity is rising worldwide at an alarming rate and is becoming a major public health concern with incalculable social and economic costs. Studies have exposed the relationship between the adiposity, inflammation and the development of other metabolic disorders, so dietary factors that influence some or all of these are of interest. Dietary phytochemicals appear to be able to target different stages of the adipocyte (fat cell) lifecycle. For example, several classes of polyphenols have been implicated in suppressing the growth of adipose tissue through modifying the adipocyte lifecycle. Many dietary phytochemicals also have strong anti-inflammatory activity, but the amount present in plants varies and may be affected by processing. In this review we summarise the likely mechanisms of action of plant phytochemicals. We highlight the major vegetable sources of polyphenols, including those with possible synergistic attributes, discuss the variation in polyphenol levels and their distribution in cultivars and outline the effects of food processing. The identification and characterisation of the anti-obesogenic properties of phytochemicals in vegetables, as well as an appreciation of the effect of cooking on phytochemical content provide significant new information supporting dietary guidelines that encourage vegetable consumption for the prevention and management of lifestyle related disease.