Preventing weed spread: a survey of lifestyle and commercial landholders about Nassella trichotoma in the Northern Tablelands of New South Wales, Australia

Nassella trichotoma (Nees) Hack. ex Arechav. (common name, serrated tussock) occupies large areas of south-eastern Australia and has considerable scope for expansion in the Northern Tablelands of New South Wales. This highly invasive grass reduces pasture productivity and has the potential to severely affect the region’s economy by decreasing the livestock carrying capacity of grazing land. Other potential consequences of this invasion include increased fuel loads and displacement of native plants, thereby threatening biodiversity. Rural property owners in the Northern Tablelands were sent a mail questionnaire that examined use of measures to prevent new outbreaks of the weed. The questionnaire was sent to professional farmers as well as lifestyle farmers (owners of rural residential blocks and hobby farms) and 271 responses were obtained (a response rate of 18%). Key findings were respondents’ limited capacity to detect N. trichotoma, and low adoption of precautions to control seed spread by livestock, vehicles and machinery. This was particularly the case among lifestyle farmers. There have been considerable recent changes to biosecurity governance arrangements in New South Wales, and now is an ideal time for regulators and information providers to consider how to foster regional communities’ engagement in biosecurity, including the adoption of measures that have the capacity to curtail the spread of N. trichotoma.

New sweetpotato cultivars to meet market needs

The Australian Sweetpotato Growers Association partnered researchers from Agri-Science Queensland (with co-funding from Horticulture Australia Limited) to identify new, high performing sweetpotato cultivars with diverse colours and tastes. The project evaluated a mix of purple, red, orange and white skin and flesh, tailored for Australian growers and consumers. Australia's sweetpotato market currently relies on one gold cultivar for 90% of national production. Major retailers were requesting a reliable supply of quality sweetpotatoes in emerging categories such as red or white skin or purple flesh. To identify suitable cultivars, over 40 new sweetpotato cultivars were virus tested, and extensively evaluated in multiple experiments in Queensland and northern New South Wales. Larger-scale plantings by growers, using standard agronomy, provided additional performance feedback under commercial conditions. In partnership with growers and wholesalers, cultivars were evaluated in field and laboratory for desired characteristics such as shape, size range, skin and flesh colour, estimates of productivity and suitability for commercial production, cooking characteristics and taste. New high performing gold cultivars had better soil insect and nematode tolerance than the current cultivars. The new colours offered diverse health-related opportunities for consumers, more anthocyanins in purple-fleshed cultivars; higher beta carotene content in new gold fleshed cultivars; and potentially lower GI in white-fleshed cultivars. To enhance adoption, the industry/research partnership will tailor agronomic guidelines to maximise on-farm performance and identify niche marketing pathways for each of the cultivars. Increased consumption of this versatile vegetable will drive sweetpotato industry development and expansion into the future.

Optimising plant bed performance through adaptive research with the Australian sweetpotato industry

A key driver of Australian sweetpotato productivity improvements and consumer demand has been industry adoption of disease-free planting material systems. On a farm isolated from main Australian sweetpotato areas, virus-free germplasm is annually multiplied, with subsequent 'pathogen-tested' (PT) sweetpotato roots shipped to commercial Australian sweetpotato growers. They in turn plant their PT roots into specially designated plant beds, commencing in late winter. From these beds, they cut sprouts as the basis for their commercial fields. Along with other intense agronomic practices, this system enables Australian producers to achieve worldRSQUOs highest commercial yields (per hectare) of premium sweetpotatoes. Their industry organisation, ASPG (Australian Sweetpotato Growers Inc.), has identified productivity of mother plant beds as a key driver of crop performance. Growers and scientists are currently collaborating to investigate issues such as catastrophic plant beds losses; optimisation of irrigation and nutrient addition; rapidity and uniformity of initial plant bed harvests; optimal plant bed harvest techniques; virus re-infection of plant beds; and practical longevity of plant beds. A survey of 50 sweetpotato growers in Queensland and New South Wales identified a substantial diversity in current plant bed systems, apparently influenced by growing district, scale of operation, time of planting, and machinery/labour availability. Growers identified key areas for plant bed research as: optimising the size and grading specifications of PT roots supplied for the plant beds; change in sprout density, vigour and performance through sequential cuttings of the plant bed; optimal height above ground level to cut sprouts to maximise commercial crop and plant bed performance; and use of structures and soil amendments in plant bed systems. Our ongoing multi-disciplinary research program integrates detailed agronomic experiments, grower adaptive learning sites, product quality and consumer research, to enhance industry capacity for inspired innovation and commercial, sustainable practice change.

