Virus diseases of annual pasture legumes: incidences, losses, epidemiology, and management

2012 ◽  
Vol 63 (5) ◽  
pp. 399 ◽  
Author(s):  
Roger A. C. Jones
Keyword(s):  
Large Scale ◽  
Current Knowledge ◽  
Subterranean Clover ◽  
Summer Rainfall ◽  
Virus Diseases ◽  
Pasture Legumes ◽  
Improvement Programs ◽  
Annual Medics ◽  
Grazed Swards ◽  
Pasture Legume

This paper reviews current knowledge concerning the occurrence, losses caused, epidemiology, and management of virus diseases of annual pasture legumes. The viruses commonly present are spread by contact, or aphid vectors either non-persistently or persistently. Whether they are seed-borne and their means of transmission are critical factors determining their incidences within pastures in climatic zones with dry summers or substantial summer rainfall. Large-scale national or state surveys of subterranean clover pastures revealed that some viruses reach high infection incidences. Contamination with seed-borne viruses was widespread in plots belonging to annual pasture legume improvement programs and seed stocks of subterranean clover, annual medics, and alternative annual pasture legumes, and in commercial annual medic seed stocks. Yield loss studies with grazed swards were completed for three common viruses: two in subterranean clover and one in annual medics. These studies demonstrated considerable virus-induced losses in herbage and seed yields, and established that virus infection causes deteriorated pastures with high weed contents even when foliar symptoms are mild. Comprehensive integrated disease management tactics involving phytosanitary, cultural, chemical, or host resistance measures were devised for these three viruses in infected pastures, and for seed-borne viruses in annual pasture legume improvement programs. Several other viruses are potentially important, but, with these, quantification of losses caused in grazed swards is lacking and information on incidences in pastures is currently insufficient. Critical research and development gaps that need addressing are identified.

Virus diseases of perennial pasture legumes in Australia: incidences, losses, epidemiology, and management

2013 ◽  
Vol 64 (3) ◽  
pp. 199 ◽  
Author(s):  
Roger A. C. Jones
Keyword(s):  
Mosaic Virus ◽  
White Clover ◽  
Large Scale ◽  
Current Knowledge ◽  
Alfalfa Mosaic Virus ◽  
South Australia ◽  
Control Measures ◽  
Virus Diseases ◽  
Virus Identification ◽  
Pasture Legumes

This article reviews current knowledge for Australia over the occurrence, losses caused, epidemiology, and management of virus diseases of perennial pasture legumes. Currently, 24 viruses have been found infecting perennial pasture legumes, and one or more viruses have been detected in 21 of these species. These viruses are transmitted by insect vectors, non-persistently or persistently, by contact or via seed. Their modes of transmission are critical factors determining their incidences within pastures in different climatic zones. Large-scale national or state surveys of lucerne (alfalfa) (Medicago sativa) and white clover (Trifolium repens) pastures revealed that some viruses reach high incidences. Infection with Alfalfa mosaic virus (AMV) was very widespread in lucerne stands, and with AMV and White clover mosaic virus (WClMV) in white clover pastures. Several other viruses are potentially important in pastures in these and other perennial temperate/Mediterranean pasture species. Data demonstrating herbage yield losses, diminished pasture persistence, and impaired nitrogen fixation/nodule function are available for AMV in lucerne, and AMV, WClMV, and Clover yellow vein virus in white clover. Integrated Disease Management approaches involving phytosanitary, cultural, chemical, and host resistance control measures are available to minimise virus infection in lucerne and white clover. Research on virus diseases of perennial tropical–subtropical pasture legumes has focussed almost entirely on virus identification, and information on their incidences in pastures, the losses they cause, and how to control them is lacking. Overall, viruses of perennial pasture legumes are least studied in South Australia and the Northern Territory. These and other critical research and development gaps that need addressing are identified.

Variability of in vitro ruminal fermentation and methanogenic potential in the pasture legume biserrula (Biserrula pelecinus L.)

