An on-farm approach to quantify yield variation and to derive decision rules for site-specific weed management

Grain yield often varies within agricultural fields as a result of the variation in soil characteristics, competition from weeds, management practices and their causal interactions. To implement appropriate management decisions, yield variability needs to be explained and quantified. A new experimental design was established and tested in a field experiment to detect yield variation in relation to the variation in soil quality, the heterogeneity of weed distribution and weed control within a field. Weed seedling distribution and density, apparent soil electrical conductivity (EC_a) and grain yield were recorded and mapped in a 3.5 ha winter wheat field during 2005 and 2006. A linear mixed model with an anisotropic spatial correlation structure was used to estimate the effect of soil characteristics, weed competition and herbicide treatment on crop yield. The results showed that all properties had a strong effect on grain yield. By adding herbicide costs and current grain price into the model, thresholds of weed density were derived for site-specific weed control. This experimental approach enables the variation of yield within agricultural fields to be explained, and an understanding of the effects on yield of the factors that affect it and their causal interactions to be gained. The approach can be applied to improve decision algorithms for the patch spraying of weeds.     

Beyond patch spraying: site-specific weed management with several herbicides

Site-specific weed management can include both limiting herbicide application to areas of the field where weed pressure is above the economic threshold (patch spraying) and varying the choice of herbicide for most cost-effective weed control of local populations. The benefits of patch spraying with several, postemergence herbicides in irrigated corn were evaluated in simulation studies using weed counts from 16 fields. Patch spraying with one, two or the number of herbicides that maximized net return for a field was simulated. With patch spraying of one herbicide, the average area of a field left untreated is 34.5%. Net return increases by $3.09 ha⁻¹ compared to a uniform application without decreasing crop yield. Additional herbicides increase the average benefits with just 4% more of the field treated. With two herbicides, the increase in net return is almost tripled and herbicide use is reduced nearly 10-fold compared to patch spraying with one herbicide, and weed control is better than the uniform application in 10 fields. Using more than two herbicides for patch spraying further reduces weed escapes, but herbicide use is greater than a uniform application in 10 fields. Growers might be more willing to adopt patch spraying if more than one herbicide is used in a field.     

不同群落结构麦田杂草的化学防治及药剂敏感性

[目的]研究除草剂在不同杂草群落结构麦田中的防治效果,探索杂草对不同药剂的敏感性,以期为麦田杂草的化学防控提供支持。[方法] 通过田间小区试验的方法,测定了不同除草剂在冬小麦阔叶杂草田、禾草田、禾阔混生田的防治效果。[结果] 结果表明：双氟磺草胺对阔叶杂草的效果最好,禾草发生较多的田块及禾阔混生田以甲基二磺隆、啶磺草胺、氟唑磺隆为好；播娘蒿、荠菜等对大部分防治阔叶杂草的药剂依然较为敏感,其中双氟磺草胺敏感性最高,并对恶性杂草猪殃殃有特效；大部分禾本科杂草对甲基二磺隆、啶磺草胺、氟唑磺隆敏感,但只有甲基二磺隆对恶性杂草节节麦有良好的防治效果。[结论] 以阔叶杂草为主的小麦田首选双氟磺草胺,以禾本科杂草及禾阔混生的小麦田宜选择甲基二磺隆。     

Early season weed mapping in sunflower using UAV technology: variability of herbicide treatment maps against weed thresholds

Site-specific weed management is defined as the application of customised control treatments only where weeds are located within the crop-field by using adequate herbicide according to weed emergence. The aim of the study was to generate georeferenced weed seedling infestation maps in two sunflower fields by analysing overlapping aerial images of the visible and near-infrared spectrum (using visible or multi-spectral cameras) collected by an unmanned aerial vehicle (UAV) flying at 30 and 60 m altitudes. The main tasks focused on the configuration and evaluation of the UAV and its sensors for image acquisition and ortho-mosaicking, as well as the development of an automatic and robust image analysis procedure for weed seedling mapping used to design a site-specific weed management program. The control strategy was based on seven weed thresholds with 2.5 steps of increasing ratio from 0 % (herbicide must be applied just when there is presence or absence of weed) to 15 % (herbicide applied when weed coverage >15 %). As a first step of the imagery analysis, sunflower rows were correctly matched to the ortho-mosaicked imagery, which allowed accurate image analysis using object-based image analysis [object-based-image-analysis (OBIA) methods]. The OBIA algorithm developed for weed seedling mapping with ortho-mosaicked imagery successfully classified the sunflower-rows with 100 % accuracy in both fields for all flight altitudes and camera types, indicating the computational and analytical robustness of OBIA. Regarding weed discrimination, high accuracies were observed using the multi-spectral camera at any flight altitude, with the highest (approximately 100 %) being those recorded for the 15 % weed threshold, although satisfactory results from 2.5 to 5 % thresholds were also observed, with accuracies higher than 85 % for both field 1 and field 2. The lowest accuracies (ranging from 50 to 60 %) were achieved with the visible camera at all flight altitudes and 0 % weed threshold. Herbicide savings were relevant in both fields, although they were higher in field 2 due to less weed infestation. These herbicide savings varied according to the different scenarios studied. For example, in field 2 and at 30 m flight altitude and using the multi-spectral camera, a range of 23–3 % of the field (i.e., 77 and 97 % of area) could be treated for 0–15 % weed thresholds. The OBIA procedure computed multiple data which permitted calculation of herbicide requirements for timely and site-specific post-emergence weed seedling management.     

