Tasmanian Institute of Agriculture

The first detailed analysis of the phenolic constituents of the reaction zones (tissue of antimicrobial defence) from the sapwood of a Eucalyptus spp. is presented. Plantation-grown Eucalyptus nitens trees with stem decay resulting from pruning wounds were sampled and extracts were prepared from healthy sapwood and from reaction zone tissue. Analysis by HPLC with ESI-MS revealed that a diverse range of hydrolysable tannins are present in both healthy sapwood and in reaction zone extracts, including over 30 gallotannins, ellagitannins and phenols. Eight tannins were unequivocally identified, including the gallotannins tri-Ogalloyl-b-D-glucose, tetra-O-galloyl-b-D-glucose and penta-O-galloyl-b-D-glucose, and the ellagitannins pedunculagin, tellimagrandin I, casuarinin, casuarictin and tellimagrandin II. The phenols gallic acid, ellagic acid and catechin were also identified. The ellagitannins (particularly pedunculagin) are considerably more abundant in the reaction zone than in the healthy sapwood and may contribute to the effectiveness of the reaction zone as an antimicrobial barrier.

The potential to use plantation-grown Acacia mangium for solid-timber products is limited by heartrot, caused by decay fungi. A rapid method of surveying logs stacked in the plantation following harvest was developed which is an alternative to timeconsuming whole tree destructive assessments. Logs were randomly chosen from the stacks using a transect method, the cutends of the logs were assessed (2199 logs in total) and heartrot severity was scored on a 1-4 scale. Surveys of harvest-age A. mangium were completed in five Indonesian locations to assess heartrot incidence and severity. The incidence of heartrot in the main stem was significantly different between some regions, ranging from 6.7% in East Kalimantan up to 46.7% in West Java. The proportion of each defect type (1-4) did not show a consistent trend across the sites. A combination of differences between plantation management (e.g. pruning), age and climate in these five regions explain the differences in heartrot incidence and severity. #

Remote sensing for evaluation of canopy health in plantation eucalypts is a realistic option for forest managers in the near future if reliable and robust methods of spectral analysis can be developed. Pot-grown eucalypts of three species important to the Australian plantation industry were used for crown-scale spectral (400-1000 nm) evaluations of vegetation indices as indicators of common symptoms of stress. When defoliation treatments (in E. globulus) or exposure to cold and nutrient deprivation (in E. pilularis) resulted in large differences in leaf cover, the red edge position and slope indices, two normalized difference vegetation indices (NDVIs), modified chlorophyll absorption ratio index 2 (MCARI2) or modified triangular vegetation index 2 (MTVI2) were most strongly correlated to leaf cover. However the NDVIs were significantly affected by soil background in a study with E. globulus. The percentage of red leaves resulting from stress treatment was most strongly correlated with the anthocyanin reflectance index (ARI) and red-green index (RGI) in both E. grandis and E. pilularis, however the RGI was affected by background type in the E. globulus study while the ARI was not. Exposure to cold and nutrient deprivation led to marked changes in leaf cover for E. pilularis but not in E. grandis and a much more reduced level of chlorophyll in E. pilularis than is suspected in E. grandis. In E. globulus, defoliation from the upper crown was easier to detect with spectral data than from the lower crown. Results were generally comparable to studies of eucalypt crown condition from native forests.

Precision monitoring of plant health via remote sensing benefits from accurate quantification of attributes such as foliar pigments related to stress. For example, pigment content (the ratio of chlorophyll to carotenoids) can be indirectly related to photosynthetic efficiency in plants and hence productivity. Optical remote sensing can potentially provide this data with high spatial accuracy via spectral reflectance. In a previous study we found that the leaf radiative transfer model PROSPECT 5 could estimate chlorophyll content in Eucalyptus globulus leaves reasonably well but prediction of carotenoids was poor. To examine the basis for poor model performance, we conducted a targeted study using both a pot experiment with E. globulus and field samples of E. globulus and E. nitens . We examined the influence of anthocyanins and waxes on the performance of the model by manipulating these variables with shade, nutrition and a wax removal treatment. The relationship between measured to...

