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Biological control of spider mites (Acari: Tetranychidae) on grape emphasizing regional aspectsPrischmann, Deirdre A. 06 July 2000 (has links)
During summer of 1998 and 1999, 34 and 10 vineyard sites, respectively, were sampled to assess spider mite pests and associated biological control by phytoseiid mites. Vineyards studied spanned five major valleys in western Oregon where grape production occurs. Leaf samples were taken from site perimeters and centers. One leaf was taken every ten meters of border length, five meters inward from the border to prevent wind-biased or extreme edge effects, while 20 leaves were taken at regular intervals from centers. Variables recorded at each site were: plant age, grape variety, chemical spray information and local vegetation occurring in proximity to vineyards. Sites were categorized as either agricultural or riparian based on what surrounding vegetation type was in the majority. Several parametric and non-parametric tests were used to analyze data, including multiple linear regressions using a computer-based genetic algorithm in conjunction with the AIC criterion to pre-select a subset of explanatory variables.
Typhlodromus pyri was the predominant phytoseiid mite and Tetranychus urticae was the most abundant tetranychid mite sampled. High levels of T. urticae were found when predator densities were very low, and low levels of T. urticae occurred when predator densities were moderate or high. Phytoseiid densities were highest in June and July, while T. urticae densities were highest from August to September. The latter's densities were significantly higher in vineyards surrounded primarily by agriculture, while phytoseiid densities were not significantly different between the two categories. Predatory phytoseiids had significantly higher densities on vineyard edges, while T. urticae densities were higher in vineyard centers. Caneberry, cherry and grape habitats appeared to be sources of predator immigration, while no vegetation type consistently served as a short-range or nearby immigration source for spider mites. Due to insufficient data, pesticide information was not included in multiple linear regression models, although certain chemicals used in vineyards can potentially impact mite populations. Impacts of surrounding vegetation type, grape variety, regional location, plant age, and presence of other mites on phytoseiid and T. urticae densities are discussed. / Graduation date: 2001
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Is everything connected? following the predators, pests, and plants within a no-till, western Montana agroecosystem /Smith, Ethan A. January 2006 (has links)
Thesis (M.S.)--University of Montana, 2006. / Mode of access: Internet. Title from title screen. Description based on contents viewed Feb. 8, 2007. Includes bibliographical references (p. 63-72).
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Ecology of the predatory mite, Pergamasus quisquiliarum Canestrini (Acari: Mesostigmata)Groth, Eric M. 25 September 1997 (has links)
Pergamasus quisquiliarum Canestini is a polyphagous predatory mite that has been shown to feed on the economically important arthropod, Scutigerella immaculata Newport (Symphyla: Scutigerellidae), Collembola, Diptera larvae, Enchytraeid worms, and miscellaneous other soil organisms. This study examined the feeding behavior of P. quisquiliarum, the effects of cover cropping and tillage practices on P. quisquiliarum populations, the biology and ecology of P. quisquiliarum in agricultural and non-agricultural sites, and the seasonal dynamics of P. quisquiliarum. The interaction of cover crop and tillage treatment was statistically significant for P. quisquiliarum populations (P<0.001). Tillage treatment was the primary factor for P. quisquiliarum populations, as very low densities of P. quisquiliarum were recovered from green manure plots, regardless of the cover crop treatment. Among no-till plots, Monida oats had the greatest densities of P. quisquiliarum, while control (fallow) and white mustard plots had the lowest densities. The two non-agricultural sites had higher densities of P. quisquiliarum than the agricultural site. Among the non-agricultural sites, P. quisquiliarum density was higher in Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) litter than in Oregon white
oak litter (Quercus garryana Dougl.), suggesting that the nature of the chemical and physical micro-environment was more suitable under Douglas-fir trees. In all sites, P. quisquiliarum attained it's greatest density in August, with a second peak in October. Minimum P. quisquiliarum densities were observed in January and February. Seasonal P. quisquiliarum densities were significantly synchronized with seasonal dynamics of it's prey items. / Graduation date: 1998
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Evaluation of the potential use of antagonistic microbes on grass species, turf and pasture, for disease control and growth stimulation.Cunningham, Debra M. January 2003 (has links)
Public tendency, of late, is to reduce liberal use of harmful synthesized chemicals for
promoting plant health. Today, biological control is becoming a commonly cited disease
control option. Biological control agents (BCAs) not only control disease , but also
promote plant growth. Application of biological control is based largely on knowledge of
control mechanisms employed by antagonists, as well as the means of application that
will ensure that an antagonistic population is established. Knowing the advantages is not
the only factor that should be considered before application commences as, the
disadvantages must be clearly outlined and explored further before a constructive
decision as on implementation of biological control. A literature review was undertaken
to provide the necessary technical information about biological control, its potential uses,
methods of application, mechanisms of action employed, advantages and disadvantages
associated with biological control application, public perceptions and the potential future
of biological control.
