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The development and implementation of a National Weed Biocontrol Pipeline Strategy
No full textClassical weed biocontrol has been used successfully to control invasive weed species in Australia for over 120 years. With an average benefit-cost ratio of 23:1, weed biocontrol is a proven valuable and effective approach to weed management in Australia. To date of the biocontrol programs undertaken in Australia, 39% are considered to produce complete or near complete control of the target weed and 30.5% partial control of the target weed. These successes can be attributed to the existence of a well-established regulatory pathway and national risk assessment framework that enables biocontrol to be undertaken safely in Australia. Despite this, implementation of biocontrol in Australia is at risk due
to diminishing agents coming through the research pipeline and variable research investment over time. Since 2014–15, the Australian Government has invested approximately $20 million in weed biocontrol projects, which facilitated significant co-investment by RDCs, CSIRO and the three States, but these programs are either concluded or nearing completion. In response to this identified risk and to further embed biocontrol into national weed management frameworks, a National Weed Biocontrol Pipeline Strategy was proposed. The aim of this strategy is to ensure that available research investment is allocated to sustain the research pipeline of prioritising weed candidates for research, native range exploration, risk assessment, biocontrol agent release, impact monitoring and evaluation. The strategy was endorsed by the Commonwealth and State governments in 2023 and the initial phase of the strategy implementation commenced in 2024. The development, implementation, and key deliverables of the National Pipeline Strategy such as the prioritisation of high threat weeds for biocontrol consideration will be discussed
Seed ecology of two invasive aquatic plant species: Cabomba caroliniana and Sagittaria platyphylla
No full textUnderstanding seed ecology is important to contribute to the management of highly invasive aquatic plant species. Cabomba caroliniana A.Gray (cabomba) and Sagittaria platyphylla (Engelm.) J.G. Sm. (sagittaria) are both significant water weeds in Australia. While cabomba is a fully submerged aquatic plant producing few seeds, sagittaria is an emergent species and a prolific seeder. The results from laboratory experiments showed that sagittaria germinated well at constant temperatures ranging from 17 to 29°C, with the highest rate of 98% germination at 21°C. Germination only occurred under light which indicates that buried seeds could not germinate even from shallow depth of 0.5 cm. In the laboratory, a controlled aging test predicted that sagittaria seeds could retain viability for 3 to 5 years. Seeds were also treated with two herbicides florpyrauxifen-benzyl and flumioxazin at five different concentrations for 24 hours to examine the effect on seed mortality. Results showed that the germination was unaffected (100%) by both herbicides. Cabomba is thought to only produce viable seeds in two populations in the Northern Territory and Victoria while other populations are thought to be sterile. There is little information available on its seed ecology. Recently, seeds of cabomba have been detected in multiple populations in Southeast Queensland and Northern New South Wales. When tested with tetrazolium (0.5%) the seeds were confirmed as viable. However, seed production was estimated to be very low at ca. 8 seeds m-2 in the warm months (December to June), and ca. 3 seeds m-2 from June to December. Cabomba seeds were successfully germinated in the laboratory, but more seed materials are now needed before a full understanding of this species seed ecology can be determined
Profitability and environmental implications of innovative practice changes and irrigation improvements
No full textThe economic and environmental benefits of practice changes and irrigation improvements are explored based on three grower case studies in the Bundaberg, Burdekin and Mackay regions that consider grower investments in best management practices, including irrigation changes. How the practice changes influenced farm economic and environmental performance are determined. Economic, biophysical and farm management data before and after the changes were used to calculate the economic benefit (Annualised Equivalent Benefit) with the Farm Economic Analysis Tool (FEAT) and an investment analysis. The economic benefit was positive for all farms, ranging from AUD29 to AUD377 per hectare per year. The same data were used to calculate indicators of environmental performance (per tonne of harvested cane) using the Cane Life Cycle Assessment (CaneLCA) tool. There were reductions in fossil-fuel use, greenhouse-gas emissions, and a potential for water pollution curtailment. For the Bundaberg case, a transition from furrow to low-pressure boom irrigation increased electricity use, which was offset by energy savings from other aspects of the production system changes. For the Burdekin case, improved water-use efficiency on a farm with permeable soils resulted in less electricity use and greenhouse gas emissions. For the Mackay case, improved utilisation of water allocation increased cane productivity and contributed to improved economic and eco-efficiency outcomes. While total water use increased, it is noted that water availability is not a constraint for the Mackay region outside of drought impacts. The Mackay case also involved a supplementary analysis of solar energy use. Overall, the case studies showed that the suites of irrigation improvements and practice changes resulted in both economic and eco-efficiency benefits
Communicate environmental science and management with user-centred interactive design to empower data-driven decision-making
No full textWe are drowning in data. Much of the data we collect never sees the light of day or is delivered in forms that are hard to access and interpret for decision-makers. The data we use to inform decision-making and reporting is often held close by scientists and data curators, and only delivered to decision-makers in highly curated formats. These formats fail to engage decision-makers because they don’t allow for data to be explored in the context of the information required to make their decisions.
