Weed populations in winter wheat as affected by crop sequence, intensity of tillage and time of herbicide application in a cool and humid climate

Abstract

Summary There is a lack of information on the combined effects of preceding crop, reduced tillage (especially no‐tillage) and the time of herbicide application on the development of weed populations and the efficiency of weed control in winter wheat in humid temperate climates. An experiment was conducted with a crop rotation (winter wheat – oilseed rape – winter wheat – maize) on a sandy loam and a loamy silt soil in the Swiss midlands to investigate the impact of different preceding crops and pre‐ and post‐emergence control of weeds in conventional tillage (CT; mouldboard plough), minimum tillage (MT; chisel plough) and no‐tillage (NT; no soil disturbance systems). When winter wheat was grown after maize and winter wheat was grown after oilseed rape, the ranking order of weed density in treatments without herbicide application was NT < MT < CT and CT < MT < NT respectively. Analysis of variance and canonical discriminant analysis showed that Epilobium spp., Sonchus arvensis, Myosotis arvensis and volunteer crops were more abundant in NT than in MT and CT. The efficiency of post‐emergence weed control was generally better than that of pre‐emergence weed control, regardless of tillage intensity.

Summer cover crops for weed management and yield improvement in organic lettuce (Lactuca sativa) production

“…Nevertheless, CDA results suggested that these weeds were significantly associated with hairy vetch, grain sorghum and sudangrass. This type of inconsistent results was reported previously (Barberi and Mazzoncini 2001;Streit et al 2005). The highest lettuce yield (22,050 kg ha −1 ) was obtained with hairy vetch (Fig.…”

“…To evaluate association between the occurrence of weed species and the cover crop treatments, a vector diagram based on the total canonical coefficient of each weed species from the canonical functions was combined into the same plot. The species are represented as vectors whose length indicates the degree of association with a direction in ordination space (Barberi and Mazzoncini 2001;Shrestha et al 2002;Streit et al 2005). The appearance of weed species vectors and cover crop treatments in the same ordination space suggests association of those weeds with the cover crops (Légère et al 2005).…”

Effects of alternative winter cover cropping systems on weed suppression in organically grown tomato (Solanum lycopersicum)

“…For example, C. nutans and C. arvensis were not controlled with any of the cover crop treatments, but CDA results show that C. nutans and C. arvensis were significantly associated with V. sativa, V. villosa, S. cereale and A. sativa. These types of inconsistencies were reported previously (Barberi and Mazzoncini 2001;Streit et al 2003).…”

“…At each sampling date, weed community composition was analyzed by means of canonical discriminate analysis with the CANDISC procedure in SAS. To evaluate how the occurrence of weed species and the cover crop treatments were associated, a vector diagram based on the total canonical coefficient of each weed species from the canonical functions was combined into the same plot (Streit et al 2003). The type and degree of association between weed species and cover crops is represented in an ordination bi-plot created by superimposing a vector diagram on the scatterplot with vectors representing weed species (Barberi and Mazzoncini 2001).…”

Evaluation of Selected Herbicides on Weed Control Efficiency and Yield of Wheat

“…The study revealed that, post emergence application of Carfentrazone-ethyl (Hammer 24EC) provided better weed control efficiency in wheat field which was attributed by lower weed density as well as biomass under this treatment when compared to other herbicidal treatments. The efficiency of post-emergence weed control in wheat was also claimed to be superior to that under pre-emergence weed control (STREIT, et al, 2003). However, combined ingredient herbicide Carfentrazone-ethyl + Isoproteuron contributed to better crop growth and development, TDM production and highest grain yield as observed through this study.…”