Chemical Herbicides and Forestation

1970 ◽  
Vol 46 (6) ◽  
pp. 458-465 ◽  
Author(s):  
R. F. Sutton
Keyword(s):  
Weed Control ◽  
Large Scale ◽  
Control Measures ◽  
Effective Control ◽  
Plantation Establishment ◽  
Weed Growth ◽  
Weeds Control ◽  
Mammalian Toxicity

Weeds commonly impair the growth of forest crop trees. Control measures rely increasingly on herbicides, large-scale use of which dates from the development of chlorophenoxyacetic herbicides in the 1940's. Weed control is not to kill weeds but to divert growth resources into crop trees. The herbicide tool becomes increasingly powerful and versatile because of new herbicides and new ways of using them. Of the organic herbicides, only phenols have high mammalian toxicity. It is highly improbable that problems could arise from use of herbicides in normal forestry operations. Herbicides make available to crop trees nutrients that would otherwise be taken up by weeds and those that are released by killed weeds. Control measures are especially important during plantation establishment. Grasses and herbs, and woody weeds are the main types of weed growth. Effective control measures may be devised for almost any situation.

scholarly journals Response of Soil Applied Herbicides at Different Application Timings on The Weed Control Efficacy and Phytotoxicity to Rice In Dry-seeded Condition

2020 ◽  
Vol 22 (1) ◽  
pp. 15-25
Author(s):  
Sharif Ahmed ◽  
Akbar Hossain ◽  
Abu Abdullah Miajy ◽  
Tahir H Awan
Keyword(s):  
Weed Control ◽  
Rice Plant ◽  
Plant Density ◽  
Control Measure ◽  
Effective Control ◽  
Application Time ◽  
Control Efficacy ◽  
Time Of Application ◽  
Significant Difference ◽  
Weeds Control

Dry-seeded rice (DSR) is a labor and water saving emerging production system. The use of pre-emergence herbicides was found to be the most effective weeds control measure under the DSR system. Although several herbicides are now available in market, the selection of right herbicides with a time of application is crucial for effective control of weeds as well as to reduce the phyto toxicity of crops. A field study in a split-plot design with three replications was conducted  to evaluate the effect of application time of soil applied herbicides (viz., 3 times - before crop sowing, after crop sowing but before the first irrigation, and after sowing and first irrigation) and four weeding regimes (viz., weed free, partial-weedy, herbicide oxadiargyl 80 g ai ha-1, and pendimethalin 1000 g ai ha-1) on weed control efficacy, crop performance as well as phytotoxicity of applied herbicides under DSR system. Rice plant stand establishment was highly influenced by application time of herbicides and weeding regimes. Application of pendimethalin at 1000 g ai ha-1 significantly reduced the density of rice plant, more so as sowing was advanced. Compared with the non-treated (partial-weedy) treatment (190 to 195 rice plants m-2), pendimethalin application before sowing, after sowing but before irrigation, and after sowing and irrigation reduced rice plant density by 48, 25 and 12%, respectively. While no significant difference was observed on plant density due to the application of oxadiargyl 80 g ai ha-1, regardless of application time. In case of weed control efficacy for individual herbicides, pendimethalin effectively controlled weeds even spraying before sowing and irrigation; but comparatively less effective than spraying after irrigation. In controlling weeds, oxadiargyl was only effective when spraying after sowing and irrigation, but not before irrigation. Grain yield was significantly increased as the time of herbicide was delayed from before sowing (2.2-2.4 t ha-1), after sowing but before irrigation (2.5-2.6 t ha-1), and after sowing and irrigation (4.0-4.1 tha-1). The results suggest that pre-emergence herbicides should be applied after sowing and irrigation for controlling weeds effectively and also reduce crop toxicity under the DSR system. Bangladesh Agron. J. 2019, 22(1): 15-25

Machine thinning of sugar beet: field trials with chemical and mechanical weed control

1966 ◽  
Vol 66 (2) ◽  
pp. 189-195 ◽  
Author(s):  
L. F. Hanbury ◽  
G. L. Maughan
Keyword(s):  
Sugar Beet ◽  
Weed Control ◽  
Large Scale ◽  
Field Trials ◽  
Control Measures ◽  
Potential Yield ◽  
Mechanical Methods ◽  
Large Scale Field ◽  
Commercial Yield ◽  
Mechanical Weed Control

