Herbicide resistance poses an increasing problem for agriculture. More and more farmers are forced to recognize that the herbicides they have been using for years are no longer providing the desired results. Farmers have known for a long time that weeds and grass weeds are a growing problem. Up to now, however, there was no current data to analyze the problem precisely and to initiate appropriate measures.

 

Agris42 has carried out 2578 resistance tests in the last two years in order to be able to analyze the problem in detail. Data from 1369 fields was evaluated annually in this process. In order to be able to create a clear picture of the current resistance situation, several fields of the farms were observed over the entire period. The fields tested are not exclusively cultivated areas that have attracted a lot of weeds. In order to be able to create an overall picture, fields that had not previously shown any problems with herbicide resistance were also observed and tested over the long term.

General observations on the subject of resistance

When evaluating the analyzes, it was found that there is herbicide resistance on every area on which weeds or weed grasses also grow. Resistance and infestation are two different factors, but they can be interdependent. Herbicide resistance must be considered as a biological defense mechanism. Plants that are herbicide resistant have an advantage over plants without herbicide resistance. They survive the treatment and can thus reproduce to the extent that the weed infestation on the cultivated areas can no longer be combated.

 

The farmer usually has no tools he can use to identify growing herbicide resistance. The problem is made even more difficult by the fact that herbicide resistance develops differently on the various cultivation areas of a farm and only individual measures allow effective, continued cultivation. Only a resistance test can offer farmers the opportunity to use an efficient herbicide management in order to be able to control herbicide resistance in their fields.

The resistance situation concerning redroot

Redroot is the greatest threat on German acreage. Herbicide resistance is particularly evident in Baden-Wuerttemberg, Thuringia, Lower Saxony and Schleswig-Holstein. In the other crop areas, redroot resistance can only be found locally and sporadically. The test series showed that on average the pressure from redroot is also higher in the affected federal states.

ACCase is more likely to be affected by herbicide resistance than the ALS active ingredients. The active grain-ingredients, such as Atlantis, Axial and Broadway, are more often affected by herbicide resistance than the active corn- or root crops-ingredients.

Tip: You can obtain further information by clicking on the federal states on the interactive map.

The resistance situation concerning wind grass

During the investigations it was found that the herbicide resistance of wind grass and redroot does not overlap in the problem areas. The eastern states of Germany and the state of Hesse are most affected by wind grass resistance.

The ALS active ingredients are more affected by the wind grass resistance than the ACCase active ingredients. In the problem areas it was found that HusarOD and Broadway are more likely to be affected by herbicide resistance than MaisterPower with the ALS inhibitors (active ingredient group B). Axial50, Agil-S and Select 240EC (active ingredient group A) are just partially affected by a resistance.

Tip: You can obtain further information by clicking on the federal states on the interactive map.

The resistance situation concerning ryegrass

Ryegrass resistance could only be found in Saxony, Hesse, Rhineland-Palatinate and Mecklenburg-Western Pomerania. A strong ryegrass infestation was found in Mecklenburg-Western Pomerania. A sometimes very strong level of resistance was found in Italian ryegrass (Lolium multiflorum); German ryegrass (Lolium perenne) is not yet affected by resistance.

All tested active ingredients are affected by ryegrass resistance, with the exception of Select 240 EC (Clethodim).

Tip: You can obtain further information by clicking on the federal states on the interactive map.

The resistance situation concerning brome

In order to get precise data on the herbicide resistance of brome, the following 5 species were tested:

  • meadow brome (Bromus commutatus)
    • more likely in the western states of Germany
  • barren brome (Bromus Sterilis)
    • more likely present in the eastern states of Germany and in the state of North Rhine-Westphalia
  • downy brome (Bromus Tectorum)
    • rarely found everywhere
  • chess (grass) (Bromus Secalinus)
    • found everywhere
  • barley brome (Bromus mollis)
    • Central Germany

Normally only a low level of brome infestation was found on the cultivated areas observed. Only a few fields had an all-over infestation. In the northern regions of Baden-Wuerttemberg and Thuringia, selective resistance was found in the barren brome.

Through the herbicide resistance analysis it was possible to deduct that so far only resistances occur in the meadow and the barren brome. Herbicide resistance is related to AtlantisFlex and Attribute (ALS) in most cases. In rare cases, ACCase resistance could also be determined.

Tip: You can obtain further information by clicking on the federal states on the interactive map.

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