Bean leafroll virus is widespread in subterranean clover (Trifolium subterraneum L.) seed crops and can be persistently transmitted by bluegreen aphid (Acyrthosiphon kondoi Shinji)

2012 ◽  
Vol 63 (9) ◽  
pp. 902 ◽  
Author(s):  
D. M. Peck ◽  
N. Habili ◽  
R. M. Nair ◽  
J. W. Randles ◽  
C. T. de Koning ◽  
...  
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Seed Production ◽  
Alfalfa Mosaic Virus ◽  
South Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Bean Leafroll Virus ◽  
Leafroll Virus ◽  
Clover Seed

In the mid 2000s subterranean clover (Trifolium subterraneum) seed producers in South Australia reported symptoms of a red-leaf disease in fields with reduced seed yields. The red-leaf symptoms resembled those caused by several clover-infecting viruses. A set of molecular diagnostic tools were developed for the following viruses which are known to infect subterranean clover: Alfalfa mosaic virus; Bean leafroll virus (BLRV); Beet western yellows virus; Bean yellow mosaic virus; Cucumber mosaic virus; Pea seed-borne mosaic virus; Soybean dwarf virus and Subterranean clover stunt virus. Surveys of subterranean clover seed production fields in 2008 in the south-east of South Australia and western Victoria identified Bean leafroll virus, Alfalfa mosaic virus and Cucumber mosaic virus as present, with BLRV the most widespread. Surveys of pasture seed production fields and pasture evaluation trials in 2009 confirmed that BLRV was widespread. This result will allow seed producers to determine whether control measures directed against BLRV will overcome their seed losses. Bluegreen aphid (Acyrthosiphon kondoi) was implicated as a potential vector of BLRV because it was observed to be colonising lucerne plants adjacent to subterranean clover seed production paddocks with BLRV, and in a glasshouse trial it transmitted BLRV from an infected lucerne plant to subterranean clover in a persistent manner.

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.

Izmir subterranean clover (Trifolium subterraneum L. var. subterraneum)

2007 ◽  
Vol 47 (2) ◽  
pp. 226 ◽  
Author(s):  
P. G. H. Nichols ◽  
G. A. Sandral ◽  
B. S. Dear ◽  
C. T. de Koning ◽  
D. L. Lloyd ◽  
...  
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
New South ◽  
South Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Good Seed ◽  
Improvement Program ◽  
South Wales ◽  
Pasture Legume

Izmir is a hardseeded, early flowering, subterranean clover of var. subterraneum (Katz. et Morley) Zohary and Heller collected from Turkey and developed by the collaborating organisations of the National Annual Pasture Legume Improvement Program. It is a more hardseeded replacement for Nungarin and best suited to well-drained, moderately acidic soils in areas with a growing season of less than 4.5 months. Izmir seed production and regeneration densities in 3-year pasture phases were similar to Nungarin in 21 trials across southern Australia, but markedly greater in years following a crop or no seed set. Over all measurements, Izmir produced 10% more winter herbage and 7% more spring herbage than Nungarin. Its greater hardseededness and good seed production, makes it better suited to cropping rotations than Nungarin. Softening of Izmir hard seeds occurs later in the summer–autumn period than Nungarin, giving it slightly greater protection from seed losses following false breaks to the season. Izmir is recommended for sowing in Western Australia, New South Wales, Victoria, South Australia and Queensland. Izmir has been granted Plant Breeders Rights in Australia.

Factors contributing to reduced productivity of subterranean clover (Trifolium subterraneum L.) pastures on acidic soils

1990 ◽  
Vol 41 (4) ◽  
pp. 669 ◽  
Author(s):  
Z Hochman ◽  
GJ Osborne ◽  
PA Taylor ◽  
B Cullis
Keyword(s):  
Seed Production ◽  
Root Rot ◽  
Seedling Survival ◽  
Soil Phosphorus ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Phosphorus Sorption ◽  
Sorption Index ◽  
Clover Seed ◽  
Root Health

