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Johnsongrass mosaic virus: resistance of maize in Australian and implications for preparedness for maize lethal necrosis
No full textJohnson grass mosaic virus (JGMV) is widely distributed in the major perennial host Johnson grass (Sorghum halepense) in southern and central Queensland and north-west New South Wales. Two strains of this aphid-transmitted potyvirus occur in Australia, the type strain (JGMV-JG) and the Krish -infecting strain (JGMV-K) which is able to infect grain sorghum hybrids/lines with the Krish resistance gene. Although the economic impact of JGMV is currently low, the virus has caused sporadic severe losses in sweet corn, maize and grain sorghum over 30 years. A secondary threat is posed by the interaction of mixed infections of JGMV (and other maize-infecting potyviruses) and the exotic maize chlorotic mottle virus (MCMV) which can lead to maize lethal necrosis (MLN). Severe losses due to MLN have been reported from eastern and central Africa, Ecuador and China. We used glasshouse and field studies to determine JGMV resistance status of commercially grown maize and sorghum. We used high pressure application of JGMV inoculum as a rapid and effective means for inoculating field plots. All ten commercial maize hybrids tested were resistant to both JGMV strains as were ten of 15 sweet corn hybrids. The resistance status of sweet corn and maize hybrids to JGMV was well correlated with published resistance levels to the related exotic maize dwarf mosaic virus (MDMV). All 15 sorghum hybrids were susceptible to JGMV-K while 10 of these hybrids were resistant to the type strain, suggesting the presence of the Krish resistance gene in their pedigree. We developed rapid LAMP assays for JGMV and MDMV to assist with monitoring for the exotic. The high resistance of maize hybrids to JGMV determined in this study provides confidence of a high level of protection against maize lethal necrosis disease in the event of an incursion of maize chlorotic mottle virus into Australia
Development of badnavirus infectious clones for research in taro and banana
No full textBadnaviruses are double-stranded DNA (dsDNA) pararetroviruses in the genus Badnavirus, family Caulimoviridae, with a genome length typically of 7 to 8 kbp. Most possess three open reading frames (ORFs) on the sense strand of the virus genome while some members also encode a fourth ORF. Replication of these viruses occurs via reverse transcription of a greater-than-genome length RNA that serves as a template both for the translation of viral proteins and for reverse transcription to replicate the genome. The dsDNA genome facilitates the relatively straightforward preparation of infectious clones in plasmid vectors, which can be agro-inoculated into host plants to reconstitute an infection. These infectious clones are useful tools for investigation of host range, symptomatology, host plant resistance and can be modified as vectors for virus-induced gene silencing. We have prepared infectious clones of three badnaviruses, including taro bacilliform virus, which infects taro (Colocasia spp.) and two banana (Musa spp.)-infecting species, namely banana streak MY virus and banana streak CA virus. The infectious clones showed high infectivity in their respective host plants. Symptoms of infection in banana varied, with some accessions showing a significant delay in the time to develop symptoms
Spot application of flupropanate results in high mortality of Sporobolus pyramidalis
No full textLiquid flupropanate applied by spot application was tested on Sporobolus pyramidalis (P.Beauv.) to expand control options. Spot application is a high concentration, low volume herbicide mix applied directly into the base of the plant tussock. This application technique is suitable for herbicides such as flupropanate due to it being a predominantly root uptake herbicide and therefore complete foliage coverage is not needed. Applying liquid flupropanate by spot application provides a non-broadcast, species selective herbicide option with limited/no off-target damage. It is a practical method for scattered infestations within pastures, natural areas, roadsides and revegetation sites. The minimal equipment needed also allows plants to be controlled in hard to access areas.
Two trials were conducted on different properties within the Gladstone region. Liquid flupropanate (Taskforce® (745 g L-1 flupropanate)) was applied at rates of 0.149, 0.2235 and 0.298 g a.i. tussock-1 and the efficacy was assessed against an untreated control. In both trials, all liquid flupropanate treatments were found to be effective for the control of S. pyramidalis, with 97.8% or higher mortality and no reproductive stems present during the following growing season
Extension and communication strategies to improve biosecurity
No full textBiosecurity is the foundation of commercial egg production, playing a crucial role in safeguarding the industry against the incursion of emergency animal diseases and ensuring food safety. With heightened concerns over disease outbreaks and foodborne illnesses, the implementation of rigorous biosecurity measures is more important than ever.
Biosecurity encompasses a range of practices designed to prevent the introduction and spread of infectious agents, protecting the health of flocks and the quality of eggs produced. Effective biosecurity protocols not only mitigate the risk of diseases such as avian influenza and Salmonella Enteritidis, but also enhance welfare and productivity.
