春大豆田杂草生态经济防除阈期研究

通过辽宁省沈阳、庄河两地的田间试验,建立了大豆田苗后有草天数或无草天数与产量损失率间的函数关系模型,明确了辽宁省春大豆田杂草的生态经济防除阈期为大豆出苗后16~40 d。在此期间内保持田间杂草少于经济防除阈值,即可确保杂草造成的减产率低于3%,又能充分发挥杂草在生态系统中的积极作用。     

Critical period of weed control in transplanted chilli pepper

Summary Field experiments were conducted from 1991 to 1993 to determine the critical period of weed control in chilli pepper. The maximum weed-infested period ranged between 0.7 and 3.2 weeks after transplanting (WAT) at a 5% yield loss level. To prevent losses in total and marketable yields, weeds should be removed 2.1 or 0.9 WAT respectively. The end of the critical period decreased as the predetermined yield loss level increased from 2.5% to 10%. The minimum weed-free period ranged between 6.7 and 15.3 WAT at a 5% yield loss level depending on crop yield category. The chilli pepper crop required an average of 12.2 weeks of weed-free maintenance to avoid losses above 5%. Using a 5% yield loss level, the duration of the critical period of weed control was 14 weeks in 1991 and 11.2 weeks in 1993, but was shortened to 5.1 weeks in 1992. The results suggest that weeds must be controlled during the first half of the crop's growing season in order to prevent yield losses.     

辽宁省大豆田杂草群落分析及防除策略

通过对辽宁省不同地区大豆田杂草调查,明确了各大豆主要种植区的杂草组成及危害情况,并针对不同地区大豆田杂草群落组成情况提出了防除策略.     

麦后夏播大豆田杂草化学防除试验

随着种植业产业结构调整 ,夏播大豆近年有所扩大 ,由于播后正值高温季节 ,杂草出苗快 ,生长旺 ,与豆苗竞争激烈 ,严重影响大豆产量和品质的提高。 2 0 0 2年 ,我们在本场岳台队进行了土壤封闭防除夏播大豆田杂草的大田试验 ,取得了较好的效果。报告于下 :1　试验设计与方法设每 6 6 7ｍ2 用 5 0 %乙草胺乳油 10 0ｍｌ (江苏常隆化工集团产品 )和 5 0 %双收封草宝乳油 (青岛双收集团产品 )两种处理 ,面积分别为 6 6 7ｍ2和 5 33 6ｍ2 ,另设不施药对照 10 0 0ｍ2 ,未设重复。试验田土质为壤土 ,ｐＨ值 6 8,麦收后整地 ;点播大豆 ,品种早生 0 …     

水花生的危害及治理

阐述了目前国内水花生的生态分布与危害情况,列举了各种治理手段及优缺点。     

The use of fomesafen for pre-emergence weed control in cotton

The herbicide fomesafen was found to be selective in preplanting and pre-emergence treatments in cotton (Gossypium hirsutum L.). It was effective due to residual soil activity in controlling some of the most troublesome weeds in cotton fields,i.e., pigweed (Amaranthus spp.), black nightshade (Solarium nigrum L.), velvetleaf (Abutilon theophrasti Medik.) and cocklebur (Xanthium spp.). The best soil activity of fomesafen was achieved from pre-emergence or preplanting applications which were activated when the soil was wetted by rain or sprinkler irrigation, but the herbicide caused damage to the crop’s foliage if rain fell just after the cotton emergence. The most effective and safest method for applying fomesafen in cotton fields was preplanting followed by mechanical incorporation to a depth of 10 cm. Combinations of fomesafen with trifluralin were effective and completed the spectrum of controlled weeds in cotton, including annual grasses, common purslane (Portulaca oleracea L.) and field bindweed (Convolvulus arvensis L.).     

