Is the validation of chemical weed control in linseed possible within the framework of a minor use procedure?

Abstract

In 1999 more than 68,000 hectares linseed was cultivated in Brandenburg. Today the production has decreased to 5,000 hectares throughout Germany. Fifty percent of the production sites are still in Brandenburg with its sandy soils. According to §§ 18, 18a PflSchG (1998) the herbicides Callisto and Ciral are approved for the control of annual mono- and dicotyledonous weeds until the end of 2014. Various products have been tested for their herbicidal activity and phytotoxic disturbance of the crop because linseed is hard to grow on many sites without chemical weed control. Until 2008 the herbicide Concert dominated linseed production because of its ability to include a wide range of different weeds through splitting application. The §18, §18a approval for Concert ended because the manufacturer recalled Concert and released Concert SX, a generic equivalent with the same active ingredients. The ingredients thifensulfuron and metsulfuron in Concert SX have been known to cause delayed blooming. In experiments with Concert SX more phytotoxic damage to the linseed crop like growth inhibition and thinning of inventory could be determined at some test sites. Since 2008 for postemergance application only Ciral is available, but insufficient effects on Galium aparine, Polygonum aviculare, Fallopia convolvulus, Viola arvensis, Chenopodium album, and Fumaria officinalis could be detected. Therefore other herbicides e.g. sulfonylurea were given particular attention in the last few years. The experimental results show that only a few of the tested herbicides, due to the phytotoxic disturbance of the linseed crop, can be used in order to widen the range of herbicides following the regulations of Artikel 51 VO 1107/2009.

Keywords

• frequency
• herbicide efficiacy
• post-emergence application
• sulfonyl-ureas