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Germination Responses of the Invasive Hedge Cactus (Cereus uruguayanus) to Environmental Factors
Get PDFHedge cactus (Cereus uruguayanus R. Kiesling; syn.: Cereus hildmannianus K. Schum.) is a columnar cactus that was introduced to Australia as an ornamental plant and has since become invasive in subhumid regions of Queensland and New South Wales. Compared with its congener, queen of the night (Cereus jamacaru DC.), which is currently invasive in both eastern and southern Africa, information on seed biology of C. uruguayanus is lacking. Experiments were conducted to study the effects of alternating day/night temperature, salt stress, water stress, and burial depth on germination and seedling emergence of four seed accessions of C. uruguayanus. Seeds were also subjected to a controlled aging test (CAT) to obtain an estimate of potential persistence under field conditions. The optimum temperature regime for germination of all accessions was 30/20 C. Germination decreased with an increase in sodium chloride (NaCl) concentration, but germination of all accessions (range 26% to 81%) occurred at 160 mM NaCl, indicating very high salt tolerance. Seed germination gradually decreased with an increase in water stress, but germination in all accessions (range 19% to 47%) occurred at –0.8 MPa. Seed viability and dormancy status were unaffected by exposure to salt level (320 mM NaCl) and water (–1.6 MPa) stress under which germination did not occur. Germination responses to all three factors were generally similar to those documented for C. jamacaru. The emergence of C. uruguayanus decreased with an increase in seed burial depth. The highest emergence (43%) was recorded for surface-sown seeds, and emergence was reduced to 0 at a burial depth of 2 cm. CAT results for two seed accessions indicated that seeds of C. uruguayanus are likely to demonstrate extended (>3 yr) persistence under field conditions, a prediction that is supported by evidence that germination of its small (2-mm) seeds is markedly reduced by burial
Multidecadal High Mortality Disease Events in Australian Domestic Geese Associated with a Novel Alphaherpesvirus, Designated Anatid Alphaherpevirus 2
Get PDFHerpesviruses are ubiquitous viruses which infect a wide range of hosts. Novel herpesviruses are being increasingly detected in free-ranging bird populations and there are growing concerns for cross-species infection and spillover events. Herein, multiple sporadic outbreaks of mortality caused by a herpesvirus are described in domestic geese in Queensland, Australia. Goose herpesvirus was initially detected in 1989 in south-east Queensland, and this article details four further recent outbreaks and reports novel genome sequencing and phylogeny of the preliminarily designated anatid alphaherpesvirus 2 (AnHV-2). Affected flocks were housed outdoors and comingled with other domesticated and wild anseriforms and other birds which were unaffected by disease. Affected geese displayed anorexia, lethargy, weakness, vomiting, and diarrhoea prior to death within 12–24 hr of the onset of clinical signs. Post-mortem examinations showed variable hepatic necrosis, splenic necrosis, fibrinonecrotising enteritis, lymphoid necrosis, necrotising thymitis, necrotising adrenalitis, and vasculitis. Intranuclear inclusion bodies were observed in hepatocytes, biliary epithelium, small intestinal mucosal epithelium, thymus, endothelial cells, ovarian stromal cells, adrenal cortical cells, and neuronal cell bodies in peripheral nerve ganglia. Transmission electron microscopy visualised herpesviral particles in virus culture supernatant, and within the nuclei of hepatocytes, biliary epithelium, and endothelial cells in case tissues. The genome sequence of this herpesvirus, designated anatid alphaherpesvirus 2 (AnHV-2), is described. While investigating goose mortalities, archived isolate from a swan with suspected herpesvirus infection was tested and genome sequencing identified a further novel herpesvirus, proposed anatid alphaherpesvirus 3 (AnHV-3). The AnHV-2 and AnHV-3 genomes were more similar to each other, with a nucleotide identity of 76.1%, than to reference genome sequences. Phylogenetically, the new genomes formed a distinct clade within the alphaherpesvirus genus Mardivirus. We sequenced four AnHV-2 genomes from different cases and these did not display consistent divergence over time or distance. Expanded surveillance and outbreak testing are recommended, facilitated by the development of a specific real-time PCR for the rapid detection of AnHV-2
Development and evaluation of real-time quantitative PCR assays for detection of Phellinus noxius causing brown root rot disease
No full textBrown root rot disease (BRRD) is a highly destructive tree disease. Early diagnosis of BRRD has been challenging because the first symptoms and signs are often observed after extensive tissue colonization. Existing molecular detection methods, all based on the internal transcribed spacer (ITS) region, were developed without testing against global Phellinus noxius isolates, other wood decay fungi, or host plant tissues. This study developed SYBR Green real-time quantitative PCR (qPCR) assays for P. noxius. The primer pair Pn_ITS_F/Pn_ITS_R targets the ITS, and the primer pair Pn_NLR_F/Pn_NLR_R targets a P. noxius-unique group of homologous genes identified through a comparative genomics analysis. The homologous genes belong to the nucleotide-binding-oligomerization-domain-like receptor (NLR) superfamily. The new primer pairs and a previous primer