AN ECONOMIC EVALUATION OF CONTROL METHODS FOR DIFFUSE AND SPOTTED KNAPWEED IN WESTERN CANADA

1979 ◽  
Vol 59 (2) ◽  
pp. 375-382 ◽  
Author(s):  
P. HARRIS ◽  
R. CRANSTON
Keyword(s):  
Biological Control ◽  
British Columbia ◽  
Economic Evaluation ◽  
Cost Effective ◽  
The Other ◽  
Western Canada ◽  
Spotted Knapweed ◽  
Control Methods ◽  
Effective Solution ◽  
Introduced Weeds

Diffuse and spotted knapweed are introduced weeds that threaten to spread throughout the uncultivated drylands of Western Canada. By 1972 approximately 30 000 ha, mostly in British Columbia, were infested, with forage reductions of up to 88%. Presently the infestation may be increasing by 10% a year and it is estimated that 8.4–10.7 million ha are susceptible to invasion by one or the other species in Western Canada. This would be disastrous to both ranching and wildlife in the region. The economics of various options for control are discussed. Biological control, which is likely to require the introduction of six agents and cost a total of $1.8 million, is the most cost-effective solution. However, until it can be fully implemented (10–20 yr) new infestations can be spot-treated with picloram. It is also economic to convert dense stands to tame pasture after killing the knapweed with picloram at 0.5 kg/ha although the knapweed is likely to begin reinvasion after 4 yr.

THE BIOLOGY OF CANADIAN WEEDS.: 89. Carduus nutans L. and Carduus acanthoides L.

1988 ◽  
Vol 68 (4) ◽  
pp. 1053-1068 ◽  
Author(s):  
A. M. DESROCHERS ◽  
J. F. BAIN ◽  
S. I. WARWICK
Keyword(s):  
Biological Control ◽  
Seed Production ◽  
Germination Rate ◽  
Effective Means ◽  
Western Canada ◽  
Control Methods ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Introduced Weeds

Carduus nutans L. and C. acanthoides L. are introduced weeds, primarily of roadsides, fields and pasturelands. Both species occur in eastern and western Canada with C. nutans more common than C. acanthoides in western Canada. High seed production and germination rate on open soil contribute to the success of the species as weeds, as do the spiny leaves and stems which deter grazing by animals. Mowing or the application of hormone-like herbicides are both effective means of control. Biological control methods have also been used for both species, but have been most successful in the control of C. nutans.Key words: Musk thistle, nodding thistle, plumeless thistle, Carduus spp.

FIRST REPORT OF THE DISPERSAL INTO MONTANA OF UROPHORA QUADRIFASCIATA (DIPTERA: TEPHRITIDAE), A FLY RELEASED IN CANADA FOR BIOLOGICAL CONTROL OF SPOTTED AND DIFFUSE KNAPWEED

1985 ◽  
Vol 117 (8) ◽  
pp. 1061-1062 ◽  
Author(s):  
Jim M. Story
Keyword(s):  
Biological Control ◽  
British Columbia ◽  
The United States ◽  
Flower Head ◽  
The Other ◽  
Centaurea Maculosa ◽  
Spotted Knapweed ◽  
European Origin ◽  
Mature Flower ◽  
Diffuse Knapweed

Two tephritid flies of European origin have been introduced into North America for biological control of spotted knapweed, Centaurea maculosa Lam., and diffuse knapweed, C. diffusa Lam. One, Urophora affinis Frauenfeld, was released in British Columbia in 1970 and in 5 states, including Montana, in 1973 (Hanis 1980a; Maddox 1979; Story and Anderson 1978). The other, Urophora quadrifasciata (Meigen), was introduced at Ned's Creek, British Columbia but was not released in the United States. The larvae of both flies induce galls (1 larva/gall) in immature knapweed flower heads and thus reduce seed production. Galls of Urophora affinis occur in the flower-head receptacle whereas galls of U. quadrifasciata are in the ovary wall. In contrast with U. affinis, which has only a partial second generation, U. quadrifasciata normally has 2 complete generations per year, induces thinner galls, and attacks more-mature flower heads than does U. affinis (Harris 1980a).

General discussion

1988 ◽  
Vol 318 (1189) ◽  
pp. 375-376
Keyword(s):  
Biological Control ◽  
The Netherlands ◽  
Multidisciplinary Approach ◽  
Plant Protection ◽  
Resistance Breeding ◽  
The Other ◽  
Control Methods ◽  
Plant Virology ◽  
And Control ◽  
Research Institute

A. K. Minks ( Research Institute for Plant Protection, Wageningen, The Netherlands ). The organizers should be given much credit for arranging this meeting on biological control where attention has been given not only to entomological but also to the other disciplines of plant protection. It is my belief that a multidisciplinary approach is the only way to develop biological control methods and to implement them successfully. In our Institute we became aware of this and recently we decided to leave the classical organizational division in entomology, mycology, plant virology, etc. sections and to change to sections named: detection, ecology, genetics and resistance breeding, and control, in which entomologists, mycologists, etc. have a much better possibility to work together.