2013 ◽  
Vol 64 (4) ◽  
pp. 409 ◽  
Author(s):  
Bidhyut Kumar Banik ◽  
Zoey Durmic ◽  
William Erskine ◽  
Phillip Nichols ◽  
Kioumars Ghamkhar ◽  
...  
Keyword(s):  
Core Collection ◽  
Volatile Fatty Acids ◽  
Germplasm Collection ◽  
Red Clover ◽  
Subterranean Clover ◽  
Ruminal Fermentation ◽  
Rumen Microbes ◽  
Pasture Legumes ◽  
Pasture Legume

Biserrula (Biserrula pelecinus L.) is an important annual pasture legume for the wheatbelt of southern Australia and has been found to have lower levels of methane output than other pasture legumes when fermented by rumen microbes. Thirty accessions of the biserrula core germplasm collection were grown in the glasshouse to examine intra-specific variability in in vitro rumen fermentation, including methane output. One biserrula cultivar (Casbah) was also grown at two field locations to confirm that low methanogenic potential was present in field-grown samples. All of the biserrula accessions had significantly reduced methane [range 0.5–8.4 mL/g dry matter (DM)] output compared with subterranean clover (28.4 mL/g DM) and red clover (36.1 mL/g DM). There was also significant variation in fermentability profiles (except for volatile fatty acids) among accessions of the core collection. Methanogenic potential exhibited 86% broad-sense heritability within the biserrula core collection. The anti-methanogenic and gas-suppressing effect of biserrula was also confirmed in samples grown in the field. In conclusion, biserrula showed variability in in vitro fermentation traits including reduced methane production compared with controls. This bioactivity of biserrula also persists in the field, indicating scope for further selection of biserrula as an elite methane-mitigating pasture.

Breeding and farming system opportunities for pasture legumes facing increasing climate variability in the south-west of Western Australia

2012 ◽  
Vol 63 (9) ◽  
pp. 840 ◽  
Author(s):  
C. K. Revell ◽  
M. A. Ewing ◽  
B. J. Nutt
Keyword(s):  
Western Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Farming System ◽  
Annual Rainfall ◽  
The South ◽  
Pasture Legumes ◽  
South West ◽  
Annual Medics ◽  
Phosphorus And Potassium

The south-west of Western Australia has experienced a declining trend in annual rainfall and gradual warming over the last 30 years. The distribution of rainfall has also changed, with lower autumn rainfall, patchy breaks to the season, and shorter springs. This has important implications for the productivity of legume pastures in the region, which is dominated by annual species, particularly subterranean clover (Trifolium subterraneum L.), annual medics (Medicago spp.), serradella (Ornithopus spp.), and biserrula (Biserrula pelecinus L.). For annual pasture legumes, appropriate patterns of seed softening and germination behaviour, efficiency of phosphorus and potassium uptake, responses to elevated levels of atmospheric CO2, and drought resistance of seedlings and mature plants will assume increasing importance. While these traits can be targeted in pasture breeding programs, it will also be important to exploit farming system opportunities to optimise the annual legume component of the feed base. These opportunities may take the form of incorporating strategic shrub reserves and grazing crops to allow for pasture deferment in autumn–winter. Perennial forages may become more important in this context, as discussed in terms of the development of the perennial legume tedera (Bituminaria bituminosa var. albomarginata C.H. Stirton).

Productivity of pasture legumes and chicory in central New South Wales

2002 ◽  
Vol 42 (1) ◽  
pp. 15 ◽  
Author(s):  
D. R. Kemp ◽  
D. L. Michalk ◽  
M. Goodacre
Keyword(s):  
White Clover ◽  
New South ◽  
New South Wales ◽  
Subterranean Clover ◽  
Summer Rainfall ◽  
Annual Rainfall ◽  
Summer Drought ◽  
Potential Yield ◽  
Pasture Legumes ◽  
South Wales