不同覆盖方式对陕西关中地区冬小麦田杂草群落的影响

为明确不同覆盖方式对陕西关中地区冬小麦田杂草群落的影响,通过连续3a定点覆盖试验,研究麦田杂草的种类、密度、重要值及生物多样性。PermANOVA结果表明,拔节期与成熟期、透明膜与黑膜及9种覆盖处理间的杂草群落均存在显著差异。群落调查结果表明,泽漆是整个生育期内所有处理的优势种,猪殃殃和荠菜主要出现在拔节期,灰绿藜和香附子主要出现在拔节期后。黑色全膜平作处理在整个生育期内杂草总密度最低,杂草种类较少,拔节期除草后的物种丰富度、香农指数和Pielou均匀度指数显著低于对照。因此,黑色全膜平作处理可有效控制麦田杂草种类,降低杂草的密度与生物多样性,可为陕西关中地区冬小麦田合理的耕作与覆盖提供参考。     

除草剂对红小豆田杂草防效的研究

试验采用随机区组设计的方法,研究了适合于红小豆田的化学除草技术。研究结果表明,收乐通作为茎叶处理剂,对红小豆田禾本科杂草防效达100%,且对红小豆安全,另外,高效盖草能、拿捕净、威霸、精稳杀得对红小豆也安全并且防效都在90%以上,是红小豆田安全有效的除草剂。本试验中尚未发现茎叶处理剂中对红小豆安全且对阔叶杂草防效较高的除草剂。在除草剂的土壤处理中,禾耐斯(1 500 mL)+赛克(750 g)+水(750 g)是一种理想配方,对红小豆安全,且对阔叶杂草的防效也好(>80%);对红小豆安全且对禾本科杂草防效较好(>77%)的处理为90%禾耐斯。     

江苏金坛茶园春季主要杂草发生危害调查研究

采用"M"形9点取样法定块调查,结果表明,金坛茶园春季杂草有40种。其中:禾本科杂草4种,占10.00%;阔叶杂草31种,占77.50%;莎草科杂草1种,占2.50%;其他杂草4种,占10.00%。多年生杂草14种,占35.00%。阔叶杂草中藤本杂草3种,占阔叶杂草的9.68%。分析比较了新、老茶园春季优势杂草的种群种类、数量区别,明确了茶园春季杂草群落组成。春季杂草相对多度大于5%的优势杂草有菵草、一年蓬、猪殃殃、繁缕、野老鹳草、酢浆草、婆婆纳、荠菜、卷耳、泥湖菜、巢菜、小飞蓬、飞廉、鼠麹、早熟禾、碎米荠、附地菜。     

3%世玛油悬浮剂与3%双氟磺草胺.唑草酮悬浮剂混配防除冬小麦田恶性杂草田间药效评价

为有效防除节节麦和一年生阔叶杂草的危害，筛选具有较好控制作用的除草剂，我们开展了3%世玛油悬浮剂与3%双氟磺草胺?唑草酮悬浮剂混配防除冬小麦田恶性杂草田间药效试验。试验表明，小麦返青期进行茎叶喷雾施药，药后30d对婆婆纳、播娘蒿、猪秧秧和荠菜株防效可达50.0%~72.5%，药后45d对婆婆纳、播娘蒿、猪秧秧和荠菜鲜株防效可达67.2％～95.8％,对节节麦鲜株防效可达81.3％。说明3%世玛油悬浮剂与3%双氟磺草胺?唑草酮悬浮剂混配可有效防除节节麦和一年生阔叶杂草，能够达到小麦返青后的最佳除草效果。同时田间调查显示该混配对小麦安全。     

Broad-scale cruciferous weed patch classification in winter wheat using QuickBird imagery for in-season site-specific control