A Note on Colour Preferences of Some Homoptera and Thysanoptera in British Columbia

1962 ◽  
Vol 94 (1) ◽  
pp. 107-107 ◽  
Author(s):  
W. H. A. Wilde
Keyword(s):  
Biological Control ◽  
British Columbia ◽  
Sweet Cherry ◽  
Control Unit ◽  
The Other ◽  
Department Of Agriculture ◽  
Canada Department ◽  
Pear Trees ◽  
Colour Preferences ◽  
Cherry Trees

In pear and sweet cherry orchards near Creston, in the Kootenay Valley of British Columbia, populations of psyllids, aphids, thrips and leafhoppers were sampled by yellow, and white, sticky board traps hung in the trees. The psyllids were adult Psylla pyricola Först., caught in pear trees; the other insects were caught in cherry trees. The latter insects were: alate Myzus cerasi (F.), adults and nymphs of Taeniothrips sp., and adult leafhoppers of the following species: Edwardsiana rosae (L.), Macrosteles fascifrons (Stål), Psammotettix lividellus (Zett.), Dikraneura absenta DeL. and C., Scaphytopius acutus (Say), Osbornellus borealis DeL. and Mohr., Neokolla hieroglyphics (Say), and Erythroneura spp. Identifications were made by the Systematics and Biological Control Unit of the Canada Department of Agriculture, Ottawa.

Effect of Temperature on Fecundity and Survival of Chrysolina quadrigemina (Suffr.) and C. hyperici (Forst.) (Coleoptera: Chrysomelidae)

1962 ◽  
Vol 94 (7) ◽  
pp. 774-780 ◽  
Author(s):  
P. Harris
Keyword(s):  
Biological Control ◽  
British Columbia ◽  
Hypericum Perforatum ◽  
The Other ◽  
Effect Of Temperature ◽  
Low Density

Four colonies of Chrysolina quadrigemina (Suffr.) and two of C. hyperici (Forst.) were released in 1951 and 1952 in the souvhern interior of British Columbia (Fig. 1) in the hope of duplicating the successful biological control of Hypericum perforatum L. in California. In 1956, Smith (1958) showed that though the colonies were still present, the weed had increased in all areas. By 1960, however, C. hyperici had greatly reduced the abundance of H. perforatum at Fruitvale (Fig. 2) while at Edgewood the beetle had disappeared. A colony of C. padrigmina at Edgewood had also disappeared and the three other C. quadrigemina colonies persisted at a low density without controlling the weed. For example, at Christina Lake (Fig. 3) a few beetles were found every year since release, though they had not always appeared in the sample plots. The annual fluctuations of the weed as indicated in the figure were probably of climatic origin as they were similar to those for the other areas. The most promising of the C. quadrigemina colonies was at Fife where, though there were few beetles in the release meadow itself, they were common on the slope below.

An economic evaluation of a telehealth network in British Columbia

2007 ◽  
Vol 13 (5) ◽  
pp. 251-256 ◽  
Author(s):  
Joseph Schaafsma ◽  
Stefan V Pantazi ◽  
Jochen R Moehr ◽  
Christine R Anglin ◽  
Nicole A Grimm
Keyword(s):  
British Columbia ◽  
Economic Evaluation ◽  
Travel Time ◽  
Opportunity Cost ◽  
Operating Cost ◽  
Cost Effective ◽  
Health Care Facilities ◽  
Travel Costs ◽  
Utilization Data ◽  
The Cost

We carried out an economic evaluation of the northernmost five sites of the British Columbia telehealth network. The videoconferencing network links health-care facilities in 12 communities with Vancouver, for clinical consultations, administrative meetings and educational sessions. The economic evaluation was based on the netcost criterion (i.e. cost of telehealth minus travel costs avoided). Cost and utilization data were obtained from client interviews and log data compiled between September 2001 and January 2003. The results showed that the subnetwork of five sites was not only cost reducing, but also cost-effective. Travel costs for administrative meetings were reduced by $724,457/annum and were greater than the annual fixed and variable costs of all the telehealth sessions ($553,740). A sensitivity analysis was conducted on six parameters: amortization period, opportunity cost of capital, operating cost of a telehealth session (by type of session), number of telehealth sessions, travel time and the opportunity cost of travel time. The study suggests that the cost-effectiveness of telehealth to remote areas will increase over time as the cost of equipment continues to fall, as network connections become cheaper and as utilization rates rise.