Australia's commercial egg sector includes operations that vary in scale and production systems; from large-scale fully integrated companies to much smaller owner-operator farms, with eggs currently produced in three main production systems: cage, barn and free-range. Regardless of size or system, all producers face similar biosecurity challenges and must implement comprehensive strategies to prevent the introduction and spread of infectious diseases. Due to the diversity of egg producers and production systems, there is no one-size-fits-all approach to communicating and engaging with each sector.
Previous studies have identified how biosecurity is currently managed across the different sectors and production systems of the Australian egg industry. These studies also provided recommendations where consultation with relevant stakeholders, and working with the different segments, is required to develop the most appropriate and applicable communication and extension strategies to target each group.
This project engaged with producers from each of the different segments through a series of online workshops. The purpose of the workshops was to identify how producers from each sector obtain their information regarding biosecurity, ways to engage and further actions to improve knowledge and adoption of biosecurity practices. The extension and communication strategy for each egg sector was developed based on the information discussed during the workshop. While there are some similarities in the approaches that should be taken regarding extension and communication practices to improve biosecurity between the sectors, there is also some differences that reflect how the different sectors engage and like to receive information.
Key themes of training, utilising industry champions to share experiences, developing templates and standard operating procedures and fostering a culture of biosecurity within the workforce and a freely accessible app for online biosecurity management were identified across sectors.
In addition to these strategies, a roadmap of actions is outlined together with a document for planning authorities to assist in understanding key biosecurity considerations when new farms are develope
First report of iris yellow spot virus infecting shallot (Allium cepa var. aggregatum) in Australia
No full textIn 2019, symptoms typical of infection by iris yellow spot virus (IYSV; family Tospoviridae, genus Orthotospovirus) were observed on shallot (A. cepa var. aggregatum) grown at the Gatton Research Facility, Department of Agriculture and Fisheries, Queensland. Initial testing by DAS-ELISA was positive for IYSV, and subsequent specific RT-PCR amplifying part of the RdRp (L-segment) and sequencing of amplicons confirmed the IYSV infection. This is the first record of IYSV infection of shallot in Australia
Evaluation of Water Use Efficiency in Mungbean using the Inverted-Bottle Pot System
No full textMungbean (Vigna radiata (L.) Wilczek) is a short-duration legume crop that is valuable for crop rotation. However, its yield potential is often limited by the water availability. Improving water use efficiency (WUE) in mungbean could increase mungbean production in water-limiting areas. Identifying genetic variability in mungbean for WUE is the first step to improving WUE and requires a fast and reliable screening method. This study evaluated twelve mungbean genotypes for WUE using Hunter’s inverted water bottle pot system (IBP) on two potting media (a potting mix of composting pine bark [UQ23] and Gatton vertosol soil). Morphology, agronomy, and physiology traits were measured and recorded, including six WUE traits. These WUE traits comprised a combination of two types of WUE (above-ground dry matter [WUEbio] and seed weight [WUEyield]) and three water consumption (total, before flowering, and after flowering [post]). Despite the difference in magnitude where plants in UQ23 used more water than in soil, the pattern of weekly water consumption was similar between these two potting media. The difference in water consumption among genotypes was observed after 46 DAS, and the peak water consumption occurred around flowering time (around 60 DAS). The variability due to the genotype-by-media interaction was very small (50%), similar heritability (0.6 for WUEbio and 0.8 for WUEyield), and strongly correlated (r>0.95, p<0.001). The ranking of genotypes based on total WUE and after-flowering WUE was reasonably similar across the two potting media. However, the ranking based on WUEyield could differ from the ones based on WUEbio. Top genotypes in WUEyield (e.g., Berken) were only ranked in the middle in WUEbio, while top genotypes in WUEbio (e.g., King) were ranked lower in WUEyield. These results indicated that the size of the plants does not always correspond to seed weight. Therefore, WUEyield would be a better target trait than WUEbio to improve yield in mungbean. This study demonstrated the use of the IBP system to detect genotypic variability in WUE among mungbean genotypes under non-limiting water conditions for screening after-flowering WUE in mungbean
The economic cost of managing Navua sedge (Cyperus aromaticus) - a monocot weed of tropical Queensland, Australia
No full textWeeds incur yearly up to 80 per hectare (89/hectare ($36.02/acre) present value. This cost did not vary between land use types (grazing vs. cropping); however, the labour component (compared to chemical and machinery) of the control cost was the greatest, especially in the grazing industry. Correlation analyses suggest control cost will continue to increase with increasing levels of Navua sedge infestation over time, especially in grazing lands. Farmers show willingness to impose strict biosecurity measures and practice integrated weed management tactics while waiting for promising biocontrol agents to minimize the spread and impact of the weed
Farming systems impact on key weed species of the northern dryland cropping region
