Red-leaf virus - a newly recognized virus disease of subterranean clover (Trifolium subterraneum L.)

1971 ◽  
Vol 22 (4) ◽  
pp. 615 ◽  
Author(s):  
AW Kellock
Keyword(s):  
Indicator Species ◽  
Virus Disease ◽  
Leaf Roll ◽  
Red Clover ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Medicago Littoralis ◽  
Mode Of Transmission ◽  
Clover Seed ◽  
Leaf Virus

A previously undescribed virus disease, for which the name subterranean clover red-leaf virus (SCRLV) is proposed, affects subterranean clover (Trifolium subterraneum L.) in the northern and southern pasture belts of Victoria. The leaves of infected plants are red and the plants may collapse and die. The virus was transmitted by the aphid Acyrthosiphon solani (Kltb.), but not by the aphids Myzus persicae (Sulz.), Aphis cracciuora Koch, or A. gossjpii Glover. The virus was not sap-transmissible nor was there any evidence of transmission through subterranean clover seed. A. solani transmitted the virus to 45 cultivars of subterranean clover, and also to white clover (T. repens L.), red clover (T. pratense L.), strawberry clover (T. fragiferum L.), strand medic (Medicago littoralis L.), and barrel medic (M. trunculata L.). The virus was not transmitted to several other indicator species. The virus persisted in the vector after a moult and thus the mode of transmission is of the circulative type. The acquisition, transmission, and availability thresholds were 6 hr, 20 min, and 4 days respectively. After an acquisition feed, the virus had a latent period of about 12 hr in the vector. SCRLV resembles other members of the leaf-roll group of persistent aphid-borne viruses. The present cryptogram for the virus is */* : */* : */* : S/Ap.

scholarly journals Harvesting subterranean clover seed – current practices, technology and issues

2021 ◽  
Vol 72 (3) ◽  
pp. 223
Author(s):  
Wesley M. Moss ◽  
Andrew L. Guzzomi ◽  
Kevin J. Foster ◽  
Megan H. Ryan ◽  
Phillip G. H. Nichols
Keyword(s):  
Soil Erosion ◽  
Case Studies ◽  
Seed Production ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Root Cause ◽  
Pasture Plant ◽  
Clover Seed ◽  
Production Industry ◽  
Pasture Legume

Subterranean clover (Trifolium subterraneum L.) is Australia’s most widely sown annual pasture legume. Its widespread use as a pasture plant requires a well-functioning seed production industry, and Australia is the only significant producer of subterranean clover seed globally. However, the sustainability of this industry is under threat due to its reliance on ageing harvest equipment and the resultant environmental impacts. In order to evaluate seed harvesting practices, technology, and issues, we report on case studies, workshops, and a survey of seed producers across southern Australia. The Horwood Bagshaw Clover Harvester, designed in the 1950s, remains the most popular subterranean clover seed harvester. We discuss its use and modifications, and document several contemporary issues facing the seed production industry. Issues are primarily soil erosion and degradation; the expensive, slow and labour-intensive harvest process; and poor reliability and maintainability of harvesters that are now at least 30 years old. We conclude the root cause of these issues is the suction harvest technology utilised by the Horwood Bagshaw Clover Harvester. Analysis of the current harvest system is provided to support the development of new approaches to harvest subterranean clover seeds.

Effect of perennial pasture species on surface soil moisture and early growth and survival of subterranean clover (Trifolium subterraneum L.) seedlings

1997 ◽  
Vol 48 (5) ◽  
pp. 683 ◽  
Author(s):  
B. S. Dear ◽  
P. S. Cocks
Keyword(s):  
Mineral Soil ◽  
Subterranean Clover ◽  
Late Summer ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Annual Grass ◽  
Growth And Survival ◽  
Eastern Australia ◽  
Standing Dead ◽  
Clover Seed