An investigation of environmental conditions experienced during the life of high-value wood components and products

Australian forest industries have a long history of export trade of a wide range of products from woodchips (for paper manufacturing), sandalwood (essential oils, carving and incense) to high value musical instruments, flooring and outdoor furniture. For the high value group, fluctuating environmental conditions brought on by changes in temperature and relative humidity, can lead to performance problems due to consequential swelling, shrinkage and/or distortion of the wood elements. A survey determined the types of value-added products exported, including species and dimensions packaging used and export markets. Data loggers were installed with shipments to monitor temperature and relative humidity conditions. These data were converted to timber equilibrium moisture content values to provide an indication of the environment that the wood elements would be acclimatising to. The results of the initial survey indicated that primary high value wood export products included guitars, flooring, decking and outdoor furniture. The destination markets were mainly located in the northern hemisphere, particularly the United States of America, China, Hong Kong, Europe (including the United Kingdom), Japan, Korea and the Middle East. Other regions importing Australian-made wooden articles were south-east Asia, New Zealand and South Africa. Different timber species have differing rates of swelling and shrinkage, so the types of timber were also recorded during the survey. Results from this work determined that the major species were ash-type eucalypts from south-eastern Australia (commonly referred to in the market as Tasmanian oak), jarrah from Western Australia, spotted gum, hoop pine, white cypress, black butt, brush box and Sydney blue gum from Queensland and New South Wales. The environmental conditions data indicated that microclimates in shipping containers can fluctuate extensively during shipping. Conditions at the time of manufacturing were usually between 10 and 12% equilibrium moisture content, however conditions during shipping could range from 5 (very dry) to 20% (very humid). The packaging systems incorporated were reported to be efficient at protecting the wooden articles from damage during transit. The research highlighted the potential risk for wood components to ‘move’ in response to periods of drier or more humid conditions than those at the time of manufacturing, and the importance of engineering a packaging system that can account for the environmental conditions experienced in shipping containers. Examples of potential dimensional changes in wooden components were calculated based on published unit shrinkage data for key species and the climatic data returned from the logging equipment. The information highlighted the importance of good design to account for possible timber movement during shipping. A timber movement calculator was developed to allow designers to input component species, dimensions, site of manufacture and destination, to see validate their product design.

'Abnormal vertical growth' : A disorder threatening the viability of the Australian macadamia industry

'Abnormal vertical growth' (AVG) was recognised in Australia as a dysfunction of macadamia (Macadamia spp.) in the mid-1990s. Affected trees displayed unusually erect branching, and poor flowering and yield. Since 2002, the commercial significance of AVG, its cause, and strategies to alleviate its affects, has been studied. The cause is still unknown, and AVG remains a serious threat to orchard viability. AVG affects both commercial and urban macadamia. It occurs predominantly in the warmer-drier production regions of Queensland and New South Wales. An estimated 100,000 orchard trees are affected, equating to an annual loss of $ 10.5 M. In orchards, AVG occurs as aggregations of affected trees, affected tree number can increase by 4.5% per year, and yield reduction can exceed 30%. The more upright cultivars 'HAES 344' and '741' are highly susceptible, while the more spreading cultivars 'A4', 'A16' and 'A268' show tolerance. Incidence is higher (p<0.05) in soils of high permeability and good drainage. No soil chemical anomaly has been found. Fine root dry weight of AVG trees (0-15 cm depth) was found lower (p<0.05) than non-AVG. Next generation sequencing has led to the discovery of a new Bacillus sp. and a bipartite Geminivirus, which may have a role in the disease. Trunk cinctures will increase (p<0.05) yield of moderately affected trees. Further research is needed to clarify whether a pathogen is the cause, the role of soil moisture in AVG, and develop a varietal solution.

