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Understanding the adhesion performance of glued laminated timber manufactured with Australian softwood and high-density hardwood species
Get PDFTo be commercialised, glued laminated timber must typically conform to a strict bond integrity assessment. While the associated testing protocols vary slightly from standard to standard, the general method consists of a series of swelling (water immersion) and shrinkage (drying) cycles. The approach is independent of the species and adhesive type. Those cycles strain the gluelines to a level depending on the species’ moisture uptake, timber dimensional movement and modulus of elasticity, as well as adhesive layer elasticity. High density and high modulus of elasticity materials frequently fail within the glueline regions rather than within the timber and therefore fail the bond integrity assessment. To better understand the mechanisms that lead to glueline failure, glulam samples were manufactured using three prominent Australian commercial timbers of various densities (Radiata pine—Pinus radiata, Southern pine—Pinus caribaea/Pinus elliottii, and Spotted gum—Corymbia citriodora) and two structural adhesive types (resorcinol formaldehyde and polyurethane). Using advanced measurement techniques (digital image correlation and strain gauges), the response of the different species and adhesive types to moisture swelling and shrinkage, as well as times at which glueline separation occurs, were captured. A relationship was observed between moisture uptake and delamination percentages with spotted gum producing significantly higher levels of delamination and significantly lower moisture uptake values, compared to both Radiata pine and Southern pine. While the polyurethane glued samples on average produced higher levels of delamination, the digital image correlation data indicates that the time at which this delamination occurs is later than the samples glued with resorcinol formaldehyde
The Distribution of Reniform Nematode (Rotylenchulus reniformis) in Cotton Fields in Central Queensland and Population Dynamics in Response to Cropping Regime
Get PDFReniform nematode (Rotylenchulus reniformis) causes significant yield loss in cotton worldwide. In 2012, its detection in the Dawson-Callide region of Central Queensland prompted extensive surveys of cotton fields. The nematode was confirmed in 68% of sampled fields, with populations ranging from 2 to 3870 R. reniformis/200 mL of soil. Soil monitoring revealed increasing populations associated with consecutive cotton crops. However, when corn or sorghum replaced cotton, soil nematode populations significantly decreased. A two-year replicated field trial demonstrated that growing a non-host crop (such as biofumigant sorghum ‘Fumig8tor’, grain sorghum, or corn) significantly reduced nematode populations in the top 15 cm of soil compared to cotton. Unfortunately, when cotton was replanted the following season, nematode populations rebounded regardless of the previous crop. Only the ‘Fumig8tor’-cotton rotation resulted in significantly lower nematode populations than continuous cotton. Vertical soil sampling showed that rotating with a non-host crop significantly reduced nematode densities to a depth of 100 cm compared to cotton. However, when the field was replanted with cotton, nematode populations recovered, unaffected by cropping or soil depth. This study emphasises the importance of monitoring reniform nematodes in cotton soils for early detection and defining distribution patterns within a field, which may improve the effectiveness of management practices. These results suggest that one rotation out of cotton is not sufficient, as populations return to high levels when cotton is grown again. Therefore, two or more rotations out of cotton should be considered to manage this nematode
The benefits and potential of pre-emptive weed biological control: Three case studies in Queensland, Australia
Get PDFInvasive weed species can have significant impacts on agriculture, biodiversity and livelihoods. The cost and feasibility of managing these species using conventional means can be prohibitive depending on the size of the infestations or the habitats in which they invade. Under these conditions, biological control is seen as a viable, sustainable means to manage many weeds. However, biological control can take many years and at considerable cost to achieve the desired level of control, due to the numerous steps that are involved, including native range surveys and host-specificity testing of potential agents. Pre-emptive biological control targeting particularly high-risk species prior to their arrival in a country or emerging weeds can be cost-effective, especially if the respective biological control agents have been utilized in other countries. While pre-emptive biological control of arthropods has been investigated previously, there are few examples of pre-emptive biological control of weed species. The invasive weed species, Chromolaena odorata, Mikania micrantha and Coccinia grandis have all been or are currently targets of pre-emptive biological control in Australia. Research on the gall fly Cecidochares connexa was initiated prior to its host, C. odorata being detected in Australia. Cecidochares connexa was eventually released in Australia to control C. odorata, after initial research on the agent found it to be suitably host specific and effective against the target weed. Cecidochares connexa has also been released in numerous other countries in Africa, Asia and the Pacific, where it is providing very good control. Australia funded research on the rust Puccinia spegazzinii as part of a project involving Fiji and Papua New Guinea