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The potential and real negative and positive effects of invasive alien species (IAS) are increasingly recognised by researchers, land managers and decision-makers. However, most of the research and knowledge stems from understandings developed from rural and natural landscapes, with relatively little derived from studies in urban settings. Small towns in particular pose a novel suite of conditions that make the study and mangment of IAS particularly pressing. Here we examined the distribution of seven woody IAS (Acacia mearnsii, Cestrum laevigatum, Eucalyptus spp., Lantana camara, Melia azedarach, Senna didymobotrya and Solanaum mauritianum) within and between five small towns in the Eastern Cape via means of drive-by road surveys of every street in each town. Across the five towns and seven IAS 4,307 individuals were recorded, with the highest densities found in the two more coastal towns. Almost two-thirds (63%) of the IAS were located in residential properties, 24 % in public spaces and 13 % on road verges, closely mirroring the proportional area of these landuses. Within the residential landuse zone specifically, the townships had between 41 % and 61 % of all the recorded IAS plants per town, followed by the affluent neighbourhoods (22 – 41 %) and lastly, the RDP neighbourhoods (6 – 32 %). Cestrum laevigatum was the most abundant woody IAS across the five towns as a whole (1,783 inviduals). The second-most abundant species was M. azedarach (914 stems) and the least recorded was S. mauritianum (44). Additionally, there were differences in the general distribution of the seven species across residential neighbourhoods, with C. laevigatum (71.2 %), M. azedarach (49.3 %) and S. mauritianum (60.0 %) concentrated in township neighbourhoods, whilst A. mearnsii (66.4 %), L. camara (64.1 %) and Eucalyptus spp. (48.6 %) were most common in the affluent neighbourhoods. This study confirms that woody IAS are widespread in small towns of the region, but that they are unevenly distributed between towns and landuses within towns, indicating the need for local-scale inventories and management.

Acacia cyclops, Acacia saligna and Acacia mearnsii are characterized as prolific invasive alien plants (IAPs) presenting a substantial ecological and economic burden on South Africa. While conventionally these species are perceived as weeds having little value, this study attempts to demonstrate their respective potential as a phytomedicinal resource in the treatment of type 2 diabetes – thereby incentivizing their eradication. Moreover, this study aimed to assess the antidiabetic and cytotoxic effects of extracts from these three invasive Australian acacias in vitro. The α-glucosidase and ɑ-amylase activities of ethanolic and aqueous extracts derived from aerial tissues of A. cyclops, A. saligna, and A. mearnsii were investigated, followed by a cytotoxicity assessment using Hoechst 33342-Propidium Iodide (PI) dual staining and quantitative fluorescence microscopy on the human colon (Caco-2) cell line. Of the extracts screened, A. saligna ethanolic bark demonstrated the highest inhibitory activity against α-amylase and α-glucosidase with an IC50 of 10.45 ± 3.79 μg/ml and 2.35 ± 0.61 μg/ml followed by leaf extract depicting strong α-glucosidase (IC50 of 3.64 ± 1.59 μg/ml) and moderate α-amylase (IC50 of 17.67 ± 3.84 μg/ml) inhibition. The IC50 values of all extracts were significantly (p ± 28.36 μg/ml) and Epigallocatechin gallate (IC50 of 68.2 ± 8.34 μg/ml). All extracts were found to be nontoxic at test concentrations on Caco-2 cells as confirmed by Hoescht 33342-PI dual staining. Overall, the findings presented in this study provide the first concurrent account of three invasive Acacias in South Africa reporting on their potential as an alternative therapeutic option for the treatment of type 2 diabetes.

The stock of biomass and nutrients has been the basis of many studies in the forest area, mainly those that evaluate the nutritional sustainability of the system. The objective of the present work was to evaluate the biomass and nutrients for the hybrid Eucalyptus urograndis and Acacia mearnsii in monospecific and mixed-species stands at the age of 9 years. For this, the study was carried out in an experimental area in South of Brazil, with three treatments: 100% E. urograndis; 100% A. mearnsii; 50% E. urograndis + 50% A. mearnsii. The hybrid E. urograndis showed lower stemwood in mixed-species planting (105.8 Mg ha−1) when compared to monospecific planting (145.5 Mg ha−1), however A. mearnsii, which increased stemwood at planting (213.9 Mg ha−1) relating to its pure planting (143.6 Mg ha−1). The nitrogen concentration in the leaves and stembark (25 and 5 g kg−1, respectively) of A. mearnsii was significantly higher than that found in the respective hybrid E. urograndis components (18 and 3 g kg−1 for leaves and stembark, respectively). A. mearnsii had higher accumulation of biomass and nutrient accumulation in the mixed-species plantation when compared to its monoculture, and the inverse was observed for the hybrid E. urograndis, thus showing that mixed-species planting exerted a competition effect on eucalyptus.

Uromycladium acaciae has damaged plantations of Acacia mearnsii in southern Africa since 2013. Uredinia of a species of Uromycladium have been known on A. mearnsii in South Africa since the 1980s. However, the recent damage is associated with telia and spermogonia. Uredinia and telia were previously treated as conspecific with a phylogenetic species concept. However, uredinia did not form after previous artificial inoculation experiments with teliospores. Controlled studies identified the optimum conditions for basidiospore infection, but the optimum conditions for sporulation and dispersal have not been identified. To investigate the life cycle and field epidemiology of Uromycladium on A. mearnsii, spores were trapped weekly and development of disease symptoms and plant phenology were monitored monthly at three plantations. Telia and spermogonia developed independently from uredinia, and nucleotide polymorphisms between rDNA of uredinia and telia were fixed based on high throughput sequencing and PCRs. All three weather variables measured had a significant effect on teliospore abundance at two of the three sites. Teliospore abundance was greatest during trapping periods when mean relative humidity was high, mean rainfall was 4–5 mm day-1, and mean temperature was 15–16°C. Teliospore counts peaked at the end of summer, potentially the result of epidemic build-up. Results support the hypothesis that despite sharing a most recent common ancestor, uredinia on A. mearnsii in southern Africa are independent to the life cycle of the telial rust, which likely constitutes a new introduction. Furthermore, teliospores of U. acaciae disperse under wet conditions; and, the wet season between October and March is the optimal period for wattle rust development. This article is protected by copyright. All rights reserved.

This study aimed at obtaining an extract enriched in phenolic compounds from the aerial parts of black wattle waste (Acacia mearnsii De Wild), characterization of its composition, and investigation of its antioxidant potential and preclinical toxicological profile. First, a phenolic compound enriched extract (PCEE) was obtained by sequential fractionation. Thereafter, the main classes of secondary metabolites present in PCEE were identified and quantified. The antioxidant, cytotoxic, and cytogenotoxic activities were evaluated using in vitro assays. Toxicological effects on locomotor function were assessed using in vivo open field and plus maze models. Cinnamic acid and coumarin were isolated from the PCEE and identified. In addition, high contents of phenolic compounds and flavonoids, responsible for the promising antioxidant activity, were quantified. The extract should a dose-dependent in vitro cytotoxicity in HaCaT cells. In the cytogenotoxicity bioassay, no differences in the mitotic index and micronuclei frequency were observed between PCEE and negative control groups. Also, there were no significant effects of the extract on the motor function. Taken together, these results show that the aerial parts of A. mearnsii can be used for obtaining bioactive compounds with the potential for promoting human and animal health.

