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1
Scott, John K. "Biology and climatic requirements of Perapion antiquum (Coleoptera: Apionidae) in southern Africa: implications for the biological control of Emexspp. in Australia". Bulletin of Entomological Research 82, n. 3 (settembre 1992): 399–406. http://dx.doi.org/10.1017/s0007485300041195.
Testo completoAbstract (sommario):
AbstractThe potential distribution of the South African weevil, Perapion antiquum (Gyllenhal), a biological control agent for the weeds Emex spp., was deter mined by the computer program CLIMEX, using its native distribution, phenology and abundance together with development parameters. The predicted distribution included parts of Hawaii where the weevil successfully controlled Emex australis and E. spinosa. In Australia, sites of past unsuccessful releases have climates that this analysis indicates are unsuitable for the insect. The most favourable regions for establishment of the weevil are near the coast in the southern half of Australia, but most of these do not overlap with regions where Emex spp. are a problem. In western Cape Province, South Africa, E. australis plants are abundant and the weevil attacks the plant after seeds have formed. In Hawaii, a fortuitous combination of climatic conditions favours the weevil during the period after seed germination, and this may be the key to its control of the weed. Sites with climatic conditions similar to successful control sites in Hawaii are not found in Australia. It was concluded that P. antiquum will be of limited use as a biological control agent in Australia even in areas suitable for its establishment.
2
Leys, AR, RL Amor, AG Barnett e B. Plater. "Evaluation of herbicides for control of summer-growing weeds on fallows in south-eastern Australia". Australian Journal of Experimental Agriculture 30, n. 2 (1990): 271. http://dx.doi.org/10.1071/ea9900271.
Testo completoAbstract (sommario):
Eighteen herbicides or herbicide tankmixes were evaluated over 3 years (1987-89) for their control of 11 important summer-growing weeds on fallows in southern New South Wales and the Wimmera area of Victoria. Each of the weeds was effectively controlled by at least 1 herbicide. The tank-mixes of glyphosate plus metsulfuron (270 + 4.2 g a.i./ha) and glyphosate plus 2,4-D ester (270 + 320 g a.i./ha) were the most effective treatments, each giving an average of 68% control of all species. Hogweed (Polygolzunz avicu1ar.e L.), prickly paddy melon (Cucumis myriocarpris Naudin), spear thistle [Cirsium vulgare (Savi) Ten.] and skeleton weed (Chondrilla juncea L.) were the species most tolerant of these 2 tank-mixes. When these species were exluded, glyphosate plus metsulfuron and glyphosate plus 2,4-D ester gave an average of 90 and 88% control, respectively, of the remaining species [common heliotrope, Heliotropiunz europaeum L.; camel melon, Citrullus larzatus (Thunb.) Matsum. and Nakai var. lanatus; prickly lettuce, Lactuca serriola L.; sowthistle, Sonchus spp.; clammy goosefoot, Chenopodium pumilio R.Br.; caltrop, Tribulus terrestris L.; stink grass, Eragrostis ciliatiensis (All.) E. Mosher]. Hogweed was most effectively controlled by 2,4-D amine plus dicamba (750 + 100 g a.i./ha) or 2,4-D ester (800 g a.i./ha); prickly paddy melon by 2,4-D amine plus triclopyr (750 + 96 g a.i./ha); spear thistle by 2,4-D amine plus dicamba (750 + 100 g a.i./ha) or glyphosate plus clopyralid (270 + 60 g a.i./ha); and skeleton weed by 2,4-D amine plus clopyralid (750 + 60 g a.i./ha). A pot experiment confirmed field observations that, as common heliotrope ages, glyphosate and glyphosate plus metsulfuron become less effective for its control.
3
Scott, J. K., e P. B. Yeoh. "Bionomics and the predicted distribution of the aphid Brachycaudus rumexicolens (Hemiptera: Aphididae)". Bulletin of Entomological Research 89, n. 1 (gennaio 1999): 97–106. http://dx.doi.org/10.1017/s0007485399000127.
Testo completoAbstract (sommario):
AbstractDevelopment rates of the aphid, Brachycaudus rumexicolens (Patch), a recent arrival in Australia and a potential biological control agent against weeds in the family Polygonaceae, were measured over a range of constant temperatures. The theoretical lower limit for development is 6.4°C and the upper limit 32°C. Maximum fecundity per day was reached at 19°C. The rate of increase peaked at about 28°C giving a population doubling time of less than two days. These values were used with the current distribution to develop a CLIMEX model to predict the potential world distribution of the aphid. The model predicts that the aphid has suitable periods of population growth in autumn and spring, and that survival is unlikely over summer in most of south-western Australia where the aphid has the potential to contribute to the biological control of the polygonaceous weeds, Emex and Rumexspecies. The model predicts that years with cool summer temperatures and late summer rains in south west Australia, such as in 1990 when the aphid was first abundant, will be particularly suitable for aphid development. These conditions occurred twice between 1985 and 1995. To increase the effectiveness of the aphid as a biological control agent of weeds in other years, augmentation by provision of alternative hosts and/or the release of mass reared individuals during autumn is proposed.
4
Walker, S. R., I. N. Taylor, G. Milne, V. A. Osten, Z. Hoque e R. J. Farquharson. "A survey of management and economic impact of weeds in dryland cotton cropping systems of subtropical Australia". Australian Journal of Experimental Agriculture 45, n. 1 (2005): 79. http://dx.doi.org/10.1071/ea03189.
Testo completoAbstract (sommario):
In dryland cotton cropping systems, the main weeds and effectiveness of management practices were identified, and the economic impact of weeds was estimated using information collected in a postal and a field survey of Southern Queensland and northern New South Wales. Forty-eight completed questionnaires were returned, and 32 paddocks were monitored in early and late summer for weed species and density. The main problem weeds were bladder ketmia (Hibiscus trionum), common sowthistle (Sonchus oleraceus), barnyard grasses (Echinochloa spp.), liverseed grass (Urochloa panicoides) and black bindweed (Fallopia convolvulus), but the relative importance of these differed with crops, fallows and crop rotations. The weed flora was diverse with 54 genera identified in the field survey. Control of weed growth in rotational crops and fallows depended largely on herbicides, particularly glyphosate in fallow and atrazine in sorghum, although effective control was not consistently achieved. Weed control in dryland cotton involved numerous combinations of selective herbicides, several non-selective herbicides, inter-row cultivation and some manual chipping. Despite this, residual weeds were found at 38–59% of initial densities in about 3-quarters of the survey paddocks. The on-farm financial costs of weeds ranged from $148 to 224/ha.year depending on the rotation, resulting in an estimated annual economic cost of $19.6 million. The approach of managing weed populations across the whole cropping system needs wider adoption to reduce the weed pressure in dryland cotton and the economic impact of weeds in the long term. Strategies that optimise herbicide performance and minimise return of weed seed to the soil are needed. Data from the surveys provide direction for research to improve weed management in this cropping system. The economic framework provides a valuable measure of evaluating likely future returns from technologies or weed management improvements.
5
Taylor, AJ. "Influence of weed competition on autumn-sown lucerne in south-eastern Australia and the field comparison of herbicides and mowing for weed control". Australian Journal of Experimental Agriculture 27, n. 6 (1987): 825. http://dx.doi.org/10.1071/ea9870825.
Testo completoAbstract (sommario):
A field experiment in autumn-sown lucerne was conducted at Tatura to quantify the growth of winter weeds and the effects of weeds on lucerne seedling establishment, plant densities and hay production over the first year of cutting. In addition, mowing treatments and a range of herbicides were evaluated with respect to weed control. Weed growth rates in spring of up to 114 kg ha-l day-1 DM and high yields of annual winter weeds excluded lucerne (Medicago sativa L. cv. Delkalb 167) almost entirely from the first hay cut and significantly reduced seedling vigour and plant densities. The unsprayed control plots yielded 9.3 t ha-1 at the first hay cut and comprised 52% capeweed, 41% ryegrass and less than 1% lucerne. In other treatments where either capeweed or ryegrass remained uncontrolled, the proportion of lucerne in the hay was low. Weeds significantly reduced lucerne yields (P < 0.01) at the first and second hay cuts of 5 cuts taken in the first season. Combinations of herbicides gave the best weed control and highest lucerne yield at the first and second cuts and significantly higher total lucerne yield. The best herbicide combination was trifluralin and bromoxynil, which controlled all weed species on the site, reduced the weed yield at the first cut by 87% below that of the control and produced the highest total lucerne yield of 14 t ha-l. The hay composition of this treatment at the first cut comprised 59% lucerne, 27% ryegrass and 14% other weed species, while at the second hay cut lucerne comprised 95% of the DM. Lucerne was the highest yielding species in all treatments at the second cut. Lucerne plant densities were lowest on the unsprayed control plots, with 56% fewer plants than for the herbicide combination treatments. Mowing in August was effective in preventing the decline in lucerne plant density that occurred on the unsprayed control plots.
6
Lemerle, D., B. Verbeek e S. Diffey. "Influences of field pea (Pisum sativum) density on grain yield and competitiveness with annual ryegrass (Lolium rigidum) in south-eastern Australia". Australian Journal of Experimental Agriculture 46, n. 11 (2006): 1465. http://dx.doi.org/10.1071/ea04233.
