The long-tailed mealybug, Pseudococcus adonidum (L.) in South Australia

1959 ◽  
Vol 10 (3) ◽  
pp. 322 ◽  
Author(s):  
TO Browning
Keyword(s):  
South Australia ◽  
Regular Sequence ◽  
Reproductive Rate ◽  
Early Spring ◽  
Behaviour Pattern ◽  
Late Winter ◽  
Spider Webs ◽  
Predatory Insects ◽  
New Generation ◽  
Orange Trees

The numbers of the long-tailed mealybug, P. adonidum (L.), on irrigated orange trees in South Australia rise and fall in a fairly regular sequence throughout the year. They are always low in summer, rise in autumn and early winter, and begin to fall gradually in late winter and spring. There is a sudden sharp rise in November followed almost at once by an equally sharp fall to the numbers characteristic of summer. This sequence may be explained in terms of the influence of weather on the survival and multiplication of the mealybugs in relation to the place where they happen to be living, the influence of predatory insects, and the behaviour pattern of the species. Food seems to play no part in this sequence except as its quality may influence behaviour. During summer the majority of the mealybugs on the leaves are to be found in specially sheltered places, such as under spider webs. There is evidence that the special quality of these places that makes them suitable for mealybugs is the greater humidity there than elsewhere. Young mealybugs on hatching are active in summer and tend to leave the shelter in which they originated and are likely to perish before they find another suitable place. At this time there are relatively few predatory insects. As autumn approaches the becomes cooler and less desiccating, and although the reproductive rate may fall the chance that young mealybugs will survive increases. This continues until the cold of winter reduces the reproductive rate to the point where it can no longer compensate for deaths and the population begins to fall. At the same time predatory insects become more numerous and take a greater toll of the population, forcing numbers still further down. In early spring the insects stop feeding and seek a sheltered place in which to reproduce. The migration from the leaves to the trunk and ground gathers momentum during September and October until the numbers left on the leaves are very low. At this time predatory insects become more numerous than they have been and the numbers of sheltering mealybugs may be greatly reduced. Then in November a new generation is produced which invades the leaves but most of these are killed quite soon by the hot dry winds which are common at this time of the year. The population falls to a low level and remains so until autumn.

Pollen vectors and pollination of faba beans in southern Australia

1991 ◽  
Vol 42 (7) ◽  
pp. 1173 ◽  
Author(s):  
FL Stoddard
Keyword(s):  
Vicia Faba ◽  
Mediterranean Climate ◽  
South Australia ◽  
Early Spring ◽  
Late Winter ◽  
Flower Visitors ◽  
Vicia Faba L ◽  
Faba Beans ◽  
Pollen Vectors ◽  
Western Victoria

Commercial crops of faba beans (Vicia faba L.) in South Australia and western Victoria were surveyed for flower visitors and incidence of pollination. Honeybees were the only pollen vectors. The incidence of pollination was never less than 50% and averaged 80%. The effectiveness of honeybees as pollen vectors contrasts with their ineffectiveness in colder climates, partly because in the Mediterranean climate beans flower in late winter and early spring when bees are in search of pollen. It is unlikely that growers of faba beans in Australia will need to provide supplementary hives to ensure adequate pollination.

Seasonal response of pasture to nitrogen fertilizer in the Mt. Lofty Ranges, South Australia

1975 ◽  
Vol 15 (73) ◽  
pp. 231 ◽  
Author(s):  
DE Elliot ◽  
AL Clarke
Keyword(s):  
Lolium Perenne ◽  
Nitrogen Loss ◽  
South Australia ◽  
Dactylis Glomerata ◽  
Trifolium Subterraneum ◽  
Early Spring ◽  
Late Winter ◽  
Potential Growth ◽  
A Site ◽  
Pasture Yield

