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Long‐term changes in weed occurrence, yield and use of herbicides in maize in south‐western G ermany, with implications for the determination of economic thresholds
Author(s) -
Keller M,
Böhringer N,
Möhring J,
RuedaAyala V,
Gutjahr C,
Gerhards R
Publication year - 2014
Publication title -
weed research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 74
eISSN - 1365-3180
pISSN - 0043-1737
DOI - 10.1111/wre.12098
Subject(s) - weed , chenopodium , weed control , galium , agronomy , biology , population , bromoxynil , yield (engineering) , competition (biology) , ecology , demography , materials science , sociology , metallurgy
Summary In 393 field experiments in Baden‐Württemberg region in south‐western Germany, herbicide efficacy, yield loss and crop tolerance of maize ( Zea mays ) were investigated between 1981 and 2011. The collected data served to determine changes in weed frequencies, in herbicide use, yield loss functions and economic thresholds (ETs). Over 60 weed species were reported. Chenopodium album and G alium aparine were the most frequent broad‐leaved weeds, the former becoming more frequent over time. Species of the genera Lamium , Polygonum , Veronica and Matricaria occurred in about every fifth trial. Alopecurus myosuroides and E chinochloa crus‐galli were the most frequent grass weeds; the former declining in frequency by 1.1% per year, the latter increasing by 1.5%. Results suggest a weed population shift towards thermophilic species. aceto‐lactate‐synthase and 4‐ HPPD ‐inhibitor herbicides became important in the 1990s. Pendimethalin and bromoxynil have been integral components of weed control since the 1980s. ETs, the point at which weed control operations provide economic returns over input costs, ranged between 3.7% and 5.8% relative weed coverage. Without weed control, no yield increase was found over 24 years. Yield increased by 0.2 t ha − 1 year − 1 , if weeds were controlled chemically. Despite intensive use of effective herbicides in maize, problematic weed species abundance and yield losses due to weed competition have increased in Baden‐Württemberg over a period of 30 years.