Effects of Different Herbicides on Weed Control in Alfalfa Field

[Objectives]The paper was to systematically study the technology of weed control in alfalfa field.[Methods]Reviving alfalfa field and newly sown alfalfa field after emergence were selected,and the effects of different herbicides on weed control and alfalfa yield were discussed.[Results]The optimal herbicides after alfalfa reviving were 5%imazethapyr and 10%imazethapyr,and the optimal dosages were 1.5 and 1.05 L/hm 2,respectively.The optimal herbicides after emergence of newly born alfalfa were 5%imazethapyr and 10%imazethapyr,and the optimal dosages were 1.5 and 0.75 L/hm 2,respectively.[Conclusions]This study will provide a technical support for high quality production of alfalfa.

A Proposed Method for Evaluating Management Feasibility When Determining Weed Control Priorities after Major Fires and Floods

Major fires and floods have enormous impacts on natural ecosystems and are predicted to increase in frequency with global warming.Land managers need to make decisions on the prioritisation of weeds for control in post-disturbance landscapes,but little is available in the way of guidance to support timely decision making.Semi-quantitative models(e.g.,scoring systems)have been employed routinely in weed risk assessment,which considers the potential impacts posed by weeds,as well as the likelihood of these impacts being realised.Some progress has been made in the development of similar models addressing the topic of weed risk management.Under conditions prevailing after major disturbances,changes(both positive and negative)can be expected in the multiple factors that determine weed management feasibility,relative to pre-disturbance conditions.A semi-quantitative model is proposed that is based on the key factors that contribute to weed management feasibility in post-disturbance environments,along with annotated modules that could be used by land managers in both post-fire and post-flood situations.The fundamental challenge for weed management in these scenarios lies in the identification of differences between weeds and native species in relation to(1)patterns of seedling emergence;and(2)detectability relative to the growth stage.These two factors will determine the timing of control actions that are designed to address the trade-off between weed control and off-target damage during the period when both types of plants are recovering from a major disturbance event.The model is intuitively sound,but field testing is required to determine both its practical value and any necessary improvement.

Technical Points of Green Prevention and Control Technology of Major Diseases and Pests in Lixian Rhubarb(Rheum palmatum L.)

Based on different types of diseases,pests and weeds in the whole growth period of rhubarb(sowing period-harvesting period),the corresponding green prevention and control technology is proposed,aiming to further reduce the application amount of pesticides and fertilizers in the production of medicinal sources of Lixian rhubarb during the"14 th Five-Year Plan"period.The results will provide a theoretical basis for increasing the promotion and application of agricultural prevention and control(including disease-resistant varieties,ecological regulation),physical prevention and control,biological prevention and control measures,thus ensuring effective protection of the ecological environment,green,healthy and sustainable development of traditional Chinese medicine agriculture in Longnan,and source quality of authentic medicinal materials.

Chemical Control of Herbicide Monosulfuron Plus Propazine 44% WP against Weeds in Millet Fields and Study on Factors Influencing Yield of Millet

[Objective] The paper was to resolve the poor efficacy or phytotoxicity problems in promotion of herbicide monosulfuron plus propazine 44% WP. [Method] Using orthogonal test and Duncan＇s new multiple range statistical analysis with four factors four levels and three factors two levels, the effects of factors such as herbi- cide dose, irrigation water volume, quality of soil preparation and soil moisture content on chemical control of monosulfuron plus propazine 44% WP against weeds and millet yield were compared in the test. [Result] Seven factors all had great impact on control effect of monosulfuron plus propazine 44% WP against weeds, of which her- bicide dose, irrigation water volume, quality of soil preparation and soil moisture content were the most important factors affecting millet yield. According to millet yield and economic benefit, the optimal scheme to ensure safe, efficient and economic control of monosulfuron plus propazine 44% WP against weeds was as follows： the dose of monosulfuron plus propazine 44% WP was 1 800 g/hm2, the soil was treat- ed after sowing and before seedling emergence; the soil should be smooth and sol- id; the soil moisture should reach 15%; the fields should not be irrigated after herbi- cide application, and the damage of weeds in millet fields could be effectively con- trolled within 45 d during high efficacy duration, especially the damage of dicotyledonous weeds. [Conclusion] The study provided useful information for comprehensive technology of weeds control and ensuring high yield and good harvest of millet.