while the target weed, M. micrantha was a target for eradication in Queensland. The rust was later approved for release in Australia to control M. micrantha following additional host-specificity testing. However, research funded by Australia overseas suggests that the rust may not be able to suppress M. micrantha populations below current levels. Consequently, while P. spegazzinii has been released in numerous countries now, it has not yet been field released in Australia. Biological control research in Australia on C. grandis is relatively new as the weed is relatively minor and not yet declared a target for biological control. Consequently, no biological control agents have yet been released in the country. Pre-emptive biological control of C. odorata and M. micrantha has been particularly cost-effective, not just for Australia, but subsequently for numerous other countries where these weeds were well-established and problematic and the respective biological control agents were later released
Three new strategies for improving biosecurity and invasive species management to build resilience in Pacific Islands
Get PDFThe inaugural Pacific Ecological Security Conference (PESC) was held in October 2022, bringing together over 100 island leaders, policy-makers, natural resource managers and global and regional invasive species experts to prioritise the critical issue of invasive species in the Pacific Islands Region. Participants confirmed that invasive species are a major threat to building and maintaining climate resilience and adaptability of Pacific Island ecosystems, as well as food security, biodiversity, sustainable livelihoods and the protection of cultural resources and way of life. Three region-wide strategic action plans were developed to guide interventions focused on the topics of invasive ants, coconut rhinoceros beetle and the use of biological control as a pest and weed management tool. These plans were the major outcome of the PESC and, when implemented, will result in coordinated activities that take a “whole-of-Pacific” approach to invasive species biosecurity and management. Here, we briefly describe the background, planning and engagement process for the three plans, summarise any country- and territory-level data obtained through the process and detail what is planned to occur over the next few years. In addition to the adoption and implementation of the strategies as a result of this inaugural PESC, we anticipate that the PESC will become the premier regional conference aimed at reducing the entry and impacts of invasive species to improve sustainability of environments and peoples of the Pacific
Wood-loving magic mushrooms from Australia are saprotrophic invaders in the Northern Hemisphere
No full textMagic mushrooms are fungi that produce psilocybin, an entheogen with long-term cultural use and a breakthrough compound for treatment of mental health disorders. Fungal populations separated by geography are candidates for allopatric speciation, yet species connectivity typically persists because there is minimal divergence at functional parts of mating compatibility genes. We studied whether connectivity is maintained across populations of a widespread species complex of magic mushrooms that has infiltrated the Northern Hemisphere from a hypothesised centre of origin in Australasia. We analysed 89 genomes of magic mushrooms to examine erosion of species connectivity in disparate populations with support from gene flow, kinship, structure, allelic diversity, and mating compatibility. We used comparative genomics and synteny to test whether the genes that produce psilocybin are under selection in natural populations of magic mushrooms. Despite phenotypic plasticity and intercontinental distribution, sexual compatibility is maintained across geographically isolated populations of magic mushrooms. Psilocybin loci have high allelic diversity and evidence of balancing selection. Australasia is the centre of origin of wood-degrading magic mushrooms and geographically separated populations are fully sexually compatible, despite minimal gene flow since differentiation from a shared ancestor. Movement of woodchips, mulch, or plants has most likely facilitated invasion of these mushrooms in the Northern Hemisphere
A new 3,6-dialkyl-α-pyrone produced by the heterologous expression of a PKS-NRPS hybrid enzyme derived from a Pestalotiopsis endophyte
No full textGenome mining of polyketide synthase (PKS)-nonribosomal peptide synthetase (NRPS) hybrid enzymes independent of trans-acting enoyl reductase using our in-house fungal draft genomic library led to the discovery of a unique PKS-NRPS hybrid enzyme, PbpsA, in a Pestalotiopsis fungus. Heterologously expressed PbpsA in Aspergillus oryzae provided a new 3,6-dialkyl-α-pyrone 1. This compound was fully characterized following the interpretation of NMR, UV, IR, and MS data. From the structure, we speculated that 1 was biosynthesized by the only PKS moiety of PbpsA, and that a 3-ethyl substitution was introduced by an endogenous enzyme from A. oryzae
Habitat partitioning in Moreton Bay bug species to inform fisheries management
