Effect of aphids and mites on herbage and seed production of subterranean clover (cv. Daliak) in response to superphosphate and potash

1992 ◽  
Vol 32 (1) ◽  
pp. 39 ◽  
Author(s):  
RF Brennan ◽  
M Grimm

The dry matter production (DM) and seed yield of subterranean clover (Trifolium subterraneum L. cv. Daliak) were reduced by infestations of redlegged earth mite (Halotydeus destructor Tucker) and blue-green aphid (Acyrthosiphon kondoi Shinji) during spring growth, flowering and burr burial. The dominance of these pests varied with season. The effects of spraying with insecticides on the DM and seed yield responses to superphosphate and potassium chloride fertilisers were measured. Responses to superphosphate were described by Mitscherlich functions for each of 3 levels of potassium chloride, except for seed yields with pest sprays. At optimum levels of superphosphate and potassium chloride, controlling pests increased DM by up to 150% (from 4.37 to 6.52 t/ha). For all levels of superphosphate, spraying to control pests where no potassium chloride was applied significantly increased DM over that on unsprayed plots that were fertilised with potassium chloride. The maximum DM response to superphosphate application was achieved at 15-20 kg P/ha. With optimum superphosphate, the value for DM depended on the combination of spraying for pests and amount of potassium chloride applied, generating a series of Mitscherlich response curves for superphosphate application with differing maximum yields. With optimum superphosphate applied, the least DM recorded within a season was 3.47 t/ha (pests not sprayed, nil potassium chloride), and the most was 6.52 t/ha (pests sprayed, 120 kg potassium chloride/ha), an increase of about 180%. At optimum levels of superphosphate and potassium chloride, controlling pests increased seed yield by up to 380% (from 290 to 1100 kg/ha). With optimum superphosphate, seed yield within a season ranged from 210 (pests not sprayed, nil potassium chloride) to 1100 kg/ha (pests sprayed, 120 kg potassium chloride/ha), an increase of 524%. With pests sprayed, seed yield declined with superphosphate applications >20 kg P/ha; the relationship was best described by a quadratic function. With pests not sprayed, seed yield did not decline with increasing amounts of superphosphate, and the relationship fitted a Mitscherlich function.


1997 ◽  
Vol 37 (3) ◽  
pp. 343 ◽  
Author(s):  
D. J. Thackray ◽  
T. J. Ridsdill-Smith ◽  
D. J. Gillespie

Summary. Controlled environment experiments were conducted to establish some of the requirements for successful mass rearing of Halotydeus destructor (redlegged earth mite). Numbers of mites reared on Vicia sativa (common vetch) cv. Blanchefleur grown alone or on a mixture of vetch with Trifolium subterraneum (subterranean clover) cv. Goulburn, were significantly higher than those on subterranean clover or Arctotheca calendula (capeweed) alone. Populations reared on vetch grown in a sandy soil were significantly higher than those reared on vetch grown in a loamy soil, pure sand or pure loam. Covering the soil surface with a natural pasture mulch increased mite numbers compared with leaving the soil bare or placing plant pots inside ventilated cages. Subsequent changes in rearing methodology produced enough mites to enable summer screening of subterranean clover lines for resistance to H. destructorfor the first time. Over 20 000 mites can be produced from vetch at one time for screening tests throughout the year.



1995 ◽  
Vol 46 (5) ◽  
pp. 1091 ◽  
Author(s):  
TJ Ridsdill-Smith

Responses of redlegged earth mite (Halotydeus destructor) to seedlings of three resistant and four susceptible varieties of subterranean clover (Trifolium subterraneum) were measured after 7 or 14 days in pot experiments in the glasshouse. With a single variety/pot, mites on resistant varieties (DGI007, EP145SubD and Rutherglen B) produced 45% of the progeny that were produced by mites on the susceptible varieties (89838G, Dalkeith, Junee and 70088B). Number of stages completed and survival were little affected by varieties. Feeding damage (silvering of cotyledons) on resistant varieties averaged 45% of that on susceptible varieties with a single varietylpot. H. destructor fed less on resistant varieties in choice than in single variety experiments. On Junee and 89838G seedlings, feeding damage was similar to that on other susceptible varieties, but there were about half as many H. destructor progeny as on Dalkeith and 70088B. Mites laid more eggs on soil away from Junee plants, compared to the other three susceptible varieties. Different factors adversely affected the number of progeny produced on resistant varieties and on Junee.



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.



