Weed Control In Sugar Beet Research Articles

Ecological and economic evaluation of conventional and new weed control techniques in row crops

The Farm to Fork strategy of the European Union aims to reduce pesticide use. In weed control, chemical measures are to be replaced mainly by mechanical ones. However, a comprehensive evaluation of mechanical methods with respect to ecological and economic parameters is not yet available. The aim of the study was to quantify relevant ecological and economic parameters of mechanical, mechanical-chemical and chemical weed control in sugar beet as a model crop. An overall consideration of the multidimensional risks for different conventional and new methods revealed that currently no method can be appraised as fully environmentally friendly. Toxicological risk assessment using the model SYNOPS-GIS indicated that broadcast spraying of conventional herbicides is associated with low toxicological risks in most soil-climate-regions and years. Broadcast spraying with herbicides such as CONVISO ONE, while beneficial for energy use, climatic effects, and toxicity to soil organisms, has the highest acute aquatic toxicity. Conventional mechanical methods, while toxicologically safe and, according to field trials, without negative effects on soil biota, soil erosion, or sugar yield, are associated with 100–150% higher greenhouse gas emissions compared to conventional herbicide application. Overall, hoeing with a solar powered robot combined with herbicide spot spraying has the greatest advantages. This technique requires relatively low resource and energy consumption, produces about 5% lower greenhouse gas emissions and has by 87% lower toxicological risk than conventional herbicide spraying. Among pure mechanical techniques, the combination of a solar-driven hoe robot with hand-hoeing appears to be most economic and environmentally sustainable.

Comparison of mechanical vs. chemical weed control in sugar beet – Environmental effects: soil erosion, earthworms, CO2e-emissions

Chemical weed control is widely criticized because of its potential ecotoxicological risks. However, the environmental effects of mechanical weeding have not been studied yet. This study aims to evaluate the effects of hoeing, herbicide spraying and combined hoeing-spraying in sugar beet on soil erosion, earthworm abundance, and greenhouse gas (GHG) emissions. Field trials were carried out in Lower Saxony on five sugar beet fields from 2019 to 2021. Runoff and soil erosion were measured by means of rainfall simulation on 2-m2 subplots after weed control. The earthworm abundance was determined in autumn using formalin expulsion. The resources consumption and GHG emissions of each weeding strategy were estimated using KTBL and Biograce online tools. The earthworm abundance was not affected by weeding strategy in most cases. Cumulative runoff and soil loss were six and eight times lower after hoeing compared to herbicide spraying, but only if the soil was crusted before rainfall simulation; otherwise, weed control did not affect soil erosion. The GHG emissions for mechanical and combined mechanical-chemical weed control were higher by factor 2.5 and 1.7, respectively, as compared to the reference chemical weed control. Hence, hoeing is, though non-toxic and erosion-retarding, the weeding strategy with the highest carbon footprint.

Comparison of mechanical and chemical weed control in sugar beet – Impact on pest insects and epigaeic predatory arthropods

In 2019 to 2021, effects of different weed control strategies in sugar beet on pests and beneficial insects were examined at seven locations in Lower Saxony. The different strategies included conventional spraying, band spraying in the row together with mechanical hoeing between the rows and mechanical hoeing between the rows along with hand hoeing in the row. The various beneficial and pest insects were caught using different trapping methods. For the majority of arthropod populations, either no differences or hardly any significant differences were reported between the three different weed control strategies. Significant effects could only be found on single dates, but these were also not directed in the same direction. According to the results from the photoeclector catches and visual assessments, hoeing three times and chemical weed control had comparable effects to the on the arthropod populations evaluated in this study.

Impact of multifunctional adjuvants on activity of herbicides and sugar roots yield

Field studies were carried out in 2017–2019 in Research and Education Centre Brody, Poznań University of Life Sciences, in order to assessment the impact of tested adjuvants on weed control in sugar beet. Treatments included phenmedipham + ethofumesate at recommended quantity (F + E, 200 + 200 g/ha) + metamitron (M, 700 g/ha) and phenmedipham + ethofumesate at reduced quantities (140 + 140 g/ha) without or with tested methylated seed oil (MSO 1, 2, 3) and standard adjuvants. Herbicides were applied three times after weed emergence. MSO adjuvants were more effective to F + E + M applied at reduced rates than standard adjuvants. The MSO adjuvants made it possible to obtain high and stable herbicidal efficiency of herbicides, regardless of varied weather conditions during and after their application. The root yield of sugar beet after application of herbicides with test adjuvants was higher than on the control and after application of reduced rates of herbicides without adjuvants.