Chemical weed control in rainfed peanuts

Field studies at Bangalore, India, demonstrated that benfiuralin, fluchloralin and profluralin were effective for the selective control of many weed species in field experiments with peanuts (Arachis hypogaea L.‘BH-8-18′). Trifluralin and dinitramine were effective against many weed species but reduced crop stand by about 10%. These two herbicides also reduced the incidence of leaf spot disease (Cercospora arachidicola) and peanut pod yields were similar to clean weeded treatments. Bentazon was ineffective on most weed species and metribuzin was lethal to the crop. Alachlor, nitrofen and chloramben were only partially effective and would require supplemental hand weeding or mechanical tillage to obtain satisfactory weed control.     

Row spacing impacts the critical period for weed control in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis>)

The knowledge on the critical crop-weed competition period is important for designing an efficient weed management program. Field studies were conducted in 2012 and 2013 at the Agricultural Research Institute, Kahramanmaras, Turkey to determine the effects of three row spacing (50, 70 and 90 cm) on the critical period for weed control (CPWC) in cotton. A four parameter logistic equation was fit to data relating relative crop yield to both increasing duration of weed interference and length of weed-free period. The relative yield of cotton was influenced by the duration of weed-infested or weed-free period, regardless of row spacing. In cotton grown at 50 cm row spacing, the CPWC ranged from 117–526 growing degree days (GDD) (V2–V11 growth stages) in 2012 and 124–508 GDD (V2–V10) in 2013 based on the 5% acceptable yield loss level. At 70 cm row spacing, the CPWC ranged from 98–661 GDD in 2012 (V2–V13) and 144–616 GDD (V2–V12) in 2013. At 90 cm row spacing, the CPWC ranged from 80–771 GDD in 2012 (V1–V14) and 83–755 GDD (V1–V14) in 2013. In order to obtain a 95% weed-free yield, the weed management should start at 16 days after crop emergence (DAE) and continued until 52 DAE (V2–V11) for crops grown in 50 cm row spacing, 15 and 60 DAE (V2–V13) for 70 cm row spacing and 11 and 67 DAE (V1–V14) for crops grown in 90 cm row spacing. This suggests that cotton grown in narrow row spacing (50 cm) had greater competiveness against weeds compared with wider row spacing (70 and 90 cm). Cotton growers can benefit from these results by improving cost of weed control through better timing of weed management.     

丙广防除直播大豆田杂草效果

40％丙广EC是江苏省通州正大农药厂研制生产的一种新型旱田土壤处理除草剂，由丙草胺与广灭灵复配而成。为明确其对大豆田杂草的防除效果及其应用技术，受该厂委托，我们于2001～2002年进行了40％丙广EC防除夏大豆田杂草田间药效试验，现将试验结果报告如下。     

Incorporation of weed spatial variability into the weed control decision-making process

Floral surveys were carried out on a field of 28 m × 100 m on the nodes of a regular 2 m × 2 m grid, using a rectangular sampling area of 25 cm × 30 cm. In total, 765 units were sampled, each one characterized by the spatial co-ordinates and the number of seedlings of different weed species. The spatial representation of the weeds was obtained with kriging. Simulations were carried out for Amaranthus spp., which had the highest frequency and density (221 plants m^?2), and Portulaca oleracea L., a species that combined a more aggregated distribution with a medium–high density (27 plants m^?2). The results obtained clearly indicated that the usefulness of geostatistical procedures depends on the type of question posed by the user. If the goal is to estimate weed density and, consequently, crop yield loss, kriging appears to overburden the decision-making process, without improving the estimates obtained. This procedure becomes useful for obtaining weed infestation maps to be used for intermittent spraying applications. The reliability of these maps increases with the number of samples used for kriging. With the more aggregated species, at least 50 samples are required to obtain an infestation map. The reduction in the area to be treated depends on the threshold level adopted and on the number of samples used for kriging. With a threshold around the break-even point for most post-emergence treatments, this reduction varies from 10% to 40% with maps obtained from 50 and 175 samples respectively. The usefulness of infestation maps obtained with kriging for improving the decision-making process is strictly dependent on the weed patch dynamics: if these patches remain relatively stable over time, kriging can be carried out periodically without overburdening the decision-making process, whereas, if they are not stable, maps need to be drawn up each year, with a significant increase in costs.     

