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1
Dillard, HR, TJ Wicks y B. Philp. "A grower survey of diseases, invertebrate pests, and pesticide use on potatoes grown in South Australia". Australian Journal of Experimental Agriculture 33, n.º 5 (1993): 653. http://dx.doi.org/10.1071/ea9930653.
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In 1991, a survey was distributed to 251 potato growers in South Australia to determine major diseases, insect and other invertebrate pests, and chemicals used to control them. The overall response rate was 48%, but of these, 24 individuals were no longer growing potatoes. The results were summarised for the State and by district (Adelaide Hills, Adelaide Plains, Murray Lands, South East). The most prevalent diseases encountered by respondents in all districts were target spot caused by Alternaria solani, and rhizoctonia canker caused by Rhizoctonia solani. Other diseases of concern to growers included late blight caused by Phytophthora infestans, seed piece decay caused by various pathogenic and saprophytic microorganisms, common scab caused by Streptomyces scabies, and leaf roll caused by potato leaf roll virus. The most commonly used fungicides for disease control were chlorothalonil (33-42% of respondents), mancozeb (30%), and cupric hydroxide (11-13%). The most commonly used seed treatments for control of seed piece decay were mancozeb (51 % of respondents), tolclofos methyl (24%), and lime (20%). Green peach aphid (Myzus persicae), potato aphid (Macrosiphum euphorbiae), potato moth (Phthorimaea operculella), and jassids and leafhoppers (Jassidae, Cicadellidae) were the pests of greatest concern to the growers. Others included Rutherglen bug (Nysius vinitor), redlegged earth mite (Halotydeus destructor), and thrips (Thripidae). The most commonly used insecticides were ethamidophos (40% of respondents), monocrotophos (22-28%), and dimethoate (7-13%).
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Henzell, Robert P., Brian D. Cooke y Gregory J. Mutze. "The future biological control of pest populations of European rabbits, Oryctolagus cuniculus". Wildlife Research 35, n.º 7 (2008): 633. http://dx.doi.org/10.1071/wr06164.
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European rabbits are exotic pests in Australia, New Zealand, parts of South America and Europe, and on many islands. Their abundance, and the damage they cause, might be reduced by the release of naturally occurring or genetically modified organisms (GMOs) that act as biological control agents (BCAs). Some promising pathogens and parasites of European rabbits and other lagomorphs are discussed, with special reference to those absent from Australia as an example of the range of necessary considerations in any given case. The possibility of introducing these already-known BCAs into areas where rabbits are pests warrants further investigation. The most cost-effective method for finding potentially useful but as-yet undiscovered BCAs would be to maintain a global watch on new diseases and pathologies in domestic rabbits. The absence of wild European rabbits from climatically suitable parts of North and South America and southern Africa may indicate the presence there of useful BCAs, although other explanations for their absence are possible. Until the non-target risks of deploying disseminating GMOs to control rabbits have been satisfactorily minimised, efforts to introduce BCAs into exotic rabbit populations should focus on naturally occurring organisms. The development of safe disseminating GMOs remains an important long-term goal, with the possible use of homing endonuclease genes warranting further investigation.
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Wicks, TJ y AR Granger. "Effects of low rates of pesticides on the control of pests and diseases of apples". Australian Journal of Experimental Agriculture 29, n.º 3 (1989): 439. http://dx.doi.org/10.1071/ea9890439.
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Fungicides and insecticides used at the recommended rate, and reduced recommended rates were applied at low volume (100 L ha-1) to apple trees in field experiments in South Australia from 1985 to 1988. At harvest the incidence of fruit damaged by fungi and insects was assessed on Golden Delicious, Red Delicious, Jonathan and Granny Smith cultivars. Mixtures of penconazole and mancozeb applied at the recommended rates of 800 mL and 4.5 kg ha-1 respectively as well as 25% and 10% of the recommended rates controlled apple scab completely in 1986, but were less effective in 1987. Azinphos-methyl applied at the recommended rate of 2.7 kg and 25% of the recommended rate reduced codling moth infestation to commercially acceptable levels of <2 % on Red Delicious only in 1987. Considerable cost savings are possible by using low rates of pesticides. Our results suggest that the use of low rates is more applicable to low valued cultivars such as Jonathans and orchards with low levels of pest and disease.