Sensor-Based Intrarow Mechanical Weed Control in Sugar Beets with Motorized Finger Weeders

The need for herbicide usage reduction and the increased interest in mechanical weed control has prompted greater attention to the development of agricultural robots for autonomous weeding in the past years. This also requires the development of suitable mechanical weeding tools. Therefore, we devised a new weeding tool for agricultural robots to perform intrarow mechanical weed control in sugar beets. A conventional finger weeder was modified and equipped with an electric motor. This allowed the rotational movement of the finger weeders independent of the forward travel speed of the tool carrier. The new tool was tested in combination with a bi-spectral camera in a two-year field trial. The camera was used to identify crop plants in the intrarow area. A controller regulated the speed of the motorized finger weeders, realizing two different setups. At the location of a sugar beet plant, the rotational speed was equal to the driving speed of the tractor. Between two sugar beet plants, the rotational speed was either increased by 40% or decreased by 40%. The intrarow weed control efficacy of this new system ranged from 87 to 91% in 2017 and from 91 to 94% in 2018. The sugar beet yields were not adversely affected by the mechanical treatments compared to the conventional herbicide application. The motorized finger weeders present an effective system for selective intrarow mechanical weeding. Certainly, mechanical weeding involves the risk of high weed infestations if the treatments are not applied properly and in a timely manner regardless of whether sensor technology is used or not. However, due to the increasing herbicide resistances and the continuing bans on herbicides, mechanical weeding strategies must be investigated further. The mechanical weeding system of the present study can contribute to the reduction of herbicide use in sugar beets and other wide row crops.

Electrical weed control in sugar beet - A comparison of pre-emergence methods

Im Zuckerrubenanbau konnen schon geringe Unkrautdichten zu enormen Ertragseinbusen fuhren. Diese wurden in der Vergangenheit durch den Einsatz von chemischen Herbiziden effektiv begrenzt. Mit Blick auf den zunehmenden Wegfall verfugbarer chemischer Wirkstoffe, wachsender Unkrautresistenzen, einen nachhaltigeren Bodenschutz und die Einhaltung anspruchsvollerer Ernahrungssicherungsstandards mussen neue Managementansatze fur einen moderneren Pflanzenschutz umgesetzt werden. Aus diesem Grund wurde die elektrische Unkrautbekampfung im Vorauflauf in der Zuckerrube, im Mulchsaatverfahren angebaut, in chemische und mechanische Unkrautbekampfungsstrategien integriert. Es wurde ein randomisiertes Blockfeldversuchsdesign mit dreimal replizierten Versuchsplots und acht Varianten angewendet, wobei einzelne Plots (100 m Lange) jeweils in 50 m getrennt, mit und ohne Glyphosat als Vorsaatanwendung behandelt wurden. Das Electroherb™ der Firma Zasso wurde mit 3 und 5 km h‑1 Fahrgeschwindigkeit und 72 kW elektrischer Nennleistung in einer 3 m Flachenbehandlung angewendet. Der Unkrautdichte nach der Vorauflauf-Applikation setzte sich hauptsachlich aus Ausfallgetreide und zweikeimblattrigen Unkrautpflanzen zusammen und betrug 5 bis 23 Pflanzen 10 m-2, wahrend ohne Glyphosatanwendung 5 bis 97 Pflanzen 10 m-2 gezahlt wurden. Der Vergleich der Wirkungsgrade zeigte, dass die Verunkrautung am besten mit der Electroherb™ Technologie kontrolliert wurde, so dass in den Parzellen ohne Glyphosatanwendung deutlich geringere Unkrautzahlen (von 5 bis 11 Pflanzen 10 m-2) vor dem Auflaufen der Zuckerruben zuruckblieben. Mechanisches Eggen auf der anderen Seite zeigte eine geringe Effizienz bei der Reduzierung von Ausfallgetreide; die durchschnittliche Unkrautdichte betrug hier 72 Pflanzen 10 m-2. Die Ergebnisse zum Zuckerrubenertrag und -qualitat werden in den Datensatz integriert und erlauben so umfassende Schlussfolgerungen zur Wirtschaftlichkeit des Electroherb™ Verfahrens zu schlussfolgern. Unsere Ergebnisse zeigen, dass die Integration von elektrischen Unkrautbekampfungsmethoden in bestehende Strategien den Einsatz von synthetisch-chemischen Herbiziden reduzieren kann und auch einen wesentlichen Beitrag zur Vermeidung von Herbizidresistenzen leisten kann.