The prevailing approach of total clearing to contain the spread of invasive plants (IP) in South Africa is generating enormous lignocellulosic wastes. This study examined the possibility of utilizing these wastes in the production of geopolymer composites for use in outdoor environments. Untreated wood particles from Acacia mearnsii and A. longifolia, as well as sugarcane bagasse residues, were incorporated into a geopolymer matrix developed from a binary precursor system of 75% fly ash and 25% metakaolin. The variables considered included precursor-activator ratio (PA), curing pattern (CP), lignocellulosic material (LM), and alkali concentration (Mcon). The production process was established using a mixed factorial experimental design. PA and CP were considered at 2 levels, while LM and MCon were considered at 3 levels. The density of the boards exceeded 1 g cm−3 and are classified as high-density boards. The boards have comparable sorption properties to the cement-bonded particleboard according to the EN 632-2: 2007 standard. However, only A. longifolia boards produced with 12 M NaOH and PA ratio of 2:1 met the mechanical strength requirements. Thermogravimetric analysis revealed that the boards are thermally stable. These results have shown that South African woody IPs are suitable for geopolymer wood composites, but there is still concern about their durability in the alkaline matrix. Scanning electron microscopy micrographs indicated mineralization of the particles and a partial degradation of hemicellulose was confirmed by Fourier transform infrared spectroscopy. Although the degraded components did not prevent geopolymer setting, there is need to further investigate the extent and means of preventing degradation as this can derail the intended use of the product.

The use of herbal plants in recent years have increased tremendously owing to their user-friendliness, accessibility, and affordability. In this study, the plant species Combretum molle and Acacia mearnsii were phytochemical screened for the existence of active organic compounds, the content of total phenols, flavonoids and antioxidants using different solvents were investigated. The functional groups existing in the plants extracts were identified using FT-IR. The total phenol contents varied from 53.74 ± 5 – 97.29 ± 3 GAE mg/g and 53.74 ± 7 – 98.58 ± 2 GAE mg/g in the extraction powders for C. molle and A. mearnsii. In C. molle, the content of total flavonoids ranged from 76.90 ± 2 – 114.54 ± 0.18 QE mg/g, while 89.40 ± 3 – 105.45 ± 0.15 QE mg/g was found in A. mearnsii. The radical scavenging activities of the solvent extracts against DPPH and the controls revealed that acetone extract of C. molle displayed 99.64% DPPH inhibition, while A. mearnsii showed a maximum activity of 85.53% at 5 µg/ml. The antimicrobial activity of the two plant species was evaluated using diffusion disk and broth dilution methods. The activity by broth dilution of ethanol, methanol and acetone extracts of C. molle exhibited MIC values (39.06 and 78.13 mg/µL) against P. aeruginosa and E. coli strains respectively, while ethanol and chloroform extracts of A. mearnsii showed (39.06 and 78.13 mg/µL) against P. aeruginosa and E. faecalis respectively. Results from this study showed that the leave extracts constitute healthy supplements with antioxidant and antibacterial potentials that could be useful in traditional medicine for the treatment of numerous infectious ailments.

Invasive alien plants (IAPs) threaten biodiversity and critical ecosystem services worldwide. There is, therefore, an urgent need to develop intervention measures to control the spread of IAPs. Efforts to control and monitor the spread of IAPs would require their current and detailed distribution over a large geographic area. Recently launched multispectral instrument on-board Sentinel-2 provides free data with good spatiotemporal and spectral resolution, compared to Landsat datasets. The Sentinel-2 dataset, therefore, can be a useful source of the IAPs spatial information required for detection and monitoring purposes. We combined Sentinel-2 data with a radiative transfer model to discriminate IAPs (Acacia mearnsii and Acacia dealbata) from surrounding native tree species in Van Reenen, KwaZulu-Natal, South Africa. The forward mode of combined PROSPECT leaf optical properties model and SAIL canopy bidirectional reflectance model, also referred to as PROSAIL was used to simulate reflectance corresponding to bands of Sentinel-MSI, while the PROSAIL model inversion retrieved leaf area index (LAI) and canopy chlorophyll contents (CCC) of the IAPs and native species. Both reflectance and retrieved properties were used to map the distribution of the species within the study area. Our results showed that A. mearnsii and A. dealbata could be accurately discriminated from the surrounding native trees using integrated PROSAIL Sentinel-2 based model. We found that CCC– and LAI-based (% accuracy = 92.8%, 91.4% for CCC and LAI, respectively) modelling produced a higher classification accuracy than field sampling-based modelling (Accuracy = 90.2% (IAP), 82.2% (NAT) and kappa coefficient = 0.84 (IAP), 0.78 (NAT)). Simulated bands corresponding to Sentinel-2 data, on the other hand, produced species maps comparable to field sampling-based maps. Overall, the integrated PROSAIL Sentinel-2 inversion approach proved suitable for detecting and mapping IAPs over a large area. Due to the high spatiotemporal coverage of Sentinel-2, satellite images, the model developed showed the potential to contribute to the IAPs monitoring systems.

The aim of this study is to assess the curing behaviour and thermal properties of phenol–formaldehyde (PF) adhesives with different degree of tannin substitution using several thermal analysis techniques. Tannin from Acacia mearnsii bark was copolymerized with PF to form a bonding agent for plywood. The resin mixture was heated at 50 °C prior to adding 40% w/w tannin solution, followed by a continuous stirring for 2 h. The amounts of tannin substitution were 20%, 30% and 40% (w/w of PF solids) and 100% PF were used as control. The study shows that the addition of tannin quickened the gel time of the resin notably, parallel with the increase in viscosity of the resin. The dry shear bond strength of the tannin phenol–formaldehyde (TPF) co-polymer ranged between 1.71 and 2.58 MPa as compared to 3.41 MPa for PF. At higher addition of tannin, the shear bond strength reduced significantly predominantly the 40% tannin substitution. Formulation containing 20% tannin was found comparable to that of neat PF. Thermal test revealed that TPF starts to degrade at a lower temperature than PF resin. All TPF resins started to cure at about 125 °C and peaked at 160 °C compared to PF that began to cure at 145 °. The DMA of the resin showed an increase in the resin stiffness with an addition of tannin. These results imply that even though TPF starts to degrade at lower temperature, the cured TPF is relatively stronger than pure PF.

We developed a two-biome (grasslands and fynbos) system dynamics model simulating invasions of three invasive alien plant species – black wattle (Acacia mearnsii) and two pine species (Pinus patula...

Invasion by exotic woody species is a major concern in grasslands worldwide. Woody invasions pose a particularly serious threat to forest–grassland mosaics globally, but the factors influencing the success of woody species in these systems, including the role of disturbances such as fire, are not well understood. In this study, we evaluated the role of fire in influencing mortality and regeneration success of three globally widespread woody invasives, Acacia mearnsii (black wattle), Cytisus scoparius (scotch broom) and Ulex europaeus (gorse) in the montane forest–grassland mosaics of the Nilgiri Biosphere Reserve in the Western Ghats biodiversity hotspot, India. Our results indicate that mortality and regeneration responses to fire are species-specific. Fire-induced adult mortality was highest in scotch broom and lowest in gorse, and high, but variable in wattle. Burning greatly increased the abundance of gorse and wattle seedlings, but only marginally increased scotch broom seedling abundance. Fire effects on invasive seedling densities were most pronounced at the edges of invasive patches. Overall, our results indicate that fires are likely to differentially affect invasion patterns of these three species, with fire potentially encouraging invasion by gorse and wattle and discouraging invasion by scotch broom.