Large-scale field trials in sugar beet were undertaken between 1961 and 1963 to examine the effects of chemical or mechanical weed control followed by machine thinning in terms of labour economy and yield of the crop. The seedling populations were left untrimmed by hand and, where the weed-control measures were completely effective or nearly so, the crops were left unweeded. Yield samples were taken both by hand and by machine so that the potential yield as well as the likely commercial yield might be determined. The chemical and mechanical methods that were studied saved about 75% of the normal labour demand and gave root yields 91.5% of those following hand work.

scholarly journals Vermicomposting of aquatic weeds: A quick review

2017 ◽  
Vol 4 (3) ◽  
pp. 133-136 ◽  
Author(s):  
Ishtiyaq Ahmed Najar
Keyword(s):  
Large Scale ◽  
Anthropogenic Activities ◽  
Effective Control ◽  
Growth Media ◽  
Aquatic Weed ◽  
Aquatic Weeds ◽  
Earthworm Species ◽  
Weed Growth ◽  
Wide Range ◽  
Rich Material

Aquatic plants play an important role in ecosystem functioning and services but they can also be deleterious if present in excess. The different anthropogenic activities result in accumulation of nutrients in aquatic ecosystems leads to eutrophication with massive weed growth and associated diverse adverse effects. Effective control/management of weeds in different aquatic systems is not only difficult but of short duration. The commonly used methods to manage/control the aquatic weeds are biological, chemical and mechanical, in addition to habitat manipulation. However, these methods can be highly disruptive causing adverse environmental effects and are relatively inefficient. On the other hand different species of earthworms can feed on wide range of weeds and convert them into stable product called vermicompost, rich in plant nutrients. Among different aquatic weeds the most extensively vermicomposted weed is water hyacinth (Eichhornia crassipes (Mart.) Solms), using different earthworm species. Among different earthworm species used for vermicomposting of aquatic weeds, Eisenia fetida (Savigny) is the most commonly used species. Vermicomposting is an efficient ecobiotechnological process that converts the aquatic weeds into nutrient rich material that can acts as suitable plant growth media for sustainable agroecosystems. Further large scale utilization of aquatic weed based vermicompost in horticulture can solve their management and disposal issues along with restoration of organic matter and nutrient depletion at low input basis.

scholarly journals Ecosystem services provision by gully control. A review

2019 ◽  
Vol 45 (1) ◽  
pp. 333 ◽  
Author(s):  
A. Romero-Díaz ◽  
E. Díaz-Pereira ◽  
J. De Vente
Keyword(s):  
Ecosystem Services ◽  
Water Conservation ◽  
Large Scale ◽  
Cost Benefit ◽  
Control Measures ◽  
Effective Control ◽  
Cost Benefit Ratio ◽  
Cultural Ecological ◽  
The Cost ◽  
Gully Control

Gully erosion causes severe damage to crops and infrastructures and affects the provision of ecosystem services worldwide. To assess the potential of gully control measures to protect ecosystem services and assess the conditions required for their large-scale implementation, this paper critically evaluates a range of gully control measures documented in the World Overview of Conservation Approaches and Technologies (WOCAT). Environmental and socio-economic impacts of technologies are assessed, as well as the implications for ecosystem services, costs and benefits of implementation, and stakeholder’s perception. It is demonstrated how gully control measures provide notable on-site and off-site benefits for socio-economic, cultural, ecological, and production goals, and to protect crucial ecosystem services. Control measures particularly contribute to soil and water conservation and to regulating ecosystem services by controlling soil erosion, water cycling, and natural hazards. Most effective control measures consist of combined vegetative and structural measures and of catchment wide interventions. While implementation of gully control can initially be expensive, on the long term, the cost-benefit ratio is usually positive. Moreover, the results emphasize the importance of evaluating control measures considering monetary aspects and all ecosystem services they provide. Nevertheless, individual farmers can often not afford the implementation and maintenance costs due to barriers for implementation and therefore require sustained institutional support. 

scholarly journals Control of a Nosocomial Outbreak of COVID-19 in a University Hospital

2020 ◽  
Vol 7 (12) ◽  
Author(s):  
Sei Harada ◽  
Shunsuke Uno ◽  
Takayuki Ando ◽  
Miho Iida ◽  
Yaoko Takano ◽  
...  
Keyword(s):  
High Risk ◽  
Large Scale ◽  
Secondary Infection ◽  
Control Measures ◽  
University Hospital ◽  
Contact Tracing ◽  
Effective Control ◽  
Primary Case ◽  
Pcr Screening ◽  
Social Distancing