Testo completoAbstract (sommario):
The variation in field pea grain yield and competitiveness with annual ryegrass due to crop density, row spacing and cultivar was determined to enable farmers to better manage weeds with cultural control tactics. Crop density varied with seeding rate, cultivar, row spacing and year. Higher seeding rates were required to reach equivalent plant densities in cv. Dinkum (short, semi-leafless) compared with cv. Dundale (tall, conventional-leaf), and at 36 cm compared with 18 cm row spacing. Field pea grain yield was reduced more at low crop densities, in Dinkum, at 36 cm row spacing, and in the presence of weeds. Percentage yield losses from weed competition were similar in both cultivars (about 70–80%) at a low density of 10 plants/m2 in 2 seasons. At higher crop densities Dinkum had a larger loss than Dundale (i.e. at 30 plants/m2 losses were 60 and 35%, respectively, compared with 50 and 5% at 60 plants/m2). Seasonal variation influenced the effect of crop density on yield loss from weeds. The percentage yield loss from weeds in 1993 ranged from about 90 to 40% at plant densities of 10 to 40 plants/m2, in contrast to 1995 when 40% yield loss occurred at all these densities. Ryegrass dry weight was reduced with increasing field pea density in both years, and in the tall more than the short cultivar in 1 year. Maintaining recommended field pea seeding rates has considerable financial benefits in both weed-free (around $100/ha) and weed-affected crops (to $400/ha). In weedy situations, integrating cultural practices such as higher seeding rates and choice of cultivar that enhance crop competitiveness will improve weed management in south-eastern Australia.
7
Giles, I., P. T. Bailey, R. Fox, R. Coles e T. J. Wicks. "Prospects for biological control of cutleaf mignonette, Reseda lutea (Resedaceae), by Cercospora resedae and other pathogens". Australian Journal of Experimental Agriculture 42, n. 1 (2002): 37. http://dx.doi.org/10.1071/ea01070.
Testo completoAbstract (sommario):
Four leaf pathogens were screened as biological control agents for the weed Reseda lutea (Resedaceae) in South Australia. Cercospora resedae isolated from Reseda luteola growing in south-eastern Australia produced a maximum damage to R. lutea seedlings of 54% of leaf area damaged at 22°C and 96% of leaf area damaged at 27°C under laboratory test conditions. By contrast, European isolates of C. resedae from both R. lutea and R. luteola produced a maximum of 10% leaf area damage to R. lutea seedlings. Field releases of Australian C. resedae failed to establish in dense populations of R. lutea on Yorke Peninsula and the mid-north of South Australia, perhaps because the climate was hotter and drier than the source locations. Attempts to enhance the effectiveness of the pathogen by passaging it through R. lutea, leaf abrasion, inundation, or the addition of surfactant or sublethal doses of metsulfuron-methyl failed to increase damage beyond that caused by the pathogen alone. The leaf pathogensAlternaria tenuissima, Cladosporium sp. and Peronospora crispula did not produce damage levels that could be useful in biological control. It is concluded that in the areas of South Australia where R. lutea is a significant weed, the prospects for control by any of these leaf pathogens are not good.
8
Seymour, M. "Narbon bean (Vicia narbonensis) agronomy in south-western Australia". Australian Journal of Experimental Agriculture 46, n. 10 (2006): 1355. http://dx.doi.org/10.1071/ea04091.
Testo completoAbstract (sommario):
Narbon bean (Vicia narbonensis L.) shows promise as a fodder, green manure and grain crop in south-western Australia. This study examines the effect of time of sowing (2 experiments), plant density (3 experiments) and reaction to herbicides (4 experiments on tolerance to herbicides and 1 experiment on removing narbon bean from a wheat crop) in 10 separate field experiments sown at 4 locations in the mallee region of Western Australia from 1998 to 2001. Narbon bean was found to be unresponsive to changes in sowing date with yield maintained until the first week of June. The optimum plant density (90% of fitted maximum) for seed yield was found to be 31 plants/m2, equivalent to sowing rates in the range of 75–100 kg/ha. A wide range of herbicides applied either before sowing or immediately after sowing and before emergence had no significant effect on grain yield. These included simazine (750 g a.i./ha), cyanazine (1.25 kg a.i./ha) and diuron (500 g a.i./ha), which were applied immediately before sowing, and imazethapyr (29 g a.i./ha), which was applied after sowing, before emergence. Diflufenican (75 g a.i./ha) was found to be the only available option for post-emergence control of broadleaf weeds. The use of the non-selective herbicides glyphosate (450 g a.i./L) and Sprayseed 250 (paraquat 135 g a.i./L and diquat 115 g a.i./L) as post-emergence herbicides was found to be unpredictable at a range of application rates. Results ranged from a yield loss of 47% to a yield increase of 23%. In an experiment to test a range of herbicides for the selective control of narbon bean within a wheat crop, numerous herbicides were found to effectively remove volunteer narbon bean indicating that narbon bean is unlikely to become a weed in most cereal cropping systems.
9
Adair, R. J., e J. K. Scott. "Distribution, life history and host specificity of Chrysolina picturata and Chrysolina sp. B (Coleoptera: Chrysomelidae), two biological control agents for Chrysanthemoides monilifera (Compositae)". Bulletin of Entomological Research 87, n. 4 (agosto 1997): 331–41. http://dx.doi.org/10.1017/s0007485300037354.
Testo completoAbstract (sommario):
AbstractThe southern African shrubs Chrysanthemoides monilifera monilifera and C. m. rotundata (Compositae) are serious weeds of native vegetation in Australia and are targets for classical biological control. In host specificity tests using 69 species from 25 families, two leaf-feeding chrysomelid beetles, Chrysolina picturata (Clark) and Chrysolina sp. B, were able to complete development on only Chrysanthemoides monilifera and C. incana. The subspecies Chrysanthemoides m. monilifera was the superior host for both Chrysolina picturata and Chrysolina sp. B. Feeding and limited development of both species occurred on Calendula officinalis; limited development by Chrysolina picturata larvae occurred on Helianthus annuus, Tussilago farfara and Cymbonotus priessianus. Chrysolina picturata and Chrysolina sp. B are considered to be Chrysanthemoides-specific and have been approved for release in Australia. Potential release sites for both Chrysolina species were chosen by comparing the climate of the insects' African distribution with climate stations within the range of Chrysanthemoides monilifera in Australia. Chrysolina picturata and Chrysolina sp. B are suited for release within the western distribution of Chrysanthemoides m. monilifera in coastal areas of south eastern South Australia.
10
Campbell, MH. "Extending the frontiers of aerially sown pastures in temperate Australia: a review". Australian Journal of Experimental Agriculture 32, n. 1 (1992): 137. http://dx.doi.org/10.1071/ea9920137.
Testo completoAbstract (sommario):
Over the past 40 years large areas of pastures on hill country in temperate Australia have been improved through aerial distribution of herbicides, pesticides, seed, and fertiliser, which has increased animal production and helped to control weeds. Refinements detailed in this review could extend the use of these techniques to promote sustainable systems by the establishment of perennial pasture species on unploughed land. It is argued that the most urgent requirement is ensuring that aerial spraying is not abolished by government regulation in response to demands by specialist groups, because perennial pasture species will not establish on hill country without prior aerial spraying of herbicides. The major technical refinement needed is the reduction of losses of establishing plants due to weed competition and dry periods during their first spring and summer. This could be accomplished by increasing the spectrum of weeds controlled by the most widely used herbicide, glyphosate; applying new herbicides that give longer weed control in spring than the presently used herbicides; using herbicides that can selectively remove annual grass weeds from establishing perennial grasses; or using strategic grazing with cattle or goats to reduce weed competition. Breeding, selecting or importing pasture species specifically designed for establishment from surface sowing has never been attempted. Attributes that could improve establishment include germination that occurs only under favourable conditions; seeds resistant to weathering on the soil surface; seedlings with fast radicle entry, hairs on the radicle, fast root development, and better seedling vigour; and for subtropical species sown in semi-arid New South Wales, tolerance of low winter temperatures. Improved distribution of herbicides, seeds and fertilisers, particularly in the more rugged hill country, is needed to ensure complete cover of the treated area with minimum drift. Techniques that allow establishment of aerially sown pastures on hill country with very acid soil are needed to facilitate the development of further, large areas of Australia.
11
Peterson, David J., e Raj Prasad. "The biology of Canadian weeds. 109. Cytisus scoparius (L.) Link". Canadian Journal of Plant Science 78, n. 3 (1 luglio 1998): 497–504. http://dx.doi.org/10.4141/p97-079.
Testo completoAbstract (sommario):
Scotch broom (Cytisus scoparius [L.] Link.) is an exotic perennial, leguminous, deciduous shrub, which during the past century has greatly expanded its range along the Pacific and Atlantic coasts of North America, and in Australia, New Zealand, South Africa, Chile, Iran, and India. This shrub rapidly invades disturbed areas, forming dense thickets, which can suppress and inhibit native vegetation, including economically important conifer seedlings. The developmental characteristics whereby Scotch broom invades new sites include specialized stem photosynthesis, prolific seed production, longevity of seeds in the soil, and nitrogen fixation. Human activities such as planting along highways for beautification and prevention of soil erosion have accelerated the problem of rapid geographical dispersal. Various methods of control (chemical, manual, and biological) together with habitat, morphology, reproductive biology, growth and development are discussed. Key words: Cytisus scoparius, Ulex europaeus, Scotch broom, invasive weeds, bioherbicides, Fusarium tumidu
12
Manrique, Veronica, Rodrigo Diaz, James P. Cuda e William A. Overholt. "Suitability of a New Plant Invader as a Target for Biological Control in Florida". Invasive Plant Science and Management 4, n. 1 (marzo 2011): 1–10. http://dx.doi.org/10.1614/ipsm-d-10-00040.1.