Integrated weed control methods utilizing planting pattern in sugar beet

The field experiment was conducted to evaluate the efficacy of different planting patterns, times of mechanical weeding and herbicide application for weed control in sugar beet. Planting pattern was designated as the main-plot with varying levels including single row 45 cm width, single row 58 cm width and twin row 62 cm row width; timing of mechanical weed control in three levels consisting of weeding at 4, 10 and 14 leaves stage of sugar beet, and herbicides in two levels as metamitron and triflusulfuron. Timing in terms of mechanical weeding and herbicide application had significant effect on weed reduction. In the majority of the cases, planting pattern effected desirable weed density and biomass reduction. The best results were attained in double-row planting at an inter-row spacing of 62 cm. With regards to time of weeding, the best results were achieved in mechanical weed control at the 4th leaf stage of sugar beet which had the highest reduction on both weed density and biomass. Metamitron+ was the most impactful on weed density and biomass. The sugar beet yield components were affected by weed control treatments but could not reach to the level of significance.

Potential yield loss in sugar beet due to weed interference in the United States and Canada

AbstractThe objective of this WSSA Weed Loss Committee report is to provide quantitative data on the potential yield loss in sugar beet due to weed interference from the major sugar beet growing areas of the United States and Canada. Researchers and extension specialists who conducted research on weed control in sugar beet in the United States and Canada provided quantitative data on sugar beet yield loss due to weed interference in their regions. Specifically, data were requested from weed control studies in sugar beet from up to 10 individual studies per calendar year over a 15-yr period between 2002 and 2017. Data collected indicated that if weeds are left uncontrolled under optimal agronomic practices, growers in Idaho, Michigan, Minnesota, Montana, Nebraska, North Dakota, Ontario, Oregon, and Wyoming would potentially lose an average of 79%, 61%, 66%, 68%, 63%, 75%, 83%, 78%, and 77% of the sugar beet yield. The corresponding monetary loss would be approximately US$234, US$122, US$369, US$43, US$40, US$211, US$12, US$14, and US$32 million, respectively. The average yield loss due to weed interference for the primary sugar beet growing areas of North America was estimated to be 70%. Thus, if weeds are not controlled, growers in the United States would lose approximately 22.4 million tonnes of sugar beet yield valued at approximately US$1.25 billion, and growers in Canada would lose approximately 0.5 million tonnes of sugar beet yield valued at approximately US$25 million. The high return on investment in weed management highlights the importance of continued weed science research for sustaining high crop yield and profitability of sugar beet production in North America.

Cultivation and Reduced-Rate Herbicides Weed Control in Sugarbeet Grown for Biofuel

AbstractSugarbeet, grown for biofuel, is being considered as an alternate cool-season crop in the southeastern United States. Previous research identified ethofumesate PRE and phenmedipham + desmedipham POST as herbicides that controlled troublesome cool-season weeds in the region, specifically cutleaf evening-primrose. Research trials were conducted from 2014 through 2016 to evaluate an integrated system of sweep cultivation and reduced rates of ethofumesate PRE and/or phenmedipham+desmedipham POST for weed control in sugarbeet grown for biofuel. There were no interactions between the main effects of cultivation and herbicides for control of cutleaf evening-primrose and other cool-season species in two out of three years. Cultivation improved control of cool-season weeds, but the effect was largely independent of control provided by herbicides. Of the herbicide combinations evaluated, the best overall cool-season weed control was from systems that included either a 1/2X or 1X rate of phenmedipham+desmedipham POST. Either rate of ethofumesate PRE was less effective than phenmedipham+desmedipham POST. Despite improved cool-season weed control, sugarbeet yield was not affected by cultivation each year of the study. Sugarbeet yields were greater when treated with any herbicide combination that included either a 1/2X or 1X rate of phenmedipham+desmedipham POST compared with either rate of ethofumesate PRE alone or the nontreated control. These results indicate that cultivation has a very limited role in sugarbeet grown for biofuel. The premise of effective weed control based on an integration of cultivation and reduced herbicide rates does not appear to be viable for sugarbeet grown for biofuel.

