Giles Hardy

According to the Food and Agricultural Organization, more than 800 million people still suffer from hunger, yet one third of food produced (equivalent to $ 1 trillion USD in value) is either lost or wasted globally each year. Postharvest losses are considered a major component of food loss and waste in the food supply chain, from raw production (total harvest) to food consumed. Losses occur due to improper handling, storage, transport, preservation techniques and infection by microorganisms, and can reach up to 45% in fresh fruits and vegetables. Postharvest diseases, particularly of perishable food crops, are predominately caused by fungal pathogens. Management practices for controlling such pathogens include physical, chemical and biological methods in addition to newer technologies such as UV radiation, nano-technology and plasma treatments. Fungicides are the most common management option due to the consistency of results, however, there is increasing demand by consumers for less chemical use, and chemical-free produce can attract premium prices for growers. New technologies are required to reduce postharvest disease losses, without exposing consumers to hazardous chemical residues. This paper reports a novel, non-chemical method for treating postharvest diseases that shows much promise – cold plasma. Our experiments indicate that this method does not have any phytotoxic effects on avocado fruit, but can inhibit pathogens in vitro following an exposure time of 3 min.

Headspace solid phase micro-extraction (HS-SPME) coupled with gas chromatography (GC) is a useful sample preparation, volatile extraction and separation method for analysis of volatile compounds from stored grain insects and their hosts. However, for using this high-quality analytical method, there is a need to optimize a range of factors to ensure good extraction efficiency. These factors include fibre selection, column selection and sample preparation. In this paper, six types of polar and non-polar fibre (100µm PDMS, 85 µm PA, 85 µm CAR/PDMS, 65 µm PDMS/DVB, 50/30 µm PDMS/CAR/DVB and 7 µm PDMS) were used to conduct the HS-SPME of volatile chemicals from wheat, wheat flour and two species of stored grain insects Tribolium castaneum (Herbst) and Rhyzopertha dominica (Fabricius). The results showed that the 50/30 µm PDMS/CAR/DVB fibre not only extracted the maximum number of volatile organic chemicals (VOCs), but also captured the largest mass of VOCs for subsequent detection by GC. Optimum sample sealing time, fibre extraction time, desorption time and temperature were 24 h, 4 h, 5 min and 250°, respectively. The GC results of volatiles from different samples gave different patterns of GC spectrum, which indicated that different volatile compounds were released from the different samples. Therefore, this study provides a detailed sequence of HS-SPME-GC optimization steps that can be applied towards the development of HS-SPME-GC methods to detect stored grain insects.

Rubus anglocandicans is the most common species of European blackberry in Western Australia (WA) and one of the few weeds of national significance in the south-west of WA. It is a major weed of conservation areas, forestry and agriculture. Exotic strains of the blackberry rust Phragmidium violaceum have been introduced to WA as biological control agents, but in most areas it seems that they are not effective, possibly due to climate. In 2007 while monitoring establishment of the released rust strains, unexplained dead and diseased blackberry plants were discovered at two locations, along the Warren River near Pemberton and the Donnelly River near Manjimup in the south-west of WA. The extent of the disease, with noticeable landscape changes due to the removal of dense blackberry infestations, has lead to it being called ‘blackberry decline’. The organism or organisms responsible for killing the blackberry plants are so effective that within a couple of years previously impenetrable stands of well established blackberry have been completely killed for at least several kilometres from the initial sightings of disease symptoms. We outline the history of the ‘decline’ phenomenon on blackberry in the south-west of WA and discuss some of the possible causes.

Surveys of nurseries and plantations of Eucalyptus species were conducted within Lao PDR in 2009. A range of pathogens were isolated including species within Phytophthora, Pythium, Fusarium, Colletotrichum, Neofusicoccum, Lasiodiplodia, Pilidiella, Calonectria, Cryptosporiopsis, Corticium and Teratosphaeria. Some diseases caused significant defoliation and loss of stock within nurseries and plantations. The presence of these diseases in combination with a changing climate poses many challenges for the future sustainable and profitable management of plantations in Lao PDR.

Remote sensing of vegetation condition using high resolution digital multispectral imagery (DMSI) is an option for land managers interested in quantifying the distribution and extent of dieback in native forest. Crown condition is assessed as reference to the physical structure and foliage (i.e. density, transparency, extent and in-crown distribution) of a tree crown. At 20 sites in the Yalgorup National Park, Western Australia, a total of 80 (Eucalyptus gomphecephala) crowns are assessed both in-situ and using 2 acquisitions (2008 and 2010) of airborne DMSI. Each tree was assessed using four crown-condition indices: Crown Density, Foliage transparency, and the Crown Dieback Ratio and Epicormic Index. DMSI data is trained against canopy condition assessment data from 2008, crown condition is predicted using only spectral data. Comparison of DMSI derived Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI) and a novel Red Edge Extrema Index (REEI) suggests the REEI is more suited to classification applications of this type.

