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Woolly apple aphid : interactions within an orchad system /Fitzgibbon, Frances, January 1996 (has links) (PDF)
Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1997. / Errata and addenda attached. Bibliography: leaves 195-211.
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The biology and management of aerial populations of woolly apple aphid, Eriosoma lanigerum (Hausmann) (Homoptera: aphididae)Heunis, J. M. (Juanita Maria) 03 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The basic biology of Eriosoma lanigerum (Hausmann) and its natural enemy,
Aphelinus mali (Haldeman), was investigated in the Western Cape Province of South
Africa.
The first instar nymph can be identified by the absence of cornicles and the
adult female by the presence of the vulva. Body length and distance between cornicles
can be used to distinguish between the 2nd
, 3rd and 4th instars.
The development of E. lanigerum was negatively influenced by temperatures
above 27DC. The net replacement rate (Ro) and intrinsic rate of increase (rm) peaked at
20DC. The theoretical lower and upper threshold temperatures for development were
estimated at 4.48DC and 28.07DC, respectively.
Crawlers of E. lanigerum migrated from the roots up into the trees during
spnng to start new infestations. Colonies became visible from December and
maximum colony numbers were reached from the end of summer until autumn, at
which time most of the colonies were parasitised by A. mali. Colony numbers
declined at the end of autumn after high parasitism and the appearance of winged E.
lanigerum. The aphid overwintered on the tree. Chemical sprays, rain during spring
and high temperature influenced population numbers negatively.
E. lanigerum can be monitored by counting the unparasitised colonies in leaf
axils of half of each of 25 trees per 2 hectare plot with 5 unparasitised colonies as the
economic threshold. Sampling error was high at 40% but increasing the number of
trees did not reduce it. Presence-absence sampling, which will reduce the time
required for monitoring, did not seriously compromise the reliability of decisions
regarding the necessity for intervention. Chemicals containing nitrogen usually sprayed for bitterpit control stimulated
the settling of E. lanigerum crawlers on Granny Smith trees, while fruit weevil
barriers for the control of Phlyctinus callos us Boh. limited crawler movement into the
trees but did not prevent colonisation.
All the postembryonic developmental stages of E. lanigerum were parasitised
by A. mali. Complete parasitism of the population was never reached as younger
instars sheltered under other aphids and mummified aphids.
Development of A. mali was not influenced negatively by high temperatures.
The minimum developmental temperature and number of degree days needed for
development of the larval stage and emergence of the adult from the mummy were
.6.72°C and 172.41°D, and 10.27°C and 109.89°D respectively. Mummies collected
during early winter survived long periods of cold storage in postdiapause. The
rrummum threshold temperature for postdiapause development of A. mali was
·10.15°C.
Most chemicals tested against A. mali adults were highly toxic to the wasp,
except endosulfan and two growth regulators, flufenoxuron and fenoxycarb. The
mortality of adults exposed to the fungicides tested was low within the first 24 hours.
The percentage emergence from the mummies was high for all chemicals tested, but
more than 60% of the adults died soon after emergence from mummies treated with
chlorpyrifos. Nearly 30% of the adults died soon after they emerged from carbaryl
(XLR-Plus) and fenthion treated mummies. The growth regulators, flufenoxuron and
fenoxycarb, did not influence fecundity adversely. / AFRIKAANSE OPSOMMING: Die basiese biologie van Enosoma lanigerum (Hausmann) en sy natuurlike
vyand, Aphelinus mali (Haldeman), in die Weskaap Provinsie van Suid-Afrika
isondersoek.
Die eerste instar nimf kan aan die afwesigheid van kornikels en die
volwassenes aan die teenwoordigheid van die vulva uitgeken word. Die
liggaamslengte en afstand tussen die kornikels kan gebruik word om tussen instar 2, 3
en 4 te onderskei.
Die ontwikkeling van E. lanigerum word nadelig deur temperature bo 27°C
beïnvloed. Die netto vervangingstempo (Ro) en intrinsieke tempo van toename (rm)
was die hoogste by 20°C. Die teoretiese minimum en maksimum temperatuur
drempelwaardes vir ontwikkeling was 4.48°C en 28.07°C onderskeidelik.