Seven experiments were established across a range of environments (latitude 33°S) in central New South Wales to evaluate 52 legume cultivars and lines against currently recommended cultivars. Plots were grazed by either sheep or cattle after each harvest. Criteria for inclusion were that lines were either commercially available or in the process of being registered. Three experiments also included chicory. Sites had from 600 to 900 mm annual rainfall and were at altitudes of 440–1000 m. The 4-year program included the dry summer of 1990–91. White clover and subterranean clover were the most productive species over time. Among subterranean clovers, the subspecies subterraneum cultivars were more productive than the yanninicum or brachycalycinum subspecies. Other species such as balansa, Persian, strawberry, red and crimson clovers, lotus major and murex medic were more variable in production. These legumes often grew well in the establishment year, but failed to persist. Lucerne was in general, not as productive as white or subterranean clover. Caucasian clover and yellow serradella should be evaluated further as conclusive judgements could not be formed. Chicory was often the most productive species in the experiments, especially over the warmer 6 months of the year. It persisted under a 6-week harvest regime and during the drought year. The newer subterranean clover cultivars, Leura, Goulburn and Denmark all exceeded the production from the previously recommended cultivars, Woogenellup and Karridale, even though no major disease was evident in the later group. The lines 89820D and 89841E were sufficiently productive to warrant further evaluation and possible development as cultivars. In contrast, while Huia, Tahora, Bonadino and Tamar were often as productive as the recommended white clover cultivar Haifa, they were not consistently better. Where summer rainfall occurs and the annual rainfall exceeds 650 mm, the greater potential yield of white clover compared with subterranean clover justifies its use. However, no white clover cultivars survived the summer drought in 1990–91 as intact plants. Further work is needed to develop more drought-tolerant cultivars.

Fate of annual pasture legumes seeds on a two-way thermo-gradient plate

2002 ◽  
Vol 24 (2) ◽  
pp. 227 ◽  
Author(s):  
G. M. Lodge ◽  
R. D. B. Whalley
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Vicia Villosa ◽  
Temperature Range ◽  
Pasture Legumes ◽  
Maximum Value ◽  
High Germination ◽  
Annual Medics ◽  
Gradient Plate ◽  
Seed Fates

Effects of diurnally alternating temperatures (5/5–45/45�C) were examined on a two-way thermogradient plate for non-dormant seeds of 14 annual pasture legumes. Seed fates (germination, temperature induced non-viability and temperature induced dormancy) were determined from daily seed counts over a 14-day period on-plate and a further 14 days after removal from the plate. These data clearly demonstrate the existence and extent of seed fates other than germination. Maximum dormancy occurred over a broad range of temperatures for seeds of Trifolium subterraneum L. var. subterraneum (Katzn. et Morley) Zohary and Heller cv. Woogenellup (40/35–30/25�C), Astragalus hamosus L. cv. Ioman (40/25–30/5�C) and Trifolium hirtum All. cv. Hykon (35/30–30/5�C). In contrast, maximum dormancy occurred over a narrow temperature range for Medicago truncatula Gaertn. var. truncatula cv. Paraggio (35/30–30/25�C), M. aculeata Willd. var. inermis (Aschers.) Heyn (30/25 and 30/20�C), and M. minima L. (35/20–35/5�C) seeds. Generally, non-viability was highest in all legumes when temperatures were greater than 35/30�C and not significantly different from the maximum value (100%) at temperatures greater than 40/30�C. At temperatures less than 35/30�C non-viability was less than the maximum (P<0.05) for seeds of all legumes, except M. truncatula cvs. Jemalong and Sephi, M. aculeata, and Vicia villosa ssp. dasycarpa (Ten.) Cav. cv. Namoi. Compared with the other subterranean clover cultivars germination levels T. subterraneum var. brachycalycinum (Katzn. et Morley) Zohary and Heller cv. Clare seeds were not significantly different from the maximum value at higher temperatures. In all annual medics, except M. aculeata germination was not significantly different to the maximum at temperatures greater than 25/20�C, with high germination (P<0.05) occurring at 30/25�C in Jemalong and M. scutellata (L.) Mill cv. Sava and at 30/20�C in Paraggio, Sephi, M. minima and M. polymorpha L. Maximum germination in Ioman and Hykon seeds occurred over a broader temperature range (35/20–15/10�C and 30/20–15/5�C, respectively) than in Namoi (30/15�C and 25/20–25/5�C). Probable implications of these data for field emergence of non-dormant seeds and soil seed reserves are discussed.