Testo completoAbstract (sommario):
AbstractThe suitability of a target weed for classical biological control should be considered early in the process of plant invasion. Concerns have been raised about the recent arrival ofMikania micranthaKunth in south Florida and its potential to spread and invade natural and managed ecosystems. This weed is native to the neotropics, and has been introduced into many Asian countries and, more recently, into Australia. In Asia,M. micranthais particularly problematic in plantation crops, but also threatens natural areas and disturbed ecosystems. Several aspects of the biology and ecology ofM. micranthaare discussed in this review to evaluate its suitability as a target of biological control in Florida. Based on an ecological niche model, the climate in southern and central Florida is highly favorable for the invasion of this weed. Previous biological control programs provide valuable information for Florida scientists about the availability of natural enemies and potential areas for future foreign surveys. Genetic comparison of the Florida population and native range populations, in addition to climate matching, should be considered when selecting areas for foreign exploration. Finally, the authors used a scoring system and risk-benefit–cost analysis to evaluateM. micranthaas a potential target for biological control in Florida. We suggest that similar feasibility evaluations should be conducted not only for well-established problematic weeds but also for new invaders with a known history of invasiveness.
13
Bailey, P., J.-L. Sagliocco, J. Vitou e D. Cooke. "Prospects for biological control of cutleaf mignonette, Reseda lutea (Resedaceae), by Baris picicornis and Bruchela spp. in Australia". Australian Journal of Experimental Agriculture 42, n. 2 (2002): 185. http://dx.doi.org/10.1071/ea01059.
Testo completoAbstract (sommario):
In South Australia, Reseda lutea is abundant, invading pastures and crops on calcareous soils while in its native Mediterranean range it is uncommon in occurrence and is not reported as a weed of cultivated crops. Its invasive behaviour in South Australia may be attributed to vegetative growth of root fragments spread by cultivation, while propagation by seed is of minor importance. Surveys in Spain, Portugal, Morocco, France, Turkey and Israel indicated that agronomic differences, particularly depth of cultivation and seeding rates of cereals may explain why it is not a crop weed in these countries. Another difference is that plants in the region of origin have an associated fauna not present in Australia. These potential biological control agents include a root-boring weevil, Baris picicornis, flower- and seed-feeding urodontids, Bruchela suturalis and B. rufipes, and a leaf spot pathogen,Cercospora resedae. Baris picicornis was introduced from France and Turkey, under quarantine, to Australia but laboratory specificity-testing demonstrated that it could complete its life cycle on 2 commercially grown cultivars of Brassica rapa (choy sum and Chinese cabbage). Because of this, it is not proposed to release B. picicornis in Australia at present. Bruchela suturalis was also introduced into Australian quarantine from France but attempts to change its annual life cycle to Southern Hemisphere seasons were not successful, and a culture could not be established. Both Baris picicornis and Bruchela spp. remain promising agents, and further work on their introduction is justified by their potential for biological control of R. lutea.
14
Felton, WL, GA Wicks e SM Welsby. "A survey of fallow practices and weed floras in wheat stubble and grain sorghum in northern New South Wales." Australian Journal of Experimental Agriculture 34, n. 2 (1994): 229. http://dx.doi.org/10.1071/ea9940229.
Testo completoAbstract (sommario):
A survey undertaken in northern New South Wales after the 1989 wheat harvest investigated the effects of cultural practices used by dryland farmers on summer weed flora. Only 50% of fallow paddocks surveyed between December and February were weedfree, and by mid January 65% had inadequate stubble cover (<1000 kg/ha) for protection from soil erosion, mainly because of excessive tillage. By February, only 10% of paddocks were being sprayed with a herbicide to control weeds. Examination of 65 uncultivated fallow wheat stubble paddocks and 25 grain sorghum crops identified 87 and 51 different weed species, respectively. In fallow paddocks where no herbicide had been used, 69 and 61 species were found in ungrazed and grazed paddocks, respectively. Where glyphosate had been used the number of species was 37 (grazed) and 39 (ungrazed), and for glyphosate plus atrazine, 23 and 18 species. The number of weed species found in grain sorghum was 29 for cultivated without atrazine, 35 for cultivated with atrazine, and 35 for no-tillage with atrazine, The most important weeds found in fallow were liverseed grass, native millet, common sowthistle, wireweed, and barnyard grasses. Black bindweed was a problem where atrazine had not been used. Native millet was the most abundant species where atrazine had been applied. In grain sorghum the most common broadleaf weeds for cultivated paddocks with no atrazine treatment were Tribulus spp., Australian bindweed, pigweed, and Bathurst burr, while the most common grass weeds were barnyard grasses, liverseed grass, stinkgrass, and native millet. When cultivation plus atrazine was used, barnyard grasses, native millet, wild oats, and liverseed grass were the most common weeds. In minimum tillage or no-tillage paddocks treated with atrazine, native millet, Queensland blue grass, liverseed grass, common sowthistle, Australian bindweed, and windmill grass were the most common weeds.
15
Cooke, JW. "Effect of fallowing practices on runoff and soil erosion in south-eastern Australia". Australian Journal of Experimental Agriculture 25, n. 3 (1985): 628. http://dx.doi.org/10.1071/ea9850628.
Testo completoAbstract (sommario):
The effect on runoff and soil loss of four methods of preparation of fallow was investigated at each of three sites in north-central Victoria. There was a chemical fallow treatment (uncultivated) and three scarified treatments (smooth, medium and rough cultivation). When the results from the three sites were combined, there was 10.7 mm runoff from the uncultivated treatment, 5.1 mm from the smooth, 0.8 mm from the medium and 0.3 mm from the rough scarified treatments. Soil loss from the uncultivated treatment was 103 g/m2 compared with 87 g/m2 from the smooth, 22 g/m2 from the medium and 13 g/m2 from the rough treatment. The concentration of sediment in the runoff was negatively correlated (R2 = -0.56 to -0.98) with runoff. It ranged from 1.21% (w/w) for the uncultivated to 5.06% (w/w) for the rough scarified treatment. The results show that a regimen of minimum scarification to produce a rough surface, and then use of herbicides to control weeds, reduces soil loss compared with either an uncultivated or a smoothly cultivated soil surface.
16
Adair, R. J., e J. K. Scott. "Distribution, life history, host specificity and suitability of an undescribed Chrysolina species (Coleoptera: Chrysomelidae) for the biological control of Chrysanthemoides monilifera (Compositae)". Bulletin of Entomological Research 81, n. 3 (settembre 1991): 235–42. http://dx.doi.org/10.1017/s0007485300033484.
Testo completoAbstract (sommario):
AbstractIn host specificity tests using 81 plant species from 27 families, an undescribed Chrysolina sp. completed its development only on Chrysanthemoides monilifera, a serious weed of native vegetation in Australia. Minor exploratory feeding, mostly by adults, occurred on 35 plant species. The Chrysolina sp. is restricted to the eastern Cape Province of South Africa where it occurs on Chrysanthemoides m. pisifera, a subspecies not yet recorded in Australia. Chrysanthemoides m. monilifera and C. m. rotundata, both naturalized in Australia, were accepted as hosts by Chrysolina sp., but adult emergence was lower on the latter subspecies. A climate comparison between a site location for Chrysolina sp. and stations within the Australian distribution of Chrysanthemoides monilifera has identified potential release sites that may be suitable for the insect. Chrysolina sp. was approved for release in Australia in 1989 and releases were initiated in 1990.
17
SPICER, K. W., e P. M. CATLING. "THE BIOLOGY OF CANADIAN WEEDS.: 88. Elodea canadensis Michx." Canadian Journal of Plant Science 68, n. 4 (1 ottobre 1988): 1035–51. http://dx.doi.org/10.4141/cjps88-125.
Testo completoAbstract (sommario):
A review is provided of information on the biology of elodea (Elodea canadensis Michx.). This submersed aquatic develops dense beds that impede water traffic and restrict water-based recreation in the southern portions of Quebec, Ontario, in British Columbia and Alberta. In some regions the dense beds decrease the efficiency of irrigated agriculture. Native to North America, elodea has recently spread to other parts of the world including Europe, Asia, South Africa, Australia and New Zealand. Elodea is beneficial in providing food and cover for insects and other small aquatic organisms, and consequently it increases food availability for fish and ducks. It also has some potential as a source of food and forage because of its relatively high nutritional content. Elodea is most frequent in clear, nutrient-rich, alkaline water. Phosphorus levels in the plant have been utilized as an indication of trends in the nutrient enrichment of water bodies. Limiting nutrients include bicarbonate and iron. Although seed formation is rare, dispersal of overwintering dormant apices and stem fragments by water and by waterfowl can result in rapid spread. Mechanical controls, including boats equipped with cutters, are the preferred methods of managing elodea, but adequate harvesting of cut material is necessary because every fragment with an axillary or terminal bud may develop into a new plant. Biological control using nonreproductive plant-eating fish is a promising area of research.Key words: Elodea canadensis, weed biology, aquatic, Canada, distribution
18
Mitchell, GJ, RJ Carter e SR Chinner. "Studies on the control of water-dropwort (Oenanthe pimpinelloides) in South Australia". Australian Journal of Experimental Agriculture 35, n. 4 (1995): 483. http://dx.doi.org/10.1071/ea9950483.