Subterranean clover seedling numbers and growth in swards containing 1 of 5 perennial pasture species [phalaris (Phalaris aquatica) cv. Sirolan, cocksfoot (Dactylis glomerata) cv. Currie, lucerne (Medicago sativa) cv. Aquarius, wallaby grass (Danthonia richardsonii) cv. Taranna, and lovegrass (Eragrostis curvula) cv. Consol] were compared with those in typical annual pastures and pure clover swards in the wheatbelt of eastern Australia. Presence of a perennial species or the volunteer annual grass (Eragrostis cilianensis) increased the rate of drying of the soil surface (0–5 cm) after late February and May rain, compared with subterranean clover swards. Perennials differed in the rate they dried the soil surface, with the more summer-active lucerne and consul lovegrass drying the profile more rapidly than phalaris. The amount of water in the surface 5 cm, 6 days after the rainfall event on 27–28 February, was strongly negatively correlated (r = –0·75, P < 0·01) with the amount of green perennial biomass, but not related to standing dead material or surface residues. Where perennials were present, a smaller proportion (2–4%) of the clover seed pool produced seedlings in response to late summer rain, compared with pure clover swards (18%). A higher proportion of the seed pool produced seedlings (19–36%) following rain in late autumn but there was no difference between species. The more summer-active perennials (cocksfoot, danthonia, and lucerne) markedly depressed the survival of emerged clover seedlings following both germinations. Of the seedlings that emerged in early March, the proportion remaining by 29 March was 57% in phalaris, 21% in lucerne, 13% in danthonia, and 1% in cocksfoot, compared with a 78% increase in seedlings in pure subterranean clover swards. By 15 May, all perennials had <2 clover seedlings/m2 surviving, compared with 37 in the annual pasture and 964 plants/m2 in pure subterranean clover. Following the May germination, the highest proportion of emerged seedlings surviving until 29 May was in the phalaris swards (40%) and least in the cocksfoot and danthonia swards (2–4%). Presence of a perennial or annual grass decreased (P < 0·05) relative water content of clover seedlings on 15 March from 74% in pure clover swards, to 48% in annual pasture, 34% in phalaris, and 29% in lucerne swards. Clover seedlings growing in pure subterranean swards on 15 March (17 days after germinating rain) were 4 times larger than those in lucerne and twice as large as those in either phalaris or annual pasture. Seed size did not differ between treatments, but available mineral soil nitrogen was significantly higher (P < 0·001) in pure subterranean clover swards (32 mg N/g) compared with perennials (3–13 mg N/g). Strategies such as heavy grazing in late summer to reduce green biomass of the perennials or sowing the perennials at lower densities may reduce the adverse effects that perennials have on subterranean clover seedlings in these drier environments.

Lucerne, phalaris, and wallaby grass in short-term pasture phases in two eastern Australian wheatbelt environments. 2. Effect of perennial density and species on subterranean clover populations and the relative success of 3 clover cultivars of different maturity

2007 ◽  
Vol 58 (2) ◽  
pp. 123 ◽  
Author(s):  
B. S. Dear ◽  
G. A. Sandral ◽  
J. M. Virgona ◽  
A. D. Swan ◽  
B. A. Orchard ◽  
...  
Keyword(s):  
Seed Yield ◽  
Seed Bank ◽  
Seedling Survival ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Climatic Conditions ◽  
Perennial Species ◽  
Growing Season Length ◽  
Herbage Yield ◽  
Clover Seed