This article explores the potential use of multi-spectral high-spatial resolution QuickBird imagery to detect cruciferous weed patches in winter wheat fields. In the present study, research was conducted on six individual naturally infested fields (field-scale study: field area ranging between 3 and 52 ha) and on a QuickBird-segmented winter wheat image (broad-scale study: area covering approximately 263 winter wheat fields, approximately 2 656 ha) located in the province of Córdoba (southern Spain). To evaluate the feasibility of mapping cruciferous weed patches in both the field-scale and broad-scale studies, two supervised classification methods were used: the Maximum likelihood classifier (MLC) and vegetation indices. Then, the best classification methods were selected to develop in-season site-specific cruciferous weed patch treatment maps. The analysis showed that cruciferous weed patches were accurately discriminated in both field-scale and broad-scale scenarios. Thus, considering the broad-scale study, classification accuracies of 91.3 and 89.45 % were obtained using the MLC and blue/green (B/G) vegetation indices, respectively. The site-specific treatment maps obtained from the best classifiers indicated that there is a great potential for reducing herbicide use through in-season, cruciferous weed patch site-specific control on both a field-scale and broad-scale. For example, it can be determined that by applying site-specific treatment maps on a broad-scale, herbicide savings of 61.31 % for the no-treatment areas and 13.02 % for the low-dose herbicide areas were obtained.     

苏州市东山蔬菜园杂草种类调查研究

运用对角线5点取样法,对苏州市东山蔬菜园内杂草进行了调查。结果表明,蔬菜园内杂草共有24科67种。其中阔叶杂草52种,占78%;禾本科杂草13种,占19%;莎草科杂草2种,占3%。相对多度达10%以上的杂草依次为牛繁缕、猪殃殃、日本看麦娘、马唐、小飞蓬、千金子、大巢菜、稗、酢浆草等9种,其中前6种相对多度在20%以上,可视为蔬菜园的优势种杂草。     

上海市郊早春杂草的生态位计测

野外调查了上海市郊261个样地早春杂草的生态重要值,共计出现106种杂草,计测了其中84种主要杂草的生态位宽度和生态位重叠值。以生态位重叠值为指标,采用主坐标排序法(principal axis analysis,PAA)对84种主要杂草的生态位重叠关系进行了二维排序,并分析了主要杂草与伴生种的生态位重叠关系。结果表明:1)生态位最宽的前10种杂草分别为猪殃殃Galium aparine(0.442)、加拿大一枝黄花Solidago Canadensis(0.341)、刺果毛茛Ranunculus muricatus(0.336)、野胡萝卜Daucus carota(0.300)、大巢菜Vicia sativa(0.297)、泽漆Euphorbia beliocopia(0.297)、荠菜Capsella bursa-pastoris(0.292)、野塘蒿Conyza bonarinisis(0.278)、波斯婆婆纳Veronica persica(0.256)、葎草Humulus scandens(0.236);2)与主要杂草猪殃殃生态需求相似的种类主要有波斯婆婆纳、葎草、加拿大一枝黄花、刺果毛茛等,与重要外来杂草加拿大一枝黄花生态相似的主要有春一年蓬、葎草、猪殃殃等,刺果毛茛的主要伴生杂草有野老鹳草、棒头草Polypogon fugax、泥胡菜Hemistepta lyrata等;3)根据生态位重叠关系,84种主要杂草大致可以分为湿生、旱生和草坪杂草3种生态类型。     

Airborne multi-spectral imagery for mapping cruciferous weeds in cereal and legume crops

Cruciferous weeds are competitive broad-leaved species that cause losses in winter crops. In the present study, research on remote sensing was conducted on seven naturally infested fields located in Córdoba and Seville, southern Spain. Multi-spectral aerial images (four bands, including blue (B), green (G), red (R) and near-infrared bands) taken in April 2007 were used to evaluate the feasibility of mapping cruciferous patches (Diplotaxis spp. and Sinapis spp.) in winter crops (wheat, broad bean and pea) and compare the accuracy of different supervised classification methods (vegetation indices, maximum likelihood and spectral angle mapper). The best classification method was selected to develop site-specific cruciferous treatment maps. Cruciferous patches were efficiently discriminated with red/blue (R/B) and blue/green (B/G) vegetation indices and the maximum likelihood classifier. At all of the locations, the accuracy of the results obtained from the spectral angler mapper was relatively low. The cruciferous weed-classified imagery of each location were created according to the method that provided the best discrimination results and were used to obtain site-specific treatment maps for in-season post-emergence control measures or herbicide applications for subsequent years. By applying the site-specific treatment maps, herbicide savings from 71.7 to 95.4% for the no-treatment areas and from 4.3 to 12% for the low-dose herbicide were obtained.     