A mitochondrial species identification assay for Australian blacktip sharks (Carcharhinus tilstoni, C. limbatus and C. amblyrhynchoides) using real-time PCR and high-resolution melt analysis

Tropical Australian shark fisheries target two morphologically indistinguishable blacktip sharks, the Australian blacktip (Carcharhinus tilstoni) and the common blacktip (C. limbatus). Their relative contributions to northern and eastern Australian coastal fisheries are unclear because of species identification difficulties. The two species differ in their number of precaudal vertebrae, which is difficult and time consuming to obtain in the field. But, the two species can be distinguished genetically with diagnostic mutations in their mitochondrial DNA ND4 gene. A third closely related sister species, the graceful shark C. amblyrhynchoides, can also be distinguished by species-specific mutations in this gene. DNA sequencing is an effective diagnostic tool, but is relatively expensive and time consuming. In contrast, real-time high-resolution melt (HRM) PCR assays are rapid and relatively inexpensive. These assays amplify regions of DNA with species-specific genetic mutations that result in PCR products with unique melt profiles. A real-time HRM PCR species-diagnostic assay (RT-HRM-PCR) has been developed based on the mtDNA ND4 gene for rapid typing of C. tilstoni, C. limbatus and C. amblyrhynchoides. The assay was developed using ND4 sequences from 66 C. tilstoni, 33. C. limbatus and five C. amblyrhynchoides collected from Indonesia and Australian states and territories; Western Australia, the Northern Territory, Queensland and New South Wales. The assay was shown to be 100% accurate on 160 unknown blacktip shark tissue samples by full mtDNA ND4 sequencing.

Stout Whiting Fishery Summary : Commercial Quota Setting for 2017

This fishery assessment report describes the commercial stout whiting fishery operation along Australia’s east coast between Sandy Cape and the Queensland-New South Wales border. The fishery is identified by a T4 symbol. This study follows methods applied in (O'Neill & Leigh, 2016a) and extends the results of that study by using the latest data available up to end of March 2016. The fishery statistics reported herein are for fishing years 1991 to 2016. This study analysed stout whiting catch rates from both Queensland and New South Wales (NSW) for all vessels, areas and fishing gears. The 2016 catch rate index from Queensland and NSW waters was 0.86. This means that the 2016 catch rate index was 86% of the mean standardised catch rate. Results showed that there was a stable trend in catch rates from 2012 to 2016, as in the previous study (O'Neill & Leigh, 2016a), with the 2015 and 2014 catch rates 85% of the mean catch rate. The fish-length frequency and age-length-otolith data were translated using two models which showed: • Where patterns of fish age-abundance were estimated from the fish-length frequency and age-length data, there were slightly decreased estimated measures of fish survival at 38% for 2014, compared to fish survival estimates in 2013 at 40%. The 2014 and 2015 estimated age structure was dominated by 1+ and 2+ old fished, with a slightly higher frequency of age 2 - 3 fish for 2015. • Where only the age-length data were used, estimates showed that from 2011 to 2014 the survival index increased. The estimated survival index increased from 35% in 2013 to 64% in 2014, indicating stronger survival of fish as they recruited and aged. Together the stout whiting catch rate and survival indicators showed the recent fishery harvests were sustainable. Since 1997, T4 management (Stout Whiting Fishery) is centred on annual assessments of total allowable commercial catch (TACC). The TACC is assessed before the start of each fishing year using statistical assessment methodologies, namely evaluation of trends in fish catch rates and catch-at-age frequencies measured against management reference points. The TACC has been under-caught in many years. For setting the 2017 T4 stout whiting TACC, the calculations covered a range of settings to account for the variance in the data and provide options for quota change. The overall (averaged) results suggested: • The procedure where the quota was adjusted based on previous TACC setting in year 2016 gave a recommended TACC for 2017 of between 1100 and 1130 t. • The procedure that focussed directly on optimising the average harvest to match target reference points gave a recommended TACC for 2017 of between 860 and 890 t. Use of these estimates to set TACC will depend on management and industry aims for the fishery.