Managing Cool-Season Weeds in Sugarbeet Grown for Biofuel in the Southeastern United States

AbstractSugarbeet, grown for biofuel, is being considered as an alternate cool-season crop in the southeastern U.S. coastal plain. Typically, the crop would be seeded in the autumn, then grow through the winter and be harvested the following spring. Labels for herbicides registered for use on sugarbeet grown in the traditional sugarbeet production regions do not list any of the cool-season weeds common in the southeastern United States. Field trials were initiated near Ty Ty, GA, to evaluate all possible combinations of ethofumesate applied PRE, phenmedipham+desmedipham applied POST, clopyralid POST, and triflusulfuron POST for cool-season weed control in sugarbeet. Phenmedipham+desmedipham alone and in combination with clopyralid and/or triflusulfuron effectively controlled cutleaf eveningprimrose, lesser swinecress, henbit, and corn spurry when applied to seedling weeds. Ethofumesate PRE alone was not as effective in controlling cool-season weeds compared to treatments containing phenmedipham+desmedipham POST. However, ethofumesate PRE applied sequentially with phenmedipham+desmedipham POST improved weed control consistency. Clopyralid and/or triflusulfuron alone did not adequately control cutleaf eveningprimrose. Triflusulfuron alone effectively controlled wild radish. In the 2013–2014 and 2014–2015 seasons, December-applied POST herbicides did not injure sugarbeet. However, in the 2015–2016 season POST herbicides were applied in late October. On the day of treatment, the maximum temperature was 25.4 C, which exceeded the established upper temperature limit of 22 C for safe application of phenmedipham+desmedipham, and sugarbeet plants were severely injured. In the southeastern United States, temperatures frequently exceed 22 C in early autumn, which may limit phenmedipham+desmedipham use for controlling troublesome cool-season weeds of sugarbeet in the region. Weed control options need to be expanded to compensate for this limitation.

Camera steered mechanical weed control in sugar beet, maize and soybean

In sugar beet, maize and soybean, weeds are usually controlled by herbicides uniformly applied across the whole field. Due to restrictions in herbicide use and negative side effects, mechanical weeding plays a major role in integrated weed management (IWM). In 2015 and 2016, eight field experiments were conducted to test the efficacy of an OEM Claas 3-D stereo camera® in combination with an Einbock Row-Guard® hoe for controlling weeds. Ducks-foot blades in the inter-row were combined with four different mechanical intra-row weeding elements in sugar beet, maize and soybean and a band sprayer in sugar beet. Average weed densities in the untreated control plots were from 12 to 153 plants m−2 with Chenopodium album, Polygonum convolvulus, Thlapsi arvense being the most abundant weed species. Camera steered hoeing resulted in 78% weed control efficacy compared to 65% using machine hoeing with manual guidance. Mechanical intra-row elements controlled up to 79% of the weeds in the crop rows. Those elements did not cause significant crop damage except for the treatment with a rotary harrow in maize in 2016. Weed control efficacy was highest in the herbicide treatments with almost 100% followed by herbicide band-applications combined with inter-row hoeing. Mechanical weed control treatments increased white sugar yield by 39%, maize biomass yield by 43% and soybean grain yield by 58% compared to the untreated control in both years. However, yield increase was again higher with chemical weed control. In conclusion, camera guided weed hoeing has improved efficacy and selectivity of mechanical weed control in sugar beet, maize and soybean.