Ammonium nitrate (0 to 200 kg ha-1 N) was applied to new areas of pure grass (Lolium perenne and Dactylis glomerata) and of mixed clover and grass (Trifolium subterraneum, L. perenne and D. glomerata) at monthly intervals from autumn (April) to late winter (August.) at a site in the Mt. Lofty Ranges, South Australia, and the pasture harvested 1 and 2 months after each application. As fertilizer applications were delayed, pasture yield responded increasingly to nitrogen. When 100 kg ha-1 was applied to grass, yield increases measured 2 months later ranged from 2 to 25 kg D.M. kg-1 N for the May and August applications respectively. Mixed pasture was less responsive than grass to later applications, because nitrogen suppressed the increasingly vigorous clover growth ; with 100 kg ha-1 N, response 2 months after the August application was 16 kg D.M. kg-1 N. Applied nitrate and ammonium disappeared rapidly from the top 30 cm of soil. Only after the May and June dressings, when rainfall was light, did significant quantities persist for one month. Some of the nitrogen loss was from leaching. Herbage harvested after two months accounted for 17 to 48 per cent of nitrogen applied at 100 kg ha-1, the largest recovery following the July dressing. The relatively small responses to high rates of nitrogen in mid winter indicate that other factors, possibly light energy, limited the potential growth of the pasture. The results suggest that nitrogen could be used either to increase the supply of grazing in early spring or the production of hay in late spring, especially where pastures lack clover.

Mouse plagues in South Australia cereal-growing areas III. Changes in mouse abundance during plague and non-plague years, and the role of refugia

1991 ◽  
Vol 18 (5) ◽  
pp. 593 ◽  
Author(s):  
GJ Mutze
Keyword(s):  
Survival Rates ◽  
South Australia ◽  
Breeding Population ◽  
Early Spring ◽  
Late Spring ◽  
Late Winter ◽  
Population Declines ◽  
Population Changes ◽  
Railway Line ◽  
Large Numbers

Mouse populations were monitored at 15 sites between 1980 and 1990, during which time one severe mouse plague, in 1980, and one minor outbreak, in 1984, were recorded. Smaller annual peaks in autumn to early winter were followed by winter population declines. Crops were colonised each year in late winter or early spring by mice from winter refuge habitats with dense, low vegetation, including roadsides and grassland along a railway line. In most years mouse numbers in crops declined during summer, but in 1983-84 they rose continuously during summer and autumn, and reached very high levels. Crops planted in 1984 were invaded by large numbers of mice which had survived through winter in the paddocks, but population levels again crashed in late spring and summer. Recorded population changes were generally consistent with plague probabilities predicted from environmental variables, except in 1985 when numbers failed to reach the predicted high levels at most sites. Population changes in crops during late spring appear to be critical in the development of mouse plagues. Large litter sizes and pregnancy rates, and variable survival rates and size of the breeding population, appear to be important factors at that time.

Nitrogen fertiliser use on rain-fed pasture in the Mt Lofty Ranges, South Australia. 1. Pasture mass, composition and nutritive characteristics

2003 ◽  
Vol 43 (6) ◽  
pp. 553 ◽  
Author(s):  
D. E. Elliott ◽  
R. J. Abbott
Keyword(s):  
South Australia ◽  
Growing Season ◽  
Early Spring ◽  
Late Spring ◽  
Late Winter ◽  
In Vitro Digestibility ◽  
Single Application ◽  
Nitrogen Fertiliser ◽  
N Rates

