| Abstract: |
Weed composition and herbicide use in sugar beet fields
varied in the last decades. This study was conducted to
determine and analyse changes in weed composition and
herbicide use strategies on regional and national scale in
Germany based on data of the Sugar Beet Cultivationsurvey
(1994–2010) and NEPTUN-survey – Sugar Beet
(2005, 2007 and 2009). On national scale, the occurrence
of the most important common weeds has partly
tripled and difficult-to-control weeds partly doubled from
1996 to 2010. Most important common weeds were goosefoot
(CHESS), knotweed (POLSS) and cleaver (GALAP)
with a spread of at least 36% up to 79%. The most difficult-
to-control weeds were knotweed (POLSS), annual
mercury (MERAN) and fool‘s parsley (AETCY), which
occurred on less than 26% of the acreage in 2010. Acreage
of mulch tillage systems and post-emergence treatments
increased, while treatment frequency was relatively
constant at approximately 3.0–3.5. Number of herbicide
products and active ingredients used per treatment were
relatively constant at 2.5 and 4.0, respectively, but treatment
index per treatment changed significantly between
the years from 2.0 to 2.4. Exemplarily, fields of exemplary
regions in the north, west and south were characterised
by specific weed compositions, which were regulated by
adopted herbicide use strategies. Strategies differed in
treatment frequency, varying from 2.9 to 4.5, number of
herbicide products per treatment, varying from 2.2 to
3.5, number of active ingredients per treatment, varying
from 3.6 to 4.8 and treatment index, varying from 1.47
to 2.51 in 2009. For the first time, the analysis of weed
composition was done in relation to herbicide use strategies
by comparable data. Weed species-specific adoption of
treatment patterns, herbicide use intensity and reduced
application rates clarify the implementation of the Integrated
Pest Management in sugar beet cultivation, which
is part of the EU-Directive 2009/128/EG for a sustainable
use of pesticides. |