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Assessment of herbicide resistant crops in reference to Germany’s Reduction Program in Chemical Plant Protection – Analysis of an 8-year experiment with glufosinate resistant oilseed rape and maize
Summary
The complete article is written in German
Results of a long-term experiment with glufosinate resistant oilseed-rape and maize were analysed regarding their importance for reduction of intensity and ecotoxicological risks of herbicide use. For this purpose, the treatment indices (BI) and SYNOPS risk potentials for biological risk were calculated. The BI in herbicide resistant maize increased in comparison with the conventional variant (1.2 vs. 0.9). In herbicide resistant oilseed rape, the BI was below the conventional variant right from the start (0.9 vs. 1.3). In both herbicide crops, SYNOPS risk potentials for aquatic organisms were reduced. In conclusion, herbicide resistant oilseed rape and maize in linkage with early or late post-emergence uses of glufosinate could be a future option that can meet main goals of Germany’s Reduction Program in Chemical Plant Protection.
Field trails on weed control in genetically modified glufosinate resistant sugar beet under ploughing and reduced tillage conditions
Summary
The complete article is written in German
In a field experiment from 1995 to 2001, options of weed control in genetically modified, glufosinate resistant (Liberty Link®) sugar beets have been evaluated. These sugar beets were cultivated under conventional (PF) and conservative tillage methods (MU). The field trail show that by using herbicide resistant sugar beets; it was possible to reduce the frequency of treatments with herbicides as well as the amount of herbicide used.
In the years 1996, 1997, 1999 and 2001 the field trials were destroyed by unknown persons. Despite that fact, it was possible to come to statements concerning the use of the herbicide resistant technology (HR Technology). Through the opportunity of a later herbicide use the integrated weed control in the sugar beet cultivation can be developed further. The control of weeds requires a very early herbicide application, since the authorized products only achieve a satisfying efficacy, if the weeds are still in the cotyledonous and first leaf stages. Therefore, under current practical conditions, a consequent and integrated weed management based on threshold levels cannot be realised. This concept applies weed control only in critical periods of sugar beet growth.
The experiment showed that the effect of Liberty 18 SL (Glufosinate 183g/l) on important arable weeds allows a later application. This could be the basis for further enhancements of weed control systems in the sugar beet cultivation and enables the sugar beet grower to conduct a more targeted weed control. Weeds mostly affect sugar beets at a later stage of development.
Through the cultivation of genetically modified, herbicide resistant sugar beets, it was possible to reduce the frequency of herbicide applications as far as to one application. The application of the soil sparing conservative cultivation method in sugar beet cultivation can be facilitated by the use of the HR-Technology. Thus, it could be possible to reduce pre-emergence treatments with herbicides.
Furthermore, the trials showed that a more flexible weed management is possible through the combination of herbicide resistant sugar beets with the herbicide Liberty 18 SL. That enables the sugar beet grower to conduct the herbicide application at a time. Thereby, soil structure damages can be minimized and consequently, the sustainability of modern agricultural cropping systems can be improved.
Experiences of introduction of imidazolinone-resistant sunflower in Hungary from the herbological point of view
Summary
Sunflower growing area reached about 450,000-500,000 hectares in Hungary in the last few years. A weak point of weed control of sunflower is the application of herbicides mainly against Ambrosia artemisiifolia (Common ragweed) and Cirsium arvense. As Hungarian soils are highly infected with these weeds, there is a need to find more reliable and effective solutions on weed control of sunflower.
Clearfield-Technology on sunflower was introduced in the spring of 2005 in Hungary on about 40.000 hectares mainly with the hybrid Rimisol. The application of this new weed control technology was observed with high expectations from the practice.
Studies were carried out in July 2005 in North-West-Hungary on some sunflower fields and the efficiency of the IMI-technology has been evaluated.
We established that early post application of Pulsar 40 SL (imazamox) that gives new possibilities for the control of dangerous weeds in sunflower, but there are some more details that should be further tested e.g. the use of pre-emergence weed control before Pulsar application. Based on our studies we also concluded that application of imazamox gives high efficacy for the control of non-planted conventional sunflower (from previous crop, as weed) on IMI-sunflower fields.