The effects of nitrogen (N) fertiliser (0–200 kg/ha) on mass, botanical composition, and N concentration (%) in herbage were examined in nine 2- or 3-year rate × time of application experiments, 14 single-year annual rate of application experiments and 15 short-term spring rate of application experiments, at 27 sites in the Mt Lofty Ranges, South Australia, in 7 years between 1970 and 1979, inclusive. Effects on in vitro digestibility and concentrations of other nutrients in herbage were examined in selected experiments.Annual applications of 200 kg N/ha increased herbage mass by an average of 2.8 t/ha (57% increase), over the average yield of unfertilised pasture of 4.6 t/ha. Subterranean clover was eliminated from the sward with this rate of N application, although this may have been exacerbated by the experimental methods used. N fertiliser application increased herbage mass throughout the growing season, except in autumn 1972 when low rainfall restricted growth and about half of the experiments were not harvested. In 5 of the 126 individual harvests, herbage mass did not respond positively to N fertiliser applications, even though clover composition of herbage declined.A single application of 50 kg N/ha in autumn increased herbage mass, 6–8 weeks later, by an average 11�kg�DM/kg N, but this N effect only persisted to a subsequent harvest in about half of the experiments, with an average residual effect of 25%. Commonly, a response to N fertiliser in the first and/or second harvests was followed by a non-responsive period and then a depression in herbage mass, where no further N fertiliser was applied. With repeated N fertiliser applications, the average responses to 50� kg� N/ha were 11 kg DM/kg N in late winter and also in early spring, similar to the autumn response, and 18�kg�DM/kg N in late spring. In a later study, a single application of 50 kg N/ha in spring, for silage or hay conservation, increased herbage mass by an average of 1.3 t/ha in late spring while the average response to 100 kg N/ha was 2.0 t/ha. Clover composition declined but was rarely eliminated from the sward by these N rates when applied only in spring.From early winter to early spring, N concentration in herbage from unfertilised pasture ranged from 3 to 4% N and then progressively declined. Relationships between herbage N concentrations and increasing N rates were either linear or curvilinear in early and late winter, whereas in spring, many of these responses to N fertiliser were sigmoidal, with a decline in herbage N concentrations being observed at low N rates. Nitrogen fertiliser applied throughout the growing season had little effect on in vitro digestibility for a wide range of pasture compositions. However, in vitro digestibility of a pure grass pasture was increased early in the growing season by applications up to 50 kg N/ha, but was depressed by the same N rates applied in late spring. Consistently, an increase in N had the following effect on the concentration of other herbage nutrients: K�increased; Ca decreased becoming more pronounced as the growing season progressed; P decreased in late spring; and Cu fell in autumn. The content of these nutrients in harvested herbage usually increased with increasing N rate, particularly when associated with large herbage mass responses to N fertiliser. The K : (Ca + Mg) ratio in herbage, a criterion for grass tetany, increased detrimentally with increasing N rate. Strategies are proposed for using N fertiliser on rain-fed pasture in the Mt Lofty Ranges.

Seasonal activity and estivation of lumbricid earthworms in the midlands of Tasmania

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey
Keyword(s):  
Soil Moisture ◽  
Adult Development ◽  
Survival Rates ◽  
Soil Surface ◽  
Early Spring ◽  
Lumbricus Rubellus ◽  
Late Winter ◽  
Cocoon Production ◽  
Density And Biomass ◽  
Earthworm Activity

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.

TEMPERATURE RESISTANCE OF GOLDFISH MAINTAINED UNDER CONTROLLED PHOTOPERIODS

1959 ◽  
Vol 37 (4) ◽  
pp. 419-428 ◽  
Author(s):  
William S. Hoar ◽  
G. Beth Robertson
Keyword(s):  
Temperature Change ◽  
Seasonal Variations ◽  
Rapid Growth ◽  
Endocrine System ◽  
Early Spring ◽  
Late Winter ◽  
Thyroid Activity ◽  
Temperature Resistance ◽  
Sudden Temperature Change

Goldfish maintained under controlled photoperiods for 6 weeks or longer were relatively more resistant to a sudden elevation in temperature when the daily photoperiods had been long (16 hours) and relatively more resistant to sudden chilling when they had been short (8 hours). The magnitude of the effect varied with the season. Thyroid activity was slightly greater in fish maintained under the shorter photoperiods. The longer photoperiods stimulated more rapid growth of ovaries during late winter and early spring. The endocrine system is considered a link in the chain of events regulating seasonal variations in resistance to sudden temperature change.