pair G1F/G1R were optimized for qPCR conditions and tested for specificity using 61 global P. noxius isolates, five other Phellinus species, and 22 non-Phellinus wood decay fungal species. While all three primer pairs could detect as little as 100 fg (about 2.99 copies) of P. noxius genomic DNA, G1F/G1R had the highest specificity and Pn_NLR_F/Pn_NLR_R had the highest efficiency. To avoid false positives, the cutoff Cq values were determined as 34 for G1F/G1R, 29 for Pn_ITS_F/Pn_ITS_R, and 32 for Pn_NLR_F/Pn_NLR_R. We further validated these qPCR assays using Ficus benjamina seedlings artificially inoculated with P. noxius, six tree species naturally infected by P. noxius, rhizosphere soil, and bulk soil. The newly developed qPCR assays provide sensitive detection and quantification of P. noxius, which is useful for long-term monitoring of BRRD status
Hymenopteran parasitoids of fall armyworm (Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)) in Australia, with the description of five new species in the families Braconidae and Eulophidae
Get PDFFall armyworm, Spodoptera frugiperda (J.E. Smith) is an invasive pest of agriculturalcrops including sweet corn and maize. The moth was first recorded in Australia inJanuary 2020 and is now considered established in most states and territories, andresearch is underway to develop management strategies. Extensive rearing ofS. frugiperda larvae and eggs occurred from March 2020 to April 2023 to under-stand the parasitoid complex present in Australia and identify potential biologicalcontrol agents. We report here on the hymenopteran parasitoids reared duringthis period, which were identified using a combination of morphology and COIDNA barcoding, and provide images, a key to species, and contextual informationto facilitate future research. Twelve species of parasitoids from five families ofHymenoptera are formally reported as parasitising S. frugiperda in Australia. Fivespecies are here described as new: Chelonus patbat Fagan-Jeffries, sp. nov.(Braconidae), Chelonus trojanus Fagan-Jeffries, sp. nov. (Braconidae), Coccygidiummellosiheroine Atkin-Zaldivar & Fagan-Jeffries, sp. nov. (Braconidae), Coccygidiumnecatrix Atkin-Zaldivar & Fagan-Jeffries, sp. nov. (Braconidae), and Euplectrus frugi-perdata Fagan-Jeffries, sp. nov. (Eulophidae)
Pseudo-linkage or real-linkage of rust resistance genes in a wheat-Thinopyrum intermedium translocation line
No full textWheat addition lines Z4 and Z5 carrying rust resistance genes from Thinopyrum intermedium (JJJsJsStSt, 2n = 6x = 42) together with three wheat lines involved in the production of these addition lines were analysed by rust response, 90K SNP genotyping, and molecular cytogenetic analysis. Seedling leaf rust (LR) responses to five diverse pathotypes indicated that the LR resistance gene(s) was located in translocation chromosome T3DS-3AS.3AL-7StS common to Z4 and Z5. The stripe rust (YR) resistance gene(s) was located in translocation chromosome T3AL-7StS.7StL, which is unique to Z4, based on the seedling YR responses to four diverse pathotypes. Backcross and selfed populations involving the addition lines and various wheat cultivars were studied to understand the inheritance of the alien resistance genes. Although inheritance studies indicated genetic linkage, the alien genes for resistance to leaf rust (LR) and stripe rust (YR) in Z4 were present in different wheat-Th. intermedium translocation chromosomes. We found that LR and YR were in pseudo-linkage, rather than true linkage
Controlling Leucaena leucocephala with encapsulated herbicides
No full textUnmanaged Leucaena (Leucaena leucocephala) can form dense woody thickets which excludes other vegetation causing environmental damage. This trial investigated eight herbicide treatments, including six encapsulated herbicides in comparison with a basal bark treatment and a drill and fill liquid herbicide solution. The field trial was established and assessed prior to treatment and at 2, 6, 12, 18 and 24 months after treatment. Five herbicide treatments resulted in high mortality of leucaena after 24 months. This trial increases the options for effectively managing larger stemmed leucaena growing amongst other desirable vegetation including within riparian and road corridors. These options also offer some environmental and worker safety benefits
Incursion of Novel Eurasian Low Pathogenicity Avian Influenza H5 Virus, Australia, 2023
No full textAustralia is a sink for low pathogenicity avian influenza viruses, with isolated circulation occurring on the continent. We report the incursion of a Eurasian low pathogenicity avian influenza H5 virus into Australia. This report benefits surveillance and diagnostic work because of the risk and current absence of highly pathogenic avian influenza A(H5N1)
Evaluating Self-Pollination Methods: Their Impact on Nut Set and Nutlet Abscission in Macadamia
