Reduction in the seed reserve of subterranean clover following the application of 2,4-D amine, dicamba, dicamba plus MCPA amine or glyphosate in spring

1992 ◽  
Vol 32 (6) ◽  
pp. 701
Author(s):  
PM Schroder ◽  
PJ Stapleton

The reduction in the net seed set by subterranean clover (mostly cv. Mount Barker), and hence the size of the seed reserve, was assessed at sites near Hamilton, Victoria, following the application of dicamba, 2,4-D amine, a mixture of dicarnba and 2,4-D amine, or glyphosate, applied at early, mid or late flowering. Similar measurements were made on pastures dominated by cv. Yarloop near Seymour, Victoria, where either 2,4-D amine or a mixture of dicamba plus MCPA amine was applied at mid flowering. The experiments were conducted in 1984 and 1985 in both districts. At Hamilton, the clover seed reserve was 147 kg/ha before the treatments were applied. By early summer, the average seed reserve was 511 kg/ha where no herbicide was used and 211, 343 and 318 kg/ha where dicamba, 2,4-D mine or glyphosate were applied. The average reduction in net seed set for these 3 treatments was 80, 46 and 39%, respectively. Applying 2,4-D arnine in addition to dicamba did not cause a further significant reduction in the seed reserve. The earlier in the flowering stage the herbicide was applied, the greater the reduction in net seed set, and so the smaller the final seed reserve. At Seymour, the Yarloop clover seed reserve was 246 kg/ha before the treatments were applied. The average Yarloop seed reserve by early summer was 754 kg/ha where no herbicide was used, 335 kg/ha where dicamba plus MCPA arnine was applied and 365 kg/ha where 2,4-D amine was applied. The average reduction in the net seed set for the 2 herbicides was 83 and 77%. This work indicates that no seed will be added to the seed reserve of Mount Barker or Yarloop subterranean clover if dicamba is applied at 1.0 L/ha before the clover reaches the mid flowering stage. As cultivars differ in their susceptibility to herbicides, extending these results to other cultivars needs to be done with caution.


1998 ◽  
Vol 38 (6) ◽  
pp. 583 ◽  
Author(s):  
A. Wallace ◽  
R. A. Lancaster ◽  
N. L. Hill

Summary. Spraytopping, the application of a low rate of non-selective herbicide (usually glyphosate or paraquat) to annual grass seed heads in the spring or early summer for seed set control is widely practised throughout Australia. While grasses are the targets of the spray treatment, annual pasture legumes may also be damaged by spraytopping, particularly if the legumes are flowering at the time of application. The effect of applying glyphosate (90, 112 or 162 g a.i./ha), paraquat (100 g a.i./ha) and glyphosate plus MCPA (90 + 150 g a.i./ha) to subterranean clover (Trifolium subterraneum L. cv. Dalkeith) and annual medic (Medicago polymorpha L. cvv. Serena, Santiago and Circle Valley) pastures at various times during flowering was investigated during the spring of 1993 and 1994. Experiments were located at Tincurrin and Tenindewa, Western Australia. Subterranean clover seed yield was most affected by applications of glyphosate (90 and 162 g a.i./ha) and glyphosate plus MCPA (90 + 150 g a.i./ha) during early–mid flowering. Seed yield was reduced by as much as 88% following application of glyphosate plus MCPA when 20% of the subterranean clover plants were flowering. Treatment with paraquat (100 g a.i./ha) during mid–late flowering reduced seed yield of subterranean clover by 25–50% in experiment 1 only. Medic seed yield was reduced up to 90% depending on cultivar when glyphosate (112 g a.i./ha) was applied during early–mid flowering. In addition to seed yield, the level of hard seed was assessed. Treatment of subterranean clover during early–mid flowering with glyphosate (90 and 162 g a.i./ha) significantly reduced the quantity of hard seed produced. Thirty–forty percent of subterranean clover seed was germinable soon after seed set, compared with 7–17% germinable for the seed from untreated plants. Treatment with glyphosate (112 g a.i./ha) reduced the proportion of hard seed in the medics when applied during mid flowering. Treatment with paraquat had little effect on the proportion of hard seed formed. This work demonstrates that using a spraytopping technique for control of seed set in annual grasses may dramatically reduce seed yield in pasture legumes. Spraytopping can further reduce the ability of legumes to persist in cropping rotations by reducing the amount of hard seed formed. Implications for practical farming systems are outlined.