Control Effect Evaluation of Herbicides for Malignant Weed Nut Grass in Sugarcane Field

In order to screen herbicides with ideal safety characteristics to control malignant weed nut grass in sugarcane field, 20% thifensulfuron methyl WP and 65% MCPA·ametryne·diuron WP were selected for the field efficacy trial. The results showed that 20% thifensulfuron methyl WP and 65% MCPA·ametryne·diuron WP had good control effect on nut grass. The optimum dosage of 20% thifensulfuron methyl WP and 65% MCPA.ametryne-diuron WP was 1 125 g/hm^2 （effective ingredients 225 g） and 3 150 g/hm^2 （effective ingredients 2 047.5 g）, respectively. These two herbicides should be dissolved in 675 kg water per hectare and applied in the vigorous growth period of nut grass （height 10-15 cm） with oriented stem leaf spraying. The control effect after 15 days could be above 87.9%.

Technical Regulations for Comprehensive Control Weeding in Millet Field

According to experiments in many years in Hebei Province, the research explored weed comprehensive control technology on millet fields in terms of application range, prevention rules, prevention object, agricultural control, physical control, and chemical control and proposed specific methods and technological indices in order to provide technological references for comprehensive control on weeds of millet fields.

Damage and Control of Poisonous Weeds in Western Grassland of China

Western grassland is the main source of living and means of production of western inhabitants. For many years, desertification and poisonous-weeds growth in grassland were resulted from over-grazing, over-reclaiming, over-spading and population growth. Western natural ecological environment is destroyed severly. Meanwhile, it has restricted the sustainable development of animal husbandry. The fast spreading poisonous-weeds, which caused grassland ecology unbalance, is one of the considerable bioecology problems and an important index of grassland degeneration. Based on analysis and induction of previous data, this article introduced the situation of poisonous-weeds disaster of western grassland in recent decades, category and distribution of poisonous-weeds, integrated control and reasonable utilization.

Control Efficiency and Crop Safety of 20% Cyhalofop-butyl WP on Grass Weeds in Direct Seeded Rice Fields

The purpose was to define the control efficiency and safety of 20% cy- halofop-butyl WP on grass weeds in direct seeded rice fields, in order to provide the basis for chemical weeding. This study measured Leptochloa chinensis（L.） Nees, Echinoch/oa crusgalli （L.） Beauv and other gramineous weed control efficiency with four concentrations of 20% cyhalofop-dutyl WP and 100 g/L cyhalofop-dutyl EC in direct seeded rice fields, and analyzed the yield-increasing effect and safety of rice. The results showed that 20% cyhalofop-butyl WP had a good control efficiency on grass weeds such as Leptochloa chinensis（L.） Nees, Echinoch/oa crusgalli（L.） Beauv and other grasses. The effective dosage of 90-150 g/hm2 was over 90.7% on Lep- foch/oa chinensis（L.） Nees and the comprehensive control effect of the grass weeds was above 86.7%, which was basically consistent with 100 g/L cyhalofop-dutyl EC. Furthermore, 20% cyhalofop-dutyl WP was high security for direct seeded rice fields. The yield of rice was increased by 10.18%-11.22% after spraying herbicide. There- fore, 20% of cyhalofop-dutyl WP can be used as a special herbicide for controlling Leptochloa chinensis（L.） Beauv in direct seeded rice fields, and has a good applica- tion prospect.

Evaluation of soil flame disinfestation(SFD) for controlling weeds,nematodes and fungi

Soil flame disinfestation(SFD) is a form of physical disinfestation that can be used both in greenhouses and on field crops. Its use for soil disinfestation in different crop growing conditions makes it increasingly attractive for controlling soilborne pathogens and weeds. But little is known about the effect on weeds and soilbrone diseases. This study reports on greenhouses and field crops in China that determined the efficacy of SFD to control weeds, nematodes and fungi. It also determined the impact of SFD on the soil physical and chemical properties(water content, bulk density, NO3^–-N content, NH4^+-N content, conductivity and organic matter) in three field trials. A second generation SFD machine was used in these trials. SFD treatment significantly reduced weeds(>87.8%) and root-knot nematodes(Meloidogyne incognita)(>98.1%). Plant height and crop yield was significantly increased with SFD treatment. NO3^–-N and NH4^+-N increased after the SFD treatment, and there was also an increase in soil conductivity. Water content, bulk density and organic matter decreased significantly in the soil after the SFD treatment compared to the control. Soil flame disinfestation is a potential technique for controlling weeds and diseases in greenhouses or in fields. SFD is a non-chemical, safe, environmentally-friendly soil disinfection method.