In a field study on four sites, soil acidity, root rot (Phytophthora clandestina), and soil phosphorus were identified as causes of 'subterranean clover decline'. Liming increased herbage and seed production at four sites, with a tendency for lime to increase herbage yields in autumn (22%) and winter (15%) but not in spring. The presence of ryegrass with clover increased total herbage yields, and reduced clover seed production, but there was no interaction with liming. Losses caused by root rot associated with P. clandestina were quantified for the first time in New South Wales. Root rot reduced survival of seedlings as well as herbage production in autumn and/or winter at three of the four sites. In the presence of the disease, lime did not improve root health or seedling survival. On two sites with high aluminium saturation of exchangeable cations (> 17%) and high phosphorus sorption index values, subterranean clover growth responded to high levels of P fertilizer. On one site, where lime increased the soil pH to above 5.5, the P sorption index was temporarily increased, and this was associated with a temporary adverse effect on herbage yields. Some possible mechanisms underlying the seasonality of lime responses are proposed and the practical implications of our findings are discussed.

Comparative productivity of some cultivars of subterranean clover (Trifolium subterraneum) in north-eastern Victoria

1968 ◽  
Vol 8 (30) ◽  
pp. 46
Author(s):  
IH Cameron ◽  
AA McGowan
Keyword(s):  
Seed Production ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Research Station ◽  
Pasture Production ◽  
Wool Production ◽  
North Eastern ◽  
The Common ◽  
Clover Seed

Eight cultivars of subterranean clover (Trifolium subterraneum L.)-Yarloop, Burnley, Bacchus Marsh, Nangeela, Clare, Portugal, Chiltern Valley, and Mt. Barker-were compared in mowing experiments at the Rutherglen Research Station in north-eastern Victoria. All eight had similar total annual yields of dry matter, but all except Chiltern Valley outyielded Mt. Barker (the common district cultivar) in most winters. Yarloop, Burnley, and Bacchus Marsh grew best in winter. Of these, Burnley has most promise, being apparently more persistent than Bacchus Marsh, and having lower oestrogenic potency than Yarloop. There was no difference in greasy wool production from wethers run at five to the acre on Mt. Barker or Bacchus Marsh pastures, despite higher pasture production on the latter. Hay was cut in two seasons ; after feeding equal amounts to each group of sheep, there was a surplus of 20 cwt an acre in favour of the Bacchus Marsh pasture. Clover seed production, winter pasture growth, and sheep liveweights also favoured Bacchus Marsh.

An epidemic of cucumber mosaic virus in South Australian lupins

1985 ◽  
Vol 36 (2) ◽  
pp. 267 ◽  
Author(s):  
E Alberts ◽  
J Hannay ◽  
JW Randles
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Vicia Faba ◽  
Transmission Rate ◽  
South Australia ◽  
Trifolium Subterraneum ◽  
Seed Transmission ◽  
Severe Stunting ◽  
Experimental Host Range

Many Lupinus angustifolius crops in South Australia showed a high incidence of severe stunting and leaf epinasty during 1983. The epidemic was attributed to infection with cucumber mosaic virus. The virus was also recovered from Trifolium subterraneum cv. Geraldton, Medicago polymorpha, Vicia faba, Erodium sp. and Arctotheca calendula growing in or adjacent to lupin crops. The experimental host range of the virus included T. subterraneum cv. Clare, T. repens, Pisurn sativum, Vicia faba and Cicer arietinum. A seed transmission rate of 12-15% was demonstrated in field-infected lupins, and it is concluded that the epidemic probably arose through primary introduction of virus into crops in seed, followed by secondary spread by aphids. The possible role of alternative host species as a reservoir is discussed.

Seeding rate, time of sowing and fertilizers for subterranean clover seed production

1973 ◽  
Vol 13 (65) ◽  
pp. 681 ◽  
Author(s):  
BJ Quinlivan ◽  
AC Devitt ◽  
CM Francis
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Major Effect ◽  
Seeding Rate ◽  
Sowing Time ◽  
Commercial Crop ◽  
Clover Seed ◽  
High Phosphate

In two experiments in successive years on a sandy soil in Western Australia, seed production of subterranean clover (Trifolium subterraneum) when sown as a commercial crop was greatly influenced by time of sowing, phosphate rates and seeding rate. Early (April) sowing, high phosphate (up to 600 kg ha-1) and higher seeding rates (up to 24 kg ha-1) all increased seed set but the major effect was that of earliness of sowing. Time of sowing interacted with phosphate rates, the time of sowing differences being only fully expressed at high phosphate rates. Artificial nitrogen applied had a significant effect on seed yield in one of the trial years.