2001 ◽  
Vol 52 (10) ◽  
pp. 973 ◽  
Author(s):  
B. S. Dear ◽  
J. M. Virgona ◽  
G. A. Sandral ◽  
A. D. Swan ◽  
B. A. Orchard

Seed production of subterranean clover (Trifolium subterraneum L.) in mixtures with lovegrass (Eragrostis curvula (Schrader) Nees cv. Consol), cocksfoot (Dactylis glomerata L. cv. Currie), phalaris (Phalaris aquatica L. cv. Sirolan), danthonia (Austrodanthonia richardsonii (Cashm.) H.P. Linder, cv. Taranna), and lucerne (Medicago sativa L. cv. Aquarius) was compared with pure and degraded (invaded by annual volunteers) annual subterranean clover pasture at 2 sites (Junee and Kamarah) in the southern wheatbelt of New South Wales. Seed yields, clover seedlings in winter, and the change in the proportion of 3 subterranean clover cultivars (Dalkeith, Seaton Park, Goulburn) when grown with and without perennials were assessed. The effect of thinning the perennials to 10 plants/m2 on clover seed set was examined at the drier site. Seed production of subterranean clover in the mixtures was depressed by up to 50% compared with the pure and degraded annual swards. Initial clover seed poduction in the mixtures was at least 60 kg/ha even in the drought year at the wetter site (Junee), and >85 kg/ha at Kamarah, the drier site (seedling establishment at Kamarah failed in the drought year). Clover seed reserves in the following 2 years progressively increased to >300 kg/ha in the perennial swards at Junee but were <100 kg/ha by the end of the third year at Kamarah. In comparison, seed reserves in the pure clover and degraded annual swards were >650 kg/ha at Junee and >350 kg/ha at Kamarah. Reducing perennial density to 10 plants/m2 at the drier site increased clover seed yield about 3-fold in the first year compared with unthinned perennial swards. The increased seed yield was due to increased numbers of burrs set and increased seeds per burr and, in all perennial pasture treatments except lucerne, increased seed size. Clover seedling regeneration in 3rd and 4th year after sowing was substantially lower in the perennial-based mixtures than annual plots, with a significant (P < 0.05) positive correlation at both sites between clover seedling regeneration and seed bank size (1996, r2 = 0.46–0.64; 1997, r2 = 0.64–0.85). Following false breaks in early autumn, clover seedling populations were substantially higher in the pure and degraded clover treatments than in most perennial treatments. The proportion of the 3 cultivars present in the seed bank at the end of the pasture phase differed between sites but the sward type only influenced the proportion at the drier site. At the medium rainfall site, the later maturing cultivar Goulburn constituted 27–54% of the seed bank and the early flowering Dalkeith 25–46%, with unsown cultivars being insignificant ( <1%). At the low rainfall site, Dalkeith was the major component (33–52%) of the seed bank but the background population of unsown cultivars constituted 11–48%, the lowest proportion being in swards without a perennial component. The proportion of Goulburn was highest (23%) in the pure sward and lowest (10%) in lucerne and phalaris. It was concluded that subterranean clover could form relatively stable mixtures with perennials in medium rainfall environments, with clover populations increasing with time. In lower rainfall environments, clover seedling populations in perennial swards may be low due to reduced seed set and decreased seedling survival following early autumn rains. In these environments earlier maturing, hard-seeded cultivars are more likely to persist in mixtures and there is more potential for unsown cultivars to constitute a greater proportion of the sward. Decreasing perennial density offers scope for improving clover seed set and survival in these environments.



