Yellow Canopy Syndrome (YCS) is a complex that currently only affects commercial sugarcane ( Saccharum sp. hybrids) in Australia. It was first detected in Far North Queensland over a decade ago and has since spread to most cane-growing areas from Far North Queensland down to Southern Queensland. YCS represents a serious challenge to not only the Australian sugarcane industry but also a potential threat to sugarcane industries worldwide. The symptoms and physiological impacts of YCS have been well described. However, despite a decade of research, the underlying causal factor(s) of YCS still need to be fully determined. Multidisciplinary research has focused on several abiotic and biotic factors to determine the symptoms and potential causes of YCS. Although not yet conclusive, the most recent research findings exploring the impact of pesticide application on YCS symptom expression levels indicate that invertebrates may play a role. Furthermore, studies have focused on optimising invertebrate sampling strategies and exploring their population dynamics in relation to YCS expression to determine which invertebrate species may be involved. Other research involves developing effective detection and surveillance approaches for YCS. This report reviews the YCS-related research published to date. It concludes that there are still some fundamental knowledge gaps that need to be addressed before the risk to other sugarcane-producing countries other than Australia can be determined and before effective YCS management strategies can be developed.

The interactions between powdery mildews (Ascomycota, Erysiphaceae), obligate biotrophic pathogens of many plants, and pycnidial fungi belonging to the genus Ampelomyces, are classic examples of specific mycoparasitic relationships. These interactions are common and finely tuned tritrophic relationships amongst host plants, powdery mildews, and Ampelomyces mycoparasites wherever these organisms co-occur in the field. Selected Ampelomyces strains have already been developed as biocontrol agents of powdery mildew infections of some crops. In Australia, their study has received little attention so far. Only a single Ampelomyces strain, included in a whole-genome sequencing (WGS) project, was known from this continent. Here, we report the isolation of 20 more Ampelomyces strains from eight powdery mildew species in Australia. Multi-locus phylogenetic network analyses of all the 21 Australian Ampelomyces strains carried out in combination with 32 reference strains from overseas revealed that the Australian strains belonged to four molecular taxonomic units (MOTUs). All those MOTUs were delimited earlier based on Ampelomyces strains isolated in Europe, North America, and elsewhere. Based on the phylogenetic analyses, two Australian strains belonging to different MOTUs were selected for WGS. Long-read (MinION) and short-read (Illumina) technologies were used to provide genome assemblies with high completeness. Both assemblies have a bipartite structure, i.e., consisted of AT-rich, gene-sparse regions interspersed with GC-balanced, gene-rich regions. These new high-quality assemblies and evidence-based annotations are important resources for future analyses of mycoparasitic interactions to disentangle molecular mechanisms underlying mycoparasitism, possible new biocontrol applications, and naturally occurring tritrophic relationships.

This research is focused on a comparative field-based study of the population dynamics and sampling methods of two mealybug species, Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Coccomorpha, Pseudococcidae) and Heliococcus summervillei (Brookes, 1978) (Hemiptera: Coccomorpha, Pseudococcidae), in sugarcane (Saccharum sp. hybrids) (f. Poaceae) over consecutive growing seasons. The research monitored and compared the above- and belowground populations and seasonal abundance of these two mealybug species in sugarcane fields in Far North Queensland, with non-destructive sampling techniques of yellow sticky traps, pan traps, and stem traps, and destructive sampling of the whole leaf and whole plant. The results indicated that S. sacchari (n = 29,137) was more abundant and detected throughout the growing season, with population peaks in the mid-season, while H. summervillei (n = 2706) showed peaks of the early-season activity. S. sacchari is primarily located on sugarcane stems and roots, compared to H. summervillei, which is located on leaves and roots. The whole-leaf collection and stem trap were the most effective sampling techniques for quantification of H. summervillei and S. sacchari, respectively. This study enhanced the understanding of S. sacchari and the first-ever record of H. summervillei on sugarcane in Australia and will contribute to the development of more effective pest management strategies.