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Carnegie, Angus J. y Geoff S. Pegg. "Lessons from the Incursion of Myrtle Rust in Australia". Annual Review of Phytopathology 56, n.º 1 (25 de agosto de 2018): 457–78. http://dx.doi.org/10.1146/annurev-phyto-080516-035256.
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Austropuccinia psidii (myrtle rust) is a globally invasive neotropical rust of the Myrtaceae that came into international prominence following extensive damage to exotic Eucalyptus plantations in Brazil in the 1970s and 1980s. In 2005, myrtle rust established in Hawaii (USA), and over the past 12 years has spread from the Americas into Asia, the Pacific, and South Africa. Myrtle rust was detected in Australia in 2010, and the response and ultimately unsuccessful eradication attempt was a lesson to those concerned about the threat of exotic pests and diseases to Australia's environment. Seven years following establishment, we are already observing the decline of many myrtaceous species and severe impacts to native plant communities. However, the recently developed Myrtle rust in Australia draft action plan identified that there is no nationally coordinated response strategy for the environmental dimensions of this threat. Recent reviews have identified a greater need for involvement from environmental agencies in biosecurity preparedness, response, and resourcing, and we believe this approach needs to extend to the management of invasive environmental pathogens once they establish.
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Coops, N., M. Stanford, K. Old, M. Dudzinski, D. Culvenor y C. Stone. "Assessment of Dothistroma Needle Blight of Pinus radiata Using Airborne Hyperspectral Imagery". Phytopathology® 93, n.º 12 (diciembre de 2003): 1524–32. http://dx.doi.org/10.1094/phyto.2003.93.12.1524.
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Dothistroma needle blight is a serious foliar disease in Australian Pinus radiata plantations causing defoliation, decreased productivity and, in extreme cases, tree death. Conventional methods of monitoring forest health such as aerial survey and ground assessments are labor intensive, time consuming, and subjective. Remote sensing provides a synoptic view of the canopy and can indicate areas affected by damaging agents such as pests and pathogens. Hyperspectral airborne remote sensing imagery (CASI-2) was acquired over pine stands in southern New South Wales, Australia which had been ground assessed and ranked on an individual tree basis, according to the extent of Dothistroma needle blight. A series of spectral indices were tested using two different approaches for extracting crown-scale reflectance measurements and relating these to ground-based estimates of severity. Dothistroma needle blight is most severe in the lower crown and statistically significant relationships were found between crown reflectance values and ground estimates using a ‘halo’ approach (which ignored each tree crown's brightest central pixels). Independent accuracy assessment of the method indicated that the technique could successfully detect three levels of Dothistroma needle blight infection with an accuracy of over 70%.
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Fraedrich, Stephen W. y L. David Dwinell. "An Evaluation of Dazomet Incorporation Methods on Soilborne Organisms and Pine Seedling Production in Southern Nurseries". Southern Journal of Applied Forestry 27, n.º 1 (1 de febrero de 2003): 41–51. http://dx.doi.org/10.1093/sjaf/27.1.41.
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Abstract The use of dazomet as a fall and spring fumigant for pine seedling production and control of soilborne pests was evaluated at two southern nurseries. Dazomet was applied at low (280–325 kg/ha) and high (493–560 kg/ha) rates and incorporated with a rototiller or spading machine. Comparisons were made with methyl bromide/chloropicrin (MBC) fumigation and nonfumigated control treatments. Dazomet incorporation method had no effect on seedling density at either nursery, and often did not affect seedling morphological characteristics. At the Georgia (GA) nursery, seedling density and morphological characteristics did not differ among fumigant treatments except in the spring study area where shoot weight was greater in the MBC treatment than the dazomet or nonfumigated control treatments. In the fall study area at the North Carolina (NC) nursery, seedling density was greater in the high-rate dazomet treatment than the nonfumigated control. Seedlings were generally larger in MBC and dazomet treatments than the control. Seedling density and morphological characteristics did not differ among fumigation treatments in the spring study area. Fumigation with MBC or dazomet generally reduced the percentage of roots withPythium andFusarium spp. compared to controls at the GA nursery and the fall fumigation area in the NC nursery. Plant parasitic nematodes were found infrequently at both nurseries and did not differ among treatments. Nutsedge (Cyperus spp.) was the major problem at the GA nursery and was effectively controlled only with MBC. Compared to the MBC treatment, the abundance of soilborne fungi and the association of certain types ofTrichoderma with roots was often lower in the dazomet treatments. The importance of these differences for long term seedling production and management of soilborne diseases is not known at this time. South. J. Appl. For. 27(1):41–51.