No full textNut set is an important determinant of yield and plays a pivotal role in orchard profitability. The complex process of nut setting is governed by numerous factors, with pollination being a critical mechanism. Macadamia cultivars exhibit both self- and cross-pollination. Self-pollination may increase nut set, so it is a trait of interest in breeding. This study investigated nut setting and nutlet abscission on four cultivars, ‘HAES 791’, ‘HAES 741’, ‘HAES 344’, and ‘A16’, using three controlled self-pollination methods: (i) autogamy (AG), entailing bagging before anthesis with no hand-pollination; (ii) geitonogamy 1 (GG1), bagging following hand-pollination using pollen from the same raceme; and (iii) geitonogamy 2 (GG2), bagging following hand-pollination using pollen from different racemes of the same cultivar. These self-pollination methods were compared against open-pollination (OP). ‘HAES 741’ and ‘HAES 791’ were partially self-fertile, while ‘HAES 344’ and ‘A16’ were self-infertile. Final nut sets per raceme for ‘HAES 741’ were 0.43 by AG, 0.65 by GG1, and 0.5 by GG2, and for ‘HAES 791’, they were 0.90 by AG, 1.25 by GG1, and 1.0 by GG2. Final nut set per raceme with OP was higher compared to self-pollination methods and ranged between 3.5–6.5. In self-fertile cultivars, nut set following the three self-pollination methods accounted for 6.5–3.7% of the nut set following OP, and nutlet abscission following self-pollination methods accounted for 20–50% of nutlet abscission following OP. No significant differences in nut set and nutlet abscission were observed among AG, GG1, and GG2. Results suggest that macadamia orchards planted with self-fertile cultivars would be less reliant on external pollinators or artificial pollination to achieve adequate yields
Water weed management with the new aquatic herbicides flumioxazin and florpyrauxifen-benzyl
No full textInvasive aquatic plants cause significant socio-economic and environmental impacts to Australia’s precious freshwater resources. Most of these aquatic weeds are difficult to manage due to a lack of effective and economical control tools. In 2021, the contact herbicide flumioxazin (Clipper herbicide) was registered by the Australian Pesticides and Veterinary Medicines Authority for control of aquatic weeds. The systemic herbicide florpyrauxifen-benzyl (ProcellaCOR) has been used for aquatic weed control in the USA since 2018 and was registered in Australia March 2024. Both herbicides are used at low application rates and have a favourable environmental profile. Therefore, they pose a low risk of non-target damage when dosed and applied appropriately for target weeds and the site-specific environmental conditions.
Lab trials were carried out with flumioxazin and florpyrauxifen-benzyl to determine control efficacy of established and emerging aquatic weeds with foliar or in-water applications. Subsequent field trials tested the herbicides in management scenarios to measure control efficacy in a range of environmental conditions and situations.
Flumioxazin provided excellent control of Amazon frogbit, kidney-leaved mudplantain, hairy water hyssop (Bacopa lanigera), cabomba, Mexican water lily and water lettuce. It also controlled sagittaria, both submerged and emergent, but the results can be variable. Florpyrauxifen-benzyl efficiently controlled parrot’s feather, Rotala rotundifolia, cabomba, water hyacinth and sagittaria. Experiments also demonstrated that flumioxazin and florpyrauxifen-benzyl cause limited to no damage to many native aquatic plants, especially valuable emergent plants along the shoreline. Both herbicides gave excellent control if applied as foliar or in-water (injection) application, depending on situation and target weed.
Together, these two new herbicides will greatly aid the efficient management of many established and emergent aquatic weeds in Australia. Ongoing research will investigate control efficacy for further target weeds, impacts on non-target aquatic plants, efficient application techniques and treatment strategies
Integrated management of Harrisia cactus - the importance of understanding every tool in the box
No full textHarrisia cactus has been an ongoing concern since its recognition for negatively impacting grazing and natural areas in the Brigalow Belt Bioregion of Queensland during the 1950s. Initial attempts to control the weed using chemicals such as arsenic pentoxide proved to be hazardous, expensive, and ultimately ineffective. In the early 1970s, a search for biological control agents was conducted in Argentina, leading to the release of four insects in Queensland. By the 1990s, two of these insects had successfully established themselves and eradicated most Harrisia at the release locations within dense infestations in central Queensland. This success was largely attributed to the Harrisia mealy bug (Hypogeococcus pungens), with assistance from a stem-boring beetle (Nealcidion cereicola). However, recent surveys indicate the persistence of numerous dense, localized Harrisia cactus infestations throughout central Queensland, which are expanding despite the presence of the mealy bug. Similarly, although the biocontrol agent is well-established in the southern Brigalow Belt, the density and spread of the weed is increasing. Local councils and landowners across the state invest substantial amounts of money in the chemical control of Harrisia cactus. Nevertheless, it is widely recognized that while this method effectively kills above-ground plant parts, large established plants can regenerate from underground tubers, necessitating continuous monitoring for regrowth and ongoing chemical application. There are clearly limitations to current best practice management of Harrisia cactus and alternative methods should be explored before the situation deteriorates further. In the last four years, we have probed the limitations of relying solely on biocontrol or chemical control and explored alternative management methods, such as livestock grazing, controlled burning, and the management of invasive animal seed dispersers. Our research highlights the importance of understanding the strengths and weakness of each potential method, being flexible in their application, monitoring results and changing tactics when required