Abstract Background Nosocomial spread of coronavirus disease 2019 (COVID-19) causes clusters of infection among high-risk individuals. Controlling this spread is critical to reducing COVID-19 morbidity and mortality. We describe an outbreak of COVID-19 in Keio University Hospital, Japan, and its control and propose effective control measures. Methods When an outbreak was suspected, immediate isolation and thorough polymerase chain reaction (PCR) testing of patients and health care workers (HCWs) using an in-house system, together with extensive contact tracing and social distancing measures, were conducted. Nosocomial infections (NIs) were defined as having an onset or positive test after the fifth day of admission for patients and having high-risk contacts in our hospital for HCWs. We performed descriptive analyses for this outbreak. Results Between March 24 and April 24, 2020, 27 of 562 tested patients were confirmed positive, of whom 5 (18.5%) were suspected as NIs. For HCWs, 52 of 697 tested positive, and 40 (76.9%) were considered NIs. Among transmissions, 95.5% were suspected of having occurred during the asymptomatic period. Large-scale isolation and testing at the first sign of outbreak terminated NIs. The number of secondary cases directly generated by a single primary case found before March 31 was 1.74, compared with 0 after April 1. Only 4 of 28 primary cases generated definite secondary infection; these were all asymptomatic. Conclusions Viral shedding from asymptomatic cases played a major role in NIs. PCR screening of asymptomatic individuals helped clarify the pattern of spread. Immediate large-scale isolation, contact tracing, and social distancing measures were essential to containing outbreaks.

scholarly journals Summer weed species incidence in Western Australia varies between seasons

Weed Science ◽  
2019 ◽  
Vol 67 (05) ◽  
pp. 589-594
Author(s):  
Catherine Borger ◽  
Abul Hashem ◽  
Mario D’Antuono
Keyword(s):  
Weed Control ◽  
Common Species ◽  
Control Measures ◽  
Future Research ◽  
Individual Species ◽  
Agricultural Fields ◽  
Raphanus Raphanistrum ◽  
Weed Species ◽  
Species Incidence ◽  
Weeds Control

AbstractAgronomic surveys of summer weed species are necessary to identify future research directions for optimal weed control, but usually focus on agricultural fields in a single season. To survey all species in the absence of weed control measures and determine species variability between seasons, a survey of 133 sites was conducted on roadsides adjoining agricultural fields throughout the Western Australian grainbelt in early 2015 and repeated in 2016 and 2017. The survey identified 144 species, but only 19 species were evident at more than 10% of sites. The most common species were weeping lovegrass [Eragrostis curvula (Schrad.) Nees], fleabane (Erigeron sp.), windmillgrass (Chloris truncata R. Br.), and wild radish (Raphanus raphanistrum L). The survey highlighted that weed species incidence varied between years. For example, C. truncata incidence was 30% in 2015 and 55% in 2016, while stinkgrass [Eragrostis cilianensis (All.) Vignolo ex Janch.] ranged from 20% in 2015 to 50% of sites in 2017. Conversely, density of individual species on the roadside was usually low, and density remained consistent between years. The survey highlighted multiple weed species that will require further research to optimize management programs. Raphanus raphanistrum and wild oat (Avena fatua L.) in particular are an issue for growers, as these species are highly detrimental winter weeds, and the survey demonstrates that they can also be common summer weeds. Control of these species with nonselective herbicides in summer as well as winter is likely to exacerbate the development of herbicide resistance.

scholarly journals A Comparison of the Characteristics of Planar and Axisymmetric Bluff-Body Combustors Operated under Stratified Inlet Mixture Conditions

2013 ◽  
Vol 2013 ◽  
pp. 1-15
Author(s):  
G. Paterakis ◽  
K. Souflas ◽  
E. Dogkas ◽  
P. Koutmos
Keyword(s):  
Large Scale ◽  
Cross Correlation ◽  
Bluff Body ◽  
Fuel Injection ◽  
Cross Flow ◽  
Flame Stabilization ◽  
Control Measures ◽  
Effective Control ◽  
Large Eddy ◽  
Flame Region

The work presents comparisons of the flame stabilization characteristics of axisymmetric disk and 2D slender bluff-body burner configurations, operating with inlet mixture stratification, under ultralean conditions. A double cavity propane air premixer formed along three concentric disks, supplied with a radial equivalence ratio gradient the afterbody disk recirculation, where the first flame configuration is stabilized. Planar fuel injection along the center plane of theleading faceof a slender square cylinder against the approach cross-flow results in a stratified flame configuration stabilized alongside the wake formation region in the second setup. Measurements of velocities, temperatures,OH∗andCH∗chemiluminescence, local extinction criteria, and large-eddy simulations are employed to examine a range of ultralean and close to extinction flame conditions. The variations of the reacting front disposition within these diverse reacting wake topologies, the effect of the successive suppression of heat release on the near flame region characteristics, and the reemergence of large-scale vortical activity on approach to lean blowoff (LBO) are investigated. The cross-correlation of the performance of these two popular flame holders that are at the opposite ends of current applications might offer helpful insights into more effective control measures for expanding the operational margin of a wider range of stabilization configurations.

scholarly journals The chemical control of weeds on sugar-cane estates of Java.

