Fruit In Australia Research Articles

The genetic variability of grapevine Pinot gris virus (GPGV) in Australia

Grapevine Pinot gris virus (GPGV; genus Trichovirus in the family Betaflexiviridae) was detected in Australia in 2016, but its impact on the production of nursery material and fruit in Australia is still currently unknown. This study investigated the prevalence and genetic diversity of GPGV in Australia. GPGV was detected by reverse transcription-polymerase chain reaction (RT-PCR) in a range of rootstock, table and wine grape varieties from New South Wales, South Australia, and Victoria, with 473/2171 (21.8%) samples found to be infected. Genomes of 32 Australian GPGV isolates were sequenced and many of the isolates shared high nucleotide homology. Phylogenetic and haplotype analyses demonstrated that there were four distinct clades amongst the 32 Australian GPGV isolates and that there were likely to have been at least five separate introductions of the virus into Australia. Recombination and haplotype analysis indicate the emergence of new GPGV strains after introduction into Australia. When compared with 168 overseas GPGV isolates, the analyses suggest that the most likely origin of Australian GPGV isolates is from Europe. There was no correlation between specific GPGV genotypes and symptoms such as leaf mottling, leaf deformation, and shoot stunting, which were observed in some vineyards, and the virus was frequently found in symptomless grapevines.

First Report of Fruit Rot of Sweet Pepper Caused by Cladosporium cladosporioides in Israel.

Sweet pepper (Capsicum annuum L.) is an important vegetable crop grown in Israel for local and export markets. Bell pepper 'Dinamo' and sweet bite pepper exhibiting fruit spotting were observed in postharvest storage of commercial farms in Giv'at Ko'ah (32°02'21″ N; 34°56'41″ E) and Arava (30°46'41″ N; 35°14'28″ E) in July, 2021. Fruit with lesions were sporadic at each facility, however, limited numbers of packaged boxes were discarded due to a high percentage of symptomatic fruit. The spots appeared as slightly sunken dark brown or black lesions, coated by a fine velvety layer of olive-grey conidia (Suppl. Fig. 1). A fungus was routinely isolated from the fruit onto potato dextrose agar amended with 50 ppm chloramphenicol (PDAC) and was tentatively identified as a Cladosporium spp. based on colony morphology and conidial appearance (Suppl. Fig. 1). Isolates (n = 6) of the fungus were cultured on malt extract agar (MEA) and PDA for morphological observation. On MEA, the pathogen sporulated profusely and conidia measured 4.5 (3 - 7) × 3.5 (2 - 4) µm and were smooth and globose or sub-globose. Ramoconidia had 0 or 1 septations and measured 13.4 (10 - 18) × 3.9 (3 - 6) µm. Conidiophores were solitary, straight or flexous, usually unbranched, and measured 60 - 350 µm. Both macro- and micronematous conidiophores were present. Hyphae were flat and immersed, olivaceous-grey, septate and rope-like. The fungus was slow growing, reaching 41.0 mm after 10 d incubation at 20°C. To confirm species identity, the isolates were grown in potato dextrose broth and DNA was extracted from the mycelium using MasterPure DNA Purification Kit (EpiCentre, Madison, WI, USA) following the manufacturer's instructions. The internal transcribed spacer (ITS) region was amplified using primers ITS 1 and ITS 4, and elongation factor-1 and actin gene regions with EF1-728F/986R and ACT-512F/783R, respectively (Carbone and Kohn, 1999). The PCR products were sequenced and a BLASTn search showed 99-100% similarity to Cladosporium cladosporioides (GenBank accession nos. MW255614.1, MK416093.1, MK306457.1), a common fungal species found worldwide as a plant pathogen and saphrophyte (Bensch et al., 2012). The ITS gene sequences for a representative isolate from each location were deposited in GenBank (accession nos. OK104139.1 and OL672241.1). To confirm pathogenicity, red bell pepper fruits (n = 8) were wounded with a sterile needle and a 12 µl drop of conidial suspension (4 x 105/ml) of each isolate was pipetted onto the wound. Control fruit received sterile water. The fruit were incubated at 100% RH in sealed containers at 20-22°C. After 7-10 d incubation small dark sunken spots developed, and by 14 d lesions formed with velvety conidial growth similar to the ones originally observed. The fungus was successfully isolated again from the lesions onto PDA and confirmed as C. cladosporioides based on colony and conidial morphology. No symptoms developed on fruit inoculated with sterile water. The pathogenicity test was repeated two times with similar results. C. cladosporioides is a cosmopolitan pathogen and has been cited causing disease on numerous crops worldwide (Bensch et al., 2012). This species was reported causing tomato leaf spot in Mexico (Robles-Yerena et al., 2019) and black mould of tomato fruit in Australia (Ma et al., 2020). Cladosporium herbarum was found causing fruit rot of bell pepper in the U.S. (Ramsey and Heiberg, 1952). Sweet peppers are widely grown in Israel, and have high economic value as an export crop. Control measures to limit losses from C. cladosporioides postharvest may be necessary if conditions are favorable for disease during prolonged storage and refrigerated transport.

