Long-term effects of 2,4-D application on plants. II. Herbicide avoidance by Chenopodium album and Thlaspi arvense

1988 ◽  
Vol 66 (2) ◽  
pp. 230-235 ◽  
Author(s):  
Larry Hume
Keyword(s):  
Life Cycle ◽  
Chenopodium Album ◽  
Herbicide Tolerance ◽  
Long Term Effects ◽  
Annual Life Cycle ◽  
Thlaspi Arvense ◽  
Immature Seeds ◽  
Winter Annual ◽  
Dichlorophenoxy Acetic Acid

Research plots in a wheat–wheat–fallow rotation at Indian Head, Sask., were sprayed annually with 2,4-dichlorophenoxy-acetic acid (2,4-D) for 36 consecutive years. Two species susceptible to 2,4-D, Chenopodium album L. and Thlaspi arvense L., were dominant in these plots. From 1981 to 1983, C. album and T. arvense seedlings that emerged during four periods of the growing season were marked and their mortality, seed production, and size recorded. From these data and other studies, 10 ways in which C. album and T. arvense managed to survive herbicide application were identified. These are intermittent germination, herbicide tolerance, small size of late-emerging seedlings, short life cycle, hardiness, failure of control practices, long-term dormancy, seed dispersal, viability of immature seeds, and winter annual life cycle of T. arvense.

Long-term effects of 2, 4-D application on plants. I. Effects on the weed community in a wheat crop

1987 ◽  
Vol 65 (12) ◽  
pp. 2530-2536 ◽  
Author(s):  
Larry Hume
Keyword(s):  
Chenopodium Album ◽  
Dry Weight ◽  
Abundant Species ◽  
Species Group ◽  
Wheat Crop ◽  
Long Term Effects ◽  
Thlaspi Arvense ◽  
Tolerant Species ◽  
The Difference

At Indian Head, Saskatchewan, there are plots that have been sprayed annually with 2,4-D for 36 years, since 1947. Herbicide application rates since 1969 in two sets of plots were 0.42 and 1.12 kg/ha, along with control plots with no application. The crop was wheat in a 3-year wheat – wheat – fallow rotation. The plots were monitored throughout the growing season in 1982 and 1983. The 14 most abundant species on these plots were grouped as susceptible, moderately tolerant, or highly tolerant to 2,4-D. These three groups differed significantly from each other with respect to the number of emerging seedlings during four separate time periods, survival to crop harvest, plant dry weight, and seed production. In all treatments, plant number and size decreased with emergence date, with only a few small plants emerging late in the season. Over the long term, 2,4-D use significantly reduced the number of plants of susceptible species, but it did not eliminate them. Reduced numbers of susceptible plants enabled the number of plants of highly tolerant species to increase. Even in plots treated with high rates of 2,4-D, plants of the susceptible species, Chenopodium album L. and Thlaspi arvense L., were still as abundant as those of any other species group. The overall effect of 2,4-D application was to reduce the difference in performance of susceptible and tolerant species, resulting in changes in quantitative aspects of community structure. No new major species has become established since 1947 as a result of 2,4-D application.

Long-Term Effects on Vegetation of Herbicide Treatments in Chaparral

Weed Science ◽  
1985 ◽  
Vol 33 (3) ◽  
pp. 353-357
Author(s):  
Jodie S. Holt ◽  
Steven R. Radosevich ◽  
Walter L. Graves
Keyword(s):  
Acetic Acid ◽  
Canopy Cover ◽  
Field Studies ◽  
San Diego County ◽  
Long Term Effects ◽  
Adenostoma Fasciculatum ◽  
Herbicide Treatments ◽  
Herbicide Effects ◽  
Dichlorophenoxy Acetic Acid