Diseases encountered within the KwaZulu-Natal Midlands on pasture and turf grasses
were determined by a once-off survey conducted over 1999/2000. The aim of the survey
was to determine broadly the management practices of farmers and groundsmen in
KwaZulu-Natal and the potential impact of these on the occurrence of weeds, insects and
diseases. The survey also addressed the level of existing knowledge about biological
control and willingness to apply such measures. In the pasture survey, farmers were
questioned about: soil type, grass species common used, irrigation , fertilization and
liming, grazing programs and weed, insect and disease occurrences and control
measures implemented. The same aspects were addressed in a survey to a
representative sample of groundsmen (turfgrass production) , including also: topdressing,
greens base used, drainage systems, mowing practices and decompaction principles.
The survey showed correlation between pest incidence and management practices
implemented. In terms of pest control, both farmers and groundsmen indicated a stronger
preference to the use of herbicides , insecticides and fungicides. Use of fungicides for
disease control by farmers is considered an often unfeasible expense, rather more
emphasis was placed on implementing cultural control methods. At present farmers do
not apply biological control strategies, but they did indicate much interest in the topic.
Alternatives to current, or lack of current, disease management strategies are important
considerations, with two new diseases identified in the KwaZulu-Natal Midlands just
within the period of this thesis. Biological control strategies are implemented by 8% of the
groundsmen surveyed, with emphasis being placed on augmenting the already present
natural predators rather than the introduction of microbial antagonists.
Although often mis-diagnosed by farmers Helminthosporium leaf spot is a common
disease in the KwaZulu-Natal Midlands on Pennisetum clandestinum (kikuyu), This
disease reduces pasture quality and detracts from the aesthetic appearance and
wearability of turfgrasses. Helminthosporium leaf spot is incited by a complex of causal
agents , Bipolaris was confirmed as the casual agent of Helminthosporium leaf spot on
kikuyu at Cedara. Disease control by two BCAs, Bacillus (B. subtilis Ehrenberg & Cohn.)
and Trichoderma (T. harzianum Rifai), as commercial formulations was tested against
the fungicide, PUNCH EXTRA®. In vitro, Trichoderma was shown to be aggressive in
controlling Bipolaris sp. In vivo, disease control achieved with Trichoderma kd was
comparative with PUNCH XTRA® but not statistically different (P>=0.05). Trichoderma and
Bacillus provided better disease control in comparison to an untreated control.
Improved growth of Lolium sp. was determined in vitro, with Trichoderma kd and Bacillus
B69 treatments. The microbe-based treatments accounted for growth stimulation, with
significant (P<=O.05) growth differences noted. A microbial activator, MICROBOOST®was
added to the treatments to improve microbial efficiency. Improved plant growth with
MICROBOOST® applications was shown.
Improved growth associated with microbial treatments, Trichoderma harzianum kd;
Bacillus subtilis B69 and Gliocladium virens Miller, Gibens, Foster and con Arx. ,was also
determined in vivo at Cedara, on L.perenne L., Festuca rubra L. and Agrostis stolonifera
L. Establishment of a suppressive soil with antagonistic microbes resulted in significant
(P<=O.05) effects on final grass coverage (except G. virens), as well increased root and
shoot lengths (P<=O.05). Increased germination rates, as expressed in vitro, were not
shown in vivo. Microbial activity with the application of MICROBOOST® showed little
effect on germination but increased root and shoot lengths significantly (P<=O.05).