Control Effect of Several Replacement Plants on Invasive Weed Eupatorium adenophorum Spreng

To select the suitable plant species controlling Eupatorium adenophorum in hilly area, ecological adaptability, competitiveness and control efficacy of many replacement plants with economic value in Guizhou Province of China were studied. The results showed that the coverage of paspalum wetsfeteini and Dolichos lablab were 100% and 93%, which increased by 3.70 and 3.44 times compared with Lolium perenne, respectively; their relative crowding coefficient with E. adenophorum were 7.09 and 22.78, which increased by 2.43 and 7.80 times compared with L perenroe, respectively. Using excavation method, the control efficacies of replacement plants were 99.3 % and 96.9%, respectively, while the control efficacy of replacement plants using mowing method was lower than 66.4%. The overwintering rate of P. wetsfeteini in the following year was 95% ; its coverage was still 100% and its control efficacy against E. adenophorum remained over 99%. D. lablab was difficult to survive the winter in the north region beyond 26.2°N, so it could only be applied as annual replacement plant. The coverage of Setaria anceps, Cajanus cajan and other test plants were less than 90%, with poor control efficacy against E. adenophorum.

Effect of wood chip application on root growth of oak seedling and weed control in northern Iran

It was hypothesized that wood chips can serve as a mulch to improve the growth of young trees by facilitating the development of their root systems, inhibiting weed germination, and suppressing weed growth. The present study was carried out in Ghorogh Nursery, Golestan Northern Iran, in order to investigate the impact of wood chips applica- tion on root growth of oak （Quercus castaneifolia） seedlings and control of weed. A three centimeter wood chip layer was used on the soil surface as the mulch treatment with bare soil as the control. The number of new roots, the length of exciting roots and the density of weeds were meas- ured after 5 and 12 weeks. Results showed that wood chip application had significant positive effect on the length of excising roots after 5 and 12 weeks compared with control seedlings. Also, weeds were reduced to near zero levels in treated plot. Our findings suggested that wood chip layer on the soil surface in the nursery can conserve soil moisture and prevent nutrient leaching from the rooting zone as well as diminish weed growth which consequently lead to production of high quality seedling.

Evaluation of New Formulation of Oxyfluorfen (23.5% EC) for Weed Control Efficacy and Bulb Yield in Onion

A field experiment were conducted for two years at Agricultural Research Station, Bhavanisagar of Tamil Nadu Agricultural University, during kharif season of 2009 and 2010 to evaluate the new formulation of oxyfluorfen (23.5% EC) on weed control in onion. Weeds constitute one of the biggest problems in agriculture that not only reduce the yield and quality of onion but also utilize essential nutrients. Hence, weed control is essential for increasing onion production. Based on two years field experimentation, it was found that pre-emergence application of oxyfluorfen (23.5% EC) at400 g.ha-1 gave significantly lower total weed density, weed dry weight and higher weed control efficiency at all the intervals. Application of new formulation of oxyfluorfen (23.5% EC) at200 g.ha-1 as pre-emergence herbicide can keep the weed density and dry weight below the economic threshold level and increase the bulb weight (42.56 and43.87 g) and yield (15940 and15610 kg.ha-1) in onion. Unweeded control accounted for lower bulb yield which inturn reflected through higher weed index of 60.6 and 56.1 per cent, respectively during both the years, due to heavy competition of weeds for nutrients, space and light.

Influence of Post Emergence Application of Glyphosate on Weed Control Efficiency and Yield of Transgenic Maize

Field experiment was conducted during kharif 2009 and rabi 2009-2010 at Tamil Nadu Agricultural University, Coimbatore to evaluate the weed control efficiency and yield potential of glyphosate resistant transgenic maize. Treatments consisted of two transgenic maize hybrids named Hishell and 900 M gold with application of glyphosate as post emergence at 900, 1800 and 3600 g a.e/hathese were compared with non-transgenic counterpart maize hybrids with application of atrazine as pre-emergence at 0.5 kg/ha followed by one hand weeding at 40 Days After Sowing along with need based insect control practices. Post emergence application of glyphosate at 900, 1800 and 3600 g a.e/ha in transgenic maize hybrids was recorded with lower weed density and higher weed control efficiency compared to other treatments. Higher grain yield was recorded with post emergence application of glyphosate at 1800 g a.e/ha in transgenic hybrid 900 M Gold and 3600 g a.e/ha in transgenic hybrid Hishell during kharif 2009 and rabi 2009-2010 seasons, respectively.