Low hanging fruit in Australia's climate policy

Australia has a history of fragmented and politically contested climate policy, and current climate policy is both piecemeal and limited in scope and ambition. Ample opportunities exist to reduce emissions through the more broad-based application of policy. This paper outlines six areas where climate policy in Australia could achieve emissions reductions at low cost: pricing emissions in industry through a modification and broadening of the existing Safeguards Mechanism; investment in assisting the transformation of the electricity grid to very high shares of renewables; a mixture of innovation support, and targeted incentives and regulatory standards in specific sectors and activities; an effective green infrastructure program to stimulate demand and raise productivity in the medium term; a community focussed structural adjustment fund that would enable disproportionately impacted communities to adapt reality of the global transition to net-zero emissions by 2050; and removing impediments to the emergence of new renewable energy-based export industries to take the place of coal and gas exports.

The effect of different drying techniques on phytochemical content and in vitro antioxidant properties of Australian‐grown prickly pears ( Opuntia ficus indica )

Abstract Prickly Pear (Opuntia ficus indica) is commonly consumed but limited by short harvesting seasons and shelf life. Drying may resolve such issues. The effects of different methods were examined to investigate the phytochemicals in Australian prickly pear (PP). White, orange and purple fruits were dried using freeze-drying, microwave, draft-oven, and dehydrator-drying (35°C, 55°C, and 75°C). Total Phenolic Content (TPC), Total Flavonol Content (TFC), Total Betalain Content (TBC), Betacyanin (BE), and Betaxanthin (IE) and antioxidant characteristics (2,2-diphenyl-1-picrylhydrazyl [DPPH], Cupric Ion Antioxidant Reducing Capacity [CUPRAC], and Ferric Reducing Antioxidant Power [FRAP]) were determined as methanolic extracts (skin/flesh). The highest content is as follows: TPC (149 ± 5.06 µgGAE; microwave; purple skin), TFC (76.6 ± 1.98 µgCE; microwave; purple-skin), TBC (4.17 ± 0.846 mg/100 g; freeze-dried; orange-skin and flesh), BE (2.29 ± 1.00 mgBE/100 g; freeze-dried; purple-flesh), IE (3.42 ± 0.569 mgIE/100 g; freeze-dried; purple-flesh); DPPH (224 ± 41.2 µMTE; freeze-dried; white-flesh), CUPRAC (2,937 ± 43.3 µMTE; microwave; purple-skin) and FRAP (1,377 ± 27.0 µMTE; microwave; purple-skin). Significant differences (p < 0.05) occurred between drying methods. When compared to freeze drying, microwaving, in some cases elicited the highest content. Practical applications The gap between the nutrient-dense prickly pear fruit, and its consumption is prominent, particularly in Australia. This is potentially the consequences of social misconceptions, a short harvesting season and shelf life, thus potentially contributing to Australia's growing food waste challenge. Therefore, such obstacles could be reduced with the use of the most appropriate drying technique in order to extend the products shelf life. Our manuscript investigates the effect of different drying techniques on the phytochemical content of the prickly pear fruit. The investigated drying methods were considered accessible to small agricultural producers, the predominant farmers for this fruit in Australia. The findings of this paper can be potentially implemented in agricultural practice, assisting with year-round food supply and reduce on-site foods waste.