The effect of the density of 3 perennial species, phalaris (Phalaris aquatica L.), wallaby grass (Austrodanthonia richardsonii Kunth), and lucerne (Medicago sativa L.), on seed set, regeneration, and the relative competitiveness of 3 cultivars of subterranean clover (Trifolium subterraneum L.) was examined in 2 environments in the south-eastern Australian wheatbelt. Seed yields of subterranean clover were inversely related to perennial density at both sites over the first 2 years, the relationship varying with perennial species. Phalaris depressed the seed yield of clover more than lucerne and wallaby grass in the second and third year at equivalent densities. Clover seed yield was positively related to clover herbage yield in late spring at both sites, and inversely related to perennial herbage yield. Clover seed yield displayed an increasing linear relationship with the proportion of light reaching the clover understorey in spring, which in turn was inversely related to perennial density and perennial herbage yield. Clover seedling regeneration in mixed swards in autumn was positively related to the size of the summer seed bank, but negatively related to perennial density. Clover seedling survival following a premature germination at Kamarah was inversely correlated to the density of phalaris and lucerne in the sward. The relative competitiveness of the 3 subterranean clover cultivars varied between sites, with climatic conditions (rainfall and growing-season length) having a greater effect on the relative cultivar performance than companion perennial species or density. The later maturing subterranean clover cv. Goulburn became the dominant cultivar at the wetter site, constituting 72% of the seed bank, but declined to only 3–8% of the seed bank at the drier site. The proportion of the early flowering cultivar Dalkeith in the seed bank increased over time at the drier site and was highest (53%) in plots with the highest perennial density. We concluded that although perennial pasture species will depress clover seed yield and subsequent regeneration, these effects could be minimised by reducing perennial densities and exploiting variations in competitiveness between perennial species as identified in this study. Sowing earlier maturing subterranean clover cultivars would only be an advantage in increasing clover content in low-rainfall environments. The findings suggest that clover seed reserves and regeneration could also be increased by using grazing management to reduce the level of shading of clover by perennials, a factor associated with reduced clover seed yield.

Effects of pH and aluminium on the growth of temperate pasture species. II. Growth and nodulation of legumes

1991 ◽  
Vol 42 (5) ◽  
pp. 893 ◽  
Author(s):  
DC Edmeades ◽  
FPC Blamey ◽  
CJ Asher ◽  
DG Edwards
Keyword(s):  
White Clover ◽  
Trifolium Pratense ◽  
Inorganic Nitrogen ◽  
Red Clover ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Lotus Corniculatus ◽  
Culture Solution ◽  
Solution Ph ◽  
Lotus Pedunculatus

Ten temperate pasture legumes inoculated with appropriate rhizobia were grown for 31 days in flowing solution culture. Solution ionic strength was approximately 2700 8M and contained inorganic nitrogen (150 , 8M NO3-) only at the commencement of the experiment. Solution pH was maintained at 4.5, 5.0, 5.5 and 6.0. Also, five aluminium (Al) treatments were imposed, with nominal Al concentrations of 0, 3, 6, 12 and 24 8M (2.5, 7.1, 8.3, 11.2 and 24.7 8M Al measured) at pH 4.5. Solution pH <6 . 0 markedly reduced total dry mass (TDM) in all cultivars of white clover (Trifolium repens) cvv. 'Grasslands Pitau, Huia, G18 and Tahora' and red clover (Trifolium pratense) cvv. 'Grassland Turoa and Pawera', and to a lesser extent in the two subterranean clover (Trifolium subterraneum) cvv. 'Tallarook and Woogenellup'. In contrast, solution pH had no effect on the growth of Lotus corniculatus cv. Maitland, while Lotus pedunculatus cv. Maku grew best at pH 4.5. Lotus pedunculatus cv. Maku grew best in solution where the sum of the activities of the monomeric Al species {Alm} was maintained at 5.9 8M. The growth of all other species was decreased with Al in solution, a 50% reduction in TDM being associated with c. 6 8M {Alm] for white clover and subterranean clover, and c. 3 8M in red clover and Lotus corniculatus cv. Maitland.