Testo completoAbstract (sommario):
Water-dropwort (Oenanthe pimpinelloides L.), a tuberous perennial herb, is currently known in South Australia from only a single locality in the Mount Lofty Ranges. There is little information on water-dropwort control, and 2 experiments were conducted to assess the effects of sowing pasture, with or without presowing herbicides, on the control of this weed. Phalaris (Phalaris aquatica L.) and perennial clovers were successfully introduced into infested pastures by direct drilling in autumn. Water-dropwort regenerated from seed more densely in unsown plots than plots of established perennial pasture, suggesting that upgrading pastures may be a strategy to reduce the rate of spread by seed of this weed. A range of herbicide treatments applied to waterdropwort at the stem elongation stage in spring before autumn sowing of pastures provided effective shortterm control. The best short-term control was provided by glyphosate at 1440 g a.i./ha; metsulfuron methyl at 6, 12, and 36 g a.i./ha; and metsulfuron methyl at 12 g a.i./ha tank-mixed with glyphosate or 2,4-D amine at 720 or 1000 g a.i./ha, respectively. These treatments, and chlorsulfuron at 21 g a.i./ha, also significantly (P<0.05) reduced water-dropwort abundance (relative to untreated areas) for up to 18 months after sowing and initially improved the density of sown pasture species, but these improvements were not evident 14 months after resowing. Although prior season herbicide treatments controlled water-dropwort in newly sown pastures, 2 separate applications of herbicides, in May and October, gave no better control of water-dropwort than a single herbicide application in spring. Water-dropwort infestations do not appear to prevent successful direct drilling of phalaris and perennial clovers. Although pasture renovation did not provide long-term suppression of water-dropwort, the maintenance of vigorous pastures may reduce the rate of population growth from seedlings of this weed. Recropping restrictions may limit the role of chlorsulfuron for water-dropwort control in pasture renovation situations.
19
Wapshere, AH. "Prospects for the biological control of silver-leaf nightshade, Solanum elaeagnifolium, in Australia". Australian Journal of Agricultural Research 39, n. 2 (1988): 187. http://dx.doi.org/10.1071/ar9880187.
Testo completoAbstract (sommario):
A survey of the distribution of the herbivores associated with the weed, Solanum elaeagnifolium, in its native range in Mexico and south-west U.S.A., has been made in relation to climate. The biological control agents considered were: a leaf-galling nematode, Orrina phyllobia; the defoliating cassidine Gratiana pallidula; chrysomelids Leptinotarsa texana and L. defecta, and tingids, Gargaphia spp.; a stem-boring curculionid, Trichobaris texana; a stem-galling cecidomyid species; the fruit-feeding gelechiid, Frumenta nephelomicta; and tephritid Zonosemata vittigera. The results of the survey suggest that the herbivores would not be sufficiently climatically adapted to the summer-drought, cereal-growing areas of southern Australia most heavily infested by the weed, to control it there. They might establish and be useful in areas less heavily infested by the weed in summer rainfall climates and in irrigated crops.
20
Lattimore, MAE. "Pastures in temperate rice rotations of south-eastern Australia". Australian Journal of Experimental Agriculture 34, n. 7 (1994): 959. http://dx.doi.org/10.1071/ea9940959.
Testo completoAbstract (sommario):
Legume-based pastures have long been an integral part of rice growing in the southern New South Wales irrigation areas and still offer potential to improve the productivity, profitability, and sustainability of the temperate rice-cropping system.This paper reviews both historical and current aspects of pastures in temperate rice rotations in southern New South Wales and highlights the importance of pastures in sustaining this cropping system as environmental pressures increase. Topics discussed include pasture species and rotations, their role in improving soil fertility and sustainability, the value of pastures in weed control, and their management for maximum profitability.
21
KNIHINICKI, DANUTA K., KATHRYN L. MCCARREN e JOHN K. SCOTT. "A new species of Aceria (Acari: Eriophyidae) damaging sowthistles, Sonchus spp. (Asteraceae), in Australia with notes on Aceria sonchi (Nalepa, 1902)". Zootaxa 2119, n. 1 (27 maggio 2009): 23–38. http://dx.doi.org/10.11646/zootaxa.2119.1.2.
Testo completoAbstract (sommario):
A new species of eriophyoid mite from Australia is described and illustrated. Aceria thalgi sp. n. causes severe curling and rolling of leaves of common introduced sowthistle, Sonchus oleraceus L. It also affects introduced Sonchus asper (L.) Hill and native Sonchus hydrophilus Boulos. The native species may be the original host for this mite. Aceria thalgi sp. n. is shown to be a separate species to Aceria sonchi (Nalepa), which forms distinctive leaf galls on Sonchus spp. in southern Europe. English translations of past descriptions of A. sonchi are included for comparison. Historical observations and records from New South Wales suggest that A. thalgi sp. n. has been known for at least 80 years prior to its recent rediscovery in Western Australia. This implies that the newly described species may be widespread across the continent. There is also a past record of similar damage symptoms occurring on sowthistles in New Zealand. Aceria thalgi sp. n. has the potential to be a useful biological control agent in Australia and Canada, where sowthistles are major weeds of agriculture.
22
Warwick, Suzanne I., e Ardath Francis. "The biology of Canadian weeds. 132. Raphanus raphanistrum L." Canadian Journal of Plant Science 85, n. 3 (1 luglio 2005): 709–33. http://dx.doi.org/10.4141/p04-120.
Testo completoAbstract (sommario):
A review of biological information is provided for Raphanus raphanistrum L. Native to the Mediterranean region, the species is widely introduced and naturalized in temperate regions around the world. In Canada, it currently occurs in all provinces except Saskatchewan and Manitoba, has only a limited distribution in Alberta, and is also absent from the Yukon, the Northwest Territories and Nunavut. It is most abundant in the Atlantic and Pacific regions and is an important weed of field crops in the Maritime provinces and Quebec. A persistent seed bank, competitive annual growth habit and high fecundity all contribute to its weedy nature and ensure that it will be a continuing problem. It can easily hybridize with cultivated radish, R. sativus L., and commonly does so when they occur together. Limited hybridization with canola, Brassica napus L., has been reported from several experimental field and greenhouse trials. Selective herbicide control is most difficult in canola and other cruciferous crops. It is the most important dicot weed in the southwestern region of Australia, primarily due to the evolution of several different herbicide-resistant biotypes. These include biotypes resistant to the acetolactate synthase (ALS)-inhibitors (group 2 herbicides) and/or photosystem II-inhibitors (group 5), and a biotype with multiple resistance to ALS-inhibitors, photosystem II-inhibitors, an auxin (2,4-D amine), and a phytoene desaturase (PSDS)-inhibitor (diflufenican). A biotype resistant to the ALS-inhibiting herbicide chlorsulfuron has also been detected in South Africa. Key words: Wild radish, Raphanus raphanistrum, herbicide resistance, canola, hybridization, RAPRA
23
Strelau, M., D. R. Clements, J. Benner e R. Prasad. "The Biology of Canadian Weeds: 157.Hedera helixL. andHedera hibernica(G. Kirchn.) Bean". Canadian Journal of Plant Science 98, n. 5 (1 ottobre 2018): 1005–22. http://dx.doi.org/10.1139/cjps-2018-0009.
Testo completoAbstract (sommario):
Two related species of Hedera spp. exist throughout Canada: English Ivy (Hedera helix L.) and Irish Ivy [Hedera hibernica (G. Kirchn.) Bean]. These species are difficult to distinguish taxonomically and clear distinctions are not always made in the literature, so we largely discuss them as a single taxon in this account. Ivy is an evergreen perennial with two distinct forms: woody vine (juvenile form) or shrub (adult form). In Canada, Hedera spp. are found naturalized along the southern coast of British Columbia (Vancouver, Vancouver Island, and the Gulf Islands) and in southwestern Ontario. During the past century, ivies have greatly expanded their ranges along the Pacific and Atlantic coasts of North America and in New Zealand, Australia, South Africa, Brazil, and Hawaii. Ivy is physiologically plastic, invading both semi-open and deeply shaded forests. It forms a dense ground cover that can inhibit native vegetation. It grows up on tree trunks and competes for soil nutrients, frequently leading to tree damage or even tree fall. Invasive characteristics include its evergreen habit, persistence, and vegetative reproductive capabilities. Humans have accelerated the spread of ivy by planting it along highway embankments and medians to control soil erosion and through widespread sale as an ornamental plant. There is debate among horticulturalists and ecologists over the destructive and advantageous effects of ivy growth and sale within North America. Various methods of control (chemical, manual, biological, and integrated) may be used to manage this species, but more research is needed to design better control techniques.
24
Morrison, SM, e JK Scott. "Variation in Populations of Tribulus terrestris (Zygophyllaceae) .3. Isozyme Analysis". Australian Journal of Botany 44, n. 2 (1996): 201. http://dx.doi.org/10.1071/bt9960201.
Testo completoAbstract (sommario):
Isozyme variation in seedlings was investigated as part of a study to identify the origins of the widespread weed and potential biological control target Tribulus terrestris L. s.1. (Zygophyllaceae). Seedlings were obtained from 30 Australian and 24 overseas collections of burrs. Polymorphism was detected in 8 of the 11 putative loci scored. Queensland and Northern Territory collections differed from other Australian and non-Australian collections, indicating that they belong to a separate and possibly native Australian species. Other Australian collections had a high genetic similarity to burrs obtained from the Mediterranean, West Asia, South Africa, Namibia and the USA, the latter being an introduced population. Two Namibian collections formed a separate group and it is possible that southern Africa, like Australia, has native and introduced plants of T. terrestris. All Indian and two Kuwait collections were grouped together and had little similarity with any other group. Tribulus terrestris in southern Australia is most likely to have originated in the Mediterranean or West Asian region.
25
Hetherington, S. D., e J. A. G. Irwin. "Pathological and molecular genetic variation in the interaction between Sporobolus spp. and Bipolaris spp." Australian Journal of Agricultural Research 50, n. 4 (1999): 583. http://dx.doi.org/10.1071/a98126.