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Watt, Michael S., Rebecca J. Ganley, Darren J. Kriticos y Lucy K. Manning. "Dothistroma needle blight and pitch canker: the current and future potential distribution of two important diseases of Pinus species". Canadian Journal of Forest Research 41, n.º 2 (febrero de 2011): 412–24. http://dx.doi.org/10.1139/x10-204.
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Globally, pitch canker and Dothistroma needle blight are two of the most important diseases of pine species caused, respectively, by the pathogens Fusarium circinatum Nirenberg & O’Donnell and Dothistroma spp. ( Dothistroma septosporum (Dorog.) Morelet and Dothistroma pini Hulbary). The potential distributions of these two diseases under current global climate have previously been modelled and contrast strongly with each other. In this study, we used the process-based niche model CLIMEX to estimate the potential distribution of both diseases in the 2080s under six scenarios that include three contrasting global climate models, each with moderate and high CO2 emissions. For both diseases, under the future climate scenarios, there was a global reduction in the potentially suitable area. Among the three global climate models, this reduction ranged from 11% to 22% for Dothistroma needle blight and from 39% to 58% for pitch canker. The projected potential ranges of both diseases were significantly reduced for Africa, South America, and Australia. In Asia and North America, substantial reductions in potential area were generally projected for pitch canker, while little change to moderate levels of expansion were projected for Dothistroma needle blight. For Europe and New Zealand, expansion of suitable climate was projected under all climate change scenarios for both diseases.
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Lakew, Biniam T., Adrian H. Nicholas y Stephen W. Walkden-Brown. "Spatial and temporal distribution of Culicoides species in the New England region of New South Wales, Australia between 1990 and 2018". PLOS ONE 16, n.º 4 (5 de abril de 2021): e0249468. http://dx.doi.org/10.1371/journal.pone.0249468.
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Culicoides are one of the smallest hematophagous flies measuring 1–5 mm in size with only females seeking blood for egg development. The present study investigated spatio-temporal distribution of Culicoides species trapped between 1990 and 2018 at 13 sites in the New England region of NSW, Australia using automated light traps. Trapping locations were divided into three subregions (tablelands, slopes and plains). Nineteen Culicoides species were identified. Culicoides marksi and C. austropalpalis were the most abundant and widespread species. Culicoides brevitarsis, the principal vector of livestock diseases in New South Wales comprised 2.9% of the total catch and was detected in 12 of the 13 locations in the study. Abundance as determined by Log10 Culicoides count per trapping event for the eight most abundant species did not vary significantly with season but trended towards higher counts in summer for C. marksi (P = 0.09) and C. austropalpalis (P = 0.05). Significant geographic variation in abundance was observed for C. marksi, C. austropalpalis and C. dycei with counts decreasing with increasing altitude from the plains to the slopes and tablelands. Culicoides victoriae exhibited the reverse trend in abundance (P = 0.08). Greater abundance during the warmer seasons and at lower altitudes for C. marksi and C. austropalpalis was indicative of temperature and rainfall dependence in this region with moderate summer dominance in rainfall. The Shannon-Wiener diversity index of species was higher on the tablelands (H = 1.59) than the slopes (H = 1.33) and plains (H = 1.08) with evenness indices of 0.62, 0.46 and 0.39 respectively. Culicoides species on the tablelands were more diverse than on the slopes and plains where C. marksi and C. austropalpalis dominated. The temporal and spatial variation in abundance, diversity and evenness of species reported in this diverse region of Australia provides additional insight into Culicoides as pests and disease vectors and may contribute to future modelling studies.
