Zusammenfassungen der Arbeitskreisbeiträge - Die DPG

Observations, field trials and analysis of a special population
of mayweed (Matricaria recutita) with resistance against
ALS-inhibitors in Schleswig-Holstein (Germany)
C. Schleich-Saidfar 1, H.G. Drobny 2, J. Perez 2, M. Feierler,
F.G. Felsenstein 3, J.-R. Gertz 1 & N. Balgheim 4
1 Landwirtschaftskammer Schleswig-Holstein,
Am Kamp 15–17, 24768 Rendsburg;
2 Du Pont Deutschland, Neu Isenburg;
3 Epilogic GmbH, Freising;
4 Universität Hohenheim, Institut für Phytomedizin
On a cereal field (winter wheat) near Husum (Schleswig-Holstein,
Northern Germany) the control of mayweed by sulfonylureas
became insufficient in 2005. For that reason field trials
were installed from 2006 – 2010 at this place. The trials
showed that the mayweed plants at this site could not be controlled
any longer by sulfonylureas. These herbicides – several
different sulfonylureas were tested – had no more effect at all
on this mayweed, all of them. Seed samples of mayweed from
these trials in 2006 were characterised in different bio-tests.
Dose response curves were obtained with ALS-inhibitors,
done by Epilogic GmbH, at Freising, Germany, initiated by Dr.
H. G. Drobny, Du Pont. The results suggested a specific target-site
resistance against ALS-inhibitors. Further analysis,
done by N. Balgheim, of tissue samples in 2007 with respective
molecular primers confirmed a known mutation at the
ALS. This was the first confirmed case of an ALS-target-site
resistance in mayweed in Germany. The mayweed from the
test-site was resistant especially against sulfonylureas, but not
against triazolo-pyrimidins. The trials showed that the mayweed
from the test site could still be controlled by pyrazolo-pyrimidins
(Florasulam – Primus). At this field sufonylureas
had been used for many years in order to control mayweed,
so an extreme selection pressure had taken place.
Management strategies were derived from the field trials:
The control of mayweed should be done best by the use of
pre-emergence herbicides respectively by these herbicides,
placed just after the emergence of the weed (flufenacet +
diflufenican – Herold or flufenacet + flutamone + diflufenican
– Bacara Forte or – on undrained sites – with IPU-,
CTU-herbicides + diflufenican). In cereals, sown late in autumn,
the control of resistant mayweed should be done by
the application of IPU or CTU (+ diflufenican) in early spring
(March). In Germany the use of CTU is allowed on undrained
fields only. Mayweed remaining from the autumn or mayweed
coming up in spring can also be controlled in spring
(April) by herbicides, containing florasulam (Primus, Starane
XL. Ariane C) or by herbicides containing bentazon (Basagran
DP) respectively by herbicides containing clopyralid
(Ariane C, Duanti) at this site. However, the possibility of
cross resistance against florasulam cannot be quite excluded,
when using it too often. Crop rotation implying the application
of herbicides with different modes of action should be
practiced at any case.
Herbicide resistance in Alopecurus myosuroides and
Apera spica-venti
Dirk Wolber
Landwirtschaftskammer Niedersachsen, Pflanzenschutzamt
Hannover
In Lower Saxony biotests for herbicide resistance with the main
grass weeds Alopecurus myosuroides and Apera spica-venti are
done in greenhouse trials. Samples are taken from regional
plant protection services and sent to the lab in Hannover.
Results from recent years showed that resistance to both grasses
is widespread. Multiple resistance in Alopecurus myosuroides to
J.Plant Dis.Protect. 2/2011
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ureas, ACCase, and ALS-inhibitors is quite common. Control
of these biotypes is very hard for the cereal farmers.
Actual status of occurrence of herbicide resistant grass
weeds in Germany
Jan Petersen 1 & Hans Raffel 2
1 University of Applied Sciences Bingen,
2 Syngenta Agro Maintal
Occurrence of herbicide resistance in grass weeds in Germany
is not a new phenomenon, however in recent years spread of
resistance and characters of resistance increased significantly.
In a resistance monitoring program of Syngenta and the
University of Applied Sciences Bingen seed samples of different
winter cereal fields in Germany were tested for resistance
to different leaf active herbicides. Alopecurus myosuroides
(ALOMY), Apera spica-venti (APESV), Lolium sp. (LOLSS) and
Avena fatua (AVEFA) were grown in a greenhouse and sprayed
in the 1 to 2-leaf stage with relevant herbicides.
77% of suspicious ALOMY samples (n = 135) showed a
resistance to cereal selective ACCase-inhibitors. But only 17%
out of these samples showed a cycloxydim resistance (indicating
an ACCase target-site-resistance). Resistance to mesosulfuron
occurs, but also on a lower level (18%). One sample
presented a combination of ALS- and ACCase-target-site resistance
in the ALOMY population. Most of the samples indicated
a cross-resistance or a multiple resistance on the basis of a
non-target-site resistance.
The monitoring on APESV (n = 213) was based on a mixture
of random and sampling on fields with resistance suspicion
(n = 213). Consequently, less biotypes showed a strong
herbicide resistance (29%). Mainly resistance was obvious to
sulfonylureas. 50% of the samples showed a reduced efficacy
and 22% a strong resistance to ALS-inhibitors. IPU-resistance
was detected in 15% of the sites. However, in 61% of the biotypes
a reduced efficacy to IPU was observed. Resistance to
pinoxaden was found in 4% of the samples. In cases of pinoxaden
resistance all biotypes showed a multiple resistance
to sulfonylureas and in some cases also to IPU. Only a few biotypes
(12%, based on 162 samples) expressed a resistance to
pyroxsulam with a cross-resistance to sulfonylureas. In these
cases often an ALS target-site resistance could be detected.
One APESV population showed a combination of an ACCase
and ALS-target-site mutation.
Some samples of AVEFA (n = 6) with control problems in
the fields were tested in the greenhouse with treatments of
ALS-inhibitors and with pinoxaden. No resistance was detected.
For LOLSS 4 samples were analysed. Three out of five samples
showed a resistance to pinoxaden. One sample showed a multiple-resistance
to flufenacet and another biotype showed a
multiple resistance also to ALS-inhibititors.
Glyphosate hormesis – an herbicide shows depth effects
Regina G. Belz
University of Hohenheim, Department of Agroecology (380b),
70593 Stuttgart, regina.belz@uni-hohenheim.de
Glyphosate is currently the most important active ingredient for
controlling weeds. However, glyphosate shows useful effects in
addition to killing weeds at high doses. The patenting of
glyphosate as an herbicide in 1970 was followed by several applications
in the non-lethal, low dose range such as in 1974 a
patent for plant growth-regulation by sub-lethal glyphosate
doses. In the hormetic dose range, where glyphosate has a
stimulating effect on plants, the usage of glyphosate to increase
the carbohydrate content of plants was patented in