Control Efficacy of Pyroxasulfone on Weeds in Corn Field

To explore the control efficacy of 85%pyroxasulfone water-dispersible granule(WG)on annual weeds in corn field as well as its safety,a randomized block design was used to conduct a field plot test of efficacy at four different test sites.After sowing before seedling,85%pyroxasulfone WG at the doses of 10,15,20,and 40 g/667 m^(2),and 55%acetochlor+atrazine suspension concentrate(SC,control agent)at the dose of 170 g/667 m^(2)in summer corn area and 260 g/667 m^(2)in spring corn area were applied,respectively.The test site without herbicide application was used as the blank control.The results revealed that after 40 d of application,the control efficacy of 85%pyroxasulfone WG reached 83.75%~98.23%on Gramineae weeds,55.22%~98.33%on broadleaf weeds,and 88.03%~98.46%on Cyperaceae weeds,but without toxicity to corns.Compared with 55%acetochlor+atrazine SC,85%pyroxasulfone WG at the dose of more than 10 g/667 m^(2)had higher control efficacy on Gramineae weeds,lower efficacy on broadleaf weeds and similar efficacy on Cyperaceae weeds.To sum up,spraying 85%pyroxasulfone WG at the dose of 15~20 g/667 m^(2)(an active component dose of 191.3~255.0 g/hm^(2))after sowing before seedling could effectively control some annual weeds in corn fields and had no toxicity to corns.The herbicide dose was greatly reduced,and thus 85%pyroxasulfone WG was recommended as an effective mean to control the main weeds in corn fields.

Influence of Rice Residue Management Techniques and Weed Control Treatments on Soil Available Plant Nutrients in Rice-Wheat Cropping System

Rice-wheat is the predominant cropping system of fertile soils of Indian, Pakistan, Bangladesh and Nepal falling in the alluvial Indo-Gangetic Plains (IGP). Management of rice residues produced after the harvest of rice crop and before sowing of the next wheat crop is a big challenge in that area. Mostly farmers burn rice residues assuming it low profile fodder and of little use. Burning of rice residues deprives the fields from many plant nutrients as they are lost during burning along with environmental pollutions and other issues. A field study was conducted for two consecutive years at the experimental area of the Department of Agronomy, Punjab Agricultural University, Ludhiana (India) to assess the impact of different rice residue management techniques and weed control treatments in wheat on soil available plant nutrients in rice-wheat cropping system. The experiment was laid out in split plot design with three replications. In main plots, five rice residue management treatments viz., no rice residue, rice residue 5 t·ha-1 (surface), rice residue 6 t·ha-1 (surface), rice residue 7 t·ha-1 (surface) and rice residue 5 t·ha-1 (incorporation) were settled and in sub plots, four weed control treatments i.e. clodinafop 60 t·ha-1, sulfosulfuron 25 t·ha-1, mesosulfuron + iodosulfuron 12 t·ha-1 and control (unweeded) were arranged. Results of the study revealed that surface application as well as incorporation of rice residues improved the organic carbon and NPK status than no rice residues. Among the residue management practices, incorporation of rice residues 5 t·ha-1 significantly improved the soil organic carbon, available nitrogen, phosphorus and potassium than no rice residue treatment in the 0 - 15 soil layer during both the years. Same trend was observed for 15 - 30 cm soil layer but differences were less wide than 0 - 15 cm soil layer. Among the weed control treatments, organic carbon was not significantly influenced. Herbicide treated plots registered significantly higher available nitrogen, phosphorus and potassium than control (unweeded) treatment in the 0 - 15 cm soil layer during both the years.

Effects of Different Herbicides on Maize Growth and Weed Control in Maize Fields

Effects of four herbicides(paraquat, acetochlor, nicosulfuron and atrazine) on the growth of maize and control effect of plant quantity and fresh weight of weeds were studied. The results showed that 15 days after spraying the herbicides on weeds,the prevention and control effect of paraquat on weeds was the optimum, and its effects on the plant quantity and fresh weight of weeds were above 81.57%; the prevention and control effect of acetochlor on weeds was the second best; the prevention and control effect of atrazine on weeds was the worst, and its effects on the plant quantity and fresh weight of weeds were only 51.04% and 37.86%. After 30 or 45 days, the prevention and control effect of atrazine and nicosulfuron on weeds in the maize fields was better than the other herbicides, and their effects on the plant quantity and fresh weight of weeds were higher than 70.00% and 85.00%. Acetochlor and paraquat had certain phytotoxicity to the growth of maize after about 15 days, and its leaves became yellow and grew slowly. On the whole, nicosulfuron had good prevention and control effect on weeds and had no phytotoxicity to the growth of maize.