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Lazreg, F., L. Belabid, J. Sanchez, E. Gallego, J. A. Garrido-Cardenas y A. Elhaitoum. "First Report of Globisporangium ultimum Causing Pythium Damping-Off on Aleppo Pine in Algeria, Africa, and the Mediterranean Region". Plant Disease 97, n.º 8 (agosto de 2013): 1111. http://dx.doi.org/10.1094/pdis-07-12-0625-pdn.
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Globisporangium ultimum (Trow) Uzuhashi, Tojo & Kakish. (syn. Pythium ultimum Trow, syn. P. ultimum Trow var. ultimum) is a known oomycetal species from Pythium s.l. causing damping-off and/or root rot on a great variety of plants throughout the world, including some pine species (Pinus L.) and conifers (2,3). Aleppo pine (Pinus halepensis Mill.) is a common native forest tree in the Mediterranean region. Pre- and post-emergence damping-off disease symptoms were observed during 2008 and 2009 in four forest nurseries from northwestern Algeria (Relizane, Sidi Belabes, and Tlemcen departments). This disease occurred under cool conditions, and Aleppo pines were significantly affected, reducing seedling emergence. Disinfected segments, about 5 mm in length, from decayed root and collar, were cultured on CMA at 25°C. This oomycetal species was identified based on the species description in Pythium keys (3,4). For the molecular identification, PCR was used to amplify the ITS region of Pythium isolates. It was amplified with the flanking primers ITS1 and ITS4, and these products were directly sequenced. Sequence data were compared to known sequences deposited in the NCBI non redundant database to confirm morphological identification. A BLAST search identified U3CR, U7CR, U1RT, U2CR, U4CR, U14CR, U7RT, and U17RT isolates (GenBank Accession Nos. JX191921, 22, 27, 29, 31, and 33 to 35, respectively) as G. ultimum based on 100% similarity with corresponding sequence of the reference isolate no. UZ056 MAFF240024 (AB468781) (3). Phytopathogenicity testing was conducted in a petri dish and pot experiment. In the petri dish experiment, a 3 mm diameter plug was transferred from a 7-day-old CMA colony to the center of a CMA petri dish, with three replicates per isolate, and three control plates were inoculated with sterile agar plugs. After 72 h, 10 Aleppo pine seeds were placed equally spaced to 1 cm from the edge of each plug. After 7 days at 22°C in the dark, germination inhibition (46.1 to 87.6%) and root growth inhibition (62.3 to 92.2%) were calculated. In the control plates, germination failure (13.4%) and root length (27.7 cm) were observed. For the pot experiment, inocula were produced by adding a 5 mm diameter plug from a 7-day-old CMA culture to a previously sterilized 500 ml flask containing 237.5 g sand, 12.5 g cornmeal, and 80 ml SDW. Nine-day-old inoculum was mixed with sterile soil at a rate of 1:3 (v:v). Inoculum was transferred to 500 ml pot, and 10 Aleppo pine seeds were planted, with three replicates per isolate, and three control pots were used. After 2 weeks, all of the isolates tested caused typical symptoms of Aleppo pine Pythium damping-off, the percentage of inoculated plants that became infected was 36.6 to 83.3%. In the control pots, no infected plants were observed. To our knowledge, this is the first report of G. ultimum causing damping-off on Aleppo pine in Algeria, Africa, and the Mediterranean Region. Before, Aleppo pine damping-off caused by G. ultimum was reported in Australia (1). References: (1) R. P. Cook and A. J. Dubé. Host-pathogen index of plant diseases in South Australia. SADA, Melbourne, Australia, 1989. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory. ARS, USDA, Bestville, MD. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , June 24, 2012. (3) S. Uzuhashi et al. Mycoscience 51:337, 2010. (4) A. J. van der Plaats-Niterink. Stud. Mycol. 21:1, 1981.
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Waller, R. A. y P. W. G. Sale. "Persistence and productivity of perennial ryegrass in sheep pastures in south-western Victoria: a review". Australian Journal of Experimental Agriculture 41, n.º 1 (2001): 117. http://dx.doi.org/10.1071/ea00049.
