Risk mapping of redheaded cockchafer ('Adoryphorus couloni') (Burmeister) infestations using a combination of novel k-means clustering and on-the-go plant and soil sensing technologies
The ability to identify areas of pasture that are more likely to support damaging levels of the soil-borne, redheaded cockchafer ('Adoryphorus couloni') (Burmeister) (RHC) would allow farmers to target expensive control measures. This study explored soil properties, measured via electromagnetic surveys (EM38), pasture biomass via active optical sensors (CropCircle™) and topography via GPS elevation survey as potential indicators of RHC population density. A combination of these variables was used to produce risk maps with an accuracy of 88% at predicting likely RHC density-categories on a dairy property in the Gippsland region of Victoria, Australia. This risk mapping protocol could be used to improve sampling programs and direct site-specific pest management.
Detection of pasture pests using proximal PA sensors: a preliminary study investigating the relationship between EM38, NDVI, elevation and redheaded cockchafer in the Gippsland region
The redheaded cockchafer ('Adoryphorus couloni') (Burmeister) (RHC) is an important, native soil-borne pest of improved pastures in South Eastern Australia. The aim of this preliminary investigation was to determine whether commonly used Precision Agriculture (PA) sensors could identify landscape attributes that correlate with RHC population density. Soil apparent electrical conductivity (soil ECa) measurements were derived from EM38, relative photosynthentically-active biomass via the normalised difference vegetation index (NDVI) derived from an Active Optical Sensor (AOS) and elevation measurements derived from dGPS (differential global positioning system) mapping. Eight paddocks across seven properties in the Gippsland region of Victoria were surveyed using a Geonics EM38, CropCircle™ AOS and a dGPS. Eighteen to twenty sample sites in each paddock were selected based on different zones of soil ECa, and the RHC (and other cockchafer species) populations were assessed at each of these sites. No RHC were found in East Gippsland confirming that the damage to pasture observed by farmers at this time was caused by a different cockchafer species. Few RHC were found across all sites, probably due to high rainfall, however correlations tended to suggest that RHC were more likely to establish or survive in areas of high elevation and low soil ECa. On one property RHC were associated with low NDVI values and at one other high NDVI suggesting more complex relationships may exist between AOS data and RHC densities. Threshold-level relationships were apparent between RHC density and elevation and ECa to suggest that a useful indicator of pest risk could be developed, at least for some areas of Gippsland, however the relationships are complex and need to be investigated further.
Developing a landscape risk assessment for the redheaded cockchafer ('Adoryphorus couloni') in dairy pastures using precision agriculture sensors
The redheaded cockchafer ('Adoryphorus couloni') (Burmeister) (RHC) is an important pest of semi-improved and improved pastures of south-eastern Australia. The third instar larvae of the RHC feed on the organic and root matter found in the soil causing reduced pasture growth and in severe cases death of plants. The control of the RHC is complicated by its lifecycle which involves the insect spending the majority of its life underground with only a brief time as an adult beetle flying. The RHC is particularly hard to control as there are no insecticides registered for use against the pest or any effective cultural control methods. ... This thesis aims to identify possible relationships between third instar RHC larvae with environmental variables which can be measured using precision agriculture sensors.
Using Objective Biophysical Measurements as the Basis of Targeted Surveillance for Detection of Grapevine Phylloxera 'Daktulosphaira vitifoliae' Fitch: Preliminary Findings
In Australia early detection of grapevine phylloxera ('Daktulosphaira vitifoliae' Fitch) is critical for the sustainability of its viticultural industry which is predominantly planted on phylloxera-susceptible ungrafted 'Vitis vinifera' L. The current range of available early detection methods, including ground surveys and aerial imagery, rely on detection of a 'weak spot' in the vineyard resulting from the expression of non-specific, often non-phylloxera related, plant stress. These methods are costly and labour intensive. Other evolving methods include chemical fingerprinting and soil-based DNA probes. However, there is a need to develop biophysical descriptors that directly indicate the potential susceptibility of vineyards to phylloxera infestation. Quantitative biophysical indicators including vine photosynthetically-active biomass (PAB), soil electrical conductivity (ECa), soil particle-size and soil chemistry have been evaluated for their ability to facilitate targeted and intensified surveillance. Phylloxera monitoring was conducted in infested vineyards in Central Victoria, Australia over two successive growing seasons. Soil ECa was derived using EM38 and PAB was derived using airborne multispectral imaging. Results indicated zones of higher ECa and higher exchangeable aluminium, were associated with higher populations of phylloxera. Further studies are required to quantify the link between phylloxera dispersal and soil parameters, however the results were encouraging for developing a grapevine susceptibility matrix as the basis for an objective monitoring protocol.