Leaf spot and dry rot of lettuce caused by Xanthomonas vitians (Brown) Dowson

1963 ◽  
Vol 14 (6) ◽  
pp. 778 ◽  
Author(s):  
DE Harrison
Keyword(s):  
Leaf Spot ◽  
Early Spring ◽  
Late Winter ◽  
Laboratory Studies ◽  
Dry Rot ◽  
Complete Destruction ◽  
Western Victoria ◽  
Valley Area ◽  
North Western

During the late winter and early spring of 1960, and again to a lesser extent in 1961 and 1962, many lettuce crops in the Murray Valley area of north-western Victoria were seriously affected by a disease characterized by blackening, dry rotting, and collapse of the affected leaves. The incidence of disease varied from about 10% up to practically complete destruction of some plantings. A yellow bacterium was consistently isolated from affected plants and proved to be pathogenic to lettuce. Laboratory studies have shown that the organism agrees closely with the recorded description of Xanthomonas vitians (Brown) Dowson, which has not, apparently, been previously studied in Australia.

Insecticide sprays, natural enemy assemblages and predation on Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae)

2014 ◽  
Vol 104 (5) ◽  
pp. 576-585 ◽  
Author(s):  
C. Monzo ◽  
J.A. Qureshi ◽  
P.A. Stansly
Keyword(s):  
Natural Enemy ◽  
Early Spring ◽  
Citrus Greening ◽  
Asian Citrus Psyllid ◽  
Late Winter ◽  
Diaphorina Citri ◽  
Citrus Groves ◽  
Arthropod Fauna ◽  
Predator Exclusion ◽  
Insecticide Sprays

AbstractThe Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is considered a key citrus pest due to its role as vector of ‘huanglongbing’ (HLB) or citrus greening, probably the most economically damaging disease of citrus. Insecticidal control of the vector is still considered a cornerstone of HLB management to prevent infection and to reduce reinoculation of infected trees. The severity of HLB has driven implementation of intensive insecticide programs against ACP with unknown side effects on beneficial arthropod fauna in citrus agroecosystems. We evaluated effects of calendar sprays directed against this pest on natural enemy assemblages and used exclusion to estimate mortality they imposed on ACP populations in citrus groves. Predator exclusion techniques were used on nascent colonies of D. citri in replicated large untreated and sprayed plots of citrus during the four major flushing periods over 2 years. Population of spiders, arboreal ants and ladybeetles were independently assessed. Monthly sprays of recommended insecticides for control of ACP, adversely affected natural enemy populations resulting in reduced predation on ACP immature stages, especially during the critical late winter/early spring flush. Consequently, projected growth rates of the ACP population were greatest where natural enemies had been adversely affected by insecticides. Whereas, this result does not obviate the need for insecticidal control of ACP, it does indicate that even a selective regimen of sprays can impose as yet undetermined costs in terms of reduced biological control of this and probably other citrus pests.

Phenological phases of pollination related to climate change

2021 ◽  
Author(s):  
Samuel Monnier ◽  
Michel Thibaudon ◽  
Jean-Pierre Besancenot ◽  
Charlotte Sindt ◽  
Gilles Oliver
Keyword(s):  
Climate Change ◽  
Pollen Season ◽  
Microscopic Analysis ◽  
Allergic Diseases ◽  
Early Spring ◽  
Late Winter ◽  
General Tendency ◽  
New Production ◽  
Start Date ◽  
Generic Term