Roadblocks to assessing climate impacts on temperate perennial fruit

Observed climate changes are already increasing pressure on agricultural productivity, highlighting the need for the construction of reliable assessments of projected climate change impacts on plant processes. Such impact assessments underpin adaptive options and indicate pathways to manage expected risk and illustrate future opportunities. Using projections of spring frost risk for pome fruit in Australia, potential barriers to construction of climate impact assessments are demonstrated. Through using various phenology models and potential future representations of frost conditions the sensitivity of future risk outcomes were assessed at two Australian orchards. It was found that potential frost risk for seven flowering datasets was entirely method dependent with either a decrease, no change or increase resulting. Three key barriers need to be overcome to provide better assessments of climate impacts for the pome fruit industry: 1) improvement of process knowledge surrounding flowering physiology; 2) confidence in phenology model selection to represent flowering; and 3) better characterisation of frost conditions (historically and into the future). Overcoming these barriers will provide a solid foundation for adaptive responses, which is particularly critical within this industry due to time and cost of transformative adaptation.

Potential impacts of rising global temperatures on Australia's pome fruit industry and adaptation strategies

Temperature has a key influence on plant growth. Rising temperatures associated with the enhanced greenhouse effect are likely to have important impacts on the plants that humans grow for food. This review examines some of the implications of elevated temperature on pome fruit in Australia, where the pome fruit industry is a valuable contributor to economic and social stability in rural regions. Many pome fruit growing regions are likely to become too hot in the future for viable production from existing tree varieties and there are few cooler regions available to establish new orchards. Nonetheless, it is anticipated that economically sustainable production in existing locations could be maintained at least in the short term by deploying adaptive strategies such as on-farm practices that help cool and protect fruit crops. Under predicted climate change scenarios the need for adaptation is clear if the Australian pome fruit industry is to survive.

Caseload midwifery bears fruit in Australia

Caseload midwifery bears fruit in Australia

Evaluation of monitoring methods for thrips and the effect of trap colour and semiochemicals on sticky trap capture of thrips (Thysanoptera) and beneficial insects (Syrphidae, Hemerobiidae) in deciduous fruit trees in Western Australia

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), plague thrips (Thrips imaginis Bagnall), and onion thrips (Thrips tabaci Lindeman) are pests of deciduous fruit trees in Australia. Yellow sticky traps and tapping buds and flowers for thrips are currently recommended for monitoring, but it is not known whether one method is more efficient than the other, or if selectivity could be optimised by trap colour, or addition of semiochemicals Thriplineams® or Lurem-TR lures to traps. The number and species of thrips caught by trapping and tapping of flowers and leaves, on different trap colours (black, blue, green, red, yellow, white), including a control (clear) and thrips semiochemicals, were evaluated in a series of trials in commercial deciduous fruit orchards in the Perth Hills, Western Australia. There was poor correlation between thrips caught on traps and tapping samples (R2 = 0.00–0.05), with tapping less likely to trigger the action threshold and yielding less than 1% of the number of thrips caught on sticky traps. More thrips (F. occidentalis, T. imaginis and T. tabaci) were caught on blue, yellow and white bases, than on clear, red, green or black bases. On commercially available sticky traps, seven times more F. occidentalis were caught on ‘Seabright blue’ traps than yellow. The addition of semiochemicals increased capture of F. occidentalis by three times on baited compared to unbaited traps, on yellow and ‘Seabright’ blue traps. Thriplineams® attracted F. occidentalis, but had no effect on the capture of T. imaginis or T. tabaci, whilst Lurem-TR attracted more F. occidentalis and also increased the capture of T. imaginis. More beneficial insects including brown lacewings (Micromus tasmaniae (Walker)) and hoverflies (Melangyna viridiceps (Macquart)) were caught on blue trap bases (1.6 times more) than other trap base colours. No beneficial insects were present during the Thriplineams® experiment, whilst Lurem-TR increased trap capture of brown lacewings by 1.3 times. A monitoring system incorporating blue sticky traps in conjunction with Thriplineams® would be more selective at detecting and monitoring F. occidentalis in deciduous fruit in Australia.