The cause of peanut kernel shrivel (PKS) syndrome, affecting peanut crops in Australia’s growing regions, is currently unknown. It is estimated that PKS is costing the peanut industry more than AUD 5 M p.a. and is a potential threat to the industry. Previous investigations have ruled out all abiotic factors and most biotic factors as the cause of PKS. This research aimed at investigating the scope, distribution, and cause of the PKS syndrome. The survey showed PKS symptoms to be present in peanut crops in all the growing regions surveyed. Based on our study of culturable microorganisms, there appears to be no clear-cut involvement of plant pathogenic bacteria and fungi; however, Fusarium spp. were revealed as the most prevalent fungi in affected plants. Moreover, the soil metagenomics study revealed Fusarium spp. as the most abundant fungal communities in the soil microbial profile, and they could contribute to the PKS syndrome. The consistent presence observed of the identified Fusarium oxysporum in PKS-affected samples could indicate a role for this pathogen in the syndrome, especially in conjunction with abiotic stressors. The pathogenicity testing of F. oxysporum resulted in very mild PKS symptoms. A separate report suggesting the involvement of phytoplasma in the PKS syndrome raises the possibility of an interplay of biotic factors in the development of this disease. Further investigation is warranted to determine the true cause or causes of this disease.

As a versatile and multipurpose plant, hemp (Cannabis sativa L.) possesses immense potential for its application in nutraceuticals, food and nutrition, fibre, and construction material. However, its broader industrial potentials are hindered by the lack of sufficient knowledge on varietal differences, phytochemical properties, food and fibre processing techniques, bioenergy application and valorisation of whole plant, clinical evidence, and standardised quality control mechanisms. In this context, we systematically reviewed 101 reviews and 655 research papers on hemp to map what we already know and what we still need to know about hemp, across its supply chain; from cultivar selection through production to end use. We reviewed the literature based on major themes and sub-themes. Existing literature spanned 33 sub-themes of hemp, which can be classified under five broad themes: production, material, health, futures, and research and education. The ‘material’ theme (42%) was the most researched, followed by ‘production’ (27%) and ‘health’ (19%). At the sub-theme level, one-fifth of the research articles covered fibre and composite material (n = 139), followed by phytochemical analysis and potency testing (n = 45), hempcrete and construction applications (n = 43), and germination and plantation techniques (n = 41). More than half of the selected research articles on hemp were published in the last three years (2020–2022), concentrated mainly in North America, Europe, and China. Cannabidiol, fibre, and seed oil were considered as the quick wins of hemp industry (hemp champions). Based on our review, we have discussed various research gaps and research priorities across the supply chain, beginning from early detection of hemp breed to valorisation of hemp hurd and industrial residue to address opportunities and challenges for the industrial development of major hemp products.

In Australia, sweetpotato (Ipomoea batatas L.) is vulnerable to root feeding insect pests such as wireworms (e.g., Agrypnus spp.). The number of registered insecticides to control these insect pests is limited and often pest pressure, for example by wireworms, is severe close to harvest, further limiting what insecticides can be applied. Incorporating biological control agents such as entomopathogenic fungi (e.g., Metarhizium anisopliae) into integrated pest management programmes may be feasible in sweetpotato. M. anisopliae has been shown to be effective in controlling more than 200 insects and it is able to reside and grow in the rhizosphere and rhizoplane, suggesting that M. anisopliae could be a promising candidate against soil insect pests. In the study presented here, M. anisopliae was formulated into calcium alginate granules fortified with nutrients. The resporulation of the fungal granules was tested on four different soil types in the laboratory. The biocontrol efficacy of the resulting fungal growth was also examined using larval mealworms, Tenebrio molitor as a model insect in the laboratory and the glasshouse. Our results indicated that sterilised soil favoured optimal fungal resporulation, although different soil types did not have a significant effect on fungal resporulation. The resulting fungal resporulation and growth on sterilised soil caused high mortality (up to 76%) of larval mealworms in the glasshouse, whereas the fungal granules applied to non-sterile soil demonstrated poor resporulation that led to low mortality (13%) of larval mealworms. The result of this study indicates that the manipulation of microbial populations in field soil is required to enhance the fungal growth and potential insect control against wireworms in the field.