Assessment of transgene spread from oilseed rape by population dynamic and molecular analyses of feral oilseed rape
Summary
The complete article is written in German
Oilseed rape ( Brassica napus L.) has a certain potential to persist not only in arable fields but also in seminatural habitats and is therefore often found on ruderal sites, along road verges and railroad tracks. In view of the future cultivation of genetically modified oilseed rape in Germany and of the possible spread of transgenes our objective was to investigate the origin and the persistence of feral oilseed rape plants. To this end, oilseed rape plants detected at 74 ruderal locations between 2001 and 2004 were characterized in a comparative way through molecular ISSR markers and biochemical seed content analysis. In addition, population dynamic parameters like seed production and seed germination were determined in order to estimate the reproduction potential of ruderal oilseed rape. The results of our survey show that chances for the formation of permanent ruderal populations are very low despite the high reproduction potential of feral oilseed rape on ruderal sites. Germination, seedling development and the formation of viable seeds are highly dependent on the type of soil surface, on competing vegetation, on the occurrence of herbivores and pathogens as well as on management measures.
Avoiding herbicide resistance in weeds and conserving the active ingredients – A challenge for field advice, research and practice considering as example black-grass ( Alopecurus myosuroides Huds.)
Summary
The complete article is written in German
Reports about efficacy of graminicides against black-grass ( Alopecurus myosuroides Huds.) and other monocotyledonous species are increasing throughout different regions of Germany. If mistakes in herbicide application can be excluded the weed populations are probably complete or partly resistant. Herbicides belonging to inhibitors of PSII, ACCase and ALS are mostly affected. An important reason for this development is the continuous or nearly continuous use of herbicides with the same mode of action (MoA). This is promoted by agricultural factors which are responsible for the increasing density of grass species in fields. A rational herbicide management is necessary to preserve the herbicides where resistance exists against one ore more mode of action. Where no resistance occurred until today strategies to prevent the spread of resistance are necessary. The use of herbicides and agriculture measures are complementary. Different mode of action has to be combined and alternate. This needs a broad enlightenment of the practitioner. Besides the advice institutions, the research and the industry must deliver their dues.
Regional study of herbicide resistance of Alopecurus myosuroides Huds. in France
Summary
Since the 1990s in the north-west of Europe, the spread of herbicide resistance in wheat weeds such as Alopecurus myosuroides Huds. (blackgrass) is becoming more and more important. In the French administrative district Côte d’Or resistance to fenoxaprop within A. myosuroides populations was first detected in 1996. In 2003, 149 fields from this district were randomly sampled and about 125 A. myosuroides populations were tested for herbicide resistance. The agronomic history of all sites was investigated. Most the populations of A. myosuroides investigated contained at least 50 % of plants with resistance to fenoxaprop. In 53 and 9 % of these populations at least 50 % of plants were resistant to flupyrsulfuron and to clodinafop, respectively. Only one population could be considered as resistant to isoproturon. Strategies for A. myosuroides control are discussed in the light of this work. Herbicide resistance of A. myosuroides in the district Côte d’Or was mapped using GIS and the software Arcview®.
Management of metabolic resistant black-grass ( Alopecurus myosuroides Huds.) populations in Germany – challenges and opportunities
Summary
In the intensive winter-wheat growing areas, characterized by winter crop mono-culture, no ploughing, early seeding times and heavy soils, typical for the coastal and river marshlands in Lower Saxony and Schleswig-Holstein, black-grass populations were selected over several years, which exhibit resistance against several herbicides from different mode of action classes. A monitoring program was conducted over years, and confirmed in 2004 again the results from 2001-2003 that practically all resistant populations had developed a metabolic resistance mechanism. On 2 locations an additional ACCase-target-site resistance was found. A mathematical model developed for metabolic resistance demonstrates that such black-grass populations can not be controlled in a sustainable manner by only relying on herbicides. A successful long-term strategy includes a combination of agronomic measures, in particular ploughing, and herbicide programs. Mixtures of different herbicides are usually more effective than sequences in programs. Herbicide programs should aim for optimum control in the fall. Lexus® (flupyrsulfuron-m) + a residual herbicide, applied early post-em fall, consistently showed high levels of control. The pre-treatment with flupyrsulfuron-m has a positive effect on the activity against black-grass of a subsequently applied ALS-inhibitor herbicide.
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