The aims of this investigation were to assess the genetic origin of two black wattle seed orchards at molecular levels and to determine genetic diversity within and among the A. mearnsii provenances planted in Southern Mpumalanga, South Africa using a reference population. The method used for sample collection, DNA extraction, PCR and genetic analysis followed the protocol developed in our laboratories for Acacia mearnsii. The overall mean alleles per locus was 8.8 among all A. mearnsii individuals; the highest number of allele was 14.0 for primer AH3-10 and the least was 3.0. for AH3-1 and AH16. The Potgieterskues provenance revealed the highest genetic diversity (He = 0.59), allelic richness (Ar = 5.78) and total number of private alleles (PA = 15), whereas Mittagong showed the lowest He = 0.50 and Ar = 4.42. An unweighted pair group method with Neighbour-joining cluster analysis and Bayesian STRUCTURE analysis, based on allele profiles of 11 microsatellite loci, separated the 281 individual trees into three distinct genetic clusters. The clustering of the samples did not strictly follow the geographic origin of individuals. Both the AMOVA and STRUCTURE analysis revealed the distinctiveness of the Potgieterskues stands with 36% of the trees related to Sheepmoor, Mittagong and Lake George provenances. The Sheepmoor, Mittagong and Lake George provenance largely grouped into the same genetic cluster with no significant genetic differentiation. The relatively larger number of unique allele from the Potgieterskues stand suggest that seed unknown to the ICFR was used to establish the orchard. Using assignment score > 95% as criteria, it was possible to trace the genetic origin of some of the trees in the Sheepmoor orchard. This work is the first of its kind for the South African wattle industry. It will provide the foundation for DNA-based molecular support to the breeding programmes.

Acacia mearnsii is a commercial forestry tree in South Africa, largely grown from open-pollinated seeds. Clonal deployment of superior selections of the species is restricted due to its poor rootin...

Understanding the drivers of biological invasions in landscapes is a major goal in invasion ecology. The control of biological invasions has increasingly become critical in the past few decades because invasive species are thought to be a major threat to endemism. In this study, by examining the key variables that influence Acacia mearnsii, we sought to understand its potential invasion in eastern Zimbabwe. We used the maximum entropy (MaxEnt) method against a set of environmental variables to predict the potential invasion front of A. mearnsii. Our study showed that the predictor variables, i.e., aspect, elevation, distance from streams, soil type and distance from the nearest A. mearnsii plantation adequately explained (training AUC = 0.96 and test AUC = 0.93) variability in the spatial distribution of invading A. mearnsii. The front of invasion by A. mearnsii seemed also to occur next to existing A. mearnsii plantations. Results from our study could be useful in identifying priority areas that could be targeted for controlling the spread of A. mearnsii in Zimbabwe and other areas under threat from A. mearnsii invasion. We recommend that the plantation owners pay for the control of A. mearnsii invasion about their plantations.

Insect predator densities and plant nutritional status can affect insect herbivore densities, but these effects have not yet been assessed in the context of an invasive species management. This study investigated the influence of (i) altered predatory arthropod abundance and community composition (top-down-effects); and (ii) altered leaf nitrogen and phosphorus levels (bottom-up-effects) as possible causes of fluctuations in herbivore abundance and herbivory on the native tree Brabejum stellatifolium in riparian sites that differ in invasion status (near pristine, heavily invaded by Acacia mearnsii, and restored). Species richness, abundance and composition of herbivorous and predatory arthropods were compared between categories. Herbivore and predator abundance, species richness and assemblage composition were significantly influenced by invasion status. As expected, herbivore abundance was significantly and positively correlated to levels of leaf damage. Leaf nitrogen levels were the highest at restored sites where herbivorous arthropods were also most abundant and the abundance of predators was intermediate. These results suggest that altered leaf nitrogen content is likely a key influence for the increased herbivore pressure on B. stellatifolium at sites under pressure from invasive A. mearnsii and its status. Bottom-up influences therefore may be more important than top-down effects on controlling herbivore abundances in these altered riparian environments.

A new Phytophthora species was found associated with gummosis in black wattle plantations in the subtropical, humid, south of Brazil. The new species Phytophthora acaciae is formally named herein based on phylogenetic and morphological analyses. This is the fourth Phytophthora species found from this pathogen complex in black wattle plantations causing gummosis in Brazil. The other three species are P. nicotianae, P. boehmeriae, and P. frigida. Phytophthora acaciae is heterothallic with amphigynous antheridia, noncaducous, papillate sporangia and is placed in the Phytophthora clade 2 based on nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) sequences. Maximum parsimony and maximum likelihood phylogenetic analyses of P. acaciae isolates based on multigene sequences, including partial DNA sequences of three nuclear protein-coding genes (β-tubulin, translation elongation factor-1α, and ras-related protein), two mitochondrial protein-coding genes (cytochrome c oxidase subunits I and II), in addition to ITS sequence data, support the delimitation of this new species on Acacia mearnsii from the other previously described clade 2 Phytophthora species. Pathogenicity trial confirmed that the new species causes necrotic lesions on the plant stem, with either the presence or absence of gum.

Abstract In the present study, the tannins from stem and root barks of Tessmannia burttii Harms (Caesalpiniaceae), a plant species abundantly growing in Tanzania and other parts of Africa, were investigated for their suitability in hides tanning. Tannin powder was extracted at selected temperatures (30, 50 and 80 °C) and the influence of each temperature on the crosslinking capacity was evaluated. The interaction mechanism between hide powder collagen and the tannins was studied by Differential Scanning Calorimetry (DSC), trinitrobenzensulfonic (TNBS) acid assay and amino acid hydrolysis methods. Extraction temperatures showed low influence on crosslinking capacity of the tannins. However, extract obtained at 50 °C exhibited best performance in terms of gap size between Tonset and Tpeak. The stem bark extract yield was higher than that from the root bark, but both were within the recommended ranges. The tannin content (61%) of T. burttii stem bark extract was above recommended value (10%), whereas its total phenolic content and total flavonoic content were found to be above that of commercial Acacia mearnsii tannin. The study of cross-linking parameters as a function of pH showed cross-linking to occur via a covalent mechanism at the basic amino groups. However, the bonds were not resistant to acid hydrolysis. The observed interaction mechanism indicated that tannins from stem and root barks of T. burttii belong to the condensed tannin, similar to A. mearnsii (black wattle), a commercial tannin source that was used in this study as a reference. Findings from this study depict that T. burttii extracts are auspicious eco-friendly alternative source of vegetable tannins to overcome the use of chromium salts in the leather industry. Graphical abstract