Common rust of maize (CR), caused by Puccinia sorghi Schwein., is found in all maize growing regions across the globe. In recent years, an increase in the incidence and severity of CR has been observed in Australia. The challenges posed by a diverse population of P. sorghi to maize breeding programs and the strategies required to deploy durable resistance were explored. Preliminary studies of diversity were conducted by phenotyping the five most diverse isolates against maize lines carrying no resistance genes and one to four resistance genes. The results showed that further genotyping studies were required. Short reads of 17 CR isolates were collected from an array of agroecological regions in Eastern Australia, and these were mapped back against the hybrid assembly of Isolate 1. A hybrid assembly between short (Illumina paired-end) and long (PacBio) reads was conducted in MaSuRCA of the first isolate collected. A draft genome of 145,963,792 bp was obtained after QUAST analysis, with a total length of 145,815,044 bp (when removing base pairs below ≥1,000). The prediction from the BRAKER pipeline identified 20,438 gene models. All 17 isolates sequenced represented unique genotypes, and no clones were detected. The 17 isolates grouped into three clusters. The diversity observed within the population of P. sorghi in Australia suggests that monogenic resistance might not be durable. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Net or web blotch (NB), caused by Didymella arachidicola, is an emerging threat causing a significant reduction in yield of peanuts in cooler production regions globally, including Australia, China, and Southern Africa. Host resistance against NB is poorly understood, with field screenings reliant on favorable climatic conditions. A rapid and effective phenotyping method is essential to differentiate between resistant and susceptible breeding lines and improve selection accuracy. In this study, a greenhouse screening method using mycelium as the inoculum to determine host response to D. arachidicola was developed. A liquid-culture mycelia suspension of the pathogen was sprayed onto 9-week-old peanut plants, and one disease assessment was made between 14 and 17 days after inoculation. Lesion growth in the greenhouse was found to correlate with disease response assessed under field conditions ( r = 89%). The phenotyping method developed in this study can facilitate the identification of NB resistance lines and assist in identifying regions of genetic resistance within the peanut host. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

The specific pre- and post-cold storage treatments needed to maintain the viability of urediniospores of rust fungi during storage are species dependent. Urediniospore collections are critical to assess pathogen evolution over time, but most importantly, to determine the efficacy of resistance genes in host plants. Puccinia sorghi, the causal agent of common rust of maize, can cause yield losses of up to 40% in susceptible varieties. The purpose of this study was to optimize the pre- and post-cold storage requirements of P. sorghi urediniospores. Here, we report that dried urediniospores had an 87% decrease in germination compared with undried spores. Urediniospores of P. sorghi were successfully stored at -80 degrees C for 24 months and remained infectious, and did not require cold shock in liquid nitrogen pre-cold storage, nor a heat shock to revive them from dormancy. Urediniospores removed from storage in a freezer at -80 degrees C germinated readily between 22 degrees C and 55 degrees C.

Metarhizium anisopliae infects and kills a large range of insects and is a promising biocontrol agent to manage soil insects, such as wireworm in sweetpotato. The presence of other soil microbes, which exhibit competitive fungistasis, may inhibit the establishment of M. anisopliae in soil. Microbially depleted soil, for example, sterilized soil, has been shown to improve the resporulation of the fungus from nutrient-fortified M. anisopliae. Prior to planting, sweetpotato plant beds can be disinfected with fumigants, such as Metham®, to control soil-borne pests and weeds. Metham® is a broad-spectrum soil microbial suppressant; however, its effect on Metarhizium spp. is unclear. In the research presented here, fungal resporulation was examined in Metham®-fumigated soil and the infectivity of the resulting granule sporulation was evaluated on mealworm, as a proxy for wireworm. The fungal granules grown on different soil treatments (fumigated, field and pasteurized soil) resporulated profusely (for example, 4.14 × 107 (±2.17 × 106) conidia per granule on fumigated soil), but the resporulation was not significantly different among the three soil treatments. However, the conidial germination of the resporulated granules on fumigated soil was >80%, which was significantly higher than those on pasteurized soil or field soil. The resporulated fungal granules were highly infective, causing 100% insect mortality 9 days after the inoculation, regardless of soil treatments. The results from this research show that the fungal granules applied to soils could be an infective inoculant in sweetpotato fields in conjunction with soil fumigation. Additional field studies are required to validate these results and to demonstrate integration with current farming practices.