Increased weed growth associated with the treatments (except G. virens) was considered
a drawback of the microbial-treatments.
Microbial treatments were also applied to pasture grasses. An in vitro grazing trial was
established at Cedara, using L. multiflorum L. to evaluate the microbe-based treatments
Trichoderma kd, Bacillus B69 and G. virens for improved pasture establishment and for
increased grazing preference by Dohne Merino sheep. Trichoderma kd was associated
with increased dry and wet biomass , but lower dry matter yields in comparison to the
control. Only G. virens accounted for a higher dry matter percentage than the control.
However, differences between the control and the microbial treatments was very small
and not significant (P>=0.05). Of the three grazing observations made, sheep showed no
grazing preference to plots with or without microbial treatments
In general, the body of this research has shown that microbial treatments have the
potential for increased disease control and growth stimulation of grasses. However, lack
of significant differences between microbial treatments and controls has raised the
question as to effect of external factors on microbial activity and survival, especially in
vivo. This raises the question as to the validity of the use of microbial treatments where
growth conditions cannot be controlled , remembering that the cost of establishment must
be covered by the economic returns from utilization. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.
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The interaction of two different fungi, Colletotrichum graminicola and Gloeocercospora sorghi, as a biological herbicide for the control of shattercaneRacine, Scott R. January 2007 (has links)
Greenhouse and laboratory experiments were conducted on the fungal bioherbicides Colletotrichum graminicola and Gloeocercospora sorghi on shattercane (Sorghum bicolor), to evaluate any potential interactions among and between these two plant pathogens for management of this weed. Intraspecific interactions were evaluated with back to back applications of C. gramincola or G. sorghi, and results indicate additive or no effects. Results indicate that interspecific interactions between C. graminicola and G. sorghi lower expected disease incidence when C. gramincola is applied first, while the opposite effect occurs when G. sorghi is applied first. Tank mixtures were also evaluated, and results indicate that no synergistic relationships occur when both species are applied simultaneously. When using spores in conjunction with the chemical herbicide RoundUp (a.i. glyphosate), applying spores with or before glyphosate results in decreased biomass loss, while applying glyphosate prior to spore application results in increased weed biomass loss. Data from intra- and interspecific interactions evaluated in vitro support these findings. / Department of Biology
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Stimulatory and inhibitory effects of UVA and UVB radiation on some physiological and pathogenic characteristics of fungal biocontrol agents to enhance mycoherbistat effectivenessGhajar, Feridon Ghasem Khan. January 2004 (has links)
Thesis (Ph.D.) -- University of Western Sydney, 2004. / A thesis submitted in fulfilment of requirements for the degree of Doctor of Philosophy. Includes bibliography.
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Control of the grape berry moth, Paralobesia viteana, using reduced-risk insecticides, cultural controls, and conservation of natural enemiesJenkins, Paul E. January 2006 (has links)
Thesis (M.S.)--Michigan State University. Dept. of Entomology, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references (p. 106-117). Also issued in print.
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Biotic barriers to colonizing new hosts by the cinnabar moth Tyria jacobaeae (L.) (Lepidoptera: Arctiidae) /Karac̦etin, Evrim. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.
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Evaluation of a plant-herbivore system in determining potential efficacy of a candidate biological control agent, cornops aquaticum for water hyacinth, eichhornia crassipes /Bownes, Angela. January 2008 (has links)
Thesis (Ph.D. (Zoology & Entomology)) - Rhodes University, 2009.
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Toadflax, fire, Mecinus janthinus, and compensatory growthAnthony, Antoinette. January 2005 (has links)
Professional paper (M.S.)--Montana State University--Bozeman, 2005. / Title from PDF t.p. (viewed on July 4, 2006). Chairperson, Graduate Committee: Theodore Weaver. Includes bibliographical references (leaves 54-57).
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