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In winter rye which is grown mostly on locations with a lighter soil texture loose silky-bent grass (Apera spica-venti) is a dominate weed grass. Because of increasing herbicide resistance the control of A. spica-venti becomes more difficult. To manage resistant weed grass populations in winter rye flufenacet is a very important active substance. However, the application of flufenacet can lead to substantially culture damage. The influence of different factors influencing the tolerance of flufenacet applications in rye was proved in field trails carried out by the Landwirtschaftskammer Niedersachsen over several years. The degree of damage of culture increased with a higher amount of flufenacet being applicated. Damage, loss of plants and yield loss caused by flufenacet application differed between grown varieties of rye. The highest damage of culture was found on sandy soils with lowest humus content. The size of rye seed had no influence on the degree of damage or yield loss of rye caused by flufenacet application. Options to use flufenacet well-tolerated for winter rye are discussed.

CONVISO SMART is a new system to control monocotyledonous and dicotyledonous weeds in ALS-inhibitor tolerant sugar beets. This system consists of an ALS-inhibiting herbicide and a sugar beet variety which is tolerant against the complementary herbicide due to classic breeding mechanisms. The herbicide CONVISO is a combination of the two active ingredients foramsulfuron and thiencarbazonemethyl. Whereas foramsulfuron is the leaf active compound, thiencarbazone-methyl is leaf as well as soil active. The product will be formulated as an oily dispersion (OD). The registration was requested with an application rate of 1 x 1 l/ha or 2 x 0.5 l/ha in ALS-inhibitor tolerant sugar beets. Application should be done from BBCH 10 – 14 of the weeds, especially of Chenopodium album as well as from BBCH 12 – 18 of the sugar beet. The estimated introduction of this system on the German market will be 2018. CONVISO is well active against the most important weeds in sugar beets, including Polygonum and Chenopodium species. Furthermore several difficult to control weeds as Aethusa cynapium and Mercurialis annua will be controlled by CONVISO. The addition of special herbicides to control those difficult weeds will no longer be necessary. The tolerance of the variety against CONVISO is very strong, which will be shown by the results of the weed free selectivity trials. Due to the high tolerance of the variety against CONVISO and the not occurring of negative herbicide effects, the full yield potential can be utilized.

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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.

Copyright of Julius-Kühn-Archiv is the property of Julius Kuehn Institut and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Julius-Kühn-Archiv is the property of Julius Kuehn Institut and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rapid development of bioengineering has been accompanied by an increasing number of genetically manipulated (transgenic) crop plants. Decisive progress has been gained in the breeding of herbicide-resistant rape, beet and maize plants. The incorporation of the so-called PAT gene from Streptomyces viridochromogenes made the mentioned crop species tolerant to the herbicide agent glufosinat (preparation 'Liberty'). Using Liberty in resistant crops includes the following benefits: better weed control, observation of damage thresholds, post-emergence application of the herbicide, better control of problem weeds, reduction of tank mixtures and spraying operations, high environmental susceptibility, favourable economic effects etc. Public arguments about the risk of growing transgenic plants include the danger of outcrossing, rise of the potential allergies, negative affects on the environment. In the USA, Canada, South America and China transgenic crop plants are already cultivated on large areas. Prejudices against the progress of bioengineering in agriculture seems to be unjustified, because the benefits are clearly prevailing, and risks, if any, undergo comprehensive checking and careful evaluation. [ABSTRACT FROM AUTHOR]