Point-of-sale evaluation of preinoculated and custom-inoculated pasture legume seed

2005 ◽  
Vol 45 (3) ◽  
pp. 161 ◽  
Author(s):  
L. G. Gemell ◽  
E. J. Hartley ◽  
D. F. Herridge
Keyword(s):  
White Clover ◽  
Red Clover ◽  
Subterranean Clover ◽  
Pass Rates ◽  
Legume Seed ◽  
Point Of Sale ◽  
Annual Medics ◽  
Assess Quality ◽  
Pasture Legume

During 1999–2003, 293 samples of preinoculated and custom-inoculated lucerne, subterranean clover, white clover, red clover and miscellaneous species (mainly other clovers) were sourced from commercial outlets and assessed for numbers of rhizobia, seed pellet pH and toxicity, and nodulation in a ‘grow-out’ test. Average rhizobial counts were 8400/seed for preinoculated lucerne, 1380/seed for subterranean clover and <100/seed for white and red clovers and for the miscellaneous species. These counts compared poorly with the average counts of 35 100/seed, 13 800/seed and 10 000/seed for freshly-inoculated lucerne, subterranean clover and white clover, respectively. Thus, overall pass rates of the preinoculated seed were reasonable for lucerne (73%), marginal for subterranean clover (32%) and very low for white clover (3%), red clover (4%) and the miscellaneous species (0%). The ‘grow-out’ tests for nodulation were positively correlated with rhizobial numbers on seed, confirming the use of plate counting of rhizobia to assess quality of pre- and custom-inoculated seed. Many of the seed pellets were toxic to the 2 clover rhizobial strains tested, although the toxicity did not affect numbers of rhizobia on the seed. In light of these results and other data on rhizobial survival on seed, we suggest the current Australian standards for rhizobial numbers on pasture legume seed at the time of sale of 500/seed (very small-seeded legumes with seed numbers >750 000/kg) and 1000/seed (other larger-seeded species, seed numbers <750 000/kg) remain in place. We recommend shelf lives be restricted to 6 months for preinoculated lucerne and the annual medics, to 6 weeks for preinoculated subterranean clover, and to 2 weeks for white clover, red clover and other miscellaneous species. In the long-term, new products and procedures will hopefully enhance the numbers and survival of rhizobia on seed such that the needs of both manufacturers and customers are satisfied.

A second generation of annual pasture legumes and their potential for inclusion in Mediterranean-type farming systems

2005 ◽  
Vol 45 (3) ◽  
pp. 289 ◽  
Author(s):  
A. Loi ◽  
J. G. Howieson ◽  
B. J. Nutt ◽  
S. J. Carr
Keyword(s):  
New Species ◽  
Second Generation ◽  
Farming Systems ◽  
Legume Species ◽  
Pests And Diseases ◽  
Pasture Legumes ◽  
Ley Farming ◽  
Acid Tolerant ◽  
Annual Medics ◽  
Pasture Legume

A second generation of annual pasture legumes and their root-nodule bacteria has been released to agriculture in Mediterranean-type environments. These new species emanate from selection activity focussed upon ‘alternative legumes’. In 1992, in response to changing constraints upon production, a program was initiated which sought species with different ideotypic traits to the traditional annual medics and clovers used in agriculture in southern Australia. Traits sought in the new species were deeper root systems, improved persistence from higher hardseed levels, acid tolerant symbioses, tolerance to pests and diseases and ease of harvesting with conventional cereal harvesters. Several cultivars of species new to Australian agriculture such as biserrula (Biserrula pelecinus), French serradella (Ornithopus sativus), gland clover (Trifolium glanduliferum) and improved varieties of arrowleaf clover (Trifolium vesiculosum) and yellow serradella (Ornithopus compressus) were developed and have had rapid adoption and impact in southern Australian ley- and phase-farming systems. This paper reviews the importance of ley farming for Australian agriculture, the shortcomings of the traditional medics and clovers and the imperatives for a second generation of annual pasture legume species to be developed. In addition to enhancing ley farming, the commercial availability of a second generation of annual pasture legume species has provided a much needed impetus for the development of more flexible and sustainable farming systems.