Wounding caused by certain silvicultural practices such as pruning and thinning can facilitate the development of wood decay. In plantation trees grown for the purpose of timber production, wood decay commonly develops from dead branches and is usually confined into the mature portion of wood than in the sound sapwood. To better predict the susceptibility (or resistance) of sapwood to decay in different wound locations, this study compared the influence of stem with branch wounding on decay extent in plantation Eucalyptus globulus and Eucalyptus nitens in Tasmania (Australia) after summer wounding and artificial inoculation with two white rot decay fungi. The amount of sapwood discoloration and decay, as well as the amount of total phenols extracted from the reaction zone (a dark colored zone produced by the accumulation of phenolics) were assessed after tree felling (13 months). In both Eucalyptus spp., greater sapwood discoloration and decay developed from stem wounds than branch ...

Incidence and spatial analysis of root rot of Acacia mangium in Indonesia. Root rot caused by Ganoderma spp. is a serious concern in commercial plantations of Acacia mangium in Indonesia. This study surveyed root rot incidence and spatial arrangement in commercial plantations and trials. In second rotation commercial plantations in Sumatra and Kalimantan, root rot incidence was recorded between 3 and 28% in trees aged from three to five years old. The compartments surveyed in Riau province and East Kalimantan had significantly higher root rot than South Sumatra. In a progeny trial of A. mangium in Java, root rot incidence was surveyed twice, when trees were eight and again at nine years old. Root rot incidence was about 7 and 13% respectively. Spatial analysis by distance indices (SADIE) revealed that infected trees were randomly distributed at the first time point but tended to become aggregated by the time of the second survey. This highlights the probability of vegetative spread of the fungus after initial introduction to the site. Assessment of root rot incidence on the basis of A. mangium provenance did not reveal any statistically significant differences.

Fungal rot of sweet cherry fruit leads to reduced yield and quality at harvest. This study investigated a range of host factors related to cherry rot and also identified the main species present in latently infected-fruit and fruit with visible rot at harvest in a Tasmanian orchard. There was a significant effect of tree cultivar on total rot found at harvest, with the cultivar "Sweetheart" associated with almost double (approx. 25 % infection) the amount of rotten fruit compared to "Regina" and "Simone" (approx. 13 %). Harvest date may have had some influence on this result, as Sweetheart fruit were harvested 2 weeks later than the other cultivars, and there was a large rainfall event just before Sweetheart harvest (rainfall can increase disease spread and infection). Crop load did not influence the amount of rotten fruit found at harvest for any cultivar, although crop load was low in this season at this site. Removing fungicide application from the point of 50 % full bloom onwards did not significantly alter disease incidence. The study found that Botrytis cinerea was the dominant rot pathogen in cherry fruit at this site and season. No evidence of Monilinia species was found in this study with the methods used, despite it being typically associated with rot of stone fruit. Fruit quality characteristics were not indicators of disease susceptibility, as very few characteristics observed to correlate with disease at harvest.