The analysis of variance is the statistical test most used for comparison of three or more means simultaneously. Its application requires, however, the compliance to some assumptions, with main emphasis on normality of the data and homoscedasticity of variances. When such requirements are not met, one of the alternatives is the data transformation to enable the continuity of the experimental evaluation. With the proposition of the Tukey’s data transformation system, understood as a power transformation system, i.e. the application of nth root on a data set (X⅟n) this statistical procedure has methodologically evolved to ensure such solutions. In the present research we proposed a complement to this system, denominated here as transformation in four steps, with inclusion of two hypothesis tests to evaluate normality and homoscedasticity. This was applied on experimental data to evaluate the amount of radiation available at soil level within stands of Acacia mearnsii De Wild. We have proposed a model for data transformation to simultaneously obtain homoscedasticity and normality. The methodology was appropriate to ensure these two statistical aspects on the experimental data, allowing comparison of eight treatments by conventional analysis of variance. Index terms: Analysis of variance, homoscedasticity, normality. A análise de variância é o teste estatístico mais utilizado para a comparação de três ou mais médias simultaneamente. Sua aplicação exige, no entanto, o cumprimento de algumas condicionantes, com ênfase principal na normalidade dos dados e homoscedasticidade das variâncias. Quando tais requisitos não são atendidos, uma das alternativas é a transformação de dados para permitir a continuidade da avaliação experimental. Com a proposição do sistema de transformação de dados de Tukey, entendido como um sistema de transformação de potência, ou seja, a aplicação de enésima raiz em um conjunto de dados (X⅟n), este procedimento estatístico evoluiu metodologicamente para garantir tais soluções. No presente trabalho foi proposto um complemento a esse sistema, denominado aqui de transformação em quatro passos, com a inclusão de dois testes de hipóteses para avaliar a normalidade e homoscedasticidade. Isto foi aplicado em dados experimentais para avaliar a quantidade de radiação disponível ao nível do solo dentro de povoamentos de Acacia mearnsii De Wild. Um modelo para transformação de dados foi proposto para obter simultaneamente homoscedasticidade e normalidade. A metodologia foi apropriada para garantir esses dois aspectos estatísticos nos dados experimentais, permitindo a comparação de oito tratamentos pela análise de variância convencional.

The acacia bark extract derived from Acacia mearnsii De Wild is rich in proanthocyanidins, whose constituent units are robinetinidol, fisetinidol, catechin, and gallocatechin. In this study, we examined the effect of proanthocyanidins on obesity and diabetes using KKAy mice, a type 2 diabetes model. KKAy mice were fed either a low-fat diet, a high-fat diet, or a high-fat diet mixed with an acacia bark extract, a proanthocyanidins fraction, and other fraction for 7 weeks. Monitoring the changes in the body weight revealed that acacia bark extract and proanthocyanidins fraction could prevent excessive weight gain resulting from a high-fat diet. In addition, increases in the fasting blood glucose level due to high-fat diet intake were found to be suppressed by acacia bark extract and proanthocyanidins fraction. Furthermore, proanthocyanidins derived from acacia bark were found to increase the expression of adiponectin in white adipose tissue, which enhances the action of insulin. In addition, acacia bark-derived proanthocyanidins suppressed gluconeogenesis and fatty acid synthesis in the liver, as well as suppressing the decrease in energy production under pathological conditions in skeletal muscle. In addition, acacia bark-derived proanthocyanidins showed AMPK activation and DPP-4 inhibitory action. Therefore, it was suggested that acacia bark-derived proanthocyanidins lowered fasting blood glucose levels through the above mechanism. These results suggest that proanthocyanidins derived from acacia bark are the active ingredients of the anti-obesity and anti-diabetic effects of acacia bark extract.

Made available in DSpace on 2021-06-25T12:36:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-02-07 Clarification of sugarcane juice is one of the most important steps in the sugar manufacturing process, considering that an efficient clarification may result in highly beneficial effects on the quality and yield of the final product, crystal or refined sugar. Currently, depending on the industrial plant and intended product, the use of calcium hydroxide, phosphoric acid and sulfur dioxide as auxiliary agents for clarification has been consolidated, the latter being questioned for causing adverse health reactions. In this context, the present study evaluated the performance of the natural black Acacia (Acacia mearnsii) tannin extract as an alternative for the sugarcane juice clarification. The results showed that tannin dosages between 300 and 500 ppm along with liming applied at pH 7.3 and 3 ppm of anionic flocculant provided the best performance, resulting in 32-34% of color removal and 89-93% of turbidity removal. Under these conditions, starch and dextran removal increased, 90 and 98%, as compared to 69% and 96%, obtained with conventional treatment. The performance of the tannin also reduced the calcium hardness of clarified juice by up to 18% compared to the conventional treatment, which in turn may prevent fouling in the subsequent steps. Sao Paulo State Univ, Dept Food Engn & Technol, Sao Jose Do Rio Preto, SP, Brazil Sao Paulo State Univ, Dept Food Engn & Technol, Sao Jose Do Rio Preto, SP, Brazil

Invasive alien species (IAS) threaten tropical grasslands and native biodiversity and impact ecosystem service delivery, ecosystem function, and associated human livelihoods. Tropical grasslands have been dramatically and disproportionately lost to invasion by trees. The invasion continues to move rapidly into the remaining fragmented grasslands impacting various native grassland-dependent species and water streamflow in tropical montane habitats. The Shola Sky Islands of the Western Ghats host a mosaic of native grasslands and forests; of which the grasslands have been lost to exotic tree invasion (Acacias, Eucalyptus and Pines) since the 1950s. The invasion intensities, however, differ between these species wherein Acacia mearnsii and Pinus patula are highly invasive in contrast to Eucalyptus globulus. These disparities necessitate distinguishing these species for effective grassland restoration. Further, these invasive alien trees are highly intermixed with native species, thus requiring high discrimination abilities to native species apart from the non-native species.Here we assess the accuracy of various satellite and airborne remote sensing sensors and machine learning classification algorithms to identify the spatial extent of native habitats and invasive trees. Specifically, we test Sentinel-1 SAR and Sentinel-2 multispectral data and assess high spatial and spectral resolution AVIRIS-NG imagery identifying invasive species across this landscape. Sensor combinations thus include hyperspectral, multispectral and radar data and present tradeoffs in associated costs and ease of procurement. Classification methods tested include Support Vector Machine (SVM), Classification and Regression Trees (CART) and Random Forest (RF) algorithms implemented on the Google Earth Engine platform. Results indicate that AVIRIS-NG data in combination with SVM recover the highest classification skill (Overall −98%, Kappa-0.98); while CART and RF yielded < 90% accuracy. Fused Sentinel-1 and Sentinel-2 produce 91% accuracy, while Sentinel-2 alone yielded 91% accuracy with RF and SVM classification; but only with higher coverage of ground control points. AVIRIS-NG imagery was able to accurately (97%) demarcate the Acacia invasion front while Sentinel-1 and Sentinel-2 data failed. Our results suggest that Sentinel-2 images could be useful for detecting the native and non-native forests with more ground truth points, but hyperspectral data (AVIRIS-NG) permits distinguishing, native and non-native tree species and recent invasions with high precision using limited ground truth points. We suspect that large areas will have to be mapped and assessed in the coming years by conservation managers, NGOs to plan restoration, or to assess the success of restoration activities, and several data procurement and analysis steps may have to be simplified.