Get PDFHabitat preferences influence partitioning in many marine taxa that can inform fisheries management. Despite this, little is known about how habitat partitioning contributes to spatial distributions in many commercially important species. This study aims to investigate habitat partitioning and influential variables affecting the distribution in Moreton Bay bug species Thenus parindicus and Thenus australiensis for the benefit of management on the east coast of Queensland, Australia. These Scyllarid lobsters spend much of their lives buried within sediment, but little research focuses on what influences the distribution of each species. In this study, a fishery-independent survey was conducted in a key commercial trawling area off the coast of Townsville to determine Thenus species distributions and habitat preferences. Variables used to examine the habitat preferences and distributions of both species included depth, sediment grain size, Trask sorting coefficient and calcium carbonate content. We found that all variables evaluated significantly affected species distributions. Multivariate analyses suggest that Trask sediment sorting coefficient and depth were the strongest influential variables. This contrasts with previous findings that mean grain size is the most important sediment parameter influencing Thenus distributions. The results indicate habitat partitioning between T. parindicus and T. australiensis but not habitat exclusion. These findings, along with the likely influential variables of species’ distributions will help better understand the habitat ecology of these lobsters and inform management for the Moreton Bay bug fishery
Decay resistance of southern pine wood containing varying amounts of resin against Fomitopsis ostreiformis (Berk.) T. Hatt
No full textResin production in wood tissues is a regular feature of pine wood species, including southern pine. High resin contents of southern pine wood may increase wood resistance against decay fungi. The current study investigated the effect of resin contents in southern pine wood on decay resistance by exposing non-extracted heartwood, mixed wood (sapwood + heartwood), and sapwood blocks with varying resin content to brown rot, Fomitopsis ostreiformis in a laboratory decay test. Matching blocks of each wood type were successively extracted in a Soxhlet using three solvents to determine resin content and were exposed to decay fungus in parallel. Results showed that mass losses in non-extracted heartwood and mixed wood depended on resin content levels, and very shallow or no mass losses were observed in blocks containing more than 31 % resin content. Sapwood experienced high mass losses, but the presence of resinous extractives significantly increased the decay resistance. All solvent-extracted blocks experienced high mass loss (53–55 %). Scanning electron microscopy showed that penetration of brown rot hyphae and cell damage depended on the resin contents of blocks. Most of the identified compounds through GC-MS belonged to oleoresins, among which monoterpene hydrocarbons, oxygenated monoterpenoids, and sesquiterpenes were more abundant in heartwood than sapwood
Genome-wide association mapping for seedling and adult resistance to powdery mildew in barley
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Two new major QTL were identified for powdery mildew resistance. We confirmed that the QTL on 7HS contributed mainly to the adult-plant resistance, while another one on chromosome arm 1HS made a significant contribution to the seedling resistance.
Abstract
Powdery mildew (PM), caused by Blumeria hordei, can occur at all post emergent stages of barley and constantly threatens crop production. To identify more genes for efective resistance to powdery mildew for use in breeding programs, 696 barley accessions collected from diferent regions of the world were evaluated for PM resistance at seedling and adult growth stages in three diferent states of Australia. These barley accessions were genotyped using DArTSeq with over 18,000 markers for a genome-wide association study (GWAS). Using the FarmCPU model, 54 markers showed signifcant associations with PM resistance scored at the seedling and adult-plant stages in diferent states of Australia. Another 40 markers showed tentative associations (LOD>4.0) with resistance. These markers are distributed across all seven barley chromosomes. Most of them were grouped into eleven QTL regions, coinciding with the locations of most of the reported resistance genes. Two major MTAs were identifed on chromosome arms 3HS and 5HL, with one on 3HS contributing to adult plant resistance and the one on 5HL to both seedling and adult plant resistance. An MTA on 7HS contributed mainly to the adult-plant resistance, while another one on chromosome arm 1HS made a signifcant contribution to the seedling resistance
Integrated pest management of nematodes in sweetpotatoes
Get PDFThe Australian sweetpotato industry (20M per year in losses (ASPG pers. com.). Root-knot nematodes (RKN) are widely distributed throughout the sweetpotato-growing areas of Queensland and northern NSW. Feeding activity affects root initiation, causes stunting, skin damage and yield loss. At project commencement there was one registered chemical (S7 classification being removed from the market) and one minor use permit for RKN control. Thus, it was crucial to find alternative control methods through soil health improvement and Integrated nematode management.
The project completed the first comprehensive nematode species survey undertaken on sweetpotato producing soils in Australia, with 85 fields sampled in an initial survey. Growers now have a greater understanding of the plant-parasitic nematodes causing yield loss and damage. A new detection of reniform nematode was made outside of the previously known range. Following the detection of guava root-knot nematode into Australia a pest alert fact sheet was produced for the industry. Experiments provided new knowledge on the effects of nematode species on sweetpotato cultivars. Results suggested that R. reniformis damage occurs at root formation resulting in fewer roots, infection with RKN (M. javanica) reduced both the number and weight of roots, and the cultivar Bellevue is moderately susceptible to M. javanica (contrary to existing information