Wounding caused by certain silvicultural practices such as pruning and thinning can facilitate the development of wood decay. In plantation trees grown for the purpose of timber production, wood decay commonly develops from dead branches and is usually confined into the mature portion of wood than in the sound sapwood. To better predict the susceptibility (or resistance) of sapwood to decay in different wound locations, this study compared the influence of stem with branch wounding on decay extent in plantation Eucalyptus globulus and Eucalyptus nitens in Tasmania (Australia) after summer wounding and artificial inoculation with two white rot decay fungi. The amount of sapwood discoloration and decay, as well as the amount of total phenols extracted from the reaction zone (a dark colored zone produced by the accumulation of phenolics) were assessed after tree felling (13 months). In both Eucalyptus spp., greater sapwood discoloration and decay developed from stem wounds than branch wounds. Sapwood discoloration and decay extended further in the axial than radial or tangential wood alignments. Fungal isolations showed that wounds challenged with the white rot decay fungi Acanthophysium sparsum and an unidentified white rot fungus always developed significantly greater sapwood discoloration and decay than the control treatment, regardless of wood alignment. In unwounded parts of the tree, total phenols were 4.7-and 6.3-fold higher in the branch sapwood compared to stem sapwood in E. globulus and E. nitens, respectively. The higher inherent level of total phenols in the branch sapwood may partly explain why less dysfunction resulted from the inoculation of branches compared to stems. Overall, E. globulus developed smaller columns of discoloration and decay than E. nitens.

In Australia large areas of forest have been closed to industrial forestry and it is necessary to compensate for lost production. Future wood products will come from intensively managed silvicultural regimes — eucalypt regrowth forest and plantations. Solid-wood regimes involving high-cost operations such as pruning and thinning will be economically sensitive to downgrade due to various types of stem defect — fungal and insect damage, staining, kino veins. In Tasmania, research over the last decade has focused on developing management strategies to minimise stem defect caused by decay fungi in both regrowth and plantation eucalypts. Under plantation conditions

Unmanned aircraft system (UAS) in combination with multispectral sensors stimulate the utilisation of site-specific technologies to manage crop production according to intrafield variability. Crop monitoring requires accurate calibration. However, radiometric calibration methods in practice are difficult to implement for UAS remote sensing as every single image requires correction due to smaller field of view and changes in light. Therefore, this paper proposes an easy radiometric calibration process for UAS-based miniature multiple camera array multispectral sensor. Results showed linear relationship between spectral reflectance and raw DN values with y-intercept value compatible with zero. It is the minimal possible surface reflectance recorded by sensor and can be used as a first point for equation development. The spectral quantification of white pseudo target was used as a second point of equation. Quantitative spectral information was generated by developing equation for every single image. An accuracy assessment was undertaken by comparing image-driven reflectance values against reflectance values measured in the field from soil and crop. The overall accuracy based on the root mean square error for the six bands ranged from 0.025% to 0.064%. The results of this study showed that the proposed method can be used for the calibration of UAS-based multispectral image .

Faidherbia albida is an important tree species in the parkland agroforestry system of the Rift Valley region, central and southeastern Ethiopia. Positive effects of F. albida on crop production are widely recognised. However, the effects of tree pruning, zone and fertiliser interactions on crop growth have not been addressed in earlier studies. A field experiment containing three levels of tree pruning (100% pruned, 50% pruned, and unpruned) as main plots, and application of recommended rates of N and P fertilisers as sub-plots, was conducted during the 2015 and 2016 growing seasons. Maize grain yield and biomass, light intensity, and soil nutrients and moisture were measured at different positions from each F. albida tree trunk (0-2, 2-4 and 4-6 m) and in crop-only plots. Biomass and yield of maize were significantly greater under tree canopies compared to crop-only plots in both the 2015 and 2016 growing seasons, regardless of pruning levels. Fertilisation significantly increased yields under tree canopies compared to crop-only plots in both years. Light intensity increased with distance from trees and with greater pruning levels. Soil carbon and nutrient concentrations and moisture content decreased with increasing distance from tree and with soil depth. These results suggest that maize production and profitability could be maintained or improved through only partial pruning of F. albida rather than pollarding, and by preferentially applying fertilisers in normal and wet years. Recommendations need to be evaluated in a total system context including other rotational crops, fuel, livestock and socioeconomic factors.