2000 ◽  
Vol 51 (3) ◽  
pp. 361 ◽  
Author(s):  
R. Chapman ◽  
T. J. Ridsdill-Smith ◽  
N. C. Turner

The impact of water stress and infestations of redlegged earth mite [Halotydeus destructor Tucker (Acarina : Penthaleidae)] on the early growth and botanical composition of a mixed subterranean clover (Trifolium subterraneum L.) and capeweed (Arctotheca calendula Levyns) pasture was investigated in a controlled environment experiment. Water stress and redlegged earth mite infestations both significantly reduced herbage production from both species. The yield of the subterranean clover was suppressed less by water stress than that of the capeweed. The differing sensitivities of the two species to water stress were attributed to differences in seedling size and growth rates at the onset of the drought. Redlegged earth mites caused greater feeding damage on cotyledons of the subterranean clover than of the capeweed. Despite this, the mites had a greater deleterious impact on the growth of the capeweed, which was suppressed both in the presence and absence of water stress. Redlegged earth mites in the presence of water stress did not significantly affect the growth of the subterranean clover. Furthermore, in the absence of water stress, the growth of the subterranean clover was greater when mites were present than when absent. The greater sensitivity of the capeweed to the effects of feeding by the redlegged earth mites was attributed to the smaller size of its seedlings at the time the redlegged earth mites were introduced. The increase in growth of the subterranean clover following the introduction of redlegged earth mites is more likely due to a change in the competitive relationships between the two plant species than to any direct effect of the mites’ feeding. Our observations indicate that the presence of water stress and redlegged earth mites significantly affects the competitive interactions between seedlings of subterranean clover and capeweed.



1996 ◽  
Vol 86 (3) ◽  
pp. 247-252 ◽  
Author(s):  
K.R. Gaull ◽  
T.J. Ridsdill-Smith

AbstractThe foraging behaviour of the redlegged earth mite, Halotydeus destructor (Tucker), in annual pasture was documented and the relative numbers of individuals foraging on subterranean clover, Trifolium subterraneum (Leguminosae), capeweed, Arctotheca calendula (Compositae) and grasses (mainly Lolium rigidum (Gramineae)), estimated in winter and spring in south-western Australia. The main feature of H. destructor foraging behaviour was the presence of aggregations ranging in size from 3–36 individuals on the adaxial surfaces of the upper canopy of the pasture. Most aggregating individuals were feeding, while most solitary and paired individuals were searching. There was no evidence that individuals aggregated for reproductive behaviour; the adult sex ratio was similar to that of the population even though immatures were under-represented in aggregations. During winter the distribution of numbers of H. destructor on subclover, capeweed and grasses in the upper canopy of pasture was similar to the estimated ground cover of these plant species. However, individuals showed host-plant selection for subclover when feeding. During spring, when the pasture plants were flowering, there were more H. destructor in capeweed flowers than in aggregations on subclover foliage. The capeweed flowers were shown to enhance the rate of H. destructor reproduction in a laboratory experiment. Most H. destructor were on or near the soil surface, with 10% at any one time on the upper canopy of the pasture. H. destructor is polyphagous, and behaved in pasture as a selective opportunist feeder.



1996 ◽  
Vol 86 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Y. Jiang ◽  
T.J. Ridsdill-Smith

AbstractResistance involving penetrability of cotyledons of subterranean clover Trifolium subterraneum (Leguminosae) by the redlegged earth mite, Halotydeus destructor Tucker, was examined in this study using several approaches. Values of penetrability, presented as mechanical strength measured with a penetrometer with a tubulated probe, of cotyledons tested 11–13 days after seeding, from nine varieties of two subspecies of subterranean clover (T. subterraneum subsp. yanninicum and subsp. brachycalicinum) were negatively correlated with feeding damage caused by H. destructor in both 3 h pairwise choice tests in a Petri dish with detached cotyledons, and in 2 week multiple choice tests in containers with seedlings. Simulation tests with different artificial membranes (Parafilm and Gladwrap) making up sachets, containing 5% glucose as a feeding stimulant, indicated that within 3 h H. destructor preferred membranes with lower strength. Field-collected young adults had significantly higher physical fitness to feed and/or gather on the artificial membrane sachet containing 5% glucose, than those from the laboratory culture, when the sachet was compared with cotyledons of either resistant (DGI007) or susceptible (Dalkeith) varieties in the choice tests. Electron microscopic observations of mite infested cotyledons of the resistant variety (DGI007) reveal that upper epidermal cell walls around penetration holes are bent inwards. Anticlinal cell walls of palisade cells appear buckled following attack by H. destructor. The results from these studies were taken as further evidence for the involvement of mechanical factors in antixenotic resistance of subterranean clover cotyledons to H. destructor.