Promising herbicides for weed control in chickpea

Abstract

Chickpea suffers severe competition due to Chenopodium album L. infestation. Two to three hoeings are generally given to check C. album but increasing labour costs and scarcity of farm labour make the manual weeding difficult. Usage of herbicides appears to be a logical solution. Pre‐emergence applications of pendimethalin or ametryn alone at 1.5 kg ai ha^?1 or one handweeding at 35–40 days after seeding following either 1 kg ai ha^?1 of pendimethalin, ametryn or fluchloralin or metribuzin at 0.3 kg ai ha^?1 applied pre‐emergence gave effective control of C. album and seed yields similar to clean‐weeded chickpeas. There was an 84% reduction in seed yield of chickpea without weeding.     

Asulam mixtures for weed control in flax

Five field experiments were conducted from 1972 to 1975 to evaluate weed control in flax (Linum usitatissimum L.) using post-emergence treatments of asulam [methyl (4-aminobenzenesulphonyl) carbamatel alone and in combination with other herbicides. The ¹⁴C-asulam absorption by leaf segments and roots of glasshouse grown wild oats (Avena fatua L.) was also investigated. Asulam at 1.12 kg/ha gave good wild oat control and acceptable control of green foxtail (Setaria viridis (L.) Beauv.). However, wild oat control was poorer when asulam was combined with other herbicides: on a 3-year average, as compared with asulam alone at equal rates, the asulam+MCPA mixture resulted in a greater antagonism and a significant 6% reduction in flax seed yield, whereas the asulam+bromoxynil/MCPA mixture gave the least antagonistic effect, improved broadleaf weed control and increased yield by 13%. In mixtures, the potassium salt of MCPA was more compatible with asulam for weed control than the amine form. Both leaf segments and roots of wild oats absorbed and distributed less ¹⁴C-asulam from solutions containing MCPA than from those containing bromoxynil or bromoxynil/MCPA.     

Non-chemical approaches to weed control in horticulture

Concern about herbicide safety has renewed interest in non-chemical systems of weed control. Alternative approaches for dealing with weeds can be broadly grouped into cultural and biological methods. Some of the options available for controlling weeds without the use of herbicides are discussed.     

Non-chemical weed control on traffic islands: a comparison of the efficacy of five weed control techniques

The efficacy of five non‐chemical weed control methods for reducing weed cover on traffic islands was investigated in the growing season of 2004. Three trial sites were divided into six treatment areas which were treated with either flame, steam, hot air, hot water, brushes or left untreated. The treatments were carried out at regular intervals throughout the growing season. The percentage weed cover was measured every second week using a 75 × 75 cm quadratic frame with 100 squares. In the control areas, a rapid increase in weed cover was observed, whereas all treatments reduced weed cover. Hot water was the most effective method, although not significantly better than hot air or steam. Hot air treatment was more effective than brushing, whereas hot water was more effective than both flaming and brushing. The doses that were used were relatively high (150–355 kg ha^?1), partly because of the irregular shape of the traffic islands and the treatment intervals were quite short in comparison with those in similar studies. However, the treatments could keep down the weeds only to a certain extent. The present knowledge of the efficacy of various weed control methods, as well as an increase in our knowledge of adequate treatment intervals, supports an optimisation of hard‐surface weed control. Data and experience gained from these trials were used to develop further calibrated application studies.     

Innovation in mechanical weed control in crop rows

Weed control within crop rows is one of the main problems in organic farming. For centuries, different weed removal tools have been used to reduce weeds in the crop rows. Stimulated by the demand from organic farmers, research in several European countries over the last decade has focused on mechanisation using harrowing, torsion finger weeding and weeding with compressed air (Pneumat). Intelligent weeders are now being developed which offer more advanced ways to control weeds, including larger ones and to leave the crop plants unharmed. One of the first commercially available intelligent weeders, the Sarl Radis from France, has a simple crop detection system based on light interception, which guides a hoe in and out of the crop row, around the crop plants. The inclusion of innovative technologies, including advanced sensing and robotics, in combination with new cropping systems, might lead to a breakthrough in physical weed control in row crops leading to significant reductions, or even elimination, of the need for hand weeding.     