Acacia mearnsii gum is not commercially exploited, being characterized as residue from A. mearnsii cultivation. This work investigated the A. mearnsii gum polysaccharide composition, its cytotoxicity and the technological effect as a stabilizer in ice cream. A. mearnsii gum showed a similar chemical structure to commercial gum Arabic and did not decrease the viability and proliferation of fibroblast cells (Balb/3T3) and hepatocarcinoma (HepG2). Rheological tests showed that the ice cream stabilized by the A. mearnsii gum had a more structured system (more interactions between the mixture components) and the same melting characteristics as the ice cream samples made with commercial gum Arabic. The results showed that A. mearnsii gum, which is actually an agro-industrial residue from tannin production for industry, is a potential stabilizing gum for the food industry, contributing to the economic development of the exploitation chain of A. mearnsii products and by-products.

In South Africa the invasion of riparian forests by alien trees has the potential to affect the country's limited water resources. Tree water-use measurements have therefore become an important component of recent hydrological studies. It is difficult for South African government initiatives, such as the Working for Water (WfW) alien clearing programme, to justify alien tree removal and implement rehabilitation unless hydrological benefits are known. The objective of this study was to investigate the water use (transpiration rates) of a selection of introduced and indigenous tree species and quantify the hydrological benefit that could be achieved through a suitable rehabilitation programme. Consequently water use within a riparian forest in the upper Mgeni catchment of KwaZulu-Natal in South Africa was monitored over a 2-year period. The site consisted of an indigenous stand of eastern mistbelt forest that had been invaded by Acacia mearnsii, Eucalyptus nitens and Solanum mauritianum. The heat ratio method of the heat pulse velocity (HPV) sap flow technique and the stem steady state (SSS) techniques were used to measure the sap flow of a selection of indigenous and introduced species. The indigenous trees at New Forest, South Africa, showed clear seasonal trends in the daily sap flow rates varying from 8 to 25 L day−1 in summer (sap flow being directly proportional to tree size). In the winter periods this was reduced to between 3 and 6 L day−1 when limited energy flux was available to drive the transpiration process. The water use in the A. mearnsii and E. grandis trees showed a slight seasonal trend, with a high flow during the winter months in contrast to the indigenous species. The water use in the understorey indicated that multi-stemmed species used up to 12 L day−1. Small alien trees (A. mearnsii and S. mauritianum used up to 4 L day−1 each. The total accumulated sap flow per year for the three individual A. mearnsii and E. grandis trees was 6548 and 7405 L a−1 respectively. In contrast, the indigenous species averaged 2934 L a−1, clearly demonstrating the higher water use of the introduced species. After spatial upscaling, it was concluded that, at the current state of invasion (21 % of the stand being alien species), the stand used 40 % more water per unit area than if the stand were in a pristine state. If the stand were to be heavily invaded at the same stem density of the indigenous forest, a 100 % increase in water use would occur over an average rainfall year.

International audience; Key messageAcacia longifoliaandAcacia mearnsiiexhibit different reproductive behavior (viability, germination, and dormancy) in relation to fire and seed maturation. The potential of invasion ofA. longifoliais stronger than that ofA. mearnsii.A. longifoliagerminates abundantly between fires and after fires, whileA. mearnsiionly germinates after fire and needs higher thermal thresholds to break dormancy.ContextFire affects environments through the modification of biological processes such as seed viability, dormancy, and germination. Seed maturation stage can modulate seed response to fire. Invasive alien species could be enhanced by forest fires.AimsTo analyze the viability, germination, and dormancy of two invasive alien species (Acacia longifolia and Acacia mearnsii) in relation to fire and seed maturation.MethodsViability of seeds was obtained performing a tetrazolium test. Additionally, we obtained germination and dormancy in mature and fresh seeds simulating fire conditions through different levels of fire factors (smoke, ash, charcoal, and heat).ResultsControl viability of seeds was 100% in the two Acacia species and maturation stages and severe heat reduced it to zero. Germination of A. longifolia varied depending on the maturation stage, being higher in fresh seeds. In A. mearnsii, germination did not change with maturation. In both species, heat stimulated germination by breaking seed dormancy. Seed maturation stage and fire factors affect the germination speed of each species differently.ConclusionFire reduces viability, stimulates germination, and breaks dormancy of the two species. Seed maturity exerts notable effects on A. longifolia reproductive behavior.

Rooting media were evaluated to identify problems contributing to poor rooting. Seven media combinations of coir and perlite were investigated, including two sources of coir (‘CG’ and ‘GS’). Final ...

There is little experimental evidence to guide the design of substrate compaction for the optimal plant water use performance of a landfill phytocap. A glasshouse study was undertaken to address this with aim to evaluate the effect of substrate compaction on the water use of a phytocap plant community. Four levels of relative compaction (RC), i.e. the ratio of dry bulk density over the standard maximum dry bulk density, (72%, 77%, 82%, and 87%) were considered. The native tree and grass species selected were typical of an Australian phytocap plant community: Themeda triandra, Microlaena stipoides, Eucalyptus camaldulensis, Eucalyptus cladocalyx, Acacia mearnsii and Allocasuarina verticillata. Plant water use was measured by weight as the difference between planted and unplanted cores over 5 drying periods occurring through the first 6 months of plant establishment traversing winter, spring and summer. Plant water use was optimal for all species at low-intermediate RC (72%, 77% and 82%), and all species except Themeda triandra, were most negatively impacted by the highest RC of 87%. The best linear model based on Akaike’s Information Criterion included a second-order term for the continuous fixed factor ‘RC’ and the categorical fixed factor ‘species’. This model showed plant water use to be optimum at a RC of 76.5% and highlighted a wide range of RC’s (70–83%), for which plant water use is not 86% and a RC

Xylem cavitation resulting in air embolism is a major cause of plant death during drought, yet the spread of embolism throughout the plant water transport system is poorly understood. Our study used optical visualization and x-ray microcomputed tomography imaging to capture the spread of emboli in stems of three drought-resistant angiosperm trees: drooping she-oak (Allocasuarina verticillata), black wattle (Acacia mearnsii), and blue gum (Eucalyptus globulus). These species have similar degrees of xylem network connectivity (vessel grouping) with largely solitary vessels. The high temporal resolution of the optical vulnerability technique revealed that in current year branches, >80% of the cavitation events were discrete, temporally separated events in single vessels. This suggests that in xylem networks with low connectivity, embolism spread between conduits leading to multiple conduit cavitation events is uncommon. A. mearnsii showed both the highest number of multivessel cavitation events and the highest degree of vessel connectivity, suggesting a link between vessel arrangement and embolism spread. Knowledge of embolism spread will help us to uncover the links between xylem anatomy, arrangement, and the path of water flow in the xylem in diverse species to ultimately understand the drivers of cavitation and plant vulnerability to drought.

To investigate the ultrastructural changes, X-ray microanalysis and leakages of protein and lipids from bacteria treated with the ethanolic extract of Acacia mearnsii. The ultrastructural changes were investigated using scanning electron microscope (SEM). The X-ray microanalyses were determined using electron dispersive spectroscopy (EDS) while the protein and lipid leakages were determined spectrophotometrically. The scanning electron microscopy indicated varied ultrastructural changes in the morphology of bacterial cells treated with the ethanol extract. The X-ray microanalysis showed significant differences between the elemental contents of extract-treated and broth-cultured and untreated bacteria strains. Lipids and proteins were leaked to a greater extent from the extract-treated bacterial strains in comparison with the broth-cultured and untreated ones used as controls. The possible antibacterial effects of the ethanol extract of A. mearnsii could be inhibition of a significant step in peptidoglycan assembly, inhibition of metabolic processes as well as the cell wall and cell membrane disruptions resulting in the efflux of lipid and protein in all the bacteria tested. This is a report identifying elemental components and associating their disintegrations in bacterial isolates with the antibacterial activities of medicinal plants. While ethanol extract of A. mearnsii caused ultrastructural changes, breakdown of elemental components into different elements and leaked lipid and protein from treated bacteria, the physiological damages to the cell wall further justify the bactericidal ability of the extract.

