Permit – Ein neues Herbizid zur Bekämpfung von Cyperus esculentus in Mais

Permit mit dem Wirkstoff Halosulfuron (750 g/kg WG) ist ein neues Maisherbizid. Die Annex I Listung liegt seit Oktober 2013 vor. Bei der Kontrolle des schwer bekämpfbaren Erdmandelgrases (Cyperus esculentus) nimmt Permit eine Sonderstellung ein. Erdmandelgras ist ein invasiver Neophyt aus der Familie der Cyperaceae (Sauergräser). Spezifische Gräserherbizide, die zur Bekämpfung von Poaceae (Süßgräser) eingesetzt werden, haben gegen Cyperaceae eine Wirkungslücke. Die Vermehrung erfolgt rasant und in Deutschland ausschließlich über Wurzelknollen (Mandeln) im Boden. Die Befallsflächen haben in Deutschland in den letzten Jahren stark zugenommen, betroffen ist vor allem Niedersachsen. Permit wurde mit Aufwandmengen von 30-50 g/ha als Einmalbehandlung sowie im Splittingverfahren in insgesamt 7 Versuchen zur Bekämpfung von Erdmandelgras in Mais getestet. Entscheidend für den Bekämpfungserfolg war der Applikationstermin. Hohe Wirkungsgrade wurden mit 30-50 g/ha Permit als Soloanwendung zu BBCH 16 des Maises erzielt (Wirkungsgrade 94-98 %), sowie durch das Splittingverfahren im 4- und 6-Blattstadium des Maises (Wirkungsgrade 94-99 %). Da Erdmandelgras in Mais häufig in mehreren Wellen aufläuft, bietet das Splittingverfahren teilweise eine höhere Wirkungssicherheit. Permit bietet damit neue Möglichkeiten, Erdmandelgras wirkungsvoll in Mais zu bekämpfen und schließt damit eine entscheidende Wirkungslücke der zurzeit verfügbaren Maisherbizide. Permit – A new herbicide for control of Cyperus esculentus in maizePermit, containing the active ingredient halosulfuron (750 g/kg WG) is a new herbicide in maize. It is listed in Annex I since October 2013. Permit plays a special role when dealing with the hard to control weed yellow nutsedge (Cyperus esculentus). Yellow nutsedge is an invasive plant belonging to the family Cyperaceae (sedges). Specific graminicides used to control Poaceae (sweet grasses) are not effective against Cyperacea. Propagation is rapid and occurs exclusively via tubers formed in the soil. Affected areas in Germany grow rapidly, especially in Lower-Saxony. Application rates from 30-50 g/ha Permit were tested in solo or split application in 7 trials to control Cyperus esculentus in maize. Application timing proved critical for successful control. High levels of control were achieved with 30-50 g/ha Permit with single applications at BBCH 16 (efficacy 94-98%) as well as with split applications at BBCH 14 and 16 of the crop (efficacy 94-99%). Because yellow nutsedge often emerges in multiple waves, the split application provides more reliable control. Permit offers new opportunities to effectively control Cyperus esculentus in maize and thus closes an important gap in the weed spectrum of currently available maize herbicides

Reduction of selection pressure of herbicides - options and limits for blackgrass management by using clethodim in oilseed rape in the presence of the Leu1781 haplotype

In field experiments the control of blackgrass (Alopecurus myosuroides, Huds.) in oilseed rape using clethodim (Select EC 240) and cycloxydim (Focus Ultra) with and without subsequent treatments with propyzamide (Kerb FLO) was tested at 6 locations in North and South Germany with assumed resistance problems. The field experiments were accompanied using molecular analysis leaf samples from the plots to seize the occurrence of black-grass with the Leu 1781 haplotype and to determine the frequency of the genotypes. The goal of the trials was to correlate the successes of blackgrass control with the occurrence of hetero- and homozygous resistant genotypes. It was shown in greenhouse trials that clethodim selects the haplotype Leu1781 more weakly (and it shows a higher partial efficacy) than cycloxydim and that heterozygous plants have a lower resistance factor than homozygous plants. The question raised whether the frequency of heterozygous plants has influence on increased efficacy of clethodim under field conditions. At 5 sites target-site resistance was detected. At one location the high proportion of heterozygous plants correlated positive with relative higher control using Select EC 240 (80%) compared to Focus Ultra (0%). At two locations with high proportion of homozygous resistant plants Select EC 240 and Focus Ultra treatments without subsequent treatments with Kerb FLO were not sufficient in solo variants. The subsequent treatments with Kerb FLO provided partly, but not sufficient control of black-grass. At one location no resistance was identified. The effect of Select EC 240 and Focus Ultra to control black-grass were comparable high in all variants with and without subsequent treatments of Kerb FLO. The investigations showed clearly a higher degree of control by plants with the haplotype Leu1781 by the active substance clethodim and pointed out the fact that the frequency of resistant genotypes (homo vs. heterozygous resistant plants) has a clear influence on the resistance selection. The use of DIMs at locations suspected to be resistant should be assured only with the help of propyzamide and nonchemical measurements (e. g. ploughing, crop rotation). The results also indicate that it is necessary to assess resistance mechanisms in resistance research individually depending on the active ingredients, inheritance and weed species