1960 ◽  
Vol 8 (1) ◽  
pp. 34-38
Author(s):  
J. Ruinard
Keyword(s):  
Adverse Effect ◽  
Weed Control ◽  
Ammonium Salt ◽  
Sugar Cane ◽  
Chemical Control ◽  
Large Scale ◽  
Harmful Effect ◽  
Surface Application ◽  
Weed Growth

The application of herbicides after the planting furrows had been made but immediately before planting did not give satisfactory weed control and had a harmful effect on the cane. The most satisfactory weed control was obtained by a surface application, immediately before furrowing, of a mixture of 20 kg. TCA and 2 kg. of the ammonium salt of 2, 4-D per ha. This treatment prevented weed growth for up to 8 weeks and had no adverse effect on cane growth. It is recommended that the cane should be planted as soon as possible after treatment. A machine designed for the large-scale application of herbicides is described. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Control of apple of Peru (Nicandra physalodes) in maize on the Atherton Tableland, Queensland

1976 ◽  
Vol 16 (82) ◽  
pp. 765 ◽  
Author(s):  
D Hawton
Keyword(s):  
Weed Control ◽  
Residual Life ◽  
Control Measures ◽  
Split Application ◽  
Competitive Effects ◽  
Late Season ◽  
Weed Growth ◽  
Wet Weather ◽  
Effect On Yield ◽  
Nicandra Physalodes

On the Atherton Tableland, Queensland, apple of Peru (Nicandra physalodes) is a problem weed in maize. The competitive effects of N, physalodes, the effectiveness of various control measures and the residual life of atrazine (2-chloro-6-ethylamino-4-isopropylamino-I ,3,5-triazine) were investigated in three experiments each repeated over two seasons. In 1973 (a late season) populations of N. physalodes as low as 4.7 m-2 reduced yields by about 35 per cent and would have caused harvester impedance in a commercial situation. In 1973-74 (an early season) N. physalodes had less effect on yield but would still have impeded harvesting. In 1973 atrazine used pre-emergence at 2.24 kg a.i. ha-1 was sufficient for satisfactory weed control. During 1973-74 when weed growth was prolonged after crop ripening by wet weather a split application of atrazine applied at 1 .12 kg a.i, ha-1 pre-emergence followed six weeks later by a further 1.12 kg a.i. ha-1 was better in controlling weeds at harvest than the single pre-emergence application. Under the conditions of these experiments atrazine used at the above rates did not cause damage to oats planted immediately after the maize harvest.

scholarly journals Selectivity of chemical weed control systems in conventional cotton

2014 ◽  
Vol 32 (4) ◽  
pp. 827-841 ◽  
Author(s):  
J.G.Z. Arantes ◽  
J. Constantin ◽  
R.S. Oliveira Jr. ◽  
G.B.P. Braz ◽  
C.A.S. Barbosa ◽  
...  
Keyword(s):  
Control Systems ◽  
Weed Control ◽  
Crop Yield ◽  
Large Scale ◽  
Block Design ◽  
Control Measures ◽  
Herbicide Application ◽  
Randomized Block Design ◽  
Crop Cycle ◽  
Over The Top

Cotton is highly susceptible to the interference imposed by weed community, being therefore essential to adopt control measures ensuring the crop yield. Herbicides are the primary method of weed control in large-scale areas of production, and usually more than one herbicide application is necessary due to the extensive crop cycle. This study aimed to evaluate the selectivity of different chemical weed control systems for conventional cotton. The experiment took place in the field in a randomized block design, with twenty nine treatments and four replications in a split plot layout (adjacent double check). Results showed that triple mixtures in pre-emergence increased the chance of observing reductions in the cotton yield. To avoid reductions in crop yield, users should proceed to a maximum mixture of two herbicides in pre-emergence, followed by S-metolachlor over the top, followed by one post-emergence mixture application of pyrithiobac-sodium + trifloxysulfuron-sodium.

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