Detection of Phylloxera Infestation in Grapevines by NMR Methods
Principal component analysis of ¹H NMR spectra of dichloromethane extracts taken from grapevine leaves reveals that phylloxera infestation of the root system causes metabolic changes in the leaves of infested grapevines, both in the field and in the glasshouse. A number of potential markers of phylloxera infestation were detected but their presence is transient and varies with the stage of the growing season. The changes in the metabolic profile caused by phylloxera infestation more closely resemble those caused by nitrogen deficiency than those induced by water stress. A reduction in the ratio of linoleic acid to linolenic acid in the triglyceride component of the leaf extract may provide an indicator of phylloxera infestation.
Monitoring and managing landscape variability in grazing systems
Precision agriculture (PA) technologies and applications have largely been targeted at the cropping and horticultural industries. Little research has been undertaken exploring the potential for PA in grazing systems. This paper reports on the results of five studies examining PA technologies and techniques in grazing systems including: spatial variability in soil nutrients and fertiliser response across the grazing landscape; spatial landscape utilisation in relationship to individual animal productivity and health; spatial variability in pasture pests; and the development of a sensor network for monitoring spatial soil moisture, soil temperature and ambient temperature across a grazing landscape. The large variability exhibited in our trials suggests there is an enormous opportunity for precision agriculture in grazing systems. Sensing and responding to this variability will require careful application of modern PA technology and a substantial investment in research to better understand spatial variability in our grazing landscapes.
Mapping redheaded cockchafer infestations in pastures - are PA tools up to the job?
The redheaded cockchafer ('Adoryphorus couloni') (Burmiester) (RHC) is a serious pest of improved pastures in south-eastern Australia and current detection relies on pasture damage becoming visible to the naked eye. Various precision agriculture sensors are able to delineate spatial variability in soil texture and moisture content as well as numerous contributing factors to the photosynthetic 'vigour' of pastures, namely biomass, canopy architecture and species composition. The aim of this paper is to seek to determine whether the same technologies can be used to identify paddock zones prone to RHC infestation. This study investigates the association between data generated by a CropCircle™ (an active optical plant canopy sensor (AOS)), an EM38, (an electromagnetic induction soil sensor), and third instar RHC larvae counts. Results indicate that the red wavelength reflected component of the AOS from the pasture canopies offered the most accurate model of third instar RHC larvae count (residual mean square error = 1.04).
Detection of Phylloxera Infestation in Grape Vines using NMR Methods
Can Phylloxera infestation cause detectable metabolic changes in grape leaves? We are investigating the existence of chemical fingerprints of Phylloxera in extracts taken from grapevine leaves and their possible use as a method of early detection of Phylloxera infestation.
Towards Improved Early Detection of Grapevine Phylloxera ('Daktulosphaira vitifoliae' Fitch) Using a Risk-Based Assessment
Grapevine phylloxera ('Daktulosphaira vitifoliae' Fitch) is a significant threat to the Australian viticulture industry, with over 80% of grapevines planted on highly susceptible, ungrafted 'Vitis Vinifera' L. Early detection of phylloxera is critical as it can spread unnoticed in the early years of infestation when vine foliar symptoms may not reflect subterranean root damage. Management strategies such as phylloxera exclusion zones (PEZ) and a number of quarantine protocols relating to movement of machinery and grape materials are already established within Australia in an attempt to contain proliferation throughout viticultural regions. Such measures are particularly important for regions like the Hunter Valley in New South Wales, Australia and the Barossa Valley in South Australia, which are phylloxera-free and sustain a high volume of viticultural production. Currently, early detection protocols include labour-intensive, systematic sampling of vine roots to inspect for the presence of phylloxera and multispectral aerial imagery to identify potentially stressed vines. Airborne remote sensing identifies weak spots in the vineyard that are not necessarily due to phylloxera infestation, rather the expression of non-specific water or nutrient related symptoms. Healthy, vigorously growing canopies may also disguise the early expression of above-ground signs of phylloxera-induced root degradation. The delayed appearance of visible symptoms, coupled with the dynamics of phylloxera infestation means current detection methods could be significantly improved through development of a risk-based monitoring strategy to indicate the potential susceptibility of vineyards to phylloxera infestation. This paper presents the targeted use of several primary and secondary detection techniques already being utilised across the viticulture industry, including EM38, Greenseeker™ and a soil-based DNA assay specific for phylloxera.