The world is experiencing serious threats from invasive alien plants that impact on ecosystem services provision. Although a lot of investment has been made in trying to come up with ways to control the spread of alien species, the majority of these ways have not been successful. Understanding the response of different tree size categories to mechanical control such as ‘cut and ring barking’ may bring long lasting solutions to the field of invasion biology. In order to understand the effect of cutting height and size (basal diameter) on control of Acacia mearnsii, we sampled plots in which all trees were cleared in the past 12, 9, 6 and 3 years. We recorded the number of stumps that coppiced and that were killed by ‘cut and ring barking’ method. We also recorded the number of coppices that were produced on each stump. Cutting height and diameter of the tree had an effect on survival. Trees with larger diameters and cut at the greatest height had lower chances of survival. Our findings confirm at least 50% success for small diameter size classes and 100% for diameters >16 cm. We conclude that mechanical control using ‘cut and ring barking’ should be used in the control of A. mearnsii, but complemented with fire, biological and chemical control in order to suppress recruitment from the seed bank.

Invasive alien plants (IAPs) pose a threat to ecosystem integrity and generally provide more disservices than services. Acacia mearnsii (black wattle) was introduced to South Africa for its...

Uromycladium acaciae is the cause of a severe wattle rust epidemic in plantations of Acacia mearnsii (black wattle) in southern Africa. Research on the biology of this damaging rust is assisting in the development of control strategies. One strategy under investigation is the identification and deployment of resistant lines of A. mearnsii. Selection of resistant families currently relies on large-scale, time-consuming and expensive field trials. In this study, we present a detailed artificial inoculation protocol for U. acaciae, which can be used to screen for resistance. The results of an experiment that used the protocol to screen the relative resistance of 12 families of A. mearnsii to U. acaciae are also presented. The developed artificial inoculation protocol can also be used to investigate several other aspects of this host–pathogen system.

Tannin extracts from the bark of Acacia mearnsii and wood of Schinopsis balansae, commonly known as Quebracho, were employed. These were modified at laboratory sale via the Mannich aminomethylation with formaldehyde and dimethylamine hydrochloride. Some reaction conditions were varied, namely the formaldehyde dosage and reaction time, while keeping the Mannich solution activation time constant, and their influence on the shear viscosity of the created bio-coagulants was evaluated. The effect of the final pH of the products on their shear viscosity was also analyzed. Up-scaling of the Mannich reaction for tannin from South Africa was performed and the procedure developed at 1-L scale was reproducible in upscaled conditions. One example of a modified South Africa tannin and the modified Quebracho tannin was subsequently selected for the treatment of an industrial wastewater and tested for color and turbidity reduction in jar tests. The effluent treatment was carried out in a single and dual system with cationic synthetic flocculation agents of different charge degree. Good turbidity and decoloration results (93 and 89% reduction, respectively) were obtained with the simultaneous introduction of a cationic, 40% charged polyacrylamide, with minimal dosage (5 ppm) of the latter additive. The tannin-based coagulant from Acacia mearnsii was successfully applied in dual system with cationic polyacrylamide flocculant for industrial wastewater treatment at pilot plant scale. It was shown to satisfactorily treat the water and generate less sludge.

A new, low cost and alternative adsorbent was prepared from black acacia bark wastes by acetosolv treatment, which consists in the use of organic solvents and inorganic acids. Both materials, black acacia bark (BAB) and acetosolv treated black acacia bark (BAB–AT) were characterized in detail and used to remove crystal violet dye (CV) from aqueous media. Adsorption parameters like pH, adsorbent dosage, kinetic, equilibrium, thermodynamics and ionic strength were evaluated to determine the efficacy and, the best conditions for CV removal. The characterization showed than the most important changes occurred in lignin portion of the material, resulting in many functional groups on the BAB–AT surface. BAB–AT presented superior potential in relation BAB, reaching removal percentages of 95%, with adsorbent dosage of 750 mg L−1 and pH of 10. Homogeneous solid diffusion model (HSDM) was able to explain the kinetic profile. The equilibrium was attained within 2 h and the intraparticle diffusion coefficients were from 10−12 to 10−8 cm2 s−1. The equilibrium was well represented by the Freundlich model. Maximum adsorption capacity was 280 mg g−1. The adsorption process was spontaneous favorable and endothermic. In summary, the acetosolv treatment is a promising alternative to transform black acacia bark wastes in and efficient adsorbent (BAB–AT), thus aggregating value to this material. BAB–AT in turn is a low cost and efficient material which can be used to treat colored effluents.

The degree to which invasive Acacia species affect South Africa’s livestock production has received little attention. We investigated the ecological impacts of Acacia mearnsii invasion on forage quality and quantity and on soil resources, along A. mearnsii invasion gradients, on South African rangelands and the subsequent conditions following clearing. Grazing capacity was reduced by 72% in densely invaded sites, whereas clearing improved grazing capacity by 66% relative to densely invaded sites within 5 years. In densely invaded sites total grass species basal cover was reduced by up to 42%. As a result, A. mearnsii reduced grazing capacity, from 2 to 8 ha required to support one large stock unit (ha/LSU) in uninvaded and densely invaded sites, respectively. Soil moisture content was lower in densely invaded sites compared with lightly invaded and cleared sites. Plant litter increased from 1.3% to 4.2%, carbon content of the soil increased from 2.0% to 4.0% and nitrogen concentrations increased from 0.1% to 0.2% in response to invasion by A. mearnsii. Clearing resulted in improved grazing capacity within 5 years. These results also showed that, if left uncontrolled, wattle species can reduce livestock carrying capacity within montane grasslands in South Africa.EDITED BY James Aronson

Summary The occurrence and diversity of entomopathogenic nematodes (EPN) and their symbiotic bacteria was evaluated in commercial forestry plantations (Eucalyptus spp., Pinus spp. and Acacia mearnsii) and indigenous forests in South Africa. EPN were most prevalent in A. mearnsii plantations, accounting for 60.7% of the isolates, while indigenous forests, plantations of Pinus spp. and Eucalyptus spp. accounted for 35.7, 3.6 and 0% of the isolates, respectively. DNA sequences of the internal transcribed spacer (ITS) and D2-D3 28S rDNA regions were used to identify the nematode species. Four Steinernema spp. were identified, including S. citrae, S. sacchari, two undescribed species, as well as Heterorhabditis bacteriophora and H. baujardi. Heterorhabditis baujardi is reported from South Africa for the first time. Analysis of 16S rRNA of the bacteria confirmed the presence of at least three Xenorhabdus species from Steinernema isolates and two subspecies of Photorhabdus luminescens from Heterorhabditis species.