Author(s):  
M.L. Smetham ◽  
D.W. Jack ◽  
Sandy E.H. Hammond

Fifteen accessions and 3 cultivars of subterranean exnected for this site. It is concluded that lateclover (Trifolium subterranean L.) were sown in autumn in shallow stony soil south of Christchurch, New Zealand. The following growing season was atypical, with drought occurring briefly but one month earlier than usual, the rest of the season being wetter than usual. Contrary to previous results highest seed yields were given by mid- to lateseason flowering lines. Early flowering lines were severely disadvantaged by the early drought, resulting in seed yields of only 20-25 kg/ha. High seed yields were linked with the ability of lines to recommence flowering after drought and continue this for a prolonged period. Two late flowering accessions, 014454B and 014205B, yielded more than 200 kg/ha seed, outyielding the late flowering cv. Tallarook in spite of this cultivar having the same ability as the other two to reflower. Six highseed yielding lines gave naturally regenerated seedling numbers near to or exceeding 1000/m2. Apparent hardseededness at the time of autumn germination averaged 49% which was lower than expected for this site. It is concluded that late fldwering lines of subterranean clover should always be included in mixtures of this species for pasture to ensure adequate regeneration in wetter than normal seasons. Keywords: accessions, cultivars, flowering, hardseededness, regeneration, seed production, Trifolium subterraneum



2015 ◽  
Vol 66 (9) ◽  
pp. 938 ◽  
Author(s):  
T. J. Ridsdill-Smith ◽  
C. C. Pavri

The use of a TIMERITE® spring spray to control redlegged earth mite (RLEM), Halotydeus destructor (Tucker) (Acari: Penthaleidae), in annual pastures was evaluated on farms across Australia. RLEM populations in autumn in the treatments sprayed in spring 1998 and 1999 were 97% lower in 1999 and 97% in 2000 in the western region (Western Australia), and 93% lower in 1999 and 93% in 2000 in the eastern region (Victoria, New South Wales and South Australia). At sites in the west, control of RLEM resulted in significant increases in subterranean clover seed yield in 1999 and in clover seedling numbers in autumn 1999 and 2000. Penthaleus major (blue oat mite) populations in autumn were 60% lower in sprayed treatments, but Sminthurus viridis (lucerne flea) populations were not affected. Differences in weather between the west (where there is a hot, dry summer) and the east (where temperature and rainfall regimes are more variable in spring and early summer) seem to cause greater RLEM control and greater benefits in subterranean clover seed yield and seedling numbers with a spring spray in the west.



1992 ◽  
Vol 32 (8) ◽  
pp. 1095 ◽  
Author(s):  
BS Dear ◽  
DJ Conlan ◽  
MF Richards ◽  
NE Coombes

The tolerance of 6 cultivars of Trifolium subterraneum (subterranean clover) to simazine applied at 0.63 and 1.25 kg a.i./ha was determined under weedfree conditions in the field by measuring herbage and seed yields. Large herbage yield losses occurred as a result of the simazine in spring in the 2 years of the experiments. In 1989, spring herbage yield losses of the cultivars at the 0.63 and 1.25 kg/ha simazine rates averaged 56 and 82%, respectively. In 1990 the spring herbage yield losses were 27 and 51%. Significant variation in tolerance was observed between cultivars in both years, with Trikkala being the most tolerant and Karridale the most susceptible cultivar. Rate of herbicide had the greatest effect on herbage yield, with cultivar having a smaller effect. In 1989, with relatively favourable spring conditions, clover seed yields were depressed by simazine, but in 1990 when drier conditions prevailed during flowering and seed set, seed yields were unaffected or slightly increased by simazine in all cultivars except the early-flowering cultivar Dalkeith. Seed yields of simazine-treated swards were 196-1480 kg/ha in 1989 and 359-686 kg/ha in 1990. The seed yield response in 1990 suggests that herbicides which retard growth in winter help to conserve soil water and, therefore, may benefit seed filling later in the season. The presence of Lolium rigidum at spraying did not reduce the effect of the herbicide on clover herbage yield and had no effect on seed set. Although simazine may reduce herbage yields and, in some cases, seed yields, its use may be justified for the control of annual grasses when other factors such as disease control, pasture quality, and level of weed competition are considered.