No full textFarming systems that reduce the reliance on herbicide use and are less susceptible to weed incursions are required into the future. A 8-year long farming system experiment, comparing diverse farming system strategies, was initiated in March 2015 at Pampas on the Eastern Darling Downs. A baseline farming system, representative of current local best management practice, and various modified farming strategies that differ in the diversity of crops grown, intensity of cropping (i.e. proportion of time in-crop), nutrient input and/or soil restoration approaches were compared. This diverse range of farming systems assessed has provided a unique platform to monitor weed population dynamics and see if the farming strategy used can influence the weed load over time. Thirty-four weed species have been identified at the site, with sowthistle (Sonchus oleraceus) recorded the most frequently. Over the course of the experiment, compared to the baseline system there has been an increase in the diversity of weeds observed in systems with lower cropping intensity, greater crop diversity, and increased nutrition. In contrast, farming systems with a higher cropping intensity saw a significant decrease in the diversity of weeds present (68% less species than the baseline), and a significantly lower weed density compared to the baseline; the average weed population density in higher intensity cropping systems was only 22.5% of the baseline. This data demonstrates that increasing the frequency of crops sown in a farming system will have a dramatic effect on the resulting weed load in the farming system. A higher intensity farming system involving a diversity of crops can provide both resilience to weed incursions (indicated by lower weed diversity) as well as suppressing weed population growth. Alternatively, farming systems with lower cropping intensity, higher nutrient availability or higher crop diversity can facilitate conditions which favour spikes in weed incursions
A case for switching to sustainable herbicides to avert a perfect storm
No full textGlyphosate and paraquat are stalwart products for weed management used in Australia for over half a century. 50 years on, we face radical changes in the global weed landscape. Weed management today is influenced directly and indirectly by:
• Exponential growth in weed resistance
• Ballooning financial cost of weeds to Australian farmers and the economy, rising above $4.26 billion in 2023
• Future food security challenges
• Trade and domestic synthetic chemical bans
• Social and customer mandates and human health concerns
• Soil and environmental concern
• Diminishing viable alternatives to synthetic herbicides
These concerns are magnifying the need for Ecologically Sustainable Development and Environmentally Sustainable Governance reporting.
The continued use of these chemicals is problematic. The desire to adopt sustainable weed management practices is here, but a suitable product is not.
Sustainable herbicides have a poor global reputation for:
• Being expensive
• Lacking efficacy compared to traditional synthetic products
• Often requiring multiple applications and more product
• Corroding equipment due to acidity
• Impacting soil pH and health
• User friendliness
New herbicides with different modes of action are urgently needed to facilitate the evolution from entrenched herbicides. Yet no major new modes of action have been introduced to the marketplace for about 20 years.
To avoid the perfect storm, we need to evolve sustainable innovative weed management techniques and modes of action. This provides a wonderful and very timely opportunity for increased collaboration between all stakeholders to develop, trial and test new solutions for agriculture.
Ammonium Nonanoate has been trialled successfully in Australian non-crop environments. Trials in the US on uncontrolled weeds in pumpkin crops revealed weed control of 88%-98% and improved yields.
This paper addresses the use of ammonium nonanoate as one viable and sustainable weed management and defoliant option for future crops
Use of Chemical and Colorimetric Changes to Age Cryptotermes brevis Frass for Termite Management
No full textDrywood termites are problematic timber pests worldwide. Cryptotermes brevis, the West Indian drywood termite, is among the most important of these pests, in part due to its cryptic nature, making it hard to detect in structures and thereby easy to transport. Primary detections are commonly made by the observation of frass deposits evacuated through kick-holes, often leading to fumigation of the building to effectively eradicate the pest. However, after treatment, new frass piles are often discovered. It is, then, challenging to determine whether this frass represents reinfestation or is simply old frass dislodged from inactive nests. This may lead to unchecked termite proliferation or expensive fumigation when it is not needed. The ability to assess the age of the found frass would allow inspectors to determine whether a new infestation has occurred. Photocolorimetry has indicated that frass darkens over time, but large differences in the starting color of frass samples limit the usefulness of this as an aging method. Gas chromatographic-mass spectrometric analysis of the hexane extracts of C. brevis frass samples aged 0–22 months found differences between fresh frass (under 6 months) and those aged over 12 months but could not distinguish between 6- and 12-month-aged frass. Eight compounds accounted for over 70% of the differences between samples and are, thus, targets for chemical analysis of frass of unknown age. While this chemical frass analysis requires fairly sophisticated analytical tools, the cost associated with these processes would pale in comparison with those for unnecessarily fumigating a structure and thus merits further refinement to increase the accessibility of the method