In die lente beweeg E. lanigerum kruipers op vanaf die wortels tot in die bome
om nuwe kolonies te begin. Kolonies is sigbaar vanaf Desember en die hoogste
koloniegetalle word aan die einde van die somer tot die herfs bereik, wanneer die
meeste van die kolonies dan ook deur A. mali geparasiteer word. Teen laat-herfs neem
koloniegetalle af as gevolg van hoë parasitisme en die verskyning van gevleuelde E.
,lanigerum. E. lanigerum oorwinter op die appelboom. Chemiese behandelings, reën
gedurende die lente en hoë temperatuur beïnvloed koloniegetalle nadelig.
E. lanigerum kan deur die aantal ongeparasiteerde kolonies in die blaaroksels
van die helfte van 25 bome per 2 hektaar blok te tel, met 5 ongeparasiteerde kolonies
as die ekonomiese drempelwaarde, gemonitor word. Die steekproefnemingsfout was
hoog (40%), maar kon nie verminder word deur die aantal bome wat gemonitor is te
verhoog nie. Steekproefneming, vir aan- of afwesigheid van kolonies, wat monitortyd sal verminder, het min invloed op die betroubaarheid van besluitnemings oor die
noodsaaklikheid van bespuitings gehad.
Stikstofbevattende chemikalieë, wat vir die beheer van bitterpit gespuit word,
stimuleer vestiging van E. lanigerum kruipers op Granny Smith bome, terwyl
snuitkewerversperrings, vir die beheer van Phlyctinus callosus Boh., die opwaartse
beweging van kruipers in die bome beperk, maar nie kolonievorming van E.
lanigerum verhoed nie.
Alle postembrioniese ontwikkelingstadiums van E. lanigerum is deur A. mali
geparasiteer. Totale parasitisme is nooit bereik nie, omdat jonger instars onder ander
bloedluise en gemummifiseerde bloedluise skuil.
Die ontwikkeling van A. mali word nie deur hoë temperature benadeel nie. Die
minimum ontwikkelingstemperatuur en graaddae, nodig vir ontwikkeling van die
larwale stadium en die verskyning van die volwassene uit die mummie, was 6.72°C
met 172.4loD en 10.27°C met 109.89°D, onderskeidelik. Mummies wat vroeg in die
winter versamel is, het lang periodes van koelopberging oorleef. Die minimum
temperatuur drempelwaarde vir A. mali ontwikkeling in postdiapouse was 10.15°C.
Die meeste van die chemikalieë wat getoets is, was hoogs toksies vir die
volwasse wesp, behalwe endosulfan en die twee groeireguleerders, flufenoxuron en
fenoxycarb. Die mortaliteit van volwassenes wat aan swamdoders blootgestel is, was
laag binne die eerste 24 uur na blootstelling. Die persentasie uitkoms vanuit mummies
was hoog vir al die chemikalieë wat getoets is, maar met chlorpyrifos het 60% van die
volwassenes net na uitkoms doodgegaan. Ongeveer 30% van die volwassenes is dood
na verskyning vanuit mummies wat met carbaryl (XLR-Plus) en fenthion gespuit is.
Die groeireguleerders, flufenoxuron en fenoxycarb, het nie die vrugbaarheid van die
parasiet merkbaar beïnvloed nie.
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Biology of subterranean populations of woolly apple aphid, Eriosoma lanigerum (Hausmann)(Homoptera:Aphididae), in apple orchardsDamavandian, M. R. 03 1900 (has links)
Dissertation (PhD (Agric))--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: A study was made of the basic biology of subterranean Eriosoma
lanigerum (Hausmann) populations in apple orchards in the Western Cape
Province of South Africa.
The absence of cornicles and the presence of a vulva could be used to
identify 1st instar nymphs and adults respectively. Body length, body width and
length of the hind femur are useful for separating 2nd
, 3rd and 4th instars.
However, separation of 2nd from 3rd instar nymphs was very unreliable.
Maximum population growth rate was at 23°C while at 30 °C
population growth was zero. The estimated minimum and maximum threshold
temperatures for development were 4.32 and more than 30°C respectively.
Numbers of underground E. lanigerum in soil samples taken using
mechanical and hand augers were similar. However, numbers of aphids in
samples were influenced by the distance from the trunk at which the samples
were taken and the presence and the type of root material in the samples.