Testo completoAbstract (sommario):
Members of the Sporobolus indicus complex, particularly Sporobolus indicus (L.) R. Br. var. major (Buse) Baaijens (Giant Parramatta Grass; GPG) and S. pyramidalis P. Beauv. (Giant Rat’s Tail Grass; GRTG), are serious pastoral weeds in coastal areas of Australia. Ovariicolous fungal pathogens from the genus Bipolaris Shoem. are agents of the disease false smut on these plants. The hosts are morphologically plastic and variation in disease susceptibility may affect the use of the fungus as a biological control agent. Variation was investigated by screening 22 clones representative of 5 taxonomic entities within the S. indicus complex with 39 fungal isolates representative of 4 Bipolaris species. Both weed entities were highly susceptible to B. ravenelii and B. crustacea and only slightly susceptible to B. cylindrica and B. australis. The converse was true for other Sporobolus entities tested. Genomic DNA was extracted from 20 Sporobolus clones (genotypes) and the RAPD technique used to generate an index of variation. This technique was able to separate the members of the complex into taxonomic groupings. There was only a 2% difference in banding patterns of S. indicus var. major clones collected in New South Wales. Variation amongst clones of S. pyramidalis was greater (15%), indicating a more genetically diverse plant population. The more variable genetic background of S. pyramidalis is more likely to provide variation in susceptibility than that of S. indicus var. major
26
Cooke, JW, GW Ford, RG Dumsday e ST Willatt. "Effect of fallowing practices on the growth and yield of wheat in south-eastern Australia". Australian Journal of Experimental Agriculture 25, n. 3 (1985): 614. http://dx.doi.org/10.1071/ea9850614.
Testo completoAbstract (sommario):
The effects on crop establishment, crop development and the yield of wheat of two methods of fallow preparation, at each of three lengths of fallow were investigated over 5 years on red duplex and associated soils in north-central Victoria. The two methods of preparation were: scarifying, which involved the repeated use of a tined tillage implement; and herbicide application, which involved the repeated use of non-residual herbicides to control weeds during the fallow phase. The three lengths of fallow were winter, spring and autumn, which were approximately 10, 8 and 2 months respectively. Grain yield on the scarifier treatments was 0.26 t/ha greater (P<0.10) than on the herbicide treatments. Grain yield on winter fallow was 0.46 and 0.56 t/ha greater (Pt0.01) than on spring and autumn fallows, respectively. Crop yield was positively correlated (R2= 0.49) with soil nitrate determined at the time the crop was sown, but was independent of available soil water content determined at that time. Winter fallowing conserved 15 and 29 mm more water than did spring and autumn fallowing respectively, and mineralized 26 and 28 kg/ha more nitrogen than did spring and autumn fallows respectively. Crop establishment (No. of plants/m of row) on the herbicide treatment was 89% (P< 0.05) of that on the scarifier treatment, but this was not the reason for the reduced grain yield on the herbicide treatment. The lower yields were caused by depressed crop vigour (number of spikes/m of row) which in turn was largely a consequence of the inefficient uptake of nitrogen. The yield benefits of scarifying appear to reflect the importance of the initial two or three cultivations.
27
D'Emden, F. H., e R. S. Llewellyn. "No-tillage adoption decisions in southern Australian cropping and the role of weed management". Australian Journal of Experimental Agriculture 46, n. 4 (2006): 563. http://dx.doi.org/10.1071/ea05025.
Testo completoAbstract (sommario):
Adoption of no-tillage sowing systems has increased rapidly in many Australian grain growing regions over the past decade. The extent of herbicide resistant weed populations in these regions has also increased over the same period. A survey of growers in the South and Western Australian cropping regions was conducted to identify opportunities for more effective tillage and weed-related extension. Trends in sowing system use are determined, as are growers’ perceptions of the long-term effects of no-tillage on herbicide costs, herbicide resistance, and soil erosion. The results suggest a major expansion in the adoption of no-tillage sowing in most South Australian cropping regions over the next 5 years, although growers expect increased herbicide costs in no-tillage systems and an increased risk of herbicide resistance. Herbicide resistance and weed control issues are the main reasons given for reducing no-tillage use. A key research and extension challenge is to develop and implement weed management strategies that are able to sustain long-term no-tillage use in a cropping environment where growers place a high value on the soil and production benefits of no-tillage, but over-reliance on herbicides can rapidly lead to resistance in major crop weeds.
28
Scott, JK, e PB Yeoh. "The Rediscovery and Distribution of Rumex drummondii (Polygonaceae) in South-Western Australia". Australian Journal of Botany 43, n. 4 (1995): 397. http://dx.doi.org/10.1071/bt9950397.
Testo completoAbstract (sommario):
Rumex drummondii Meisn., a south-western Australian endemic vascular plant species recorded from widely separated localities, had not been collected for 46 years and was considered possibly extinct. The methods developed from search theory, which has been used for finding lost people or objects, were applied to finding R. drummondii, starting from previous records. Eleven populations of the species were discovered within a 50 km radius in the Kalgan River and Manypeaks region. A disjunct population of six plants was found in 1992 in a parking area at a crossing of the Moore River, 480 km north north west of the others, but had disappeared by 1994. Surveys in the Gingin Brook and Moore River region and between Kalannie and Kulja, another disjunct record, failed to find further plants. The species occupies temporarily wet depressions, lake edges and roadside excavations and dam edges protected from grazing by sheep; habitats also occupied by congeneric weedy species. The species occurs on road verges and farmland and is known from one nature reserve. The rediscovery of R. drummondii enables it to be included in the assessment of potential biological control agents for related weed species in the genera Emex and Rumex.
29
van der Meulen, A. W., I. J. Reeve e B. M. Sindel. "Weed management on grazing properties: a survey of livestock producers in New South Wales and Victoria". Australian Journal of Experimental Agriculture 47, n. 12 (2007): 1415. http://dx.doi.org/10.1071/ea06179.
Testo completoAbstract (sommario):
Social research was conducted to explore factors influencing weed management on grazing properties in southern Australia. Face-to-face interviews were held with 122 livestock producers, 94 written questionnaires were returned and 90 grazing properties were visited and rated for weed incidence and management effort. Segmentation techniques revealed three groups, on the basis of farmer demographics and farm characteristics. These groups varied significantly in the range of control methods used, weed management effort, difficulties encountered with weed control and attitudes towards weed control. Respondents were also grouped into four categories with respect to weed control methods: minimal control, mechanical control, grazing control and maximal control. Control groups differed significantly in terms of the number and complexity of methods used, difficulties encountered with weed control, levels of weed awareness and the value placed on various sources of information about weed control. Characteristics of effective weed managers were considered and three factors were identified as underpinning success with weed control. These are referred to as the three ‘Ds’: diligence, diversity and deliberation. These factors have been used to define a three dimensional framework, within which the diversity of approaches towards weed control can be understood.
30
Bortolussi, G., J. G. McIvor, J. J. Hodgkinson, S. G. Coffey e C. R. Holmes. "The northern Australian beef industry, a snapshot. 4. Condition and management of natural resources". Australian Journal of Experimental Agriculture 45, n. 9 (2005): 1109. http://dx.doi.org/10.1071/ea03262.
Testo completoAbstract (sommario):
Natural resource management practices were surveyed on 375 northern Australian beef properties in 8 regions during 1996–97. These producers represented a broad cross section of the beef industry in terms of geographical location, size of enterprise, and herd and ownership structures. More than 48% of producers reported land degradation (erosion, salinity, weeds, etc.) and >68% reported woody weeds on their properties. Eucalypt (Eucalyptus and Corymbia spp.) and wattle (Acacia spp.) regrowth were universally common native woody weeds. Parkinsonia (Parkinsonia aculeata) was widespread across all survey regions occurring with the greatest frequency in northern regions. A range of native and exotic woody weed species were regionally significant. Brigalow (Acacia harpophylla) regrowth was mainly reported in the central Queensland and Maranoa South West regions. Prickly acacia (Acacia nilotica) was mainly reported in central and north-west Queensland. Rubber vine (Cryptostegia grandiflora) was mainly reported in northern Queensland with a significant presence in central coastal and north-west Queensland. Infestations with multiple weed species were common. Although many producers reported the presence of problem woody weeds, only 3–29% indicated that weed management was practised. Most producers (67–100%) used fire. The intended purpose of fire varied across survey regions but fire was commonly used to reduce rank material, reduce fire risk, control woody weeds and for grazing management. Seasonal conditions and variability restricted fire use. Assessment by visual observation was a commonly used practice for determining stocking rate. Between 4–20% of producers were using visual observation combined with some form of calculation of stocking rate at the end of the growing season to determine stocking rate. A majority (>67%) of producers used some form of paddock spelling or regeneration practice. Many producers (47–89%) considered that they used conservative stocking rates. Carrying sufficient stock to meet income requirements was significantly (P<0.05) correlated with the percentage of producers reporting woody weeds as a problem on their property. In the 5 years preceding the survey, >66% of producers had increased the number of stock watering points, and more than 85% of producers had erected fencing. Most fencing was for new paddocks and laneways, or to replace old fences, and was not associated with new stock watering points. However, the installation of new stock watering points was associated with the creation of new paddocks. Planned future fencing focused on creating new paddocks or laneways or replacing old fences. The results are discussed in relation to contemporary natural resource management issues and the future approaches to and challenges of implementing sustainable rangeland management.
31
Mound, Laurence A., e Miguel C. Zapater. "South American Haplothrips Species (Thysanoptera: Phlaeothripidae), with a new species of biological control interest to Australia against weedy Heliotropium amplexicaule (Boraginaceae)". Neotropical Entomology 32, n. 3 (settembre 2003): 437–42. http://dx.doi.org/10.1590/s1519-566x2003000300009.
Testo completo
32
Peirce, JR. "Morphological and phenological variation in three populations of saffron thistle (Carthamus lanatus L.) from Western Australia". Australian Journal of Agricultural Research 41, n. 6 (1990): 1193. http://dx.doi.org/10.1071/ar9901193.