We take data that is ordinarily hidden in detailed reports, or languishing in files on data portals, and make it accessible to a wider audience by creating interactive data visualisations and dashboards that communicate environmental science and management outputs and outcomes. Taking a user-centred design approach, that engages decision-makers throughout the design process allows us to fully understand what information is most important to various audiences and design accordingly.
We have found that by liberating obfuscated data and delivering it through interactive web applications designed and developed with the user at front of mind, decision-makers are empowered to explore data and engage in effective adaptive management.
Too much great work in environmental management goes unseen by decision-makers, thus limiting their capacity to continue to be advocates for the science and management actions that drive our sector. Communicating data through user-centred interactive design makes it more accessible and empowers environmental managers to make more informed decisions
The Avocado Road to Robustness
No full textProducing a robust avocado that can withstand the rigours of the supply chain to reach the consumer in a state of acceptable quality is a priority for the Australian avocado industry. This animated video aims to de-mystify the complex and interacting factors that influence avocado robustness.
It focuses on the importance of pre-harvest mineral nutrition and how optimal fruit nutrient balance for robustness may be achieved through good orchard management practices
Is phytoplasma titre correlated with symptom development in Banana Wilt Associated Phytoplasma disease in Papua New Guinea?
No full textBanana wilt associated phytoplasma (BWAP) is associated with lethal yellowing in banana in Papua New Guinea (PNG) and the Solomon Islands. The banana wilt associated phytoplasma is also associated with Bogia coconut syndrome (BCS) in coconuts and lethal yellowing in other palms. Although the disease was reported in the early 1990s, the pathogenicity of the phytoplasma in the host has not been investigated. Most research regarding pathogenicity has traditionally focused on phytoplasma’s that cause growth and flower abnormalities. Phytoplasmas are hypothesised to initially exist as endophytes and only become pathogenic once the titre in the host reaches a certain threshold. This has been investigated in crops such as grapevine, plum and apple, however this has not been investigated for BWAP. We sought to determine the relationship between symptom development and phytoplasma titre in banana hosts. Hence, we tested the hypothesis that BWAP titre is correlated with symptom severity in banana. Plants with BWAP symptoms were collected and the presence of phytoplasma confirmed using PCR based diagnostics. All banana plants were individually scored for symptom severity using a scale we developed to score disease severity from 0-3 based on presence and prevalence of certain visual symptoms. Real time PCR was conducted to obtain cycle threshold (Ct) values for banana tissues and to estimate phytoplasma titres. Correlation of symptom development to pathogen titre was determined by comparing Ct values of individual plant parts to the same plant part of different plants expressing different stages of disease severity. Asymptomatic plants were also included in the analyses. Our results suggest that BWAP titre 21 in banana hosts is correlated with disease progression. Future research will focus on identifying pathogenicity genes of the BWAP and the level of the expression thereof at different stages of disease developmen
Critical Review on the Use of Extractives of Naturally Durable Woods as Natural Wood Protectants
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Extractives, the non-structural component of woody biomass, are frequently targeted for their biocidal potential due to their evolutionary success in deterring pests in both standing trees and downed woody debris. Effective extractive utilization also offers an alternative product stream, where extractives are removed from the woody biomass that can further be used as feedstock for downstream processes (i.e., pulping, nanocellulose production, and biochar) once the extractives are removed. This review aims to provide details on prior studies using wood extractives as wood protectants, highlight the limitations to this approach, and discuss the research opportunities.