CONVISO® SMART – an innovative approach of weed control in sugar beet

KWS SAAT SE and Bayer CropScience AG are jointly developing and commercializing an innovative system of weed control in sugar beet for the global market under the name of CONVISO SMART. The technology is based on the breeding of sugar beet cultivars that are tolerant to herbicides of the ALS-inhibitor-class with a broad-spectrum weed control. This will give farmers a new opportunity to make sugar beet cultivation easier, more flexible in its timing and more efficient. The use of CONVISO, as new herbicide in sugar beet, will make it possible to control major weeds with low dose rates of product and reduced number of applications in the future. The tolerance is based on a change in the enzyme acetholactate synthase, which is involved in the biosynthesis of essential amino acids. This variation can occur spontaneously during cell division. During the development, sugar beets with this spontaneously changed enzyme were specifically selected and used for further breeding of CONVISO SMART cultivars. As such, these varieties are not a product of genetic modification. Field studies with CONVISO SMART hybrids showed complete crop selectivity and a broad and reliable efficacy against a large range of major weeds. The bio-dossier for an EU-wide registration of CONVISO was submitted in April in 2015. The variety inscription process is in preparation in different countries. The system CONVISO SMART is scheduled to be available to farmers in 2018 at the earliest.

Potenzial der mechanischen Unkrautkontrolle in Zuckerrüben zur Herbizideinsparung

Weed control in sugar beet (Beta vulgaris) is usually performed with herbicides applied across the whole field at several timings in the early growth stage of sugar beet. It was tested if herbicide input could be reduced with a combination of preventive, mechanical and chemical weed control strategies. In field experiments conducted at 6 locations mechanical weeding in the inter-row area was combined with band application of herbicides in the intra-row area. At one location, precision farming technologies including camera steering and GNSS-RTK steering were used. Weed densities of up to 91 plants m-2 were detected in the untreated control plots. Band spraying in combination with inter-row hoeing reduced herbicide input by 50 to 75% compared to uniform herbicide applications. Weed control efficacy was 72% in the conventional herbicide treatments, 87% for the combination of weed hoeing and band spraying, 78% for precision hoeing with camera steering and 84% for precision hoeing with GNSS-RTK steering system. Weed control treatments increased white sugar yield (WSY) by 30% compared to the untreated control. The combination of mechanical weed control, band application of herbicides and precision hoeing have shown promising concepts for integrated weed management resulting in significantly reduced herbicide input and high weed control efficacy.

Effectiveness of Repeated Reduced Rates of Selective Broadleaf Herbicides for Postemergence Weed Control in Sugar Beet ( Beta V ulgaris )

Field experiments were conducted at three sites (Karaj, Mashhad and Orumieh, Iran), during 2005 to determine the influence of reduced rates of broadleaf herbicides in different combinations on sugar beet and weeds. Experiments were laid out in a randomized complete block design with factorial arrangement of the treatments and three replications. The treatments were 10 different combined herbicides that applied at recommended (full rates) and reduced rates (half rates). Data were recorded 30 days after herbicide application on percentage of weed density and biomass reductions. The data for individual traits were subjected to the ANOVA technique and significant means were separated by the 's multiple range test. The analysis of the data showed that herbicide combinations and herbicide doses were statistically significant for all the parameters investigated except weed frequency reduction at and Orumieh. The interaction of herbicide combinations and doses could not reach the level of significance in any of the traits examined. The results indicated more efficacies of herbicides combinations when they used repeatedly in low-than labeled dose.

Response of imidazolinone-tolerant volunteer oilseed rape to herbicides and herbicide mixtures used for broadleaved weed control in sugar beet