1999 ◽  
Vol 39 (7) ◽  
pp. 839 ◽  
Author(s):  
B. S. Dear ◽  
G. A. Sandral

Summary. The effect of the herbicides pyridate, imazethapyr and a bromoxynil + diflufenican mixture on subterranean clover (Trifolium subterraneum L.) (cvv. Trikkala and Karridale) and lucerne (Medicago sativa L.) (cv. Aurora) seedlings was examined in randomised plot field experiments in 2 successive years. Responses were compared against an unsprayed control and a standard bromoxynil application. The herbicides and the rates of product applied were: bromoxynil + diflufenican (0.5, 1.0 L/ha), imazethapyr (0.18, 0.3 L/ha), pyridate (1.0, 3.0 L/ha), and bromoxynil (1.4 L/ha). Weeds were removed by hand from the subterranean clover experiments but not the lucerne experiments. Pyridate and imazethapyr were the least phytotoxic of the herbicides applied on both subterranean clover and lucerne. The bromoxynil + diflufenican mixture was the most phytotoxic, causing severe leaf burn and a depression in herbage biomass in both species. Despite the high level of phytotoxicity by some treatments, none of the herbicides reduced lucerne seedling numbers. Lucerne herbage yields in late spring were higher in most sprayed plots compared with the unsprayed control due to the removal of weed competition. Seed yield responses in subterranean clover due to herbicide application ranged from negative responses up to –21% with pyridate to positive responses up to 92% with the bromoxynil + diflufenican treatment relative to the weed-free, unsprayed control. The positive responses were attributed to increased availability of soil water during seed set in treatments in which herbicides suppressed legume biomass. There was a good correlation in both 1992 (R2 = 0.85–0.89) and 1993 (R2 = 0.63–0.73) between the depression in herbage yield in spring and the increase in seed set relative to the control. Soil water under the subterranean clover cultivar Karridale in spring was highest in the bromoxynil and imazethapyr treatments, which produced a large reduction in biomass, and lowest in the control and pyridate treatments, which had showed the least depression in biomass 60 days after treatment application. Although some herbicides cause a high level of phytotoxicity, their use in weedy subterranean clover–lucerne mixtures is justified in view of the small negative, and potentially large positive, effects on subterranean clover seed yield and the increased lucerne yields later in the season due to weed suppression.



2018 ◽  
pp. 97-106
Author(s):  
Sonya T Olykan ◽  
Richard J Lucas ◽  
Carmen SP Teixeira ◽  
Richard A Subtil ◽  
Derrick J Moot

The ‘Red Flats’ on Omarama Station in the Mackenzie Basin, has a winter cold, summer dry environment and soils with low plant available water (<60 mm in the top 1 m), and low pH(H2O) (5.2) and high aluminium (8 mg/kg) below 75 mm. The site received 3 t of lime, 300 kg sulphur-super, boron (B), molybdenum (Mo) and herbicides to eliminate hieracium (Hieracium pilosella). Twelve cultivars of subterranean clover (Trifolium subterraneaum), ‘Bolta’ balansa clover (T. michelianum), and perennial ‘Rossi’ red clover (T. pratense), were direct-drilled in February 2016. Over the next 3 years their frost tolerance, productivity and persistence were compared with the resident haresfoot clover (T. arvense). Balansa and the subterranean clovers all survived the 2016 and 2017 winters. The subterranean clovers maximum yield was 4.3 t DM/ ha after successful germination in February 2016 when sufficient rain extended the spring growing season into November. Subterranean clover cultivars from subspecies subterraneum yielded well in 2016, averaging 3.3 t DM/ha, as did the brachycalycinum ‘Antas’ with 3 t DM/ha. During the short season of 2017, the subterraneum ssp. cultivars ‘Denmark’ and ‘Karridale’ established the highest ground covers and ‘Antas’ the lowest. In 2018, ‘Antas’ had the lowest emergence rate and autumn yield. ‘Karridale’ had the highest re-establishment rate and the yanninicum ‘Trikkala’ the highest autumn yield (1.3 t DM/ha). Cultivars with low hardseededness ratings were the most successful at re-establishment in autumn 2017. Balansa clover was also persistent. In the favourable 2016 growing season the late-flowering resident haresfoot clover grew into early summer and yielded 3.7 t DM/ha. Red clover yielded 1 t DM/ha in 2016, but did not persist. Results suggest that medium-late flowering softer seeded subterranean clover cultivars and ‘Bolta’ balansa clover, are suitable for this environment.