Abstract
Naturally durable wood pre-dates preservative-treated wood and has been demonstrated to offer a suitable service life for certain applications where preservative-treated wood is not feasible. Heartwood extractives have been demonstrated to impart bio-deteriorative resistance to naturally durable wood species. These extractives are typically found in the heartwood of living trees and are produced either by the death of parenchyma cells or as the result of external stimuli. The mechanisms of natural durability are not well understood, as heartwood extractives can be extremely variable in their distribution, composition, and efficacy in both living and harvested trees. The underlying complexity of heartwood extractives has hindered their standardization in residential building codes for use as wood preservatives. The use of naturally durable lumber is not always feasible, as woods with exceptionally durable heartwood do not typically yield lumber with acceptable machining properties. A potential approach to overcome the inherent difficulty in establishing guidelines for the appropriate use of naturally durable wood is to focus solely on the extractives as a source of bioactive protectants based on the strategies used on living and dead wood to repel the agents of biodeterioration. This critical review summarizes the relevant literature on naturally durable woods, their extractives, and their potential use as bio-inspired wood protectants. An additional discussion will be aimed at underscoring the past difficulties in adopting this approach and how to overcome the future hurdles
Broiler farming practices using new or re-used bedding, inclusive of free-range, have no impact on Campylobacter levels, species diversity, Campylobacter community profiles and Campylobacter bacteriophages
Get PDFA multi-stage option to address food-safety can be produced by a clearer understanding of Campylobacter's persistence through the broiler production chain, its environmental niche and its interaction with bacteriophages. This study addressed Campylobacter levels, species, genotype, bacteriophage composition/ levels in caeca, litter, soil and carcasses across commercial broiler farming practices to inform on-farm management, including interventions.Broilers were sequentially collected as per company slaughter schedules over two-years from 17 farms, which represented four commercially adopted farming practices, prior to the final bird removal (days 39–53). The practices were conventional full clean-out, conventional litter re-use, free-range–full cleanout and free-range–litter re-use. Caeca, litter and soil collected on-farm, and representative carcases collected at the processing plant, were tested for Campylobacter levels, species dominance and Campylobacter bacteriophages. General community profiling via denaturing gradient gel electrophoresis of the flaA gene was used to establish the population relationships between various farming practices on representative Campylobacter isolates. The farming practice choices did not influence the high caeca Campylobacter levels (log 7.5 to log 8.5 CFU/g), the carcass levels (log 2.5 to log 3.2 CFU/carcass), the C. jejuni/C. coli dominance and the on-farm bacteriophage presence/levels. A principal coordinate analysis of the flaA distribution for farm and litter practices showed strong separation but no obvious farming practice related grouping of Campylobacter. Bacteriophages originated from select farms, were not practice-dependent, and were detected in the environment (litter) only if present in the birds (caeca).This multifaceted study showed no influence of farming practices on on-farm Campylobacter dynamics. The significance of this study means that a unified on-farm risk-management could be adopted irrespective of commercial practice choices to collectively address caeca Campylobacter levels, as well as the potential to include Campylobacter bacteriophage biocontrol. The impact of this study means that there are no constraints in re-using bedding or adopting free-range farming, thus contributing to environmentally sustainable (re-use) and emerging (free-range) broiler farming choices
Ontogenetic Changes in the Feeding Behaviour of Helicoverpa armigera Larvae on Pigeonpea (Cajanus cajan) Flowers and Pods