The present study was designed to characterize the polyphenols isolated from Acacia mearnsii bark crude extract (B) and fractions (B1-B7) obtained by high-speed counter-current chromatography (HSCCC) and evaluate their anti-inflammatory and carbolytic enzymes (α-glucosidase and α-amylase) inhibitory activities. Fractions B4, B5, B6, B7 (total phenolics 850.3, 983.0, 843.9, and 572.5 mg·g-1, respectively; proanthocyanidins 75.7, 90.5, 95.0, and 44.8 mg·g-1, respectively) showed significant activities against reactive oxygen species (ROS), nitric oxide (NO) production, and expression of pro-inflammatory genes interleukin-1β (IL-1β) and inducible nitric oxide synthase (iNOS) in a lipopolysaccharide (LPS)-stimulated mouse macrophage cell line RAW 264.7. All the extracts suppressed α-glucosidase and α-amylase activities, two primary enzymes responsible for carbohydrate digestion. A. mearnsii bark samples possessed significantly stronger inhibitory effects against α-glucosidase enzyme (IC50 of 0.4-1.4 μg·mL-1) than the pharmaceutical acarbose (IC50 141.8 μg·mL-1). B6 and B7 (IC50 17.6 and 11.7 μg·mL-1, respectively) exhibited α-amylase inhibitory activity as efficacious as acarbose (IC50 15.4 μg·mL-1). Moreover, B extract, at 25 µg·mL-1, significantly decreased the non-mitochondrial oxidative burst that is often associated with inflammatory response in human monocytic macrophages.

The Zimbabwean forestry industry, which contributes significantly to the economy, was introduced in the 1940s and is dominated by Pinus spp., Eucalyptus spp. and Acacia mearnsii De Wild. This paper...

Mimosa (Black wattle) tannin extract is one of the few industrially available natural sources of polyphenols. Even if its composition is rather known, limited attempts for its purification were done until now. A Soxhlet extraction, using various solvents, with single and sequential processes was performed, and the separated fractions were analytically investigated. Yield, molecular mass, phenolic and condensed tannin contents, antioxidant activity and FT-IR spectroscopy have shown that the ethyl acetate fraction strongly contains antioxidants and low molecular mass tannins (also hydrolyzable), while the alcoholic fractions contain purified flavonoids with higher molecular mass; the final residues resulted enriched in carbohydrates and ashes. Sequential extractions optimize the class of compounds extracted according to the specific application. Conforming to statistical analysis, significant correlations have been observed between phenolic content and the antioxidant activity, as well as between molecular masses and ashes content.

Invasive alien plants that have seeds with innate dormancy, and thus large, persistent soil-stored seed banks, are particularly difficult to manage. Dormant seeds typically require specific stimuli as cues for germination, resulting in mass recruitment. Sound understanding of germination stimuli may provide options to aid the management of invasives. We investigated the response of two invasive trees, Acacia mearnsii and A. melanoxylon , and an indigenous ecological analogue, Virgilia divaricata , to different germination stimuli (chipped (manually), hot water exposure, dry heat pulse, smoke, and no treatment) at two temperature regimes (winter ~ 12 °C and summer ~ 20 °C) to explore how their germination requirements may be used to favour V. divaricata in areas cleared of the invasives. Chipped and hot water exposure resulted in the highest germination in all three species. Virgilia divaricata responded marginally better than the invasives to the dry heat pulse, particularly at 20 °C. However, the three species mostly responded comparably to the stimulus–temperature combinations, suggesting that manipulation of stimuli is not a feasible option for management of the invasives at a large scale. In the absence of any stimulus (~ akin to conditions associated with aboveground clearing of alien vegetation cover), germination was poorer in V. divaricata than in the invasive species especially at 20 °C, providing motivation for focusing Acacia management operations in cooler seasons in areas where V. divaricata seed banks occur. Another option is to sow V. divaricata seeds that have been chipped or exposed to hot water in areas cleared of the invasives of which the seeds would not have received stimuli.

Vegetable tannins are complex polyphenols, which occur widely in nature. Traditionally, natural tannins have been used for tanning leather. In Brazil, the main tannin-based products are obtained from Acacia mearnsii, which is a leguminous tree native to Southeastern of Australia, and the first seeds were brought to Brazil in 1928. The main cultivation of acacia was established in Rio Grande do Sul state due to the possibility of raw material for charcoal, adhesives to fuel and for tanning leather. The leather tanning processes based on plant tannins are thought to be less harmful than chromium-based tanning, and it has been used as a sustainable alternative. However, there is scarce information about the environmental impact of the leather tanning processes, with most studies reporting inhibitory effects against microorganisms at high doses and stimulatory and positive health effects at low concentrations. The aim of this study was to evaluate the toxicity of tannin preparations extracted from A. mearnsii in Saccharomyces cerevisiae. Vegetable tannin toxicity in yeast was tested using two tannin treatments in different concentrations. In general, the results showed toxicity of vegetable in yeast, BY4741 and gsh1Δ strains.

Uromycladium acaciae causes a serious rust disease in plantations of non-native Acacia mearnsii (black wattle) in South Africa. Little is known about the biology of U. acaciae, making disease control difficult. Germination studies and artificial inoculations were conducted to identify the optimal environmental conditions for infection by U. acaciae. Germination of teliospores, basidiospores, and urediniospores was assessed at seven temperatures, with or without light. The effect of temperature on infection was also assessed. As was the effect of dew period length on germination of teliospores, production of basidiospores and infection. Teliospores and urediniospores germinated between 5 and 30 °C, with an optimum at 15–25 °C. Basidiospores were produced and germinated at temperatures between 5 and 25 °C, with an optimum at 15–20 °C. The optimum temperature for infection by basidiospores was 15–20 °C. All spore types germinated in 6–24 h under optimal conditions. However, production of basidiospores was severely reduced if teliospore germination was interrupted by dry periods, even if teliospores were re-wetted. Symptoms and telia developed on only one plant exposed to a dew period of less than 12 h, with a dew period of 48 h found to be optimal. Artificial inoculation experiments showed that U. acaciae was only able to infect young, growing tissues. Results of this research can be used to develop an artificial inoculation protocol for resistance screening and in disease risk modelling and forecasting.

Australian acacias have significant impacts on the habitats that they invade. For example, they can increase nutrient input and alter natural nutrient cycles. Here we assessed how the invasive Acacia mearnsii and native Virgilia divaricata , both nodulating legume trees with similar growth forms and general ecologies, compared in terms of N and P nutrient content, nutrient resorption and their Biological Nitrogen Fixation (BNF) capacities where they co-occur within forest margins in South Africa. Fresh and senesced leaf samples were collected in sympatric populations and analysed for N and P concentrations. We also measured the δ15N/δ14N isotope ratio, and used it to calculate percentage nitrogen derived from the atmosphere. The two species were very similar in their total nutrient content, but V. divaricata showed strong dependence on available P which determined its dominant source of N. It had a higher use of BNF, an energetically-expensive process, than the invasive species. Acacia mearnsii was also more efficient in N resorption than the native species. Our results highlight nutritional economy differences between these two ecologically similar species and provide further data on reasons for the success of A. mearnsii compared to native tree species.