Testo completoAbstract (sommario):
Saffron thistle (Carthamus lanatus L.), an erect spiny annual herb, is a weed of pasture and cereal crops in some agricultural areas of southern Australia. Cypselas (achenes or seeds) were collected from mature plants at three sites near Salmon Gums, Moorine Rock and Greenough in Western Australia and grown at South Perth. Two forms were observed and could be distinguished by differences in their phenology and the shape of cotyledons and achenes. After two generations at South Perth, germination in the presence or absence of leaching with water or after storage at daily fluctuating temperatures of 15-60�C indicated that there were differences between forms as well as between different accessions of the same form. This result suggests that genetic as well as environmental factors influence the breakdown of dormancy and promote germination. Differences in germination were detected when a single accession was sown at two sites, one in the south and the other in the north of the cereal-growing region of Western Australia. Low rainfall and temperatures in autumn were primarily responsible for slow and staggered germination at the more southern site. The protracted germination of saffron thistle in the southern cereal-growing districts creates a problem for cultural control and correct timing of herbicide applications.
33
Ndlovu, Mpilonhle S., Julie A. Coetzee, Menzi M. Nxumalo, Reshnee Lalla, Ntombifuthi Shabalala e Grant D. Martin. "The Establishment and Rapid Spread of Sagittaria Platyphylla in South Africa". Water 12, n. 5 (21 maggio 2020): 1472. http://dx.doi.org/10.3390/w12051472.
Testo completoAbstract (sommario):
Sagittaria platyphylla Engelm. (Alismataceae) is a freshwater aquatic macrophyte that has become an important invasive weed in freshwater systems in South Africa, New Zealand, Australia, and recently China. In South Africa, due to its rapid increase in distribution and ineffective control options, it is recognised as one of the country’s worst invasive aquatic alien plants. In this paper, we investigate the spread of the plant since its first detection in 2008, and the management strategies currently carried out against it. Despite early detection and rapid response programmes, which included chemical and mechanical control measures, the plant was able to spread both within and between sites, increasing from just one site in 2008 to 72 by 2019. Once introduced into a lotic system, the plant was able to spread rapidly, in some cases up to 120 km within 6 years, with an average of 10 km per year. The plant was successfully extirpated at some sites, however, due to the failure of chemical and mechanical control, biological control is currently being considered as a potential control option.
34
Kwong, Raelene M., Linda M. Broadhurst, Brian R. Keener, Julie A. Coetzee, Nunzio Knerr e Grant D. Martin. "Genetic analysis of native and introduced populations of the aquatic weed Sagittaria platyphylla – Implications for biological control in Australia and South Africa". Biological Control 112 (settembre 2017): 10–19. http://dx.doi.org/10.1016/j.biocontrol.2017.06.002.
Testo completo
35
Morrison, SM, e JK Scott. "Variation in Populations of Tribulus terrestris (Zygophyllaceae) .2. Chromosome Numbers". Australian Journal of Botany 44, n. 2 (1996): 191. http://dx.doi.org/10.1071/bt9960191.
Testo completoAbstract (sommario):
Variation in chromosome number was investigated as part of a study to identify the origins of the widespread weed and potential biological control target Tribulus terrestris L. s.1. (Zygophyllaceae). Three ploidy levels, tetraploid 2n = 24, hexaploid 2n = 36 and octoploid 2n = 48, were detected in 24 Australian and 24 overseas collections. Northern Territory and Queensland collections, possibly representing a native species of Tribulus, had counts of 2n = c. 24. The majority of collections of T. terrestris in southern and north-western regions of Australia had counts of 2n = c. 36, but two collections had counts of 2n = c. 24. Collections from South Africa and Namibia also had a mixture of tetraploid and hexaploid forms. The USA, Mediterranean and West Asian samples (except for three Kuwait samples) were all hexaploid. All Indian and three Kuwait samples were the only octoploid collections observed. These ploidy levels agree with those previously reported for T. terrestris. It was concluded that the polyploid complex has an allopolyploid origin. The predominantly hexaploid collections in Australia indicate an overseas origin, and the presence of two tetraploid collections points to two or more separate introductions of T. terrestris into Australia. Counts for T. micrococcus and T. occidentalis were 2n = c. 48, which provide further evidence for a base number of x = 6 or 12 for the genus.
36
Anderson, W. K., G. B. Crosbie e W. J. Lambe. "Production practices in Western Australia for wheats suitable for white, salted noodles". Australian Journal of Agricultural Research 48, n. 1 (1997): 49. http://dx.doi.org/10.1071/a95133.
Testo completoAbstract (sommario):
Wheat cultivars acceptable for the Noodle wheat segregation in Western Australia were compared with cultivars suitable for the Australian Standard White (ASW) grade over the period 1989–93. Yield and grain quality responses to sowing time, nitrogen fertiliser, soil type, and cropping history were examined to determine management practices most likely to result in wheat grain suitable for the production of white, salted noodles. Thirty experiments were conducted in the 300–450 mm average annual rainfall zone between Three Springs in the north (approx. 29° 30′S) and Newdegate in the south (approx. 33°10′S). The ASW cultivars, Spear, Kulin, and Reeves, outyielded the Noodle cultivars, Gamenya and Eradu, by 8–10% on average, but the yield difference was less at later sowings. The optimum sowing time was early May for most cultivars. The new cultivars, Cadoux (Noodle) and Tammin (potential Noodle, but classiffied General Purpose), tested in 1992 and 1993 in 12 experiments showed an optimum sowing time of late May, as did other midseason cultivars. Grain yields of May-sown crops were increased by 13 kg for every 1 kg of nitrogen applied, compared with 3 : 1 for June-sown crops. Previous legume history of the site and grass weed control in the crop also influenced the grain protein percentage. It was concluded that adoption of production guidelines that include sowing at, or near, the break of the season with about 40 kg/ha of nitrogen fertiliser, a rotation that includes 2-3 years of legume crop or pasture in the previous 5 years, and adequate grass weed control will result in an excellent chance (>80%) of producing grain proteins within the receival standards for the Noodle grade. Flour swelling volume (FSV), an indicator of noodle eating quality, was negatively correlated (not always significantly at P = 0·05) with grain protein percentage in 7 out of 8 experiments. FSV values were larger from sites located in the south of the study area and this appeared to be independent of protein and time-of-sowing effects. Small grain sievings (<2 mm) were increased by sowing after the end of May, especially in the longer season cultivars.
37
McKay, AG, RM Floyd e CJ Boyd. "Phosphonic acid controls downy mildew (Peronospora parasitica) in cauliflower curds". Australian Journal of Experimental Agriculture 32, n. 1 (1992): 127. http://dx.doi.org/10.1071/ea9920127.
Testo completoAbstract (sommario):
Postharvest development of downy mildew (Peronospora parasitica) symptoms in export cauliflower curds has resulted in economic losses to growers in south-western Australia. Neutralised phosphonic acid sprays applied onto cauliflowers in the field within 3 weeks of harvest reduced this disease. Two applications of 2.4 kg a.i./ha, 21 and 7 days before harvest, reduced the incidence of curds affected by downy mildew from 92% in untreated plots to 8%. The maximum phosphonate residue in curds at harvest was 12 �g/g, while control curds contained no detectable phosphonate. No effects of phosphonic acid on crop appearance or maturity were observed, and while a small (8%) reduction in curd weight was significant (P = 0.039), there was no yield trend with increasing phosphonic acid rate.
38
Heap, J. W. "Biology and control of Reseda lutea L. 1. Seed biology and seedling growth". Australian Journal of Agricultural Research 48, n. 4 (1997): 511. http://dx.doi.org/10.1071/a96107.
Testo completoAbstract (sommario):
Reseda lutea L. is a major perennial weed of alkaline cropping soils in South Australia. Seed biology and early seedling growth of R. lutea were studied in field and laboratory experiments to gain information needed for effective control strategies. Recovery of intact seeds buried for 4 years in the field at 50 and 150 mm was 77–96%. Germination of this seed was 33–63% (50 mm) and 0% (150 mm). Germination patterns differed markedly between seed collected from 2 populations. Seed germinated at all constant and fluctuating temperatures between 10 and 35° C with the maximum (88%) at 25°C constant. Mean temperature, rather than constancy or fluctuation, determined the germination rate. Light strongly inhibited germination. Seedling shoot growth was slow but tap root growth was rapid, reaching 350 mm within 28 days of emergence. Secondary roots arose 3–7 days after emergence and shoot buds formed on the roots within 28 days. R. lutea was found to be well adapted for persistence in cultivated fields with a temperate climate.
39
Jones, R., e R. Medd. "Economic analysis of integrated management of wild oats involving fallow, herbicide and crop rotational options". Australian Journal of Experimental Agriculture 37, n. 6 (1997): 683. http://dx.doi.org/10.1071/ea97036.
Testo completoAbstract (sommario):
Summary. The primary objective of this study was to estimate the economic benefits associated with an integrated weed management approach for wild oats (Avena fatua and A. ludoviciana) in northern New South Wales involving chemical and non-chemical controls. The paper presents a framework for assessing the population dynamics of wild oats and the economics of a range of control options over 15 years. Wild oats is a weed primarily of winter crops which, as a consequence of its persistence and its impact upon yields, leads to significant economic losses in the grain growing regions of Australia. In this study, a dynamic programming model is developed to examine the impact of a range of management strategies for the control of wild oats in wheat. The strategies evaluated include conventional herbicide control to reduce weed densities, the use of selective herbicides to reduce seed set of the weed, and summer crop and winter fallow rotational options which provide a break in the cereal cycle and allow accelerated control of wild oat populations. The hypothesis for the study, that strategies which involve measures that directly reduce seed production and minimise wild oats seed bank populations will yield the greatest economic benefit, is acceptable based on the findings of the study. The work also shows that a dynamic programming model provides a means of determining the optimal combination of strategies over time for various initial values of the seed bank. The methodology is considered to have general application as a framework for evaluating the economics of weed control problems in annual cropping systems.