2D Color-Intensity Representation of Ultrasonic Thickness Gauge Measurements

2020 ◽  
pp. 1192-1198
Author(s):  
M.S. Mohammad ◽  
Tibebe Tesfaye ◽  
Kim Ki-Seong
Keyword(s):  
Cost Effective ◽  
The Other ◽  
Thickness Gauge ◽  
Color Intensity ◽  
Digital Readout ◽  
Flat Surfaces ◽  
Video Cameras ◽  
Wide Range ◽  
Cost Effective Alternative ◽  
Ultrasonic Thickness

Ultrasonic thickness gauges are easy to operate and reliable, and can be used to measure a wide range of thicknesses and inspect all engineering materials. Supplementing the simple ultrasonic thickness gauges that present results in either a digital readout or as an A-scan with systems that enable correlating the measured values to their positions on the inspected surface to produce a two-dimensional (2D) thickness representation can extend their benefits and provide a cost-effective alternative to expensive advanced C-scan machines. In previous work, the authors introduced a system for the positioning and mapping of the values measured by the ultrasonic thickness gauges and flaw detectors (Tesfaye et al. 2019). The system is an alternative to the systems that use mechanical scanners, encoders, and sophisticated UT machines. It used a camera to record the probe’s movement and a projected laser grid obtained by a laser pattern generator to locate the probe on the inspected surface. In this paper, a novel system is proposed to be applied to flat surfaces, in addition to overcoming the other limitations posed due to the use of the laser projection. The proposed system uses two video cameras, one to monitor the probe’s movement on the inspected surface and the other to capture the corresponding digital readout of the thickness gauge. The acquired images of the probe’s position and thickness gauge readout are processed to plot the measured data in a 2D color-coded map. The system is meant to be simpler and more effective than the previous development.

Gemmae in Tetralophozia setiformis (Anastrophyllaceae, Marchantiophyta) and their second record in Eurasia

2017 ◽  
Vol 51 ◽  
pp. 242-250
Author(s):  
M. V. Dulin
Keyword(s):  
British Columbia ◽  
Asexual Reproduction ◽  
Leaf Shape ◽  
Leaf Size ◽  
Komi Republic ◽  
The Other ◽  
Widespread Species ◽  
Northern Urals ◽  
Sexual And Asexual Reproduction ◽  
Murmansk Region

Tetralophozia setiformis is a widespread species occurring usually without organs of sexual and asexual reproduction. Gemmae of Tetralophozia setiformis were observed for the second time in Russia and Eurasia in the Northern Urals, Komi Republic. They form compact masses over upper leaves. The compact masses consist largely (70 %) of immature gemmae. Description of gemmae and gemmiparous shoots from the Northern Urals and their comparison with those from the other known localities, namely British Columbia (Canada) and the Murmansk Region (European Russia) were carried out. The gemmiparous plants of T. setiformis from the Northern Urals have approximately the same width as plants without gemmae but they are shorter. The leaves of gemmiparous plants from the Northern Urals are similar to leaves of gemmiparous plants from British Columbia. The leaf shape in upper part of the gemmiparous shoots varies from the typical to ± modified from gemmae production. These leaf shape transitions include reduction of leaf size and lobe number from 4 to 2–3, suppression of development and disappearance of characteristic teeth at the base of sinus. Gemmae size (17 × 22 μm) of plants from the Northern Urals is within variability recorded for plants from the Murmansk Region and British Columbia.

scholarly journals The influence of two wildfires and biological control agents on the population dynamics of Melaleuca quinquenervia in a seasonally inundated wetland

2021 ◽  
Vol 14 (1) ◽  
pp. 3-8
Author(s):  
Philip W. Tipping ◽  
Melissa R. Martin ◽  
Jeremiah R. Foley ◽  
Ryan M. Pierce ◽  
Lyn A. Gettys
Keyword(s):  
Biological Control ◽  
Population Dynamics ◽  
Seedling Recruitment ◽  
Additional Treatment ◽  
Seed Rain ◽  
The Other ◽  
Melaleuca Quinquenervia ◽  
Biological Control Agents ◽  
Seedling Mortality ◽  
Sapling Growth

AbstractThe potential of Melaleuca quinquenervia (Cav.) S.T. Blake to reinvade cleared areas was evaluated over a 13-yr period that included two wildfires and the introduction of biological control agents. The first wildfire occurred in 1998 and was followed by a mean of 591.5 recruited seedlings m−2. Recruits from that fire were cleared 7 yr later in July 2005 for a second experiment to evaluate seedling recruitment into cleared areas. Seed rain, seedling recruitment and mortality, and sapling growth rates were measured in four plots located around individual large reproductive trees. A second natural wildfire in 2007 burned through those plots, leading to increases in seed rain followed by a pulse in recruitment of 21.04 seedlings m−2, 96.5% fewer than after the 1998 fire. Recruits in half of the plots around each tree were then treated with regular applications of an insecticide to restrict herbivory by biological control agents, while herbivory was not restricted in the other half. There was no difference in seedling mortality between treatments 1,083 d post-fire (2007) with 96.6% seedling mortality in the unrestricted herbivory treatment and 89.4% mortality in the restricted herbivory treatment. Recruits subjected to the restricted herbivory treatment grew taller than those in the unrestricted herbivory treatment, 101.3 cm versus 37.4 cm. Many of the recruits were attacked by the biological control agents, which slowed their growth. Although solitary M. quinquenervia trees retain some capacity to reinvade areas under specific circumstances, there was a downward trend in their overall invasiveness at this site, with progressively smaller recruitment cohorts due to biological control agents. Land managers should prioritize removing large reproductive trees over treating recently recruited populations, which can be left for many years for the biological control agents to suppress before any additional treatment would be needed.

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