AGWEST Sothis: Trifolium dasyurum (eastern star clover)

2007 ◽  
Vol 47 (12) ◽  
pp. 1512 ◽  
Author(s):  
A. Loi ◽  
B. J. Nutt ◽  
C. K. Revell ◽  
R. Snowball
Keyword(s):  
Dry Matter ◽  
Eastern Mediterranean ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Late Winter ◽  
Long Period ◽  
Pasture Legumes ◽  
Mediterranean Regions ◽  
World Agriculture ◽  
Annual Medics

Trifolium dasyurum C. Presl. (eastern star clover) is a species native to the eastern Mediterranean regions. AGWEST Sothis is the first cultivar of eastern star clover released to world agriculture. It has high levels of dry matter and seed production and seed can be harvested with modified grain harvesters. AGWEST Sothis is suitable for use on acid and alkaline fine-textured soils in low to medium rainfall areas (325–450 mm) in southern Australia. AGWEST Sothis is an early to mid-maturing variety, flowering ~100 days after emergence in Perth, Australia. Individual seeds weigh ~6 mg. In regenerating stands, AGWEST Sothis germinates very late in the season compared with traditional pasture legumes such as subterranean clover (Trifolium subterraneum L.) and annual medics (Medicago spp.) and weeds. The delay in germination allows the use of non-selective herbicides or intensive grazing after the break of season for a long period 3–6 weeks to obtain >90% control of troublesome crop weeds. In spite of its late germination, AGWEST Sothis grows rapidly in late winter/spring and can become a productive legume-dominant pasture for grazing or forage conservation.

Polysaccharides of tropical pasture herbage. VII. Identification of a new pinitol galactoside from seeds of Trifolium subterraneum (subterranean clover) and analysis of several pasture legume seeds for cyclohexitols and their galactosides

1977 ◽  
Vol 30 (7) ◽  
pp. 1583 ◽  
Author(s):  
RJ Beveridge ◽  
CW Ford ◽  
GN Richards
Keyword(s):  
Gas Chromatography ◽  
Periodate Oxidation ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Tropical Pasture ◽  
Borohydride Reduction ◽  
Pasture Legumes ◽  
Legume Seeds ◽  
Ethanol Extracts ◽  
Pasture Legume

A pinitol galactoside isolated from ethanol extracts of seeds of T. subterraneum has been shown to be 1D-2-O-(α-D-galactopyranosyl)-4-O- methy-chiro-inosito (1). The structure is based on successive periodate oxidation, borohydride reduction, hydrolysis and acetylation (Smith degradation), yielding the tetraacetate of 2-O-methyl-L-xylitol. The seeds of 39 pasture legumes from 13 different genera and 26 species have been analysed by gas chromatography for (1), myo-inositol, D-(+)- pinitol and galactinol.

Flower initiation in pasture legumes. III. Flower initiation in Medicago tribuloides Desr. and other annual medics.

1955 ◽  
Vol 6 (2) ◽  
pp. 258 ◽  
Author(s):  
Y Aitken
Keyword(s):  
Low Temperature ◽  
Subterranean Clover ◽  
Late Summer ◽  
Flower Initiation ◽  
Commercial Variety ◽  
Barrel Medic ◽  
Pasture Legumes ◽  
Annual Medics ◽  
Long Photoperiod

Observations on barrel medic (Medicago tribuloides Desr., commercial variety) sown throughout the year in the field showed that the flower initiation of the winter sowings was the most rapid and that of the late summer sowings the most delayed. This delay was due to the absence of sufficiently low temperature following germination. Low temperature and long photoperiod accelerate flower initiation in barrel medic as in subterranean clover. Five types of annual medic that persist under Mallee conditions are similar in their flower initiation character to that of the "second-early" varieties of subterranean clover.

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