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The proliferation of weeds in agricultural fields competes directly with crops for essential resources such as, leading to reduced crop yields and economic profitability. The objective of this study was to evaluate the effect of weed management practices on dry bean productivity and economic profitability. Field experiments were conducted between 2018 and 2019 following a Randomized Complete Block Design with four replications and seven treatments. The treatments included: MW (Manual hoe weeding 21DAS), H1 (paraquat 3 l ha−1), H2 (acetochlor 3 l ha−1), H3 (atrazine 3 l ha−1), H1H2 (paraquat 1.5 l ha−1plus acetochlor 1.5 l ha−1), H1H3 (paraquat 1.5 l ha−1 plus atrazine 1.5 l ha−1) and H2H3 (atrazine 1.5 l ha−1 plus acetochlor 1.5 l ha−1). Dry seed yield obtained in 2018 were similar regardless of treatments. However, in 2019, among the herbicides, H1 induced the highest yield (1t ha−1), while the lowest (0.45 t ha−1) was recorded with H2. In addition, the decrease in yield under MW (0.86 t ha−1) was due to the high density of following species: Cynodon dactylon, Commelina benghalensis, Imperata cylindrica, Bidens pilosa, Euphorbia heterophylla and Euphorbia hirta. The economic analysis of treatments using the Ratio Cost Value (RVC > 1) classified them in descending order: MW > H1 > H2H3 > H3 > H1H3 > H2 > H1H2. However, when the cultivated area to be weeded is expanding and labor becomes scarce, the rains are regular and abundant, manual hoeing may become tedious. In this case, the application of 3 l ha−1 of paraquat becomes an alternative to manual hoeing for farmers wishing to increase dry bean seed production. [ABSTRACT FROM AUTHOR]

In recent decades, cereal agriculture across main producing areas in Spain has progressively adopted direct sowing, associated with an increased use of herbicides in pre-sowing. Weedy species from genus Avena have been observed after the application of glyphosate in wheat. Here, Avena fatua (two accessions), Avena byzantina and Avena sterilis subsp. sterilis, one accession each, were taxonomically characterized by a biometric study. Dose-response trials confirmed that one A. fatua accession evolved to resistance, because it was four times more resistant (R) than the others, ascribed as susceptible (S). In addition, based on LD50, A. byzantina and A. sterilis had low susceptibility to glyphosate, with 604 and 458 g ae ha−1. Shikimic acid accumulation was able to discriminate between high susceptible (A. fatua (S)), low susceptible (A. byzantina and A. sterilis), and low resistant (A. fatua (R)) populations. On the other hand, the study revealed that A. fatua (R), A. byzantina and A. sterilis had low foliar uptake and decreased movement of glyphosate. In addition, the metabolism study showed less metabolite accumulation in A. byzantina and A. fatua (S). However, at 96 h after glyphosate application, A. fatua (R) and A. sterilis were able to convert more than 30% of glyphosate to aminomethylphosphonic acid (AMPA) and sarcosine. Enzyme basal activity and I50 values predicted high affinity between the herbicide and the target enzyme for all accessions, thus indicating that a target-site (TS) mechanism is probably not involved in the differences in glyphosate susceptibility. In closing, non-target site (NTS) mechanisms could participate both in A. fatua R to glyphosate, and low susceptibility in A. byzantina and A. sterilis from Spain. [ABSTRACT FROM AUTHOR]

Abstract: Glyphosate is world-wide seen as the most widely used herbicide ingredient. In Germany, from 1999 to 2010, the use of glyphosate based herbicides (GBH) increased by 100%. Many agronomical benefits are attributed to glyphosate, but there is also public criticism. To analyse current application patterns and to assess the agronomical importance of GBH in Germany, a survey was carried out among 896 arable farmers. The survey took place in early 2011, taking 2009 as a reference year. In Germany, cultivation of transgenic crops is generally not permitted and, therefore, herbicide resistance trait does not play any role in application patterns. Based on farmer''s statements, a calculated application area of 4.3 million hectare arable land was estimated, representing 39% of total arable area. Three application modes receive major proportions of glyphosate use, these are: pre-sowing (20.7% of application area), pre-harvest (11.2%) and stubble application (68.1%). Among the field crops, oilseed rape (including oilseed rape stubbles) is treated with 27.5% of the nation-wide glyphosate amount followed by winter barley (20.1%) and winter wheat (15.8%). Without using glyphosate, farmers expect an increase in the share of ploughed arable land from 38.1% to 71.4%. Also, without glyphosate the use of cultivator on stubble land is expected to increase about 1.6 passes on average. If applied pre-sowing, glyphosate could save herbicide applications in the following crop. Saving one application of a post-emergence herbicide was estimated by farmers for corn and sugar beet (46% of pre-sowing applications), silage maize (40%), oilseed rape (27%), and winter wheat (22%). Most applications are applied on off-crop fields, so farmers did not quote any observation of yield savings due to glyphosate. The nation-wide economic benefit of glyphosate due to savings of other agricultural measures such as soil cultivation and post emergence herbicides is calculated between 79 and 202 million Euro per year, depending on glyphosate price. We conclude, that glyphosate offers large benefits to farmers, though some routine applications results in only moderate economic benefit compared to the non chemical practices being replaced. Developing decision rules for farmers might allow for an optimum allocation of glyphosate use. [Copyright &y& Elsevier]

Abstract: Chemical control of weeds in seedbed sown onion (Allium cepa L. cv. Geza 20) and the effect of different herbicides on onion seedlings and weed growth were investigated in two field experiments conducted at the central Jordan Valley during the 1998/1999 growing season. Weed competition reduced average onion fresh yield by 62% compared with the weed-free control. Out of 14 herbicides tested in 16 treatments, oxadiazon at a dose of 0.75kgaiha−1 and oxyfluorfen at 0.6kgaiha−1, both applied as pre-sowing and post-emergence to onion seedlings resulted in the highest seedlings yield and the lowest weed biomass. Post-emergence application of both herbicides gave a similar yield of onion seedlings to that of the weed-free control. Paraquat at 20gaiha−1 significantly increased yield of onion seedlings over the weed-infested control and other herbicides tested. Many of the herbicides used including pronamid, prometryn, methabenzthiazuron, diphenamid, metribuzin and pyrazon were phytotoxic to seedbed sown onion in both sites and reduced seedlings growth and stand below the weed-infested control. Oxadiazon in pre-sowing and oxyfluorfen in post-emergence application were the best in controlling many “hard to kill” weeds including Chenopodium murale, Malva sylvestris, and Cyperus rotundus, and in increasing seedlings yield, while oxyfluorfen in a post-emergence application treatment was the best of all herbicides used. [Copyright &y& Elsevier]