More aphids were recorded close to the trunk, and at a given distance from
the trunk more aphids were recorded if there was root material in the sample,
especially if the roots were galled. early autumn (February, March) and declined during winter, especially if the
winter rainfall was high. These cycles coincided with the nitrogen cycles in the
roots.
Embryos were also present in all instars throughout the year. There
were more embryos in the 4th instar and adult aphids than in the other instars.
The highest number of embryos in the 4th instar and adult aphids occurred
during spring, which coincided with peak nitrogen levels in the roots of apple
trees. Nitrogen levels in root material adjacent to galls and in ungalled roots
were higher than in root galls.
A number of entomopathogenic fungi, including species of
Conidiobolus, Hirsufella and Beauveria were found. Their present contribution
to biological control is not known.
A straw mulch suppressed subterranean E. lanigerum population levels
at least as well as the soil insecticide, imidacloprid, currently in use. / AFRIKAANSE OPSOMMING: 'n Studie van die basiese biologie van ondergrondse bevolkings van
, Eriosoma lanigerum (Hausmann) is in appelboorde in die Weskaap Provinsie
van Suid-Afrika uitgevoer.
Die afwesigheid van kornikels en die aanwesigheid van 'n vulva kon
gebruik word om die 1ste instar nimfe en volwassennes onderskeidelik te
identifiseer. Liggaamslengte, liggaamsbreedte en die lengte van die agterste
femur kon gebruik word om die 2de
, 3de en 4de instars van mekaar te
onderskei. Onderskeiding tussen 2de en 3de instar nimfe was egter baie
onbetroubaar.
Maksimum bevolkingsgroei het by 23°C plaasgevind, terwyl dit nul was
by 30 °C. Die beraamde minimum en maksimum temperature vir ontwikkeling
was by 4.32 en meer as 30°C onderskeidelik.
Getalle van ondergrondse E. lanigerum in grondmonsters wat geneem
is met gebruik van meganiese en hand bore was eenders. Getalle plantluise in
monsters is egter beïnvloed deur die afstand vanaf die stam waarby die
monsters geneem is en die teenwoordigheid van wortelmateriaal in die
monsters. Meer plantluise is aangeteken as daar wortelmateriaal in die
monsters was, en veral as daar galle op die wortels was. Die appelbloedluis was dwarsdeur die jaar ondergronds aktief.
Bevolkingsvlakke het gedurende die vroeë somer (November, Desember) en
vroeë herfs (Februarie, Maart) toegeneem, en gedurende die winter
afgeneem, veral as die winterreënval hoogwas.
Embrio's was ook teenwoordig dwarsdeur die jaar. Daar was meer
embrio's in die 4de instar en volwasse plantluise as in die ander instars. Die
hoogste aantal embrio's in die 4de instar en volwasse plantluise het in die lente
voorgekom, wat saamgeval het met piek stikstofvlakke in die wortels van
appelbome. Stikstofvlakke in wortelmateriaal aangrensend aan wortels en in
wortels sonder galle was hoër as in wortelgalle.
Talle entomopatogeniese swamme, insluitend spesies van
Conidiobolus, Hirsufella en Beauvaria IS gevind. Hulle huidige bydrae tot
biologiese beheer is nie bekend nie.
'n Strooideklaag het ondergrondse bevolkingsvlakke van E. lanigerum
tot ten minste dieselfde mate as die grondinsektedoder, imidacloprid, wat tans
in gebruik is, onderdruk.
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The pest status and management of woolly aphid in an Australian apple orchard IPM program /Nicholas, Adrian Harry. January 2000 (has links)
Thesis (Ph. D.) -- University of Western Sydney, Hawkesbury, 2000. / Includes bibliographical references (leaves 160-187).