1991 ◽  
Vol 31 (6) ◽  
pp. 777
Author(s):  
MDA Bolland

The effect of superphosphate applications (0, 25, 50, 75, 100 and 125 kg P/ha to the soil surface) on the dry matter (DM) herbage production of dense swards of subterranean clover (Trifolium subterraneum cv. Junee) and yellow serradella (Ornithopus compressus cv. Tauro) was measured in a field experiment on deep, sandy soil in south-western Australia. The swards were defoliated with a reel mower at weekly intervals from 88 to 158 days after sowing, to a height of 2 cm for the first 9 cuts, 4 cm for the tenth cut and 5 cm for the eleventh cut. Yellow serradella was more productive than subterranean clover. Consequently, for the relationship between yield and the level of phosphorus (P) applied, yellow serradella supported larger maximum yields and required less P than subterranean clover, to produce the same DM herbage yield. Maximum yields of yellow serradella were 12-40% larger. To produce 70% of the maximum yield for yellow serradella at each harvest, yellow serradella required about 50% less P than subterranean clover. However, when yields were expressed as a percentage of the maximum yield measured for each species at each harvest, the relationship between yield and the level of P applied was similar for both species, and they had similar P requirements.



1955 ◽  
Vol 6 (5) ◽  
pp. 673 ◽  
Author(s):  
KD McLachlan

Subterranean clover (Trifolium subterraneum L.) was grown on 32 virgin soils in pot cultures, and the yield responses to phosphorus, sulphur, and molybdenum were determined for each soil. The soils were collected from a wide area in eastern Australia, extending from south-western Victoria to southern Queensland. Sulphur deficiency occurred almost as frequently as phosphorus deficiency. In fact, 75 per cent. of the soils were deficient in both phosphorus and sulphur. Thirty-one per cent. were deficient in all three elements. The effect of the interaction between the elements on the occurrence and intensity of the deficiencies is shown. Molybdenum responses were obtained only after the other deficiencies had been corrected. A deficiency in one of the elements is no indication of deficiency or sufficiency of either of the other two. There was no correlation between the occurrence or intensity of the deficiencies and the geological origin of the soil parent material, the climate of the regions from which the soils were collected, or such soil characters as colour, organic matter, and texture. Responses to phosphorus were less on the black earths than on the red or yellow podzolic soils; those on the red earths were intermediate. The intensity of sulphur deficiency increased, and the intensity of molybdenum deficiency decreased, with increasing soil pH.



2007 ◽  
Vol 58 (2) ◽  
pp. 123 ◽  
Author(s):  
B. S. Dear ◽  
G. A. Sandral ◽  
J. M. Virgona ◽  
A. D. Swan ◽  
B. A. Orchard ◽  
...  

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.



2001 ◽  
Vol 41 (2) ◽  
pp. 169 ◽  
Author(s):  
Y. J. Ru ◽  
J. A. Fortune

The nutritive value of 26 cultivars of dry, mature subterranean clover was evaluated at Shenton Park, Perth, Western Australia. The cultivars were divided into 3 maturity groups according to flowering time and each cultivar was sown in blocks comprising 4 replicates. The plots were grazed by sheep at 2-week intervals during the growing season. Dry mature plant material and soil were sampled in summer to examine the effect of grazing and cultivar on seed yield and nutritive value of feed residues. Cultivars heavily grazed in spring had a low herbage mass. There was no difference in seed yield and seed weight between heavily and lightly grazed cultivars. Dry matter digestibility and mineral content of dry residues was inconsistent for the 2 grazing treatments. The dry matter digestibility of dry, mature subterranean clover ranged from 40 to 56%, with a wide range of crude fibre, nitrogen and mineral content for the 26 cultivars. While most minerals in the dry residues were above the requirement for sheep, 7 cultivars had a zinc content less than the maintenance requirement for sheep. There was an imbalance for all cultivars in calcium: phosphorus with a range of 4–10: 1. Concurrent estimates on the yield and composition of seed indicated that seed can be resource of minerals for grazing animals in summer. Most cultivars had a seed yield over 100 g/m2 with that of 9 cultivars being over 130 g/m2. Seed was rich in nitrogen, sodium, phosphorus, potassium, magnesium, zinc and copper, and poor in sodium, calcium and manganese. However, there were no cultivars with an appropriate ratio of calcium and phosphorus. The imbalance in nitrogen and sulfur was a result of high nitrogen content with the ratio ranging from 19: 1 to 29: 1.



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