Photosynthesis in wheat (Triticum aestivum L.) pericarps may contribute appreciably to wheat grain yield. Consequently, we investigated the temporal variation of traits related to photosynthesis and sucrose metabolism in the pericarps and flag leaves of three wheat genotypes, Huandoy, Amurskaja 75 and Greece 25, which are reported to differ in expression of genes related to the C4 pathway in wheat grain. Significant site-specific, genotypic and temporal variation in the maximum carboxylation rate (Vc max ) and maximum rates of electron transport (J max ) (biological capacity of carbon assimilation) were observed early in ontogeny that dissipated by late grain filling. Although the transcript abundance of rbcS and rbcL in flag leaves was significantly higher than in the pericarps, in line with their photosynthetic prominence, both organ types displayed similar expression patterns among growth stages. The higher N concentrations in the pericarps during grain enlargement suggest increased Rubisco; however, expression of rbcS and rbcL indicated the contrary. From heading to 14days post-anthesis, wheat pericarps exhibited a strong, positive correlation between biological capacity for carbon assimilation and expression of key genes related to sucrose metabolism (SPS1 , SUS1 and SPP1 ). The strong correlation between spike dry weight and the biological capacity for carbon assimilation along with other findings of this study suggest that metabolic processes in wheat spikes may play a major role in grain filling, total yield and quality.

Powderymildews are among the most important plant pathogensworldwide, which are often attacked in the field bymycoparasitic fungi belonging to the genusAmpelomyces. The taxonomy of the genusAmpelomyces is unresolved, butwell-supportedmolecular operational taxonomic units were repeatedly defined suggesting that the genus may include at least four to seven species. Some Ampelomyces strains were commercialized as biocontrol agents of crop pathogenic powdery mildews. However, the genomic mechanisms underlying theirmycoparasitismare still poorly understood. To date, the draft genome of a single Ampelomyces strain, designated asHMLAC05119, has been released. We report a high-quality, annotated hybrid draftgenome assemblyofA. quisqualis strain BRIP 72107, which, based on phylogenetic analyses, is not conspecific with HMLAC 05119. The constructed genome is 40.38Mb in size, consisting of 24 scaffolds with an N50 of 2.99Mb and 96.2% completeness. Our analyses revealed "bipartite" structure ofAmpelomyces genomes, whereGC-balanced genomic regions are interspersed by longer or shorter stretches ofAT-rich regions. This is also a hallmark of many plant pathogenic fungi and provides further evidence for evolutionary affinity of Ampelomyces species to plant pathogenic fungi. The high-quality genome and annotation produced here provide an important resource for future genomic studies of mycoparasitisim to decipher molecular mechanisms underlying biocontrol processes and natural tritrophic interactions.

Fertilisers are essential in modern agriculture to enhance plant growth, crop production and product quality. Recent research has focused on the development of delivery systems designed to prolong fertiliser release. This study introduces a new technology to encapsulate and release molecules of fertilisers by using multi-layered electrospun nanofibre as a carrier. Single-layer poly L-lactic acid (PLLA) nanofibres loaded with urea were fabricated using electrospinning. Triple-layer nanofibrous structures were produced by electrospinning polyhydroxybutyrate (PHB) nanofibres as external layers with PLLA nanofibres impregnated with urea fertiliser as the middle layer. Scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometry (FTIR) were employed to characterize the morphology of electrospun nanofibres. Urea release dynamic was analysed using a total nitrogen instrument (TNM-1). The results indicated that triple-layered urea-impregnated nanofibrous structures led to lower initial rate of nitrogen release and slower release rate of cumulative nitrogen which extended for more than three months. It is concluded that triple-layer nanofibrous structures have the potential for slow release delivery of fertilisers.