北沙参田杂草化学防除技术研究

[目的]探索适用于北沙参田阔叶杂草防除的除草剂品种及其使用。[方法]采用小区试验研究精噁唑禾草灵、氯吡嘧磺隆、灭草松、异丙隆以及氟磺胺草醚与精喹禾灵混用对海滨滩涂北沙参田杂草的防除效果。[结果]375 g a.i./hm~225%氟磺胺草醚EC与67.5 g a.i./hm~210%精喹禾灵EC混用药后45 d对田间杂草总体株防效约75%,鲜重防效约80%,且对北沙参生长未产生明显药害。[结论]试验结果为有效解决北沙参田阔叶杂草危害问题提供了参考。     

春油菜华油杂62除草剂高效组合筛选研究

[目的]筛选出适宜春油菜华油杂62田地化学除草的药剂及推荐用量.[方法]对春油菜田进行杂草调查,并通过大田试验研究了几种化学除草剂对春油菜田杂草的防除效果.[结果]通过杂草调查,油菜田以禾本科杂草与阔叶杂草混生为主,阔叶杂草种类较多.油菜田化学除草时,采用单一药剂处理很难达到预期效果,以2种药荆混用效果较佳.[结论]生产中建议采用精喹禾灵＋胺苯磺隆为茎叶处理药剂,推荐用量25％胺苯磺隆150 g/hm^2＋ 10.8％精喹禾灵乳油600 ml/hm^2.     

20％氰氟草酯WP对水稻直播田禾本科杂草的防除效果及安全性评价

该文旨在研究20％氰氟草酯WP对水稻直播田禾本科杂草的防控效果和应用安全性,为水稻直播田草害的化学防控提供依据.在大田试验中采取4种浓度的20％氰氟草酯WP和100 g/L氰氟草酯EC对水稻直播田千金子、稗草等禾本科杂草的防除效果进行了测定,且对水稻的增产效果和安全性进行了分析.20％氰氟草酯WP对水稻直播田千金子、稗草等禾本科杂草具有良好的防除效果,有效成分用量90～150 g/hm2对千金子防效在90.7％以上,对禾本科杂草的综合防效均在86.7％以上,与对照药剂100 g/L氰氟草酯EC基本一致.且20％氰氟草酯WP对直播田水稻高度安全,施药后能提高水稻产量,增产幅度为10.18％～11.22％.20％氰氟草酯WP可作为水稻直播田防除千金子的特效药剂,有着良好的应用前景.     

Evaluation of an algorithm for automatic detection of broad-leaved weeds in spring cereals

Lack of automatic weed detection tools has hampered the adoption of site-specific weed control in cereals. An initial object-oriented algorithm for the automatic detection of broad-leaved weeds in cereals developed by SINTEF ICT (Oslo, Norway) was evaluated. The algorithm (“WeedFinder”) estimates total density and cover of broad-leaved weed seedlings in cereal fields from near-ground red–green–blue images. The ability of “WeedFinder” to predict ‘spray’/‘no spray’ decisions according to a previously suggested spray decision model for spring cereals was tested with images from two wheat fields sown with the normal row spacing of the region, 0.125 m. Applying the decision model as a simple look-up table, “WeedFinder” gave correct spray decisions in 65–85% of the test images. With discriminant analysis, corresponding mean rates were 84–90%. Future versions of “WeedFinder” must be more accurate and accommodate weed species recognition.     

Two-Year Weed Seedling Population Responses to a Post-Emergent Method of Site-Specific Weed Management

Field experiments were conducted to determine how a site-specific weed management practice in Zea mays L. influenced the numerical and spatial distribution of a naturally occurring weed infestation in Z. mays and the succeeding Beta vulgaris L. crop. Compared to conventional broadcast herbicide applications, site-specific herbicide applications reduced herbicide load by 11.5 and 98.0% in two separate Z. mays fields. The broad range in outcomes was attributed to the spatial aggregation and density of target weed populations. While herbicide use was successfully reduced at field locations with low weed density, most survivors of multiple control tactics were in locations with the highest initial density. A greater understanding of interactions between weed management and weed density would increase the likelihood that site-specific weed management offers long-term improvements over conventional approaches.     

新疆南部棉区棉田杂草调查

采用等距取样法对新疆南部棉区棉田杂草进行了调查,结果表明:新疆南部棉田杂草有16科42种,其中禾本科杂草占16.7%,阔叶杂草占80.9%,莎草科杂草占2.4%,1年生杂草占57.1%,多年生杂草占42.9%;稗草、扁秆草、田旋花、灰绿藜为新疆南部棉田优势杂草,芦苇为棉田主要杂草。