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Genetic analysis for resistance to Woolly Apple Aphid in an apple rootstock breeding populationSelala, Mapurunyane Callies January 2007 (has links)
Masters of Science / Genetic analysis for resistance to Woolly Apple Aphid in apple rootstock breeding populations MC Selala MSc Thesis, Department of Biotechnology, Faculty of Science, University of the WesternCape. The Woolly Apple Aphid (WAA) Eriosoma lanigerum (Hausm.) (Homoptera: Aphididae) is economically one of the most important pests in apple commercial production in the Western Cape province, South Africa. The apple cultivar Northern Spy possesses a single major gene (Er1) responsible for E. lanigerum resistance. This cultivar has been used as a commercial rootstock in apple breeding programmes. There are other genes also implicated in resistance to E. lanigerum from other cultivars. Manipulation and pyramiding of the E. lanigerum
resistance genes (Er1, Er2 and Er3) might provide a necessary control for commercial apple production. The aim of this study was to construct a genetic linkage map for apple using
microsatellite markers. The use of marker-assisted selection would greatly benefit local apple breeding programmes. Ninety six seedlings from a Northern Spy × Cox Orange Pippin mapping population were used for genetic linkage construction. Phenotypic data collection and analysis were performed to determine the E. lanigerum infestation patterns and the levels of resistance conferred by the Er1 gene from Northern Spy using 52 in vitro propagated seedlings in the greenhouse. Classification and quantification analysis showed association patterns between first assessments (30 days) to second assessment (60 days) in all replicate blocks. Roots and shoots data showed that it could be useful in quantitative trait loci (QTL) analysis, but may be used in different QTLs beingidentified due to the variations between roots and shoots data. A preliminary linkage map was constructed using a mapping population from Northern Spy × Cox Orange Pippin (96 seedlings).Fluorescently labelled published and predicted
microsatellite markers were used in map construction. Primers were optimised using single apple cultivar and the detection of polymorphisms using nine apple cultivars. Optimised markers were multiplexed for high throughput data generation using the Polymerase Chain Reaction (PCR) technique. Multiplexed PCR products were pooled and analysed on an ABI 310 PRISM™ Genetic Analyser to determine allele fragment sizes, and the inherited segregation types in the seedlings. Computer software GenoTyper® 2.5.2 and JoinMap® 3.0 was used in data analysis from ABI 310 PRISM™Genetic Analyser and linkage map
construction. Seventy two markers were used in linkage map construction, which produced nine linkage groups with some segments from the same linkage group. Twenty-one markers were aligned on the map 20 published and one predicted. Only one linkage group consisted of five markers while other linkage groups had two markers each. This study has proved that th preliminary linkage map could be used as the basis of a complete linkage map of Northern Spy × Cox Orange Pippin.
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The effect of spirea aphid (Homoptera: aphididae) feeding and nitrogen fertilization on the growth of young apple trees, with comparisons to apple aphidKaakeh, Walid 07 November 2008 (has links)
The overall goal of this research was to determine the effects of spirea aphid, Aphis spiraecola Patch, feeding and nitrogen fertilization on net photosynthesis (Pn), leaf chlorophyll content and greenneess, growth, dry matter accumulation, and carbohydrate concentrations of young apple trees, with comparisons to apple aphid, Aphis pomi DeGeer. Trees were artificially infested and grown in an unheated greenhouse with screened ends.
The spirea aphid responded differently to various nitrogen treatments. Aphid density increased at a faster rate on trees receiving higher nitrogen application. The leaf nitrogen concentration increased significantly and linearly with increasing amount of urea application in both infested and control leaves. Also, a significant difference in leaf nitrogen concentration was found at each urea application rate between infested and control leaves.
Spirea aphid feeding and sooty mold accumulations caused significant reductions in photosynthetic rates, leaf chlorophyll content, and greenness. Pn increased linearly with increasing chlorophyll content and greenness; nitrogen rates caused an increase in Pn and leaf greenness. Aphid-days accumulations were strongly correlated to Pn and greenness at each nitrogen rate applied. Accumulation of callose at the phloem sieve plates in response to spirea aphid feeding occurred but to a lesser degree than from other aphids reported on apple and pecan leaves.
Accumulation of fresh and dry weights in all tree parts (leaves, lateral shoots, trunk, rootstock, and roots) during the growing season were affected by both spirea aphid and nitrogen fertilization. The spirea aphid reduced accumulation of fresh and dry weights in all tree partitions when trees were harvested at the end of the first growing season. These reductions were still lower than the control when trees were harvested at the ten-leaf stage the following spring. The spirea aphid caused a significant reduction in lateral shoot growth at the end of the growing season and at the ten-leaf stage. Fresh and dry weights of all tree partitions tended to increase with increasing rates of nitrogen.