Economic weed control with grass carp

Abstract

Conventional methods of aquatic weed control meet increasing objections on economic and/or environmental grounds. An alternative approach is the use of grass carp (Ctenopharyngodon idella Val.), a herbivorous fish. This biological method has mainly been used in Europe and the USA, but since 1976 an Egyptian‐Dutch project has studied the potential of this approach for the Egyptian irrigation systems. All aspects of the production and use of grass carp have been studied and evaluated, Egyptian personnel have been trained, a large‐scale breeding station has been established and practical use of the technique has begun. The programme has shown that a stocked grass carp population not only provides effective weed control, but it also increases the protein production in Egyptian waterways substantially. If managed well, this production can provide continuous revenues that far outweigh the costs of weed control. The necessary management techniques developed are mainly based on yearly restocking with grass carp and cooperation between irrigation authorities and professional fishermen. The experience described in this paper will be of interest to many other countries.     

辽宁省水稻田杂草生态经济防除阈期研究

通过在沈阳、新宾、东港、盘山4地2年的田间试验,建立了水稻移栽后有草天数或无草天数与产量损失率间的函数关系模型,明确了辽宁省水稻田杂草的生态经济防除阈期为水稻移栽后14～34 d.在此期间内保持田间杂草少于经济防除阈值,既可确保杂草造成的减产率低于3%,又能充分发挥杂草在生态系统中的积极作用.     

Modelling the correlation between plant phenology and weed emergence for improving weed control

The efficiency of weed control practices could be improved if their timing is linked to weed emergence dynamics. A study was conducted in a pre‐alpine valley in northern Italy to evaluate whether the phenological phases of some perennial plants could serve as reliable indicators of time of weed emergence and thus be an alternative to bioclimatic models for supporting management decisions. Weed emergence was observed from 2003 to 2004 in five sites at different altitudes. The emergence dynamics of the main weeds were modelled with a Gompertz model. The phenology of 10 common shrubs and a tree was monitored by visual assessment. The flowering and fruit‐ripening phases of the most useful shrubs were modelled with a lognormal model. Correlation analysis between the two functions was used to study the correspondence between plant phenology and weed emergence. Flowering and fruit‐ripening phases of the shrubs were well described by the lognormal model. The correlation analysis between the lognormal model and Gompertz model showed correspondences between the phenological phases and emergence dynamics of the main weeds. The proposed method can be used to examine shrub phenology–weed emergence correlations and consequently for supporting weed management, under certain conditions.     

Critical periods for weed control in cotton in Turkey

Field studies were conducted over 4 years in south‐eastern Turkey in 1999–2002 to establish the critical period for weed control (CPWC). This is the period in the crop growth cycle during which weeds must be controlled to prevent unacceptable yield losses. A quantitative series of treatments of both increasing duration of weed interference and of the weed‐free period were applied. The beginning and end of CPWC were based on 5% acceptable yield loss levels which were determined by fitting logistic and Gompertz equations to relative yield data representing increasing duration of weed interference and weed‐free period, estimated as growing degree days (GDD). Total weed dry weight increased with increasing time prior to weed removal. Cotton heights were reduced by prolonged delays in weed removal in all treatments in all 4 years. The beginning of CPWC ranged from 100 to 159 GDD, and the end from 1006 to 1174 GDD, depending on the weed species present and their densities. Practical implications of this study are that herbicides (pre‐emergence residual or post‐emergence), or other weed control methods should be used in Turkey to eliminate weeds from 1–2 weeks post‐crop emergence up to 11–12 weeks. Such an approach would keep yield loss levels below 5%.     

Efficacy of chemical weed control in spring cereals in Finland

A national survey was conducted in Finland from 1982 to 1984 to determine the main weed species in spring cereals and the efficacy of herbicides on Finnish farms. The most common dicotyledonous weeds producing the highest biomass in spring cereals were Chenopodium album L., Galeopsis spp. L., Stellaria media (L.) Vill. and Lapsana communis L. The main grass weed was Elymus repens (L.) Gould. The average reduction of weed biomass by herbicide treatment was 75%. More reliable efficacy was obtained with herbicide mixtures than with MCPA alone.