Get PDFDespite substantial research examining caterpillar–plant interactions, changes in the feeding behaviour of lepidopteran larvae as they develop are poorly understood. In this study, we investigated ontogenetic changes in the behaviour of Helicoverpa armigera larvae feeding on reproductive structures of pigeonpea (Cajanus cajan). Specifically, we examined the preference for and avoidance of pigeonpea flowers and pods of first, second, third, and fourth instar H. armigera larvae. We also conducted a no-choice assay to compare the ability of third and fourth instar larvae to penetrate pigeonpea pod walls, which act as a physical defence against herbivory. When presented with a choice between pigeonpea pods and flowers, different instars behaved differently. First and second instar larvae largely avoided pigeonpea pods, instead feeding on flowers; third instar larvae initially avoided pods, but by 24 h, did not strongly discriminate between the structures; and fourth instars demonstrated a preference for pods. When initially placed on pods, first instars were slower than other instars to leave these structures, despite pods being suboptimal feeding sites for small caterpillars. We identified a clear instar-specific ability to penetrate through the pod wall to reach the seeds. Most third instar larvae were unable to penetrate the pod wall, whereas most fourth instars succeeded. Third instars suffered a physiological cost (measured by relative growth rate) when boring through the pod wall, which was not observed in fourth instars. Our study further illuminates the insect–plant interactions of the H. armigera–pigeonpea system and provides evidence for the significant changes in feeding behaviour that may occur during lepidopteran larval development
Biocrusts, ecological indicators in the Australian rangelands
No full textThe Australian rangelands that cover around 70% of the country (~6 million km2) are inhabited by some of the most extensive and diverse biocrusts globally. These regions are predominately managed as natural grazing lands. Across northern Australia where the climate is influenced by the monsoon (wet season) biocrusts dominated by cyanobacteria and liverworts occupy the interspaces between grass plants as a coherent layer that binds the upper millimetres of soil and forms a living cover of photoautotrophic (cyanobacteria, algae, lichens and bryophytes), and heterotrophic (bacteria, fungi and archaea) organisms. During the dry season biocrusts are inactive, then recover at the onset of the wet season, actively participating in nitrogen and carbon fixation and accumulation. To identify the role of biocrusts as ecological indicators, we modelled their distribution, diversity and function across microhabitats. We also determined how biocrust community dynamics had been influenced by long-term fire and grazing management regimes.
At Victoria River Research Station (Kidman Springs, NT), after 30 years of fire research we compared managed burning practices at 2, 4 or 6-yearly intervals on two soil types (calcarosol, vertosol). Biocrusts were resilient and recovered rapidly from fire, where diversity and genetic function altered seasonally, between soil types, and fire regimes. Post-fire, after a wet season (cattle excluded), biocrusts recovered with significantly more carbon and nitrogen in the surface soils of cooler fire treatments every four years.
At Wambiana Cattle Station (QLD), grazing trials have been established for 25 years. When paddocks were rested from cattle grazing every second year, biocrusts in duplex soils recovered to levels comparable to ungrazed natural sites. In red-yellow earths, there were biocrust hotspots that provided protection to the soil surfaces when there was a loss of grass cover during drought. Biocrust diversity and function differed between soil type and management (moderate and heavy stocking).
This research demonstrates that the top centimetre of biocrust-rich soil is central to ground cover integrity and is essential to soil nutrient cycling and fertility. Biocrusts are an important indicator for overall vegetative recovery post fire, grazing and drought disturbances. The principles of land cover condition based on landscape function should include biocrust presence as a metric that describes landscape resilience, as opposed to bare unprotected ground. Importantly, land managers can apply this research to grazing practices that show that giving the land rest periods timed to coincide with the wet season allows time for biocrust organisms to recover from disturbance