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Loss of perennial ryegrass (Lolium perenne L.) from the pasture within several years of sowing is a common problem in the higher rainfall (550–750 mm annual rainfall), summer-dry regions of south-eastern Australia. This pasture grass came to Australia from northern Europe, where it mostly grows from spring to autumn under mild climatic conditions. In contrast, the summers are generally much drier and hotter in this region of south-eastern Australia. This ‘mismatch’ between genotype and environment may be the fundamental reason for the poor persistence. There is hope that the recently released cultivars, Fitzroy and Avalon, selected and developed from naturalised ryegrass pastures in south-eastern Australia for improved winter growth and persistence will improve the performance of perennial ryegrass in the region. Soon-to-be released cultivars, developed from Mediterranean germplasm, may also bridge the climatic gap between where perennial ryegrass originated and where it is grown in south-eastern Australia. Other factors that influence perennial ryegrass persistence and productivity can be managed to some extent by the landholder. Nutrient status of the soil is important since perennial ryegrass performance improves relative to many other pasture species with increasing nitrogen and phosphorus supply. It appears that high soil exchangeable aluminium levels are also reducing ryegrass performance in parts of the region. The use of lime may resolve problems with high aluminium levels. Weeds that compete with perennial ryegrass become prevalent where bare patches occur in the pasture; they have the opportunity to invade pastures at the opening rains each year. Maintaining some herbage cover over summer and autumn should reduce weed establishment. Diseases of ryegrass are best managed by using resistant cultivars. Insect pests may be best managed by understanding and monitoring their biology to ensure timely application of pesticides and by manipulating herbage mass to alter feed sources and habitat. Grazing management has potential to improve perennial ryegrass performance as frequency and intensity of defoliation affect dry matter production and have been linked to ryegrass persistence, particularly under moisture deficit and high temperature stress. There is some disagreement as to the merit of rotational stocking with sheep, since the results of grazing experiments vary markedly depending on the rotational strategy used, climate, timing of the opening rains, stock class and supplementary feeding policy. We conclude that flexibility of grazing management strategies is important. These strategies should be able to be varied during the year depending on climatic conditions, herbage mass, and plant physiology and stock requirements. Two grazing strategies that show potential are a short rest from grazing the pasture at the opening rains until the pasture has gained some leaf area, in years when the opening rains are late. The second strategy is to allow ryegrass to flower late in the season, preventing new vegetative growth, and perhaps allowing for tiller buds to be preserved in a dormant state over the summer. An extension of this strategy would be to delay grazing until after the ryegrass seed heads have matured and seed has shed from the inflorescences. This has the potential to increase ryegrass density in the following growing season from seedling recruitment. A number of research opportunities have been identified from this review for improving ryegrass persistence. One area would be to investigate the potential for using grazing management to allow late development of ryegrass seed heads to preserve tiller buds in a dormant state over the summer. Another option is to investigate the potential, and subsequently develop grazing procedures, to allow seed maturation and recruitment of ryegrass seedlings after the autumn rains.
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Lodge, GM. "Management practices and other factors contributing to the decline in persistence of grazed lucerne in temperate Australia: a review". Australian Journal of Experimental Agriculture 31, n.º 5 (1991): 713. http://dx.doi.org/10.1071/ea9910713.