The percentage and the amount of nonstructural carbohydrates (NSC) in all tree partitions were reduced by spirea aphid feeding and were positively related to nitrogen rate. At the ten-leaf stage in the second season, similar results were obtained.
Development of spirea aphid and apple aphid was similar on trees fertilized with a moderate rate of nitrogen. Pn and leaf greenness declined to a similar extent with accumulated aphid-days, for both aphid species. Aphid species did not affect any of tree growth or NSC accumulation. / Ph. D.
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Genetic diversity of root-infesting woolly apple aphid Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae) populations in the Western CapeTimm, Alicia (Alicia Eva) 03 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Characterizing the genetic structure of a pest population can provide an understanding of the factors
influencing its evolution and assist in its ultimate control. The aim of the present study was to characterize
the genetic structure of woolly apple aphid Eriosoma lanigerum (Hausmann) populations in the Western
Cape Province in South Africa. Since this economically important apple pest has not previously been
characterized at molecular level, it was necessary to evaluate methods for determining the genetic structure
of E. lanigerum populations. Two different molecular techniques were evaluated viz. random amplification
of polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP). This study represents
the first application of the latter technique to members of the Aphididae.
Aphids were sampled from four regions in the Western Cape in South Africa viz. Elgin, Ceres, Vyeboom and
Villiersdorp. A spatially nested sampling design was used to establish the distribution of the genetic
variance of aphids. A total of 192 individuals from 13 farms were analysed. Ten RAPD primers were
chosen for analysis from an initial assay of 25 after fragment reproducibility had been confirmed. For AFLP
analysis three different rare-cutting restriction enzymes were evaluated for AFLP analysis, viz. EcoRI, SseI
and MluI. The latter yielded the best results in combination with the frequent-cutting enzyme MseI.
Twenty-five AFLP selective primer pairs were evaluated, out of which five were chosen for analysis of the
total population.
Two hundred and fifty AFLP fragments and 47 RAPD fragments were scored for analysis. Both analyses
indicated that a low level of genetic variation was apparent in E. lanigerum populations and that no
differentiation resulted from geographic isolation. From RAPD analyses it was deduced that all variation
could be attributed to differences between individuals. AFLP analysis indicated that, whereas genetic
differences in E. lanigerum populations between orchards were negligible, a significant portion of genetic
variation could be attributed to differences between farms and individuals within farms.
Therefore, AFLP analysis allowed for finer discrimination of the genetic structure of E. lanigerum
populations than RAPD analysis and is recommended for studies of other aphid species. The fact that most
of the genetic variation present in E. lanigerum populations could be found on small spatial scales indicated
that sampling individuals over a wide geographic area was an ineffective way of detecting the genetic
diversity present in E. lanigerum populations. The low level of variation in populations is most likely due to
the exclusive occurrence of parthenogenetic reproduction, founder effects (including distribution of infested
plant material from a limited source) and selective factors such as the use of resistant rootstocks or
pesticides. Furthermore, the low level of variation found indicated that the possibility of controlling E.
lanigerum in the Western Cape using host plant resistance is favourable. Thus, plant breeders developing resistance to E. lanigerum can expect plant entries to be exposed to most of the genetic diversity present in
Western Cape populations, regardless of location. / AFRIKAANSE OPSOMMING: Die bepaling van die genetiese struktuur van 'n landboukundige plaagpopulasie kan lei tot begrip van die
faktore wat die populasie beïnvloed en kan uiteindelike beheer vergemaklik. Die doel van die huidige studie
was om die genetiese struktuur van die appelbloedluis Eriosoma lanigerum (Hausmann) in die Wes-Kaap
Provinsie van Suid-Afrika te bepaal. Aangesien hierdie belangrike appelplaag nie van tevore op molekulêre
vlak bestudeer is nie, was dit nodig om metodes vir die bepaling van die genetiese struktuur van E.
lanigerum populasies te evalueer. Twee molekulêre tegnieke is geëvalueer, nl. lukraak geamplifiseerde
polimorfiese ONS (RAPD) en geamplifiseerde fragment-lengte polimorfismes (AFLP). Hierdie studie is die
eerste om laasgenoemde tegniek te gebruik om lede van die Aphididae te bestudeer.