Durch den hoheren Anteil von Raps ( Brassica napus ) in Zuckerrubenfruchtfolgen kann in den nachgebauten Kulturen zunehmend Ausfallraps auftreten. Der Sulfonylharnstoff Triflusulfuron gilt als wichtiger Baustein bei der Ausfallrapskontrolle in Zuckerruben. Durch die Einfuhrung Imidazolinon-toleranter Rapssorten (Clearfield ® -Raps) kann sich die Herbizidauswahl und somit die Ausfallrapskontrolle in Zuckerruben jedoch verandern, da bei den Ausfallrapspflanzen eine partielle Kreuzresistenz gegen ALS-Inhibitoren vorliegt. Ziel der Untersuchung was es, sechs verschiedene Herbizidstrategien auf ihre Wirksamkeit gegen Imidazolinon-toleranten Ausfallraps zu uberprufen. Imidazolinon-toleranter Ausfallraps zeigte eine ausgepragte Kreuzresistenz gegen Triflusulfuron im Feld (mittlerer Wirkungsgrad 14 %). Auch die Kombination mit dem Wirkstoff Metamitron fuhrte zu keiner zufriedenstellenden Erhohung des Wirkungsgrades. In diesen Fallen zeigten sich deutliche Unterschiede zwischen Imidazolinon-empfindlichen und -toleranten Rapssorten. Eine Reduktion der Sprossfrischmasse von > 90 % bei Imidazolinon-tolerantem Ausfallraps wurde durch Herbizidmischungen mit den Wirkstoffen Desmedipham, Phenmedipham, Ethofumesat, Chloridazon und Quinmerac erreicht. Die Ergebnisse zeigten, dass Triflusulfuron fur die Erfassung von Imidazolinon-tolerantem Ausfallraps wenig geeignet ist, alternative Wirkstoffe jedoch vorhanden sind. Generell muss dem Ausfallrapsmanagement bei Anbau von Imidazolinontolerantem Raps uber die gesamte Fruchtfolge hinweg eine hohe Aufmerksamkeit geschenkt werden, beginnend mit einer geeigneten Bodenbearbeitung nach der Rapsernte, gefolgt von einer effektiven chemischen Kontrolle mit einer Kombination der Wirkstoffe Metamitron, Phenmedipham, Desmedipham, Ethofumesat und Lenaciel in nachgebauten Zuckerruben. Stichworter: Ausfallrapsmanagement, Clearfield ® , Fruchtfolge, Herbizidtoleranz, Imidazolinone, Triflusulfuron, Winterraps Response of imidazolinone-tolerant volunteer oilseed rape to herbicides and herbicide mixtures used for broadleaved weed control in sugar beet Due to a higher proportion of oilseed rape ( Brassica napus ) in sugar beet rotations, volunteer oilseed rape can occur in increased numbers in subsequent crops. The sulfonylurea triflusulfuron is widely used for broad-leaved weed control in sugar beet, but may no longer be effective to control imidazolinone-tolerant volunteers when imidazolinone-tolerant oilseed rape is grown, which is due to a cross-tolerance to ALS-inhibiting herbicides. Aim of the study was to evaluate six different herbicide strategies for the control of tolerant volunteer oilseed rape. As a result, imidazolinone-tolerant oilseed rape showed a distinctive cross-resistance to triflusulfuron in the field. Mean herbicide efficacy was 14 % and was only slightly increased by combination with metamitron. Imidazolinone-susceptible and -tolerant oilseed rape varieties showed different response to the herbicide treatments. A significantly higher reduction of plant fresh mass (shoot) > 90 % was caused by herbicide treatments that included the active ingredients desmedipham, phenmedipham, ethofumesate, chloridazon and quinmerac. The results showed that triflusulfuron is no longer suitable to control volunteers if they are derived from imidazolinone-tolerance expressing varieties. However, alternative herbicides are available. Generally, increased attention has to be paid to volunteer management within the whole crop rotation if imidazolinonetolerant oilseed rape is grown. Appropriate tillage strategies after oilseed rape harvest have to be followed by effective herbicide treatments in the subsequent sugar beet, for example a mixture of metamitron, phenmedipham, desmedipham, ethofumesat and lenaciel. Keywords: Clearfield ® , crop rotation, herbicide tolerance, imidazolinones, oilseed rape, triflusulfuron, volunteer management

Changes in Application System - Influence on Herbicides Residue in Soil and Sugar Beet Roots