Pupal release of the Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), in the sterile insect technique: seasonal variation in eclosion and flight

The Queensland fruit fly, Bactrocera tryoni (Froggatt), is the most significant pest of edible fruit in Australia. For the control of B. tryoni using sterile insect technique (SIT), either pupae or adults may be released. Using pupal release, this study tested the seasonal effect of different pupal loadings on eclosion and the flight of sterile B. tryoni. Pupal eclosion boxes were loaded with either 200, 350, 500, 650 or 800 g of pupae during five periods of the fruit fly season (August, October, December, February and April). Adult flies were allowed to emerge and the remaining pupal debris was sampled to determine the per cent emergence and per cent fliers. The duration of emergence, dye retention on the ptilinum of the flies, and temperature and relative humidity externally and internally of the eclosion boxes were recorded. The percentage of emergence was influenced by both pupal loading and the period of release. Overall, the percentage of emergence was lower for loadings of 200 and 350 g of pupae in August, October and April as compared with the 500 g or higher loadings. This difference was not apparent in December or February. The mean percentage of emergence for each pupal loading in December, February and April was well above 65%, the minimum required emergence parameter for successful sterile B. tryoni release. Across all pupal loadings, the percentage of fliers was greater than 99.3% in December, 87.8% in February and 80.8% in April. A high percentage of fliers (>92.7%) was recorded in October, but the percentage of emergence in August and October was below 65% for all pupal loadings; thus pupal release is a suboptimal SIT method during this period of time. Dye on the ptilinum was detected on every fruit fly sampled across all pupal loadings and release periods. Minimum temperature for optimal pupal emergence should not fall below 10°C, and the maximum should not exceed 35°C. Minimum temperature for successful flight should not fall below approximately 6°C while the maximum temperature should exceed 16°C. The described pupal release system is considered a possible option for use as part of an SIT program against B. tryoni under suitable environmental conditions in Australia.

Potential to reduce the spatial density of attract and kill traps required for effective control of Carpophilus spp. (Coleoptera: Nitidulidae) in stone fruit in Australia

Attract and kill (A&K) is an effective control technique for Carpophilus spp. attacking stone fruit but high cost has limited its adoption by growers. Field experiments during two successive growing seasons evaluated the potential to reduce the spatial density of A&K traps from three traps per ha (3 A&K) to two traps per ha (2 A&K), against medium to low beetle populations. Fruit damage in 2 A&K and 3 A&K treated blocks was significantly lower than in pesticide-treated control blocks. However there were no significant differences in blocks treated with either 2 A&K or 3 A&K traps in either season. The results suggest that the number of traps per ha can be reduced without reducing the efficacy of the A&K treatment where Carpophilus population levels are medium to low.

Pathogenic diversity of avocado and mango isolates ofColletotrichum gloeosporioidescausing anthracnose and pepper spot in Australia