Plantluise is verkry van vier verskillende gebiede in die Wes-Kaap Provinsie van Suid-Afrika nl. Elgin,
Ceres, Vyeboom en Villiersdorp. 'n Hierargiese sisteem is gebruik om die verspreiding van die genetiese
variasie van plantluise te bepaal. In totaal is 192 individue van 13 plase geanaliseer. Tien RAPD inleiers is
gekies uit 'n analise van 25 verskillende inleiers nadat fragment reproduseerbaarheid bevestig is. Drie
verskillende restriksie ensieme is geëvalueer vir AFLP analise nl. EcoRI, SseI en Mlul. Die beste resultate is
verkry toe MluI saam met MseI gebruik is. Vyf-en-twintig AFLP selektiewe inleier pare is geëvalueer
waarvan vyf gekies is vir analise van die totale populasie.
Twee-honderd-en-vyftig AFLP fragmente en 47 RAPD fragmente is gedokumenteer vir analise. Beide
RAPD en AFLP analises het getoon dat daar 'n lae vlak van genetiese variasie in E. lanigerum populasies is
en dat geen differensiasie as gevolg van geografiese isolasie ontstaan het nie. Uit RAPD analise is daar
afgelei dat al die variasie toegeskryf kon word aan verskille tussen individue. AFLP het aangetoon dat
alhoewel verskille in E. lanigerum populasies tussen boorde laag was, kon 'n hoë persentasie van die variasie
toegeskryf word aan verskille tussen plase en individue binne plase.
AFLP analise het meer insig in die genetiese struktuur van E. lanigerum populasies verskaf, en word dus
aanbeveel vir studies van ander plantluise. Omdat meeste van die genetiese variasie oor klein geografiese
afstande verkry word, is steekproefueming oor groot gebiede 'n ondoeltreffende manier om die genetiese
variasie binne 'n monster te meet. Die lae vlak van genetiese variasie is waarskynlik te wyte aan
partenogenetiese vermeerdering, stigter gevolge (insluitend verspreiding van geïnfesteerde plantmateriaal
vanaf 'n beperkte bron), sowel as selektiewe faktore soos die gebruik van bestande onderstokke en
insekdoders. Verder dui die lae vlak van variasie aan dat die moontlikheid vir beheer deur
gasheerplantbestandheid goed is in die Wes-Kaap. Planttelers kan verseker wees dat hulle plante blootgestel
sal wees aan meeste van die genetiese variasie in die Wes-Kaap appelbloedluis populasies ongeag hulle
ligging.
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Variability in abundance of the rosy apple aphid (Dysaphis plantaginea), the role of its alternate host (Plantago major), and potential control strategies in organic apple orchards in British ColumbiaBrown, Amanda Erica 05 1900 (has links)
The rosy apple aphid, Dysaphis plantaginea, (Homoptera: Aphididae) is a serious pest of apples in British Columbia (BC), Canada and especially in organic orchards where conventional controls cannot be used. The goals of this study were to determine the environmental or management factors of an orchard that lead to high aphid populations, to conduct an economic assessment of the damage, to determine the timing of autumn migration, and to test several autumn and spring chemical control methods and two novel autumn mechanical control methods targeting the aphids while on their alternate host, Plantago major.
To explain the variation among orchards, I evaluated several potential correlates of aphid density: abundance of the alternate host (plantain, Plantago major), foliar tree nitrogen, tree age, tree planting density, and the application of an oil treatment in spring. Stepwise regression indicated that foliar nitrogen and tree age explain 27% of the variation. Orchards receiving a spring oil application had a 53% lower average aphid infestation level. Plantain abundance was not related to aphid population on apple. However, experimental manipulation of leaf angle from the ground and size showed that significantly more alate and apterous aphids occurred on large, low angle leaves. Mowing prior to spring aphid migration was associated with 75% fewer alatae and apterae on the plantain.
The loss in harvest resulting from aphid damage ranged from 3% to 76% of the crop. Effective autumn control depends on accurate timing of aphid flight. The peak of female flight occurred on the 27th of September, 2007 at 11:56 hours daylength (sunrise to sunset) and the peak of male flight occurred on the12th of October, 2007 at 11:02 hours daylength. Aphid densities in the spring of 2008 were very low, making comparisons between treatments and controls difficult. Autumn applications of Superior dormant oil and kaolin clay were not effective. The PureSpray Green treatments of two October applications and one April application showed a significant reduction in rosy apple aphid infested clusters compared with the untreated control. Mowing and rotavating did not result in a significant reduction in aphid infestation level.