This study investigated the interactions between insecticides (acephate and indoxacarb) and fungal entomopathogens ( Beauveria bassiana [Bals.‐Criv.] Vuill. strain B27, Metarhizium anisopliae [Metschn.] Sorokin strain ECS1, and a commercial B. bassiana product, Velifer ® Biological Insecticide) for controlling the macadamia seed weevil, Kuschelorhynchus macadamiae Jennings and Oberprieler, in the laboratory and glasshouse. In the laboratory, additive interactions between insecticides at their full field concentrations (776 mg AI/L of acephate and 75 mg AI/L of indoxacarb) and fungal entomopathogens at 10 7 conidia/ml (ECS1 and B27) or at full field concentration (0.5 ml of Velifer ® /L) were seen at 6 days and 12 days post‐application. Under the same experimental conditions, synergistic interactions against K. macadamiae were observed 6 days post‐application when fungal entomopathogens at 2.5 × 10 6 conidia/ml or at 25% of full field concentration (Velifer ® ) were co‐applied with insecticides at 25% of their full field concentrations, whilst additive interactions were again observed at 12 days post‐application. In the glasshouse, additive interactions between insecticides (at full field concentrations) and fungal entomopathogens (at 10 7 conidia/ml, or at full field concentration for Velifer ® ) were obtained at 6 days and 12 days post‐application. The results from this study suggest that acephate and indoxacarb have both synergistic and additive effects against K. macadamiae when deployed together with fungal entomopathogens, depending on the initial concentrations of mixture components. Combined application of entomopathogens with compatible insecticides promises to provide more effective management of K. macadamiae than individual chemical applications.

Kuschelorhynchus macadamiae is a major pest of macadamias in Australia, causing yield losses of up to 15%. Our previous studies have shown the weevil is susceptible to Beauveria bassiana and Metarhizium anisopliae . The aim of this study was to investigate horizontal transmission of both fungal species to healthy weevils from both infected adults and weevil cadavers. In a confined environment the mortality of healthy adults caused by the transmission of conidia from live fungus-infected adults was < 50%. Under similar experimental conditions, the mortality of healthy adults reached 100% when exposed to conidiated cadavers. However, when conidiated cadavers were used in more spacious environments (insect cages), the mortality of adults was < 80%. Using scanning electron microscopy, it was observed that all healthy adults had conidia attached to all external parts of the body. This suggests that although the conidia were readily transferred to the adults, the lower mortality in the larger insect cages could be the result of an unfavourable environmental factor such as low humidity. The presence of conidia attached to all the adults indicated that they did not show any discriminatory behaviour such as avoidance of conidiated cadavers infected by these two fungal species. The results from this study show that there is potential for enhanced control of adult K. macadamiae via transmission from either fungus-infected adults or conidiated cadavers and this could strengthen sustainable pest management in macadamias.

The causal agent of maize common rust (CR), Puccinia sorghi, has increased in incidence and severity in Australia in recent years, prompting the assessment of sources of resistance and a preliminary survey of the diversity of P. sorghi populations. The maize commercial hybrids tested carried no resistance to 14 isolates of P. sorghi and had infection types comparable with that of a susceptible check. The resistance gene Rp1_D that remained effective in the United States for 35 years was ineffective against 7 of the 14 isolates. Maize lines carrying known "resistance to Puccinia" (Rp) genes were inoculated with the five isolates considered most diverse based on year of collection (2018 or 2019), location (Queensland or Victoria), and host from which they were isolated (maize or sweet corn). Lines carrying the resistance genes RpG, Rp5, Rp1_E, Rp1_I, Rp1_L, RpGDJ, RpGJF, and Rp5GCJ were resistant to all five isolates and to isolates collected in many agroecological regions. These lines were recommended as donors of effective resistance for maize breeding programs in Australia. Lines carrying no known resistance or resistance genes Rp8_A, Rp8_B, Rp1_J, Rp1_M, Rp7, and Rpp9 (conferring resistance to P. polysora) were susceptible to all five isolates. Differential lines carrying resistance genes Rp1_B, Rp1_C, Rp1_D, Rp1_F, Rp1_K, Rp3_D, or Rp4_A were either resistant or susceptible depending upon the isolate used, showing that the isolates varied in virulence for these genes. Urediniospore production was reduced on adult compared with juvenile plants, presumably due to changes in plant physiology associated with age or the presence of adult plant resistance.