Acacia mearnsii (black wattle) plantations in South African cover approximately 110 000 ha, with Uromycladium acaciae (wattle rust) found from Limpopo to the Western Cape of South Africa. This disease of black wattle causes reductions in growth, and mortalities with severe infections. Although a limited number of fungicides have been screened for the control of wattle rust, these contain similar active ingredients and need to be applied repeatedly to be effective. Not only is this costly, but there is also the possible development of fungicide resistance. In October 2015 a trial was initiated in southern KwaZulu-Natal to determine the effectiveness of varied application schedules and adjuvants of fungicide for the management of wattle rust. The main aim was to reduce the application interval. The trial was laid out in a randomised complete block design with three replicates. The 2 × 4 factorial combination consisted of two adjuvants application schedules (42 or 56 d between application) and four adjuvants...

Recently, Acacia crassicarpa has been planted in peatland areas with acidic soil in Indonesia for use in pulp and paper materials. Its bark is not suitable to produce bleached pulp; hence, it is discarded as waste. Meanwhile, in South Africa and other countries, Acacia mearnsii has been planted for a long time, and its bark extracts have been used as a leather tanning agent. First, the structure of condensed tannin from the bark waste of A. crassicarpa is characterized. The yield of the extracts obtained from A. crassicarpa using a 70% acetone aqueous solution (7% based on bark weight) is less than that obtained from A. mearnsii (34%). A novel flavan dimer from the condensed tannin, specific to A. crassicarpa, is isolated from the bark extracts. To the best of our knowledge, this dimer is a new compound as evidenced from pyrolysis–gas chromatography–mass spectrometry and nuclear magnetic resonance analyses; it corresponds to a gallocatechin–catechin flavan dimer with the absence of one oxygen atom at the 3C of the pyran ring. In addition, 2,4,6-trimethoxybenzoic acid methyl ester is identified as a novel pyrolysis product obtained from the cleavage of the pyran ring.

The native forest-tree pathogen Ceratocystis tsitsikammensis infects native trees (e.g. Virgilia divaricata) and Acacia mearnsii, an invasive alien and important forestry tree in South Africa. We explored the physiological effects of infection by this fungus on these two tree species, within the context of the Biotic Resistance Hypothesis (BRH). The effects of infection on physiological and resource capture parameters were measured, in conjunction with lesion length. Infected V. divaricata trees changed their N economy by relying more on soil derived N and less on biological nitrogen fixation. Infected A. mearnsii trees altered their biomass allocation into below ground investments. The species responded differently to infection, hence it was not clear which was most negatively affected. Results do support numerous studies that base tests of pathogenicity on lesion length. These results hold important conservation and economic relevance as A. mearnsii is both an invasive tree species and a forestry tree.

The biosynthesis of silver nanoparticles (Ag-NPs) using the hydrosol extract of the dry stem bark of Acacia mearnsii as reducing and capping agents, and their antinociceptive properties are hereby reported. By varying the temperature and reaction time, the temporal evolution of the optical and morphological properties of the as-synthesized material was investigated. The NPs were characterized by UV–visible absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS) and x-ray diffractometry (XRD) The optical analyses show that the position of the maximum surface plasmon resonance (SPR) peak is red-shifted as the reaction temperature decreased. The TEM micrographs show that the as-synthesized Ag-NPs are spherical while the X-ray diffraction shows that the material is highly crystalline with face-centered cubic structures. The anti-inflammatory efficacy, analyzed by the formalin model, indicates that the as-synthesized Ag-NPs are very effective, with an inhibition rate of about 76%.

BackgroundRecent studies demonstrated that warming and elevated carbon dioxide (CO2) indirectly affect the soil microbial community structure via plant root exudates. However, there is no direct evidence for how the root exudates affect soil microbes and how the compositions of root exudates respond to climate change.ResultsThe results showed that warming directly decreased biomass of soil-borne bacteria and fungi forAcacia mearnsiiDe Willd but it did not impact soil microbial community forEucalyptus urophylla S.T. Blake. In contrast, elevated CO2had strong direct effect on increasing soil microbial biomass for both plant species. However, plant roots could significantly increase the secretion of antibacterial chemicals (most probable organic acids), which inhibited the growth of bacteria and fungi in elevated CO2environment. This inhibitory effect neutralized the facilitation from increasing CO2concentration on microbial growth.ConclusionsWe concluded that climate change can directly affect microorganisms, and indirectly affect the soil microbial community structure by changes in composition and content of plant root exudates.

A new epidemic disease caused by the rust fungus Uromycladium acaciae emerged in 2013/2014 causing defoliation, branch, and stem deformations in plantations of Acacia mearnsii (black wattle) in South Africa. This study investigated the level of genetic resistance to the rust fungus Uromycladium acaciae in six progeny tests from two different trial series. A total of 269 open pollinated families of different levels of improvement, ranging from wild selections to fourth cycle generations were included in the study. Families originated from land race subpopulations of South Africa and from Australian provenances. Rust severity was assessed across all the trials at 6 months of age. In the rust screening trials, different measures of rust incidence were assessed at 6, 12, and 17 months, as well as tree height and mirid damage at 12 months. In the progeny trial series, tree height, stem defects, and gummosis were measured at 36 months. Results suggested that rust incidence is under moderate genetic control at the family level. The coefficient of additive genetic variation was large (59.4%) for the disease incidence. The family mean heritability for rust disease was $$ {h}_{fm}^2=0.48\pm 0.16 $$ in the progeny trial series, whereas it was $$ {h}_{fm}^2=0.33\pm 0.06 $$ in the rust screening trials. Among the rust assessment methods, 6-month rust incidence (yes/no) assessment produced higher heritability estimates. With some exceptions, Australian provenances from low altitude sites along the eastern coast of Victoria and the south east coast of New South Wales showed high tolerance to rust, better growth, low gummosis incidence but poor stem form. All the South African sources showed high rust susceptibility and had average or below average growth, gummosis incidence, and stem form. For rust disease improvement, the South African material should be avoided and the best existing Australian families should be used for further breeding. In addition, new seed sources from Australia should be infused to the breeding program in order to increase the genetic diversity while increasing genetic gain for the rust, gummosis, and growth.

Tannins from Acacia mearnsii were encapsulated using four different sol-gel methods acid (SGAR), basic (SGBR), silicate (SGSR) and non-hydrolytic (SGNHR) routes. The hybrid materials were analyzed using a set of techniques to characterize their structure, texture and morphology. The antimicrobial performance of the encapsulated materials was evaluated against different microorganisms (Staphylococcus aureus, Escherichia coli, Aspergillus niger and Candida sp.). The data showed that the encapsulation route significantly affects the characteristics of the resulting hybrid materials. Better functional performances were obtained using the silicate route, which produced mesoporous materials with a small surface area (0.96m2g-1) and small particle size (

The assessment of the policy framework governing Invasive Alien Species (IAS) control is of critical importance in conservation. The undertaking of a SWOT analysis of such a framework is necessary because it enhances the efficacy of IAS control. The aim of this study is to carry out a SWOT analysis of the policy framework guiding the control of the spreading of Acacia mearnsii and other IAS in the Golden Gate Highlands National Park in South Africa, as well as the implementation of restorative measures in the park and adjacent communities in line with the recommendations of the Convention on Biodiversity. A comparative analysis of this framework and the hierarchical framework that was developed during the European Union Conference on Freshwater Invasives - Networking for Strategy in 2013 is undertaken. The results indicate the need to strengthen park-community relations, upgrade existing legislation, and boost the technical capacity of South African national parks to identify, detect, monitor and predict IAS invasions, both within the parks and their surroundings. This knowledge is important for developing future policies on IAS control in South Africa.