2003 ◽  
Vol 11 ◽  
pp. 189-192
Author(s):  
Tom and Anne Costello

The Hawarden basin is typified by dry, hot conditions over summer, which makes it difficult to retain ryegrass/white clover pastures on the lighter soils. These conditions have led to the introduction of better-adapted species such as the annual, subterranean clover. The mid-flowering cultivar 'Mt Barker' was first sown in the 1930s; then the earlyflowering 'Woogenellup' and late 'Tallarook' were used in the 1960s. The 'Mt Barker' type became dominant in these old pastures. The key factors for good subterranean clover growth were soil fertility (particularly P and S), space following dry summers for seedlings to re-establish, and moisture in the spring to maximise herbage yield. A visit to Australia in 1996 prompted the inclusion in new sowings of the late-flowering 'Leura' at high sowing rates (8-10 kg/ ha). It has taken 5 years for seed stocks to build to a level where we can identify good seedling strikes of 'Leura'. Two of the autumns over this period were very difficult and hindered normal establishment. Rainfall is erratic in North Canterbury, which affects the success of subterranean clover from one year to another. Dry summer conditions are optimal for subterranean clover strikes, as the pasture opens, and when the autumn break occurs, more than 2 000 subterranean clover seedlings/m2 can be produced. Autumn grazing management, when recovering from extreme drought, is critical because pasture must be spelled for 6 weeks to allow the subterranean clover to establish. However, if the autumn is wet, pasture cover must be controlled so that subterranean clover seedlings are not smothered. Set-stocking is best in spring to control pasture cover, but grazing should not be too hard during the flowering and seed set period. Subterranean clover seed yields of up to 250 kg/ha have been achieved from old pastures, but this is less seed than is produced under Australian conditions. Pasture renovation using the baker boot drill to re-introduce grasses and new cultivars of subterranean clover has been successful following very dry summers. Lamb growth rates have been excellent on subterranean clover-based pastures and these have increased the farm's meat production and reduced the cost of maintaining pastures. Key words: grazing management, North Canterbury, seedling establishment, seed set, subterranean clover



2000 ◽  
Vol 51 (2) ◽  
pp. 267 ◽  
Author(s):  
B. S. Dear ◽  
P. S. Cocks ◽  
A. D. Swan ◽  
E. C. Wolfe ◽  
L. M. Ayre

A mixture of 3 subterranean clover (Trifolium subterraneum L.) cultivars (cvv. Goulburn, Seaton Park, and Dalkeith) was grown with 5–40 plants/m2 of phalaris (Phalaris aquatica L.) or lucerne (Medicago sativa L.) for 3 years at Wagga Wagga, NSW (147°21´E, 35°03´S). Clover seed yield was assessed each year, the number of regenerating clover seedlings was counted, herbage yield of clover and the perennials was measured, and the change in perennial density recorded. The influence of perennials on water availability in spring and light during clover seed set was also examined. The impact of perennial density on clover was assessed using regression analyses. In each of the 3 years, subterranean clover seed yield was negatively related to perennial density, but phalaris suppressed clover seed yield more than equivalent densities of lucerne in 2 of the years. Clover seed yield was positively related (R2 = 0.30–0.85) to clover biomass in spring in all 3 years (except for subterranean clover in phalaris in 1994) and to the proportion of total photosynthetically active radiation reaching the clover canopy beneath the perennial (R2 = 0.33–0.83) in 2 of the 3 years. There was a positive relationship between clover seedling regeneration in autumn and size of the summer seed bank in both years in lucerne (R2 = 0.40–0.76) and in 1 year in phalaris (R2 = 0.76) and a negative association between perennial density and clover seedling regeneration. The rate at which the surface profile (0–37 cm) dried in spring was independent of phalaris and lucerne density over the 3 years and did not differ from that of pure clover. The late season clover cultivar, Goulburn, constituted between 57% and 79% of the seed bank following seed set, substantially more than the earlier flowering cultivars, Seaton Park and Dalkeith. Neither perennial density nor species changed the relative competitiveness of the 3 cultivars. The high seed yield of Goulburn and the lack of a perennial-induced change in surface soil water in spring suggest that growing perennials in association with subterranean clover does not increase the level of moisture stress during clover seed set. The good performance of Goulburn is attributed to superior competitive ability for light in late spring. The basal area occupied by lucerne and phalaris increased with perennial density in each of the first 2 years. However, in the third year, phalaris basal area was similar at all densities. The findings suggest that sowing low densities of lucerne should assist in promoting seed yield and regeneration of subterranean clover. Management of phalaris, which has the capacity to substantially increase plant size at low densities, may require additional strategies such as more frequent grazing in spring.



1973 ◽  
Vol 13 (65) ◽  
pp. 681 ◽  
Author(s):  
BJ Quinlivan ◽  
AC Devitt ◽  
CM Francis

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.



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