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The literature relevant to the grazing management of lucerne in temperate Australia is reviewed with emphasis on the factors likely to affect its persistence. Knowledge of lucerne physiology is used to question the validity of the traditional methods of managing grazed stands, which rely mainly on using 10% flowering as a guide to root carbohydrate levels. From these data several alternative management guidelines are proposed that may lead to increased persistence; however, for long-term persistence, there is little doubt that lucerne needs to be grazed leniently and at a late stage of maturity. Several grazing experiments indicate that grazing periods of 16-20 days should have no effect on persistence, provided that the rest period between successive grazings is 35 days or longer. Data from other countries and Australian data from a limited number of experiments also indicate that grazing in either autumn or winter may substantially reduce production and could affect persistence. Three grazing studies in New South Wales were used to highlight critical differences in experimental design which make comparisons among experiments difficult. Standardised sowing rates and grazing management, and statistical procedures which account for the genotype x management x environment interaction, are suggested to improve the extrapolation of results from experiments to other environments. Persistence of different lucerne types under grazing, particularly those recently imported from the U.S.A. or bred in Australia, is considered. While it has been proposed that grazing effects may be related to crown structure, interactions with other factors which affect persistence may also occur. If grazing can be considered to be stressful to a lucerne plant then it could interact with other stresses, caused by moisture deficit, excessive moisture, insect pests and disease, to reduce persistence. Additionally, considerable variation in varietal resistance to some pests and diseases has been recorded in haycut stands, and so there may also be cultivar x grazing effects. All of these factors could combine to affect the persistence of a particular cultivar under grazing. Patterns of lucerne decline were either continuous or step-like. Continuous decline was associated with prolonged grazing, grazing and moisture stress, grazing under waterlogged conditions, or grazing in situations where the incidence of disease was likely to be high. To understand the reasons why plants fail to persist, measurements need to be made frequently and a1 regular intervals, and the moisture and disease status of the site needs to be accurately monitored. The adequacy of different methods of measuring stand persistence is also questioned. The implications for graziers, researchers and lucerne breeders are discussed.
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Nordblom, T. L., T. R. Hutchings, R. C. Hayes, G. D. Li y J. D. Finlayson. "Does establishing lucerne under a cover crop increase farm financial risk?" Crop and Pasture Science 68, n.º 12 (2017): 1149. http://dx.doi.org/10.1071/cp16379.
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Rainfed farms in south-eastern Australia often combine annual cropping and perennial pasture phases with grazing sheep enterprises. Such diversity serves in managing diseases, pests and plant nutrition while stabilising income in the face of wide, uncorrelated variations in international commodity prices and local weather over time. We use an actuarial accounting approach to capture the above contexts to render financial risk profiles in the form of distributions of decadal cash balances for a representative 1000-ha farm at Coolamon (34°50ʹS, 147°12ʹE) in New South Wales, Australia. For the soil and weather conditions at this location we pose the question of which approach is better when establishing the perennial pasture lucerne (Medicago sativa L.): sowing with the final crop of the cropping phase, or sowing alone following the final crop? It is less expensive to sow lucerne with the final crop, which can provide useful income from the sale of grain, but this practice can reduce pasture quantity and quality in poorer years. Although many years of field research have confirmed that sowing lucerne alone is the most reliable way to establish a pasture in this area, and years of extension messages to this effect have gone out to farmers, they often persist in sowing lucerne with their final cereal crops. For this region, counting all costs, we show that sowing lucerne alone can reduce farm financial risk (i.e. probability of negative decadal cash balances) at stocking rates >10 dry sheep equivalents (DSE)/ha, compared with the practice of sowing lucerne with a cover crop. Establishing lucerne alone allows the farmer the option to profitably run higher stocking rates for higher median decadal cash margins without additional financial risk. At low stocking rates (i.e. 5 DSE/ha), there appears to be no financial advantage of either establishment approach. We consider the level of equity, background farm debt and overhead costs to demonstrate how these also affect risk-profile positions of the two sowing options. For a farm that is deeply in debt, we cannot suggest either approach to establishing lucerne will lead to substantially better financial outcomes.
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Kishlyan, N. V., V. D. Bemova, T. V. Matveeva y V. A. Gavrilova. "Biological peculiarities and cultivation of groundnut (a review)". Proceedings on applied botany, genetics and breeding 181, n.º 1 (12 de abril de 2020): 119–27. http://dx.doi.org/10.30901/2227-8834-2020-1-119-127.