Infection of alternative hosts associated with narrow-leafed lupin (Lupinus angustifolius) and subterranean clover (Trifolium subterraneum) by cucumber mosaic virus and its persistence between growing seasons

1994 ◽  
Vol 45 (5) ◽  
pp. 1035 ◽  
Author(s):  
SJ McKirdy ◽  
RAC Jones
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Host Species ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Seed Transmission ◽  
Lupinus Angustifolius ◽  
Minor Role ◽  
Alternative Hosts ◽  
A Minor

Under conditions of natural cucumber mosaic virus (CMV) spread, eight alternate host species found associated with Lupinus angustifolius (narrow-leafed lupin) and/or Trifolium subterraneum (subterranean clover) were infected commonly and another nine sporadically. Five of these were new records. Because seed of herbaceous plant hosts provides a possible route for virus persistence through dry summer conditions, CMV seed transmission was tested for in alternative hosts. Seed of seven species systemically infected following sap inoculation was tested, but CMV seed transmission was only detected in M. polymorpha (0.7%) and M. indica (0.1%). When seed of 14 potential alternative host species that became systemically infected through natural virus spread was tested, CMV seed transmission was found only in C. decumbens (0.5%). No CMV was detected in Citrullus lanatus growing as a deep-rooted, herbaceous summer weed following CMV-infected L. angustifolius crops, or in the perennial Acacia saligna growing adjacent to a previously CMV-infected L. angustifolius field. CMV persisted through seed transmission over summer for up to 5 years in grazed, self-regenerated T. subterraneum swards. It is concluded that under the conditions of broadacre agriculture, in the Mediterranean-type climate of Western Australia, weed hosts are unlikely to be an important means by which CMV persists over summer, but seed transmission in naturalized M. polymorpha and C. decumbens may occassionally play a minor role. Moreover, despite being seed-borne in T. subterraneum, CMV did not persist readily enough from year to year in grazed swards for T. subterraneum pastures to play more than a minor role as a CMV source for infection of L. angustifolius .

Factors affecting competition between subterranean clover and a barley cover crop

1973 ◽  
Vol 13 (60) ◽  
pp. 56 ◽  
Author(s):  
AA McGowan ◽  
WA Williams
Keyword(s):  
Seed Production ◽  
Light Transmission ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Early Spring ◽  
Late Winter ◽  
Factors Affecting ◽  
Competition For Light ◽  
Clover Seed ◽  
Main Factor

Subterranean clover (Trifolium subterraneum) was sown with barley (Hordeum vulgare) in autumn under a variety of management treatments. Clover seed production was increased when barley emergence was delayed by seed treatment with CCC or paraffin wax, or by delayed sowing, when barley seeding rates were reduced, or when barley was clipped in late winter. The main factor limiting growth of the undersown clover was competition for light, especially in late winter and early spring when light transmission through the barley crop dropped below 60 per cent. Despite a dry spring, interspecific competition for moisture evidently imposed very little restriction on clover growth and seed production. Competition for nitrogen may have occurred earlier in the season.

THESIS SUMMARY STUDIES OF ALFALFA MOSAIC VIRUS AND SUBTERRANEAN CLOVER RED LEAF VIRUS

1979 ◽  
pp. 163-164
Author(s):  
P.B. Teh
Keyword(s):  
Mosaic Virus ◽  
Alfalfa Mosaic Virus ◽  
Subterranean Clover ◽  
Test Plant ◽  
Transmission Frequency ◽  
Virus Source ◽  
Leaf Virus

AMV was shown to be transmitted by sap, aphids and through lucerne seed, but not by Cuscuta. Virus source and test plant influenced transmission frequency. Sap-inoculation tests showed that 20 species of plants were susceptible to this virus. Thirteen species of plants from the fields where AMV had been detected were tested but only three were found to be infected with the virus.

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