Changes in Application System - Influence on Herbicides Residue in Soil and Sugar Beet RootsThe aim of performed investigation was to evaluate the influence of changes in herbicide application system on herbicide residues in soil and sugar beet roots. Chemical weed control in sugar beet was carried out by herbicides that included substances such as phenmedipham, desmedipham, ethofumesate, metamitron, triflusulfuron and surfactant adjuvant applied in three different systems: two times application at bare soil (preemergence) and postemergence application (weeds in phase of 2-4 leaves) - system "A", 3 times split, postemergence application (full dose of herbicide mixture) - system "B" and 4 times application at 7 to 10 day intervals starting at the beginning of weed emergence - system "C". Samples of soil and roots of sugar beet were taken at the day of lifting. Herbicide residues were analysed using HPLC with UV-detection. At lifting time, in soil samples, where herbicides were applied in system "A", the residues of metamitron amounted from 0.0097 to 0.0132 mg/kg. Sum of all detected residues of applied substances amounted 0.0341-0.0458 mg/kg. In sugar beet root samples, the residues amounted to respectively, 0.0049-0.0064 and 0.0136-0.0247 mg/kg. The application of herbicides in "B" and "C" systems caused a significant decrease of residues by about 50% (system "B") and 65% (system "C") on average, in comparison with results obtained for herbicide application in "A" system. Residues of active substances determined in roots of sugar beet did not exceed acceptable limits (MRLs).

Practical experiences with a system for site‐specific weed control in arable crops using real‐time image analysis and GPS‐controlled patch spraying

SummaryInformation on temporal and spatial variation in weed seedling populations within agricultural fields is very important for weed population assessment and management. Primarily, spatial information allows a potential reduction in herbicide use, when post‐emergent herbicides are only applied to field sections with high weed infestation levels. This paper presents a system for site‐specific weed control in sugar beet, maize, winter wheat, winter barley, winter rape and spring barley. The system includes on‐line weed detection using digital image analysis, computer‐based decision making and Global Positioning System‐controlled patch spraying. In a 2‐year study, herbicide use with this map‐based approach was reduced in winter cereals by 6–81% for herbicides against broad leaved weeds and 20–79% for grass weed herbicides. Highest savings were achieved in cereals followed by sugar beet, maize and winter rape. The efficacy of weed control varied from 85% to 98%, indicating that site‐specific weed management will not result in higher infestation levels in the following crops.

The effect of root‐absorbed PSII inhibitors on Kautsky curve parameters in sugar beet

SummaryThe effects of the photosystem II inhibitors metamitron and terbuthylazine on the shape of the Kautsky (chlorophyll fluorescence induction) curve were investigated in sugar beet grown in hydroponic culture. The objective of the study was to trace recovery processes following herbicide injury using Kautsky curve parameters. Metamitron is used for selective weed control in sugar beet because it is metabolized in this crop. In contrast, terbuthylazine is toxic to sugar beet. Two hours after treatment, various fluorescence induction curve parameters, such as maximum quantum efficiency (FV/Fm), the relative changes at the J step (Fvj) and area (the area between the Kautsky curve and maximum fluorescence, Fm), were affected by metamitron at concentration ranges of 70–280 mg active ingredient (a.i.) L−1 in plants treated at the four‐true‐leaf stage. Shortly after herbicide application, Fv/Fm was more affected by the hydrophilic metamitron [log(Kow) = 0.83] than by the lipophilic terbuthylazine [log(Kow) = 3.21], but these differences between compounds were alleviated as metamitron was metabolized and terbuthylazine was not. Terbuthylazine at 1 mg a.i. L−1 affected sugar beet at the four‐ and six‐true‐leaf stages to the same extent, whereas metamitron at a dose of 140 mg a.i. L−1 affected much more at four‐ than at the six‐true‐leaf stage. Sugar beet recovered from metamitron injury even at high doses (140 and 280 mg a.i. L−1). Fluorescence induction curve parameters were similarly affected by terbuthylazine and, although sugar beet recovered from terbuthylazine injury at low doses (<0.2 mg a.i. L−1), the Kautsky curve was irreversibly affected at higher doses (1–10 mg a.i. L−1), leading finally to plant death. Older plants were affected later, and recovered sooner, from both herbicides.