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Variability in abundance of the rosy apple aphid (Dysaphis plantaginea), the role of its alternate host (Plantago major), and potential control strategies in organic apple orchards in British ColumbiaBrown, Amanda Erica 05 1900 (has links)
The rosy apple aphid, Dysaphis plantaginea, (Homoptera: Aphididae) is a serious pest of apples in British Columbia (BC), Canada and especially in organic orchards where conventional controls cannot be used. The goals of this study were to determine the environmental or management factors of an orchard that lead to high aphid populations, to conduct an economic assessment of the damage, to determine the timing of autumn migration, and to test several autumn and spring chemical control methods and two novel autumn mechanical control methods targeting the aphids while on their alternate host, Plantago major.
To explain the variation among orchards, I evaluated several potential correlates of aphid density: abundance of the alternate host (plantain, Plantago major), foliar tree nitrogen, tree age, tree planting density, and the application of an oil treatment in spring. Stepwise regression indicated that foliar nitrogen and tree age explain 27% of the variation. Orchards receiving a spring oil application had a 53% lower average aphid infestation level. Plantain abundance was not related to aphid population on apple. However, experimental manipulation of leaf angle from the ground and size showed that significantly more alate and apterous aphids occurred on large, low angle leaves. Mowing prior to spring aphid migration was associated with 75% fewer alatae and apterae on the plantain.
The loss in harvest resulting from aphid damage ranged from 3% to 76% of the crop. Effective autumn control depends on accurate timing of aphid flight. The peak of female flight occurred on the 27th of September, 2007 at 11:56 hours daylength (sunrise to sunset) and the peak of male flight occurred on the12th of October, 2007 at 11:02 hours daylength. Aphid densities in the spring of 2008 were very low, making comparisons between treatments and controls difficult. Autumn applications of Superior dormant oil and kaolin clay were not effective. The PureSpray Green treatments of two October applications and one April application showed a significant reduction in rosy apple aphid infested clusters compared with the untreated control. Mowing and rotavating did not result in a significant reduction in aphid infestation level.
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Variability in abundance of the rosy apple aphid (Dysaphis plantaginea), the role of its alternate host (Plantago major), and potential control strategies in organic apple orchards in British ColumbiaBrown, Amanda Erica 05 1900 (has links)
The rosy apple aphid, Dysaphis plantaginea, (Homoptera: Aphididae) is a serious pest of apples in British Columbia (BC), Canada and especially in organic orchards where conventional controls cannot be used. The goals of this study were to determine the environmental or management factors of an orchard that lead to high aphid populations, to conduct an economic assessment of the damage, to determine the timing of autumn migration, and to test several autumn and spring chemical control methods and two novel autumn mechanical control methods targeting the aphids while on their alternate host, Plantago major.
To explain the variation among orchards, I evaluated several potential correlates of aphid density: abundance of the alternate host (plantain, Plantago major), foliar tree nitrogen, tree age, tree planting density, and the application of an oil treatment in spring. Stepwise regression indicated that foliar nitrogen and tree age explain 27% of the variation. Orchards receiving a spring oil application had a 53% lower average aphid infestation level. Plantain abundance was not related to aphid population on apple. However, experimental manipulation of leaf angle from the ground and size showed that significantly more alate and apterous aphids occurred on large, low angle leaves. Mowing prior to spring aphid migration was associated with 75% fewer alatae and apterae on the plantain.
The loss in harvest resulting from aphid damage ranged from 3% to 76% of the crop. Effective autumn control depends on accurate timing of aphid flight. The peak of female flight occurred on the 27th of September, 2007 at 11:56 hours daylength (sunrise to sunset) and the peak of male flight occurred on the12th of October, 2007 at 11:02 hours daylength. Aphid densities in the spring of 2008 were very low, making comparisons between treatments and controls difficult. Autumn applications of Superior dormant oil and kaolin clay were not effective. The PureSpray Green treatments of two October applications and one April application showed a significant reduction in rosy apple aphid infested clusters compared with the untreated control. Mowing and rotavating did not result in a significant reduction in aphid infestation level. / Land and Food Systems, Faculty of / Graduate
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