40
Pankhurst, CE, HJ McDonald e BG Hawke. "Influence of soil-water matric potential on the control of Pythium root infection of wheat with metalaxyl in two contrasting soils of South Australia". Australian Journal of Experimental Agriculture 35, n. 5 (1995): 603. http://dx.doi.org/10.1071/ea9950603.
Testo completoAbstract (sommario):
Under prevailing climatic conditions, treatment of winter-sown wheat with metalaxyl (seed dressing, granule, or soil drench applications) significantly limited seed infection by Pythium species but did not give a significant yield response in separate field trials conducted on 2 contrasting soil types in South Australia. However, following irrigation of trial plots (which raised the soil-water matric potential from about -0.09 MPa to -0.02 MPa) during the first 3 weeks of wheat growth in 1989, metalaxyl granule treatment was effective in limiting seed and root infection by the 2 dominant Pythium species present, P. irregulare and P. echinulatum, and gave a significant increase in grain yield on both soil types. This effect of soil-water matric potential was confirmed in growth cabinet experiments in which metalaxyl was shown to be more effective in controlling infection of wheat by P. irregulare in both soil types when the soil-water matric potential was maintained at -0.02 MPa than at a soil-water matric potential of -0.1 MPa.
41
Morokhovets, V. N., Т. V. Morokhovets, T. V. Shterbolova, Z. V. Basay e A. A. Baimuhanova. "Test results of the new herbicide Flex in soybean crops in Primorsky Territory". Siberian Herald of Agricultural Science 49, n. 2 (22 maggio 2019): 16–26. http://dx.doi.org/10.26898/0370-8799-2019-2-2.
Testo completoAbstract (sommario):
The biological and economic efficiency of the new herbicide Flex in post-emergence application to soybean crops of the variety Sphera was studied. The tests were carried out incompliance with the standard methods in the form of the plot experiment in 2017, 2018 on brown meadow podzolized soils in the south of the Far East. The preparation was tested in the consumption rates of 1.25 and 1.5 l/ha when the crop reached the development phase of two triple leaves as opposed to the standard herbicide Galaxy Top in the rate of 1.7 l/ha. It was found that Flex has a high herbicidal activity against all dicotyledonous annual and perennial species of weeds. Common ragweed (Ambrosia artemisiifolia L.) and Asian copperleaf (Acalypha australis L.) were highly sensitive to the preparation even in the minimum consumption rate. Especially strong toxic effect of Flex was produced on such weeds in the rosette phase as Asiatic dayflower (Commelina communis L.), lamb’s quarters (Chenopodium album L.), field milk thistle (Sonchus arvensis L.), creeping thistle (Cirsium setosum (Willd.) Bieb.) and common mugwort (Artemisia vulgaris L.). Consistent application of graminicide Fuzilade Forte in the rate of 1.5 l/ha after treatment of soybean crops with herbicide Flex contributed to an almost complete elimination of annual grass weeds. The high biological efficiency of the experimental preparation contributed to a significant increase in crop yield. In 2018, when it was applied in the minimum rate of 1.25 l/ha, the yield achieved was 0.94 t/ha, exceeding the control value by 3.3 times. The highest yield increase of soybean seeds (1.12 t/ha on average for 2 years) was obtained with the use of herbicide Flex in the maximum consumption rate of 1.5 l/ha. Application of herbicide Flex to soybean crops in the rates of 1.25 and 1.5 l/ha alongside with the preparation Trend 90 in the rate of 0.2 l/ha proved to be highly effective in eliminating annual and perennial dicotyledonous weeds (in early stages of development) from soybean crops.
42
Unkovich, Murray, Therese McBeath, Rick Llewellyn, James Hall, Vadakattu VSR Gupta e Lynne M. Macdonald. "Challenges and opportunities for grain farming on sandy soils of semi-arid south and south-eastern Australia". Soil Research 58, n. 4 (2020): 323. http://dx.doi.org/10.1071/sr19161.
Testo completoAbstract (sommario):
Sandy soils make up a substantial fraction of cropping land in low rainfall (<450 mm p.a.) south and south-eastern Australia. In this paper we review the possible soil constraints to increased production on these soils in this region. Many of these soils have a very low (<3%) clay content and suffer from severe water repellency, making crop establishment and weed control problematic. Crops which do emerge are faced with uneven soil wetting and poor access to nutrients, with crop nutrition constraints exacerbated by low fertility (soil organic matter < 1%) and low cation exchange capacity. Zones of high penetration resistance appear common and have multiple causes (natural settling, cementation and traffic induced) which restrict root growth to <40 cm. Crop water use and grain yield are therefore likely to be well below the water-limited potential. Water repellency is readily diagnosed and where apparent should be the primary management target. Repellency can be mitigated through the use of furrow and other sowing technologies, along with soil wetting agents. These techniques appear to be affected by site and soil nuances and need to be refined for local soils and conditions. Once crop establishment on water repellent soils has been optimised, attention could be turned to opportunities for improving crop rooting depth through the use of deep tillage or deep ripping techniques. The required ripping depth, and how long the effects may last, are unclear and need further research, as do the most effective and efficient machinery requirements to achieve sustained deeper root growth. Crop nutrition matched to the water-limited crop yield potential is the third pillar of crop production that needs to be addressed. Low soil organic matter, low cation exchange capacity, low biological activity and limited nutrient cycling perhaps make this a greater challenge than in higher rainfall regions with finer textured soils. Interactions between nutrients in soils and fertilisers are likely to occur and make nutrient management more difficult. While amelioration (elimination) of water repellency is possible through the addition of clay to the soil surface, the opportunities for this may be restricted to the ~30% of the sandy soils of the region where clay is readily at hand. The amounts of clay required to eliminate repellency (~5%) are insufficient to significantly improve soil fertility or soil water holding capacity. More revolutionary soil amelioration treatments, involving additions and incorporation of clay and organic matter to soils offer the possibility of a more elevated crop yield plateau. Considerable research would be required to provide predictive capacity with respect to where and when these practices are effective.
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KOLESIK, PETER, e ALAN R. WOOD. "Redescription of Mitodiplosis graminis (Diptera: Cecidomyiidae), a gall midge inhibiting the flowering of pyp grass Ehrharta villosa (Poaceae) in South Africa". Zootaxa 4614, n. 1 (7 giugno 2019): 173. http://dx.doi.org/10.11646/zootaxa.4614.1.8.
Testo completoAbstract (sommario):
Mitodiplosis graminis Kieffer, the only species of the genus Mitodiplosis (Diptera: Cecidomyiidae), was described in 1914 as the causative agent of an unspecified gall on pyp grass Ehrharta villosa (Poaceae) in South Africa. The type specimens are presumed lost. We reared all developmental stages of the gall midge, redescribe here the male and female, and describe for the first time the gall, egg, larva and the pupa. Diagnosis of the genus Mitodiplosis is extended. The gall is a large thickening of the stem that becomes malformed and does not produce flowers. Pyp grass is an environmental weed in Australia and New Zealand and M. graminis can potentially be used as a biological control agent. With a wing length of over 6 mm in some specimens, M. graminis is one of the largest species of Cecidomyiidae.
44
Wood, A. R., A. den Breeÿen e F. Beed. "First Report of Smut on Imperata cylindrica Caused by Sporisorium schweinfurthianum in South Africa". Plant Disease 93, n. 3 (marzo 2009): 322. http://dx.doi.org/10.1094/pdis-93-3-0322a.
Testo completoAbstract (sommario):
Imperata cylindrica (L.) Raeusch. (Poaceae) is indigenous to the old world but is a problem weed in tropical areas throughout the world (1). A smut fungus was observed frequently on this grass at a single site near Pretoria (25°44′19″S, 28°15′39″E), South Africa during April of 2006. On the basis of the following characteristics, it was identified as Sporisorium schweinfurthianum (Thüm.) K. Vánky (2). Panicles were systemically infected and all ovaries in infected inflorescences were replaced by spores. Spores were globose or subglobose, brown, 10 to 14 × 9 to 12 μm (average 11.2 × 9.8 μm; n = 25), wall 1 μm thick, and finely verruculose. Hyaline, thin-walled sterile cells were present. This identification was confirmed by K. Vánky (personal communication to A. R. Wood). To our knowledge, this is the first report of this smut species from southern Africa. A voucher specimen has been deposited in the South African National Collection of Fungi, ARC-Plant Protection Research Institute (PREM 59895). To test pathogenicity, soil in 15 pots with individual 1-month-old seedlings was drenched with an aqueous suspension of 1 × 108 spores ml–1 amended with 0.1% Tween 80. Before treatment, the pots were placed on pot trays and remained immersed in the spore suspension in the trays at 28°C (relative humidity <80%) for 24 h. To maintain the spore concentration in the soil, the pots were not watered until 7 days after inoculation. Distilled water amended with 0.1% Tween 80 was applied as control treatments to a further 15 pots with plants. Five of the treated plants produced panicles within 4 months of inoculation. Of these, all the ovaries of four emerging inflorescences were completely replaced with a brown, powdery mass of teliospores. No smutted panicles developed on the control plants. This smut fungus may have potential as a classical biological control agent for use against I. cylindrica by reducing dispersal by seed. References: (1) L. G. Holm et al. The World's Worst Weeds: Distribution and Biology. University Press of Hawaii. Honolulu, 1977. (2) K. Vánky. Australas. Plant Pathol. 29:155, 2000.
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Bell, L. W., G. A. Moore, M. A. Ewing e S. J. Bennett. "Establishment and summer survival of the perennial legumes, Dorycnium hirsutum and D. rectum in Mediterranean environments". Australian Journal of Experimental Agriculture 45, n. 10 (2005): 1245. http://dx.doi.org/10.1071/ea04227.