Repeated Reduced Rates of Broadleaf Herbicides in Combination with Methylated Seed Oil for Postemergence Weed Control in Sugarbeet (Beta vulgaris)1

Field trials were conducted at five sites from 2001 through 2003 to determine the influence on sugarbeet and weeds of repeated broadcast and banded reduced rates of desmedipham plus phenmedipham, triflusulfuron, and clopyralid in combination with either 1.5 or 3% v/v methylated seed oil (MSO). Desmedipham plus phenmedipham, triflusulfuron, and clopyralid were applied POST three times at 5 to 7 d intervals at either 25, 50, 75, or 100% of a 180 plus 180 plus 18 plus 100 g ai/ha dosage (full rate). When averaged over all herbicide rates, crop injury was 6% greater, but common lambsquarters control was 5% higher, and crop yield was 15% greater with broadcast compared with banded herbicide application. In most situations, adding MSO at 3% rather than 1.5% did not improve weed control. Sugarbeet injury was lowest (11%) and the average weed control was 86% when herbicide rates (with 1.5% MSO) were 25% of the full rate (microrate). Applying an herbicide rate (with 1.5% MSO) that was 50% of the full rate (half rate) increased crop injury from 11% with the microrate to 18% with the half rate and elevated average weed control from 86% with the microrate to 92% with the half rate. Common lambsquarters control increased from 81% with the microrate to 89% with the half rate. Sugarbeet root yield was 23 t/ha when no herbicide was used, 48 t/ha with the microrate, and 49 t/ha with the half rate compared with 54 t/ha when the full rate was applied without MSO. Increasing herbicide rates to 75% of the full rate (three-quarter rate) (with 1.5% MSO) increased crop injury to 27% and average weed control to 96%. Applying 1.5% MSO to the full rate increased crop injury to 35% with no improvement in average weed control over that achieved with the full rate without MSO.Nomenclature: Clopyralid; desmedipham; phenmedipham; triflusulfuron; common lambsquarters, Chenopodium album L. #3 CHEAL; sugarbeet, Beta vulgaris L. ‘Beta 1775’, ‘Beta 4546’, ‘HM1639RZ’.Additional index words: Adjuvants, crop tolerance, crop yield.Abbreviations: DAT, days after treatment; full rate, desmedipham plus phenmedipham, triflusulfuron, and clopyralid at 180 plus 180 plus 18 plus 100 g/ha; half rate, desmedipham plus phenmedipham, triflusulfuron, and clopyralid at 90 plus 90 plus 9 plus 50 g/ha; microrate, desmedipham plus phenmedipham, triflusulfuron, and clopyralid at 45 plus 45 plus 4.5 plus 25 g/ha; MSO, methylated seed oil; three-quarters rate, desmedipham plus phenmedipham, triflusulfuron, and clopyralid at 135 plus 135 plus 13.5 plus 75 g/ha.

Weed Control in Sugar Beet using Genetically Modified Herbicide‐tolerant Varieties – A Review of the Economics for Cultivation in Europe

AbstractGenetically modified sugar beet varieties have been developed to be tolerant to glyphosate and glufosinate. To date, research regarding other active ingredients did not result in additional herbicide‐tolerant varieties and the approval of glufosinate‐tolerant varieties for market access has been withdrawn by the applicant. Therefore, only glyphosate‐tolerant varieties could be introduced for cultivation in the short run. Results concerning efficacy and cost of weed control using these varieties and the complementary herbicides were extensively reported in various contributions, mostly on a national level. Based on these results, the economics of weed control for sugar beet production in Europe were reviewed and aspects of integrated control, risk management, and issues of sustainable development of crop production are discussed. Efficient weed control is possible in almost any field situation with glyphosate at about 2 kg a.i. ha−1, compared with conventional herbicides at 6 kg ha−1 or higher, depending on weed infestation level. Cost savings for weed control with glyphosate would amount to an average of €150 ha−1, without any great deviation across different sites and states. A technology fee of about €40 ha−1 is assumed. The high selectivity of glyphosate may result in a 1–3 % higher yield performance of the crop. All assumptions being considered, total cost savings of €180 × 106 year−1 were calculated for the area of 1.7 × 106 ha in the main EU sugar beet‐growing countries. A risk management by implementing a monitoring programme is compulsory, and systems of identity preservation or quality assurance are needed in order to enable the production of conventional and genetically modified sugar beet in coexistence. To date, costs are unknown for these measures. Because of the favourable ecotoxicological behaviour of glyphosate and the possibility of threshold‐based weed control, this new technology could provide an excellent option towards sustainable development of the crop. However, political reasons and the lack of acceptance of genetically modified varieties by the consumer have prevented the market entry of GMHT sugar beet to date, so that conventional herbicides will continuously be used in the future.