Colletotrichum gloeosporioides is a major fungal pathogen of avocado and mango fruit in Australia and overseas. It causes anthracnose and stem-end rot in these crops but has also been identified as the causal pathogen of pepper spot of avocado and tear stain of mango. Research was initiated to determine the pathogenic diversity of pepper spot, with emphasis on avocado. Eighty C. gloeosporioides isolates obtained from avocado and mango fruit showing anthracnose and pepper spot symptoms were screened for pathogenicity, comparative aggressiveness and cross-infection potential by inoculating onto detached avocado and mango fruit, avocado leaf petioles and branches of young, grafted nursery trees, as well as avocado fruit and pedicels still attached to the tree. On detached, ripening avocado and mango fruit in the laboratory, it was found that pepper spot isolates were as capable as anthracnose isolates of causing anthracnose lesions. However, avocado isolates were significantly (P < 0.05) more aggressive than mango isolates on avocado fruit and mango isolates were significantly (P < 0.05) more aggressive than avocado isolates on mango fruit. In field inoculations, pepper spots were formed on developing avocado fruit and pedicels on the tree. Likewise, pepper spots developed on petioles and branches of nursery avocado trees, but not on their leaves. When all isolates were grouped according to symptom or host of origin, significant differences in lesion severity were demonstrated between isolates on avocado petioles in the glasshouse, with avocado pepper spot isolates being the most aggressive, followed by avocado anthracnose isolates then mango isolates from both anthracnose and pepper spot, respectively. On unripe avocado fruit in the field, the pattern was generally similar with the mango isolates being the least aggressive. There were more and less pathogenic strains present in the pathogen populations from both mango fruit and avocado fruit but neither were restricted to anthracnose or pepper spot groupings. Generally, a higher percentage of the most aggressive isolates was from avocado pepper spot. When isolates were grouped according to the orchard of origin, there were significant differences in aggressiveness to avocado both in the glasshouse and the field.

Three Neofabraea species on pome fruit in Australia

Several Neofabraea species are important branch canker and fruit rot pathogens of pome fruit. In Australia, N. alba is common, whereas other Neofabraea species are rarely seen. All Australian herbarium specimens for these latter species were re-examined and β-tubulin sequences obtained. Victorian collections were determined to be Neofabraea perennans, whereas two New South Wales collections and a Western Australian collection were an undescribed species of Neofabraea, previously known only from Portugal and Canada. Despite bl]References in the Australian literature, Neofabraea malicorticis was not found and is considered to be exotic to Australia.

Phenology of carpophilus beetle populations (Coleoptera: Nitidulidae, Carpophilus spp.) in a fruit dump in northern Victoria

Carpophilus spp. are important pests of stone fruit in Australia. Maintenance of good orchard hygiene has been promoted as a way of reducing pressure from Carpophilus spp. In northern Victoria, Australia, it is common practice for fruit processors to dispose of waste fruit in dumps, many of which are near orchards. The importance of such dumps to Carpophilus spp. was not previously known. Seasonal variation of Carpophilus spp. in a fruit dump in Cobram, northern Victoria, was studied from September 1998 to September 2000. Three locations within the dump were randomly selected and inspected for presence of adults, larvae and pupae of Carpophilus spp. at regular intervals. Adults were used to determine species composition. Three species, C. hemipterus, C. humeralis and C. davidsoni were observed, with the former almost always dominant throughout monitoring. Carpophilus davidsoni was recorded only twice and in small numbers. The greatest number of C. hemipterus adults occurred during autumn and spring. Larval populations were high in late spring and early autumn and overwintering occurred as adults, larvae and pupae. The potential of populations of Carpophilus spp. in the fruit dump to cause damage in nearby ripening stone fruit is discussed.

Optimising ripening temperatures of Cavendish bananas var. 'Williams' harvested throughout the year in Queensland, Australia

Varying banana ripening temperatures were examined throughout the year to ensure optimum quality and shelf life of commercially ripened fruit in Australia. Cavendish bananas (var. 'Williams') were harvested throughout the year 2000 and were ripened at 14, 16, 18 and 20°C with 300 μL/L ethylene on 2 consecutive days until fruit were more yellow than green and then subsequently stored at 22°C until the end of the experiment. Ripening bananas at 14 and 16°C extended shelf life by up to 50 and 32%, respectively. However, ripening bananas at 14 and 16°C did increase peel discolouration, especially on bananas chilled in the field in winter. Bananas ripened at 18 or 20°C throughout the year had an average shelf life of 6 days and consistently lower peel discolouration. Therefore, ripening at 18 or 20°C throughout the year results in a better visual appearance of the fruit, which is essential for consumers.