Synergistic Effects of Herbicide Adjuvants on Weeds Control and Safety Determination in Field Application

The effects of 9 plant adjuvants on the control of Stellaria japonica and Poa pratensis by 3 herbicidesor mixtures,including MCPA-Na+Clethodim,Atrazine and Bentazon,were studied by pot experiments.The results showed that all these 9 plant adjuvants could significantly promote the control effects of MCPA-Na+Clethodim on 2 weeds,except Jiabajin for Poa pratensis.The control effect on plant number and fresh weight of Stellaria japonica increased by 90.6%~100.0%and 47.6%~56.2%respectively 10 d after the treatment,and 25.1%~96.4%and 17.7%~90.4%for Poa pratensis respectively.Pharmacodynamics,Doctor lemon oil,Pamiere,Beirunsu and Wynote had better synergistic effects.Plant adjuvants had little synergistic effect on Atrazine and Bentazon in the early stage which was 10 d after the treatment.However,when it was 20 d after the treatment,adjuvants like Yaoxiaoling,Pamiere and Beirunsu could significantly increase the control effect of Atrazine on Stellaria japonica.Yaoxiaoling,Jiabajin and Beirunsu could promote the synergistic effect of Bentazon on Poa pratensis.Adding herbicide Yaoxiaoling could increase the herbicide control effect,fresh weight control effect,plant height and fresh weight inhibition rate of weeds in maize and flax fields.And the herbicide phytotoxicity was not obvious.The combinations of plant adjuvants with 4 herbicides including Atrazine,Nicosulfuron Mesotrione Atrazine,Nicosulfuron Atrazine,and Bentazon;had better control effects on weeds in maize fields,while MCPA-Na+Clethodim+adjuvants had better control over weeds in flax fields.

Impacts of Different Weeding Methods on Weeds Control in Tobacco Fields in Anshun City

[Objective] The paper was to explore weed control measures in tobacco fields in Anshun City. [Method] Different treatments on weed control were conducted in tobacco fields in Anshun City, Guizhou Province, from 2017 to 2019. [Result] Various treatments had no negative effect on tobacco plant growth in the field, and had different degrees of control effects on five dominant weeds, including Digitaria sanguinalis, Setaria viridis, Fagopyrum dibotrys, Commelina communis and Chenopodium album. White mulching film and 50% butralin·clomazone EC 160 m L/667 m^(2) + white mulching film had the worst performance, which had extremely significant or significant differences with other treatments. There was no sig-nificant difference among most treatments, and the overall effects were comprehensive(multi-factor) treatment > double factor treatment > single factor treatment. [Conclusion] Combination control is recommended in practical tobacco production.

Weed and insect control affected by mixing insecticides with glyphosate in cotton

Field studies were conducted in 2012 and 2013 to evaluate weed and insect control efficacy with glyphosate at 1 230 g ai（active ingredient） ha^（-1） and the insecticides acephate（728 g ai ha^（-1））,carbosulfan（135 g ai ha^（-1））,endosulfan（683 g ai ha^（-1））,imidacloprid（32 g ai ha^（-1））,or lambda-cyhalothrin（23 g ai ha^（-1））,as well as glyphosate tank-mixed with these insecticides.Four of the most common weeds in cotton,common purslane,false daisy,goosegrass,and lambsquarters,were manually sown in the cotton field and treated with glyphosate alone or in combination with insecticides.Glyphosate efficacy,based on visual estimates of control and weed fresh weight at 21 d after treatment（DAT）,was unaffected by the addition of insecticides.Four weeds were controlled by 93-97%and 86-100%（visual rating） and reduced weed fresh biomass by98-99%and 96-100%with glyphosate alone and its combination with insecticides,respectively.Addition of glyphosate to acephate improved cotton aphid control compared with acephate alone.However,addition of glyphosate to carbosulfan,endosulfan,imidacloprid,or lambda-cyhalothrin did not affect the aphid control when compared with the insecticide alone treatments.These results indicate that cotton producers could potentially integrate weed and insect management strategies by choosing suitable insecticide mixing partners with glyphosate,thereby reducing the application costs without sacrificing the efficacy of the glyphosate or the insecticides.

A Computer System for Forecasting the Threshold Period for Crop Weed Control

In this article, a model of a weed control threshold forecast system has been established, with related model solving, data checking, database setting up, and system engineering illustration. Moreover, it is tested by a software with data from a sugar cane planting experimental field in Yunnan, China. The methodology behind the detailed system analysis, design, and engineering has been discussed. The issue of how to create a dynamic data-dependent forecast model of a threshold forecast system, whose threshold changes according to the change of planting environment has been solved. Hence an effective solution has been initiated for further development on an agricultural expert system.