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Peanut is one of the most important crops in the Fabaceae Lindl. (Leguminosae L.) family. South America is considered to be the homeland of peanut, but now this crop is cultivated in America, Africa, Australia, Europe and Asia. The modern phylogenetic system of the genus Arachis L. includes 79 wild species and one cultivated species of common peanut (A. hypogaea L.). Diploid species contain 2n = 20 chromosomes of the A, B or D genome, tetraploids have A and B genomes. The А and В genomes are sequenced. Special biological features of all peanut varieties are the presence of chasmogamous and cleistogamous flowers and the development of pods only underground (geocarpy). Along with high requirements for improving the quality of oil and food products, much attention is paid to their safety: resistance to aflatoxin contamination and mitigation of allergenicity. Peanut cultivars vary in plant habit, shape and color of pods and seeds. Their growing season in Africa, Latin America and Asia is from 160 to 200 days, so early-ripening forms need to be selected for the south of the Russian Federation. Breeders from the Pustovoit Institute of Oil Crops (VNIIMK) have developed peanut cultivars with a yield of 2.0–3.3 t/ha and growing season duration of 115–120 days, adaptable to the environments of Krasnodar Territory. At present, there is no large-scale peanut production in Russia, nor any breeding efforts are underway. As for the world, along with conventional breeding practices (individual selection, intra- and interspecies crosses, etc.), peanut is widely involved in genomic studies. A number of cultivars highly resistant to pests, diseases and drought have been released. Over 15,000 peanut accessions are preserved in the world’s gene banks, including 1823 accessions in the collection of the Vavilov Institute (VIR). Utilization of the worldwide genetic resources of peanut and use of modern research technologies will contribute to the revival of peanut cultivation in Russia.
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Li, J., V. L. Gaskins, H. J. Yan, Y. G. Luo y W. M. Jurick II. "First Report of Mucor Rot on Stored ‘Gala’ Apple Fruit Caused by Mucor piriformis in Pennsylvania". Plant Disease 98, n.º 8 (agosto de 2014): 1157. http://dx.doi.org/10.1094/pdis-02-14-0149-pdn.
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Mucor piriformis E. Fischer causes Mucor rot of pome and stone fruits during storage and has been reported in Australia, Canada, Germany, Northern Ireland, South Africa, and portions of the United States (1,2). Currently, there is no fungicide in the United States labeled to control this wound pathogen on apple. Cultural practices of orchard sanitation, placing dry fruit in storage, and chlorine treatment of dump tanks and flumes are critical for decay management (3,4). Cultivars like ‘Gala’ that are prone to cracking are particularly vulnerable as the openings provide ingress for the fungus. Mucor rot was observed in February 2013 at a commercial packing facility in Pennsylvania. Decay incidence was ~15% on ‘Gala’ apples from bins removed directly from controlled atmosphere storage. Rot was evident mainly at the stem end and was light brown, watery, soft, and covered with fuzzy mycelia. Salt-and-pepper colored sporangiophores bearing terminal sporangiospores protruded through the skin. Five infected apple fruit were collected, placed in an 80-count apple box on trays, and temporarily stored at 4°C. Isolates were obtained aseptically from decayed tissue, placed on potato dextrose agar (PDA) petri plates, and incubated at 25°C with natural light. Five single sporangiospore isolates were identified as Mucor piriformis based on cultural characteristics according to Michailides and Spotts (1). The isolates produced columellate sporangia attached terminally on short and tall, branched and unbranched sporangiophores. Sporangiospores were ellipsoidal, subspherical, and smooth. Chlamydospore-like resting structures (gemmae), isogametangia, and zygospores were not evident in culture. Mycelial growth was examined on PDA, apple agar (AA), and V8 agar (V8) at 25°C with natural light. Isolates grew best on PDA at rates that ranged from 38.4 ± 5.3 to 34.5 ± 2.41 mm/day, followed by AA from 30.5 ± 1.22 to 28.5 ± 2.51 mm/day, and V8 from 29.2 ± 3.0 to 26.7 ± 2.17 mm/day. Species-level identification was conducted by isolating genomic DNA, amplifying a portion of the 28S rDNA gene, and directly sequencing the products. MegaBLAST analysis of the 2X consensus sequences revealed that all five isolates were 99% identical to M. piriformis (GenBank Accession No. JN2064761) with E values of 0.0, which confirms the morphological identification. Koch's postulates were conducted using organic ‘Gala’ apples that were surface sanitized with soap and water, then sprayed with 70% ethanol and allowed to air dry. Wounds 3 mm deep were created using the point of a finishing nail and then inoculated with 50 μl of a sporangiospore suspension (1 × 105 sporangiospores/ml) for each isolate. Ten fruit were inoculated with each isolate, and the experiment was repeated. The fruit were stored at 25°C in 80-count boxes on paper trays for 14 days. Decay observed on inoculated ‘Gala’ fruit was similar to symptoms originally observed on ‘Gala’ apples from storage and the pathogen was re-isolated from inoculated fruit. This is the first report of M. piriformis causing postharvest decay on stored apples in Pennsylvania and reinforces the need for the development of additional tools to manage this economically important pathogen. References: (1) T. J. Michailides, and R. A. Spotts. Plant Dis. 74:537, 1990. (2) P. L. Sholberg and T. J. Michailides. Plant Dis. 81:550, 1997. (3) W. L. Smith et al. Phytopathology 69:865, 1979. (4) R. A. Spotts. Compendium of Apple and Pear Diseases and Pests: Second Edition. APS Press, St. Paul, MN, 2014.