Differential tolerance of annual medics, Nungarin subterranean clover and hedge mustard to broadleaf herbicides

1992 ◽  
Vol 32 (1) ◽  
pp. 49 ◽  
Author(s):  
RR Young ◽  
KJ Morthorpe ◽  
PH Croft ◽  
H Nicol
Keyword(s):  
Sodium Salt ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Effective Control ◽  
Medicago Littoralis ◽  
Annual Medics ◽  
Seed Yields ◽  
Test Plants ◽  
Degree Of Recovery

The tolerance of 5 species of annual medics (Medicago spp.), Trifolium subterraneum cv. Nungarin, and hedge mustard (Sisymbrium orientale) to a range of post-emergence broadleaf herbicides was tested over 2 years. The least damaging to M. truncatula was 2,4-DB, which provided more consistent and effective control of hedge mustard than the other chemicals tested, including the less expensive tank mix of 2,4-DB + diuron. MCPA amine or sodium salt (300 g a.i./ha), bromoxynil (420 g a.i./ha), and tank mixes containing MCPA amine (150-175 g a.i./ha) severely damaged annual medics, particularly M. truncatula, with flowering delayed by up to 21 days, and dry matter and seed yields often significantly (P<0.05) reduced. Seed yields of most test plants indicated a degree of recovery from herbicide damage assessed visually after 10 days. Hedge mustard was not always as severely damaged by MCPA amine as was M. truncatula. Nungarin subterranean clover and M. aculeata SAD 2356 were more tolerant than the M. truncatula cultivars of MCPA amine, MCPA sodium salt, MCPA tank mixes, and bromoxynil, and less tolerant of 2,4-DB. Medicago littoralis, M. polymorpha and M. laciniata were severely damaged by bromoxynil but were more tolerant of MCPA than M. truncatula.

Effect of tillage practices on the fate of hard seeds of subterranean clover in a ley farming system

1985 ◽  
Vol 25 (3) ◽  
pp. 568 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Farming System ◽  
Conventional Tillage ◽  
No Tillage ◽  
Minimum Tillage ◽  
Tillage Practices ◽  
Tillage Treatment ◽  
Clover Seed

In a rotation of 1 year pasture/l year crop, a subterranean clover (Trifolium subterraneum cv. Daliak) pasture was either left untilled or subjected to minimum or conventional tillage. One set of tillage treatments was imposed in each ofthree crop years while another set of treatments was imposed in only the first crop year. Regenerating clover plants were prevented from setting seed. In the first crop, 44% of the clover seeds were buried below 2 cm of soil by minimum tillage; this proportion was 65% in the conventional tillage treatment. In the first pasture regeneration year, seedling densities were highest in the no-tillage treatment. Conversely, there were more residual seeds in the tilled treatments and, in the second and third pasture regeneration years, this led to higher seedling densities than in the no-tillage treatment. The effects of tillage were more marked in the conventional than in the minimum-tillage treatment. Clover establishment was improved by repeat tillage operations which returned some of the buried seeds closer to the soil surface. Although more seedlings overall were obtained from the no-tillage treatment, the disadvantage of fewer seedlings in the tilled treatments was offset by the spread of seedling establishment over a number of pasture years. This spread, which would be more marked with harder-seeded cultivars, could be desirable in environments in which clover seed production is unreliable.

Boron deficiency in pasture based on subterranean clover (Trifolium subterraneum L.) is linked to symbiotic malfunction

2015 ◽  
Vol 66 (11) ◽  
pp. 1197 ◽  
Author(s):  
Leo J. Hamilton ◽  
Kevin F. M. Reed ◽  
Elainne M. A. Leach ◽  
John Brockwell
Keyword(s):  
N2 Fixation ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Effective Strain ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Boron Deficiency ◽  
Initial Application ◽  
Clover Root ◽  
Clover Seed