Testo completoAbstract (sommario):
The genus Dorycnium has been identified for its potential use as a forage plant for southern Australia, but little is known about factors affecting establishment and survival. This investigation examined some factors affecting the establishment of D. hirsutum and D. rectum in Mediterranean environments of south-west Western Australia. The population dynamics of D. hirsutum and D. rectum seedlings were investigated during the summer drought in 4 environments. The effect of time of sowing on establishment and survival of D. hirsutum was tested as a management option for improving establishment of these species. Poor seedling performance was observed in both Dorycnium species. Less than 20% of D. rectum plants survived the summer drought at all locations, compared with >50% for D. hirsutum seedlings. Poor seedling vigour coupled with weed competition resulted in low plant numbers at 2 sites. Compared with autumn sowings, populations of D. hirsutum sown in August and September had lower plant densities before summer due to poorer seedling emergence. Plant numbers declined during the summer in all plots, but losses were greatest in those sown in September. In both experiments, small D. hirsutum plants survived in plots where little competition was present. Improvements in seedling vigour may be possible with plant breeding but establishment methods that reduce weed competition are valuable. Spring sowing may enable effective weed control before seeding, but later sowings run the risk of reducing seedling emergence and survival.
46
Drew, E. A., V. V. S. R. Gupta e D. K. Roget. "Herbicide use, productivity, and nitrogen fixation in field pea (Pisum sativum)". Australian Journal of Agricultural Research 58, n. 12 (2007): 1204. http://dx.doi.org/10.1071/ar06394.
Testo completoAbstract (sommario):
Grain legumes grown in low-rainfall (<300 mm per annum) cropping regions of southern Australia have at times failed to provide the rotational benefits observed in other regions, such as improved cereal yields in the season following a legume. ‘In-crop’ herbicides were identified as one possible factor that may have been negatively affecting the legume–rhizobia symbiosis. To test this hypothesis and identify possible mechanisms behind any observed effects, field trials were conducted at Waikerie (South Australia) in 2001, 2003, and 2004. Field pea (Pisum sativum L.) was grown and treated with one of several herbicides 5 weeks after sowing. Crop yellowing, biomass, nodulation, and nitrogen (N2) fixation were assessed 3 weeks after spraying, and biomass, yield, percent nitrogen derived from fixation (%Ndfa), and N2 fixation (2003, 2004) were assessed at the end of the season. Some herbicides stunted plant growth and caused crop yellowing 3 weeks after application; however, none of the herbicides affected N nutrition of peas. Despite this, in 2003, half of the herbicides assessed reduced the %Ndfa by 34–60% relative to unsprayed control plots. Herbicide effects on the measured parameters followed similar trends over each year of the 3-year study. However, effects were rarely significant in 2004 as the trials were primarily affected by low rainfall, indicating that environmental parameters play a key role in determining the severity of herbicide effects on symbiotic N2 fixation. The possible mechanisms behind herbicide-induced damage to the pea–rhizobium symbiosis are discussed, including reduced photosynthetic capacity of plants exposed to herbicides.
47
Witt, A. B. R., A. J. McConnachie e R. Stals. "Alcidodes sedi (Col.: Curculionidae), a natural enemy of Bryophyllum delagoense (Crassulaceae) in South Africa and a possible candidate agent for the biological control of this weed in Australia". Biological Control 31, n. 3 (novembre 2004): 380–87. http://dx.doi.org/10.1016/j.biocontrol.2004.07.008.
Testo completo
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Turner, Neil C., e Senthold Asseng. "Productivity, sustainability, and rainfall-use efficiency in Australian rainfed Mediterranean agricultural systems". Australian Journal of Agricultural Research 56, n. 11 (2005): 1123. http://dx.doi.org/10.1071/ar05076.
Testo completoAbstract (sommario):
Mediterranean environments are characterised by hot, dry summers and cool, wet winters. The native vegetation in Mediterranean-climatic regions is predominantly perennial shrubs and trees intermixed with annual forbs. In south-western Australia, the spread of agriculture has seen the well adapted perennial vegetation replaced by rainfed annual crops and pastures. This has increased waterlogging and secondary salinity, thereby causing loss of productivity in ~10% of the cleared land area. To reduce deep drainage and make the agricultural systems environmentally sustainable requires the re-introduction of perennial vegetation in the form of belts of trees or shrubs, and phase-farming systems with perennials such as lucerne replacing annual pastures between the cropping years. To be economically viable, agricultural productivity needs to increase by at least 3% per annum. Yields of dryland wheat, the predominant crop in the Mediterranean agricultural regions of Australia, have increased at ~1%/year for the century preceding the 1980s and since then by nearly 4%/year. Increases have arisen from both genotypic and agronomic improvements. Genotypic increases have arisen from selection for earliness, early vigour, deep roots, osmotic adjustment, increased transpiration efficiency, improved disease resistance, and an improved harvest index from high ear weight (grain number) at flowering and high assimilate storage and remobilisation. Agronomic increases have arisen from early sowing that has been enabled by minimum tillage, increased fertiliser use, especially nitrogen, weed control, and rotations to improve weed control, minimise disease risk, and increase nitrogen availability. Evidence is presented suggesting that the rapid increase in yield of wheat in the last two decades has likely arisen from the rapid adoption of new technologies. For productivity to be maintained in the face of the increasing requirement to be environmentally sustainable will be a challenge and will require better integration of breeding and agronomy.
49
White, C. L., M. v.-H. Staines, N. Phillips, P. Young, F. Coupar, J. R. Ashes e S. K. Gulati. "Protected canola meal increases milk protein concentration in dairy cows fed a grass silage-based diet". Australian Journal of Experimental Agriculture 44, n. 9 (2004): 827. http://dx.doi.org/10.1071/ea03132.
Testo completoAbstract (sommario):
Low concentrations of protein in milk occur during the summer–autumn in south-west Australia. This is the period, on dryland farms, when the diet of lactating cows typically consists of grass silage and a mixture of crushed lupins and cereal grain. This experiment was conducted to test the hypothesis that supplying protected canola meal would increase the protein concentration of milk and, possibly, milk yield in cows fed grass silage and a lupin–cereal concentrate. Sixty Holstein cows in mid lactation were allocated to 2 equal-sized dietary treatment groups: control (lupin) or protected canola meal. The control diet consisted of 14.5 kg DM grass silage (annual ryegrasses–subterranean clover) and 5.4 kg DM of crushed lupins and barley (4:1) per head per day. For the protected canola meal diet, 2.15 kg DM protected canola meal replaced 2.15 kg lupins. The protected canola meal was produced by treating solvent-extracted canola meal with formaldehyde, to produce a product with an in sacco fractional degradability of 0.29 at a rumen fractional outflow rate of 0.08/h. The equivalent degradability of untreated canola meal was 0.80 and of lupin was 0.83. Cows were individually fed the concentrate ration twice daily, after each milking, then were managed as a single herd in dry lots and fed grass silage. By the end of 8 weeks, cows fed the protected canola meal diet had higher milk protein concentrations (30.7 v. 29.2 g/L; P<0.05) and higher liveweights (604 v. 593 kg; P<0.05). Milk yield (L/day) was increased by 1 L/day, but this effect was not significant (P>0.10). Fat concentration was unaffected by diet (P>0.05). Since the only difference in treatment was the replacement of a portion of lupins with protected canola meal, the results indicate that a deficiency of metabolisable amino acids contributes to the low milk protein concentrations recorded during summer–autumn in south-west Australia. Whether this was acting primarily through a stimulus of appetite, or directly on milk components, could not be determined because silage intakes were not recorded.
50
Johnston, W. H., P. S. Cornish, T. B. Koen e V. F. Shoemark. "Eragrostis curvula (Schrad.) Nees. complex pastures in southern New South Wales, Australia: a comparison of Eragrostis curvula cv. Consol and Medicago sativa L. cv. Nova under intensive rotational management". Australian Journal of Experimental Agriculture 45, n. 10 (2005): 1255. http://dx.doi.org/10.1071/ea04080.
Testo completoAbstract (sommario):
The productivity, carrying capacity and liveweight performance of wether sheep grazing pastures of Eragrostis curvula cv. Consol and Medicago sativa cv. Nova, which were also sown with annual grasses and Trifolium subterraneum, were compared under an intensive 4-paddock rotational grazing regime in a ‘put-and-take’ grazing experiment at Wagga Wagga, New South Wales from November 1993 to August 1996. The productivity of the pastures was broadly similar, with production peaks of >1000 kg/ha in winter and >3000 kg/ha in spring and summer in paddocks that had been spelled for 6 weeks. Although annual species contributed a high proportion of the total herbage mass in spring, over the remainder of the year, both pastures were dominated by their respective perennials. E. curvula maintained an average plant density of approximately 20 plants/m2. The density of M. sativa declined noticeably during the 3 years, and at the end of the experiment M. sativa plants in 1 replicate of the experiment were killed by rising groundwater and dryland salinity. The long-term average stocking rate of E. curvula and M. sativa pastures were similar (12.1 v. 12.5 sheep/ha) and both pastures were capable of sustaining high stocking rates for lengthy periods in spring and summer. Sheep grazing M. sativa tended to be heavier than animals grazing E. curvula, and they produced, on average, 1.1 kg (or 21%) more wool. However, M. sativa was more difficult to establish and its costs for weed and insect control were higher. Therefore, although it was more productive, it might not have been the most economically viable of the 2 pastures. The implications of the findings were discussed within a whole-farm context and it was concluded that E. curvula has a complimentary role to M. sativa for sowing on landscapes and in situations to which M. sativa is poorly adapted.