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Healey, Adam L., Mervyn Shepherd, Graham J. King, Jakob B. Butler, Jules S. Freeman, David J. Lee, Brad M. Potts et al. "Pests, diseases, and aridity have shaped the genome of Corymbia citriodora". Communications Biology 4, n.º 1 (10 de mayo de 2021). http://dx.doi.org/10.1038/s42003-021-02009-0.
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AbstractCorymbia citriodora is a member of the predominantly Southern Hemisphere Myrtaceae family, which includes the eucalypts (Eucalyptus, Corymbia and Angophora; ~800 species). Corymbia is grown for timber, pulp and paper, and essential oils in Australia, South Africa, Asia, and Brazil, maintaining a high-growth rate under marginal conditions due to drought, poor-quality soil, and biotic stresses. To dissect the genetic basis of these desirable traits, we sequenced and assembled the 408 Mb genome of Corymbia citriodora, anchored into eleven chromosomes. Comparative analysis with Eucalyptus grandis reveals high synteny, although the two diverged approximately 60 million years ago and have different genome sizes (408 vs 641 Mb), with few large intra-chromosomal rearrangements. C. citriodora shares an ancient whole-genome duplication event with E. grandis but has undergone tandem gene family expansions related to terpene biosynthesis, innate pathogen resistance, and leaf wax formation, enabling their successful adaptation to biotic/abiotic stresses and arid conditions of the Australian continent.
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Tang, Xinggang, Yingdan Yuan, Xiangming Li y Jinchi Zhang. "Maximum Entropy Modeling to Predict the Impact of Climate Change on Pine Wilt Disease in China". Frontiers in Plant Science 12 (23 de abril de 2021). http://dx.doi.org/10.3389/fpls.2021.652500.
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Pine wilt disease is a devastating forest disease caused by the pinewood nematode Bursaphelenchus xylophilus, which has been listed as the object of quarantine in China. Climate change influences species and may exacerbate the risk of forest diseases, such as the pine wilt disease. The maximum entropy (MaxEnt) model was used in this study to identify the current and potential distribution and habitat suitability of three pine species and B. xylophilus in China. Further, the potential distribution was modeled using the current (1970–2000) and the projected (2050 and 2070) climate data based on two representative concentration pathways (RCP 2.6 and RCP 8.5), and fairly robust prediction results were obtained. Our model identified that the area south of the Yangtze River in China was the most severely affected place by pine wilt disease, and the eastern foothills of the Tibetan Plateau acted as a geographical barrier to pest distribution. Bioclimatic variables related to temperature influenced pine trees’ distribution, while those related to precipitation affected B. xylophilus’s distribution. In the future, the suitable area of B. xylophilus will continue to increase; the shifts in the center of gravity of the suitable habitats of the three pine species and B. xylophilus will be different under climate change. The area ideal for pine trees will migrate slightly northward under RCP 8.5. The pine species will continue to face B. xylophilus threat in 2050 and 2070 under the two distinct climate change scenarios. Therefore, we should plan appropriate measures to prevent its expansion. Predicting the distribution of pine species and the impact of climate change on forest diseases is critical for controlling the pests according to local conditions. Thus, the MaxEnt model proposed in this study can be potentially used to forecast the species distribution and disease risks and provide guidance for the timely prevention and management of B. xylophilus.