Poor agricultural productivity has led to food shortages for smallholder farmers in Ethiopia. Agroforestry may improve food security by increasing soil fertility, crop production, and livelihoods. Agroforestry simulation models can be useful for predicting the effects of tree management on crop growth when designing modifications to these systems. The Agricultural Production Systems sIMulator (APSIM) agroforestry tree-proxy model was used to simulate the response of maize yield to N fertilizer applications and tree pruning practices in the parkland agroforestry system in the Central Rift Valley, Ethiopia. The model was parameterized and tested using data collected from an experiment conducted under trees and in crop-only plots during the 2015 and 2016 growing seasons. The treatments contained three levels of tree pruning (100% pruned, 50% pruned, and unpruned) as the main plots, and N fertilizers were applied to maize at two rates (9 or 78 kg N ha−1) as sub-plots. Maize yield predic...

Background and Aims: Bunch rot symptoms can appear weeks after the infection of grape flowers by Botrytis cinerea. Quantitative polymerase chain reaction (qPCR) detects changes in the DNA mass of a target organism and is a potential tool for studying quiescent infections. The aim was to optimise a duplex qPCR to quantify B. cinerea DNA in the background of endogenous Vitis vinifera DNA. Methods and Results: Three DNA extraction techniques and three probe sets were compared. The optimised qPCR using the Bc3 probe set was 1000-fold more sensitive than other probe sets, with a threshold cycle value of <33 for as little as 1 picogram of B. cinerea DNA. The duplex assay successfully detected an increasing amount of B. cinerea DNA when mixed with V. vinifera DNA or of B. cinerea conidia when added to grape receptacles. Conclusions: Duplex assays quantifying B. cinerea DNA in the background of endogenous grape DNA were efficient and sensitive, with calculation of a pathogen coefficient allowing comparison of results among assays. Significance of the Study: The results demonstrate the potential to monitor symptomless, quiescent infections and to investigate the consequence of an intervention (e.g. a fungicide treatment) before disease symptoms are visible.

The first detailed analysis of the phenolic constituents of the reaction zones (tissue of antimicrobial defence) from the sapwood of a Eucalyptus spp. is presented. Plantation-grown Eucalyptus nitens trees with stem decay resulting from pruning wounds were sampled and extracts were prepared from healthy sapwood and from reaction zone tissue. Analysis by HPLC with ESI-MS revealed that a diverse range of hydrolysable tannins are present in both healthy sapwood and in reaction zone extracts, including over 30 gallotannins, ellagitannins and phenols. Eight tannins were unequivocally identified, including the gallotannins tri-Ogalloyl-b-D-glucose, tetra-O-galloyl-b-D-glucose and penta-O-galloyl-b-D-glucose, and the ellagitannins pedunculagin, tellimagrandin I, casuarinin, casuarictin and tellimagrandin II. The phenols gallic acid, ellagic acid and catechin were also identified. The ellagitannins (particularly pedunculagin) are considerably more abundant in the reaction zone than in the healthy sapwood and may contribute to the effectiveness of the reaction zone as an antimicrobial barrier.

Xylem defence responses occurring in pot-grown Eucalyptus nitens (Maiden) saplings were analysed within the ®rst few weeks following stem wounding and inoculation with the non-aggressive decay fungus Ganoderma adspersum (Schulz). The fungus colonized the dead xylem cells up to 5 mm above and below the wound after 30 days. Evidence of xylem cell death and discolouration was detectable within 12 h and vessel tyloses were present after 3 days. Concentration of tetra-galloylglucose increased by 3. 5-fold within 24 h, while the trend for total phenols was a slow increase reaching a maximum after 21 days. Suberin was not detected. Early accumulation of water content has been proposed as a defence component of host± pathogen interactions in woody angiosperm xylem, but this was not obvious for E. nitens. Nuclear magnetic resonance imaging (NMR imaging or MRI) was used to measure small-scale distributions in moisture content around the inoculated stem wounds in intact E. nitens saplings. Some moisture accumulation was detectable at lesion margins of wounds analysed after 3 weeks. However, this was not detectable by gravimetric measurements. This increase in moisture content may be a consequence of wound physiology rather than an active defence response.