Wireworms have the potential to cause significant damage to sweetpotato, particularly late in the season. [...]

Urea is the most common form of nitrogenous fertiliser. Recently, research has focused on the development of delivery systems to prolong fertiliser release and prevent fertiliser loss through leaching and volatilization. This study investigates and compares single- and double-layered hollow nanofibrous yarns as novel delivery systems to encapsulate and release urea. Single-layered hollow poly l-lactic acid (PLLA) nanofibre yarns loaded with urea fertiliser were fabricated using a customized electrospinning. Double-layered hollow nanofibre yarns were produced by electrospinning polyhydroxybutyrate (PHB) nanofibres as an outer layer, with urea-impregnated PLLA nanofibres as the inner layer. Scanning electron microscopy (SEM) with an energy-dispersive spectroscopy (EDS) was used to characterize the morphology of hollow electrospun nanofibre yarns. A total nitrogen instrument (TNM-1) was used to study the urea release from single- and double-layered hollow nanofibres yarn in water. A Carbon:Nitrogen (CN) elemental analyser determined encapsulated nitrogen in PLLA nanofibres samples. Results indicated that urea-impregnated double-layered hollow nanofibre yarns significantly started nitrogen releasing at much lower amount during first 12 h compared to single-layered hollow nanofibre yarns (P value=0.000). In conclusion, double-layered hollow nanofibre yarn has potential as an effective alternative to current methods for the slow release of fertilisers and other plant-required chemicals.

BACKGROUND:Integrating fungal biocontrol agents into crop protection programs dominated by synthetic pesticides is an important first step towards developing an integrated pest management (IPM) program; however, their successful integration relies on an understanding of how their performance may be impacted by the remaining agrochemicals deployed for managing other pests and diseases. In this study we tested 10 formulated pesticides used in macadamia production at different concentrations to determine their effects on the germination, mycelial growth and sporulation of Metarhizium anisopliae and Beauveria bassiana in vitro. Further tests with laboratory-grade actives of the noncompatible pesticides were conducted to determine whether any antagonistic effects were caused by the active constituent or by formulation additives.RESULTS:At their registered concentrations, formulated trichlorfon, acephate and indoxacarb were compatible with M. anisopliae, whereas B. bassiana showed compatibility with formulated trichlorfon, acephate, indoxacarb, sulfoxaflor and spinetoram. Bioassays using laboratory-grade active constituents indicated that the adverse impact of formulated beta-cyfluthrin on both fungal species and that of formulated methidathion on B. bassiana is probably due to components of the emulsifiable concentrate formulations rather than their active constituents. Diazinon was the only insecticidal active that showed high toxicity to both fungal species. The two fungicides, carbendazim and pyraclostrobin, were toxic to both fungal species at all tested concentrations.CONCLUSION:Our results identify which pesticides used on macadamias in Australia are compatible and incompatible with entomopathogenic fungi. Future studies on pesticide degradation rates will help define the spray intervals required to eliminate these adverse effects.

Weevils are significant pests of horticultural crops and are largely managed with insecticides. In response to concerns about negative impacts of synthetic insecticides on humans and the environment, entomopathogenic fungi (EPF) have been developed as an alternative method of control, and as such appear to be "ready-made" components of integrated pest management (IPM) programs. As the success of pest control requires a thorough knowledge of the biology of the pests, this review summarises our current knowledge of weevil biology on nut trees, fruit crops, plant storage roots, and palm trees. In addition, three groups of life cycles are defined based on weevil developmental habitats, and together with information from studies of EPF activity on these groups, we discuss the tactics for integrating EPF into IPM programs. Finally, we highlight the gaps in the research required to optimise the performance of EPF and provide recommendations for the improvement of EPF efficacy for the management of key weevils of horticultural crops.