Stout Whiting Fishery Summary : Queensland Total Allowable Catch for 2016

In Queensland, stout whiting are fished by Danish seine and fish otter-trawl methods between Sandy Cape and the Queensland-New South Wales border. The fishery is currently identified by a T4 symbol and is operated by two primary quota holders. Since 1997, T4 management has been informed by annual stock assessments in order to determine a total allowable commercial catch (TACC) quota. The TACC is assessed before the start of each fishing year using statistical methodologies. This includes evaluation of trends in fish catch-rates and catch-at-age frequencies against management reference points. The T4 stout whiting TACC for 2014 was adjusted down to 1150 t as a result of elevated estimates of fishing mortality and remained unchanged in 2015 (2013 TACC = 1350 t quota). Two T4 vessels fished for stout whiting in the 2015 fishing year, harvesting 663 t from Queensland waters. Annual T4 landings of stout whiting averaged about 713 t for the fishing years 2013–2015, with a maximum harvest in the last 10 fishing years of 1140 t and a maximum historical harvest of 2400 t in the 1995. Stout whiting catch rates from both Queensland and New South Wales were analysed for all vessels, areas and fishing gears. The 2015 catch rate index was equal to 0.85, down 15% compared to the 2010–2015 fishing year average (reference point =1). The stout whiting fish length and otolith weight frequencies indicated larger and older fish in the calendar year 2014. This data was translated to show improved measures of fish survival at about 38% per year and near the reference point of about 41%. Together, the stout whiting catch rate and survival indicators show the fishery was sustainable. Earlier population modelling conducted for the year 2013 also suggested the stock was sustainable, but the estimate was only marginally above the biomass for maximum sustainable yield. Irrespective, reasons for reduced catch rates should be examined further and interpreted with precaution, particularly given the TACC has been under-caught in many years. For setting of the 2016 TACC, alternate analyses and reference points were compared to address data uncertainties and provide options for quota change. The results were dependent on the stock indicator and harvest procedure used. Uncertainty in all TACC estimates should be considered as they were sensitive to the data inputs and assumptions. For the 2016 T4 fishing year, upper levels of harvest should be limited to 1000–1100 t following procedure equation 1, with target levels of harvest at 750–850 t for procedure equation 2. Use of these estimates to set TACC will depend on management and industry intentions.

Comparison of growth traits between abundant and uncommon forms of a non-native vine, Dolichandra unguis-cati (Bignoniaceae) in Australia

Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry) (Bignoniaceae), is a major environmental weed in Australia. Two distinct forms of this weed (‘long’ and ‘short’ pod), with differences in leaf morphology and fruit size, occur in Australia. The long pod form has only been reported in less than fifteen localities in the whole of south-east Queensland, while the short pod form is widely distributed in Queensland and New South Wales. This study sought to compare growth traits such as specific leaf area, relative growth rate, stem length, shoot/root ratio, tuber biomass and branching architecture between these forms. These traits were monitored under glasshouse conditions over a period of 18 months. Short pod exhibited higher values of relative growth rates, stem length, number of tubers and specific leaf area than long pod, but only after 10 months of plant growth. Prior to this, long and short pod did not differ significantly. Higher values for these traits have been described as characteristics of successful colonizers. Results from this study could partly explain why the short pod form is more widely distributed in Australia while long pod is confined to a few localities.

Nutrient loading on free range layer farms

A considerable proportion of the dietary nutrients consumed by poultry are excreted in the manure. This becomes an important issue on free range farms, if manure and/or nutrients are not removed periodically from the range areas. The nutrients and trace elements in manure can accumulate in the soil and become toxic to vegetation, while also causing pollution of ground and surface water through leaching. Soil samples were collected from fourteen free range layer farms both on the range and control areas (with no exposure to poultry) to investigate comparative soil nutrient concentrations. Nutrient concentrations were also compared between fixed and rotational ranges and between farms having different bird densities. At each site, soil was collected from 10 sampling points, arranged diagonally in a grid across both the range and control areas. A sampling probe was used to collect soil from the top 10 cm depth. These were submitted for a standardised lab analysis (Apal Agricultural Laboratory, SA, Australia). Data was subjected to analysis of variance and means considered significant at P < 0.05.

Rangeland profitability in the northern Gulf region of Queensland: understanding beef business complexity and the subsequent impact on land resource management and environmental outcomes

The farm-gate value of extensive beef production from the northern Gulf region of Queensland, Australia, is ~$150 million annually. Poor profitability and declining equity are common issues for most beef businesses in the region. The beef industry relies primarily on native pasture systems and studies continue to report a decline in the condition and productivity of important land types in the region. Governments and Natural Resource Management groups are investing significant resources to restore landscape health and productivity. Fundamental community expectations also include broader environmental outcomes such as reducing beef industry greenhouse gas emissions. Whole-of-business analysis results are presented from 18 extensive beef businesses (producers) to highlight the complex social and economic drivers of management decisions that impact on the natural resource and environment. Business analysis activities also focussed on improving enterprise performance. Profitability, herd performance and greenhouse emission benchmarks are documented and discussed.