Field and glasshouse experiments confirmed the occurrence of boron (B) deficiency in subterranean clover (Trifolium subterraneum L.) pasture in eastern Victoria. Diminished productivity was linked to the small-seededness of clover and the poor effectiveness of clover root-nodule bacteria (rhizobia, Rhizobium leguminosarum bv. trifolii). Productivity, especially of clover and clover seed, increased following applications of up to 6 kg B ha–1 (P < 0.001). The response was delayed, occurring several years after the initial application of B, unless the land was resown with fresh clover seed inoculated with an effective strain of rhizobia. B deficiency in the nodulated legume induced conditions within the plant and or its rhizobia that led to impaired nitrogen (N2) fixation. Glasshouse research indicated that populations of soil-borne rhizobia taken from B-deficient soils were poorly effective in N2 fixation and that rhizobia from soils growing subterranean clover cv. Leura were significantly less effective (P < 0.05) than rhizobia from a soil growing cv. Mt Barker. Additionally, subterranean clover seed generated in B-deficient soils was at least one-third smaller than the seed of commercial seed but responded to inoculation with effective rhizobia. This indicated that any symbiotic malfunction of clover from B-deficient soils was not due to an inability to respond to nitrogen per se. On the other hand, cv. Leura from B-deficient soils fixed significantly less N2 than commercial cv. Leura when each was inoculated with rhizobia from B-deficient soils.

Studies on nodulation responses to pelleting of subterranean clover seed.

1961 ◽  
Vol 12 (4) ◽  
pp. 578 ◽  
Author(s):  
JA Thompson
Keyword(s):  
Seed Coat ◽  
Field Experiments ◽  
Chemical Constituents ◽  
Chemical Properties ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Coating Materials ◽  
Physical Separation ◽  
Clover Seed

In a series of field experiments on seven soils of pH 6.0 or higher, nodulation of subterranean clover (Trifolium subterraneum L. var. Tallarook) was improved by pelleting the seed with various glues and coating materials, prior to inoculation with dry peat inoculum. On these soils the responses were not related to the chemical properties of the pellet materials. The beneficial effect was apparently the result of physical separation of the seed coat and inoculum. It is postulated that pelleting of seed protects the inoculum from an antibiotic, whlch has been found in subterranean clover seed coats, and which is active against Rhizobium in culture. On a soil of pH 5.1 a nodulation response to two types of pelleting materials was apparently related to the chemical constituents of the coating materials. In this soil there was less evidence of the importance of physical separation of the inoculum from the seed coat. It seems likely that soils may differ considerably in their ability to inactivate the antibiotic. Nodulation was not improved by in situ fumigation, prior to sowing, of two soils of pH 6.0 and 6.6, which indicated that antagonism by soil microorganisms was not the cause of poor nodulation in these soils. Significant nodulation responses to pelleting were obtained in sowings in these fumigated soils.

Diseases of broad bean (Vicia faba L. major) and green pea (Pisum sativum L.) in Tasmania caused by subterranean clover red leaf virus

1978 ◽  
Vol 29 (5) ◽  
pp. 1003 ◽  
Author(s):  
GR Johnstone
Keyword(s):  
Broad Bean ◽  
Leaf Roll ◽  
Subterranean Clover ◽  
Aphid Transmission ◽  
Pisum Sativum L ◽  
Bean Plants ◽  
Subterranean Clover Stunt Virus ◽  
Efficient Vector ◽  
Green Pea ◽  
Leaf Virus

A leaf-roll disease of broad bean, similar to that induced by bean leaf roll virus (BLRV) in Europe, is common in Tasmania. Subterranean clover red leaf virus (SCRLV) was transmitted to subterranean clover test seedlings by using its most efficient vector, Aulacorthum solani (Kalt.), from 84% of 204 randomly selected affected broad bean plants. The disease was reproduced in broad bean with SCRLV in controlled aphid transmission tests. Effects of infection on yield were severe, as further pod set was markedly reduced after symptoms of infection developed. There was some variation among cultivars in their response to infection. The virus occurred as commonly in green pea crops as in broad bean. In pea it caused a top yellowing, but most commercially grown pea cultivars had some tolerance. Subterranean clover stunt virus (SCSV) caused symptoms in broad bean and pea which were also similar to those induced by SCRLV. However, SCSV was rarely found infecting plants in Tasmanian pea and bean crops. BLRV, SCRLV and SCSV share many properties in common and with some other viruses.

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