&lt;p&gt;Knowledge:&lt;/p&gt;&lt;p&gt;Rising CO2 levels and climate change may be resulting in some shift in the geographical range of certain plant species, as well as in increased rate of photosynthesis. Many plants respond accordingly with increased growth and reproduction and possibly greater pollen yields, that could affect allergic diseases among other things.&lt;/p&gt;&lt;p&gt;The aim of this study is the evolution of aerobiological measurements in France for 25-30 years. This allows to follow the main phenological parameters in connection with the pollination and the ensuing allergy risk.&lt;/p&gt;&lt;p&gt;Material and method:&lt;/p&gt;&lt;p&gt;The RNSA (French Aerobiology Network) has pollen background-traps located in more than 60 towns throughout France. These traps are volumetric Hirst models making it possible to obtain impacted strips for microscopic analysis by trained operators. The main taxa studied here are birch, grasses and ragweed for a long period of more than 25 years over some cities of France.&lt;/p&gt;&lt;p&gt;Results:&lt;/p&gt;&lt;p&gt;Concerning birch but also other catkins or buds&amp;#8217; trees pollinating in late winter or spring, it can be seen an overall advance of the pollen season start date until 2004 and then a progressive delay, the current date being nearly the same as it was 20 years ago, and an increasing trend in the quantities of pollen emitted.&lt;/p&gt;&lt;p&gt;For grasses and ragweed, we only found a few minor changes in the start date but a longer duration of the pollen season.&lt;/p&gt;&lt;p&gt;Discussion:&lt;/p&gt;&lt;p&gt;As regards the trees, the start date of the new production of catkins or buds is never the 1&lt;sup&gt;st&lt;/sup&gt; of January but depends on the species. For example, it is early July for birch. For breaking dormancy, flowering, and pollinating, the trees and other perennial species need a period of accumulation of cold degrees (Chilling) and later an accumulation of warm degrees (Forcing). With climate change these periods may be shorter or longer depending of the autumn and winter temperature. Therefore, a change in the annual temperature may have a direct effect on the vegetal physiology and hence on pollen release. It may also explain why the quantities of pollen produced are increasing.&lt;/p&gt;&lt;p&gt;The Poaceae reserve, from one place to another and without any spatial structuring, very contrasted patterns which make it impossible to identify a general tendency. This is probably due to the great diversity of taxa grouped under the generic term Poaceae, which are clearly not equally sensitive to climate change.&lt;/p&gt;&lt;p&gt;Conclusion:&lt;/p&gt;&lt;p&gt;Trees with allergenic pollen blowing late winter or early spring pollinate since 2004 later and produce amounts of pollen constantly increasing. Grasses and ragweed have longer periods of pollination with either slightly higher or most often lower pollen production.&lt;/p&gt;

Cytokinins and abscisic acid in hardening winter wheat

1990 ◽  
Vol 68 (7) ◽  
pp. 1597-1601 ◽  
Author(s):  
John S. Taylor ◽  
Munjeet K. Bhalla ◽  
J. Mason Robertson ◽  
Lu J. Piening
Keyword(s):  
Triticum Aestivum ◽  
Abscisic Acid ◽  
Winter Wheat ◽  
Leaf Tissue ◽  
Triticum Aestivum L ◽  
Early Spring ◽  
Growth Chamber ◽  
Late Winter ◽  
Sequence Of Events ◽  
Freeze Dried

During overwintering in a northern climate, winter wheat goes through a hardening process, followed by dehardening in late winter – early spring. This sequence of events may be partially controlled by changes in endogenous hormone levels. Crowns and leaf tissue from field grown winter wheat (Triticum aestivum L. cv. Norstar) seeded at the beginning of September were collected and freeze-dried at monthly intervals during the winters of 1985–1986 and 1986–1987. Material was also sampled and freeze-dried from seedlings grown in a growth chamber under hardening conditions (21 °C for 2 weeks plus 3 °C for 6 weeks) or nonhardening conditions (3 weeks at 21 °C). The tissues were analysed for cytokinins and abscisic acid. Cytokinin levels, measured with the soybean hypocotyl section assay, declined from October onwards and then rose to a peak in late winter (January and February, winter 1986–1987; February and March, winter 1985–1986), subsequently declining again. Abscisic acid, quantitated as the methyl ester by gas chromatography with an electron capture detector, increased in level from October to December, then decreased to a relatively low level between January and March. Hardened seedlings from the growth chamber contained significantly higher abscisic acid levels and significantly lower cytokinin levels than did the nonhardened seedlings. Key words: abscisic acid, cytokinins, hardening, Triticum aestivum, winter wheat.

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