Respiration assays are routinely used for investigating microbial metabolic activity in soil, but usually after a period of "conditioning" whereby dry soil is rewetted and incubated for a period of days. We showed that rewetting and incubation of soil with or without amendments cause changes in microbial populations that are dependent on the type of amendment. As these amendments resulted in altered basal respiration levels and SIR profiles, they call into question the suitability of soil conditioning as pretreatment for soil microbial analyses. When testing soils from an experiment involving various amendments we have found that different substances can inhibit, rather than stimulate, respiration following rewetting. We suggest further investigation of "CO2 burst inhibition" for the purpose of developing a method that does not require naturally dry or air dried soil to undergo conditioning prior to a SIR assay.

Australasia to identify emerging plant diseases, carriers of these diseases, and the role of hosts in the transmission of disease. In Australia, a cause for concern and currently listed as a category 1 emergency pest pathogen is Phytophthora ramorum. It has a wide host range and causes widespread damage in nurseries and private estates across Europe and is devastating coastal forest ecosystems of western USA, mainly in California (Rizzo and others 2002, Werres and others 2001). Several Australasian plant species, including Griselinia littoralis (New Zealand broadleaf), Eucalyptus haemastoma (Australian scribbly gum), and Pittosporum undulatum (Victorian box), have already been listed as natural hosts of P. ramorum based on field observations and pathogenicity tests in the USA and Europe (Hüberli and others 2006, RAPRA 2007). While P. ramorum has not been detected in New Zealand or Australia, a preliminary study has identified ecosystems that could be conducive to disease development in Australia (W. Smith unpublished data). It is a pathogen that the region cannot afford as the threat and management implications of this pathogen on natural ecosystems, agriculture and horticulture may potentially be far worse than that currently posed by P. cinnamomi (O’Gara and others 2005). The study aims to provide knowledge of potential hosts and therefore carriers of the pathogen, provide data for the establishment of robust quarantine practices and reduce the risk of an introduction of P. ramorum into Australasia.

Most Phytophthora surveys in native ecosystems in Australia have focused exclusively on isolations from samples of soil and symptomatic plant tissue including the extensive vegetation health surveys conducted in Western Australia (WA) (1). The outbreak of P. ramorum in California and Europe, where early detection of an infested area was important to the success of containment and eradication efforts, has popularised the stream surveys in native ecosystems. In Australia, it has recently been used to detect Phytophthora spp. in Victoria resulting in several species being isolated from four streams which varied according to the winter and summer sampling season (2). In our study, the baiting technique was used to survey a wide range of WA’s waterways for Phytophthora spp. during October to early December 2008.

The aim of our experiments was to develop protocols that can be used to contain and eradicate spot infestations of P. cinnamomi that, if untreated, are likely to threaten extensive areas of native vegetation or areas of high conservation value. Treatment regimes were guided by two assumptions: 1) within the selected sites, transmission of the pathogen is by root-to-root contact, and 2) the pathogen is a weakly competitive saprotroph. In Western Australia (WA), treatment and control plots were set-up along an active disease front within scrub-heath vegetation dominated by Banksia spp. Treatments, applied sequentially and in combination, included: 1) destruction of the largest plants within disease free vegetation forward of the disease front; 2) destruction of all plants to create a ‘dead zone’; 3) installation of physical root barriers and subsurface irrigation for the application of fungicide/s; 4) surface applications of fungicides selective against oomycetes (triadiazole and metalaxyl-M), and 5) surface injection and deep (± 1 m) treatments with Metham-sodium. In a separate experiment in Tasmania (TAS), combined treatments including vegetation removal, Ridomil and Metham-sodium and root barriers, or Ridomil and root barriers alone, were applied to experimental plots within active disease centres in Eucalyptus-Banksia woodland. In the WA experiment, P. cinnamomi was not recovered (by soil baiting) from plots after treatment with Ridomil and metham-sodium. In the TAS experiment, similar results were achieved with combined treatments (vegetation removal + Ridomil + metham sodium) but in plots treated with Ridomil alone, recoveries of P. cinnamomi increased after initially showing a significant reduction in recoveries.

The most serious foliar disease of eucalypt plantations in WA is Mycosphaerella leaf disease (MLD) (1). Since the commencement of the plantation industry, several fungal species contributing to MLD, previously known only in eastern Australia or overseas, have been reported on E. globulus in WA. Initially only three species were identified (2). More recently, five new records from WA (M. aurantia, M. ellipsoidea, M. mexicana and M. fori) have been identified that have not been recorded elsewhere in Australia (1, 3). Currently, 13 species of Mycosphaerella have been recorded in WA from Eucalyptus (3). Re‐examination of cultures adds six new species that have yet to be described from E. globulus in WA. The impact of MLD on growth of E. globulus plantations in WA was examined in a chemical exclusion trial at two plantations in the Albany region.