Field studies were established in 1974 and 1975 at various locations in San Diego County, CA, to evaluate several herbicides for the control of chamise (Adenostoma fasciculatumH.&A.) and redshank chamise (Adenostoma sparsifoliumTorr.). Herbicide effects on vegetation were reevaluated in 1982. Plots originally treated with 2.2 or 4.5 kg ae/ha of glyphosate [N-(phosphonomethyl)glycine] had virtually no chamise regrowth 8 yr after treatment. The herbicides 2,4-D [(2,4-dichlorophenoxy)acetic acid], combinations of 2,4-D with 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] or dichlorprop [2-(2,4-dichlorophenoxy) propionic acid], fosamine [ethyl hydrogen (aminocarbonyl)phosphonate], triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}, tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea}, and picloram (4-amino-3,5,6-trichloropicolinic acid) had no long-term effects on chamise. Soil collected in 1982 from glyphosate-treated plots contained similar numbers of chamise seeds but fewer seeds of other species compared to untreated plots. Canopy cover of redshank chamise was similar in treated and untreated plots after 8 yr. These results document the effectiveness of glyphosate in killing the underground root-crown of chamise, which prevented sprouting, but not redshank chamise.

Electoral Competitiveness and Turnout in British Elections, 1964–2010

2015 ◽  
Vol 5 (4) ◽  
pp. 775-794 ◽  
Author(s):  
Jack Vowles ◽  
Gabriel Katz ◽  
Daniel Stevens
Keyword(s):  
Life Cycle ◽  
Voting Behavior ◽  
Multilevel Models ◽  
Election Study ◽  
Long Term Effects ◽  
Specific Effects ◽  
Competitive Environments ◽  
Voting Age ◽  
Short And Long Term

Analyzing the British Election Study from 1964 to 2010, we examine the influence of electoral context on turnout, focusing on the closeness of elections in terms of lagged seat and constituency-level winning margins. Using cross-classified multilevel models to account for individual and contextual factors and disentangle life cycle, cohort- and election-specific effects, we find that closeness strongly affects voting behavior, particularly among new electors. Widening seat margins in British elections over the last decades have had a persistent impact on turnout. Respondents who faced less competitive environments when young are more likely to abstain in subsequent elections than those reaching voting age after close-fought races. We conclude that variations in competitiveness have had both short- and long-term effects on turnout.

Effects of Structural Deterioration and Infrastructure Upgrading on the Life-cycle Seismic Resilience of Bridge Networks

2018 ◽  
Author(s):  
Luca Capacci ◽  
Fabio Biondini
Keyword(s):  
Life Cycle ◽  
Network Connectivity ◽  
Long Term Effects ◽  
Road Transportation ◽  
Earthquake Scenarios ◽  
Structural Deterioration ◽  
Highway Network ◽  
Infrastructure Investments ◽  
Seismic Resilience

<p>The life-cycle seismic resilience of aging bridges and road transportation networks is investigated considering the long-term effects of bridge structural deterioration and network upgrading interventions under uncertainty. The proposed methodology is applied to a highway network with spatially distributed reinforced concrete (RC) bridges exposed to chloride-induced corrosion and different earthquake scenarios. A new road segment including a bridge is added over the lifetime to strengthen the network connectivity and improve the system resilience. The results show the detrimental effects of structural deterioration at the network scale and the benefits of infrastructure investments for network upgrading to enable long-term resilient infrastructures.</p>

scholarly journals The long-term effects of in-work benefits in a life-cycle model for policy evaluation

2011 ◽  
Author(s):  
Monica Costa Dias ◽  
Jonathan Shaw ◽  
Costas Meghir ◽  
Richard Blundell
Keyword(s):  
Life Cycle ◽  
Policy Evaluation ◽  
Life Cycle Model ◽  
Long Term Effects ◽  
Cycle Model

Ovarian Dysfunction in Fetally Irradiated Beagles

1977 ◽  
Vol 35 ◽  
pp. 658-659
Author(s):  
T. M. Seed ◽  
M. H. Sanderson ◽  
D. L. Gutzeit ◽  
T. E. Fritz ◽  
D. V. Tolle ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Low Dose ◽  
Long Term Effects ◽  
Ovarian Dysfunction ◽  
Dose Rates ◽  
Highly Sensitive ◽  
Microscopic Evaluation ◽  
Ovarian Pathology ◽  
Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

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