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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Stress physiology and biological weed control : a case study with Canada thistle (Cirsium arvense (L.) Scop.)

Forsyth, Sheila Florence. January 1983 (has links)
The success of biological weed control programs has been limited by a lack of understanding of the stress physiology of insect damage and pathogen development. This case study with the perennial weed, Cirsium arvense, (L.) Scop. evaluated the stress of five natural enemies. Attack by a seed head predator, Orellia ruficauda (F.) caused about 21.5% predation and may reduce seed dispersal. The stress of stem gall formation (Urophora cardui (L.)) is greatest when the gall occurs on young plants and on the mainshoot and defoliation simulation (Cassida rubiginosa Muller) is most effective at high levels on young plants. In nature, however, the latter two natural enemies are not synchronized with these susceptible stages, thereby reducing their effectiveness. Although Cleonus piger Scop., a root crown inhabitant, can result in plant death, regeneration of damaged vascular tissue can occur. Plants which emerge systemically infected with Puccinia punctiformis (Str.) Rohl. (rust) rarely survive the season. A matrix model simulating the effects on Canada thistle population dynamics by the natural enemies was applied.
2

Development of a Colletotrichum dematium as a bioherbicide for the control of fireweed

Léger, Christian. January 1997 (has links)
An anthracnose-inducing pathogen, Colletotrichum dematium, was studied as a bioherbicide for Epilobium angustifolium. A comparative study involving other C. dematium isolates suggests that the isolate from E. angustifolium is a forma specialis and should be designated as Colletotrichum dematium f.sp. epilobii. The most severe damage was achieved on seedlings using a conidial density of $1 times 10 sp9$ conidia m$ sp{-2}$. Virulence decreased with plant maturity. Satisfactory levels of control were limited to long dew duration ($>$18 h) and high temperature treatments. Of various adjuvants tested, significantly higher levels of control were achieved when inoculum was sprayed in a vegetable oil emulsion (25% v/v). An inoculum buffered to acidic pH levels (pH 3.0) similarly increased level of control compared with an unbuffered conidial suspension and the adjustment to more alkaline pH levels using the citrate-phosphate buffer (pH $>$ 4.0), inhibited disease expression. In host range studies, C. dematium f.sp. epilobii was restricted to the Onagraceae family. Both Camissonia bistorta and Clarkia pulchella were susceptible whereas the fungus was highly virulent on all but one E. angustifolium ecotype. Among nine commercial tree species tested for susceptibility yellow birch (Betula alleghaniensis) was susceptible to the fungus when conidia were applied in an oil emulsion. The application of inoculum in a tank mix combination with the oil emulsion and a low rate of glyphosate provided significant growth control of E. angustifolium seedlings (7-wk-old), whereas the effectiveness of this suspension significantly decreased with plant maturity. Under controlled conditions, post-emergence application of an oil-based formulation including the ground colonized substrate of another bioherbicide candidate of E. angustifolium, Alternaria sp., significantly reduced above-ground biomass when provided a 12-h dew and applied at a rate as low as $5 times 10 sp6$ conidia m$ sp{-2}$.
3

Stress physiology and biological weed control : a case study with Canada thistle (Cirsium arvense (L.) Scop.)

Forsyth, Sheila Florence. January 1983 (has links)
No description available.
4

Development of a Colletotrichum dematium as a bioherbicide for the control of fireweed

Léger, Christian. January 1997 (has links)
No description available.
5

Effects of granular nematicides on nematode populations and corn yields

Lash, Leo Duane January 2011 (has links)
Digitized by Kansas Correctional Industries
6

Pasteuria pentrans as a biocontrol agent of Meloidogyne species and its field evaluation in Malawi

Daudi, Andrew Timothy January 1991 (has links)
No description available.
7

Field and glasshouse studies of aphids on the interaction of partial plant resistance and biological control

Gowling, G. R. January 1989 (has links)
No description available.
8

The reproductive biology and behaviour of #Leptomastidea abnormis', a hymenopterous parasitoid of the citrus mealybug #Planococcus citri'

Jackson, Alison January 1995 (has links)
No description available.
9

Studies on the physiology and biochemistry of infective juveniles of entomopathogenic steinernematid nematodes

Patel, Mavji Nanji January 1997 (has links)
No description available.
10

The chitinolytic system in Metarhizium anisopliae

Valadares, Maria Cleria Cordeiro January 1995 (has links)
No description available.

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