Improved management of Avena ludoviciana and Phalaris paradoxa with more densely sown wheat and less herbicide

Abstract

Summary The effectiveness of crop competition for better weed control and reducing herbicide rates was determined forAvena ludoviciana and Phalaris paradoxa. Four experiments, previously broadcast with seeds of the two weeds in separate plots, were sown with three wheat densities, and emerged weeds were treated with four herbicide doses (0–100% of recommended rate). The measured crop and weed traits were first analysed across experiments for treatment effects. Grain yield and weed seed production data were then analysed using cubic smoothing splines to model the response surfaces. Although herbicide rate for both weeds and crop density for P. paradoxa had significant linear effects on yield, there was a significant non‐linearity of the response surface. Similarly, herbicide rate and crop density had significant linear effects on weed seed production, and there was significant non‐linearity of the response surface that differed for the weed species. Maximum crop yield and reduction in seed production of P. paradoxa was achieved with approximately 80 wheat plants m−2 and weeds treated with 100% herbicide rate. For A. ludoviciana, this was 130 wheat plants m−2 applied with 75% herbicide rate. Alternatively, these benefits were achieved by increasing crop density to 150 plants m−2 applied with 50% herbicide rate. At high crop density, application of the 100% herbicide rate tended to reduce yield, particularly with the A. ludoviciana herbicide, and this impacted adversely on the suppression of weed seed production. Thus, more competitive wheat crops have the potential for improving weed control and reducing herbicide rates.

Controle de papuã (Brachiaria plantaginea) em soja em função da dose e da época de aplicação do herbicida clethodim

“…Estudos relacionados sugerem, também, que é possível aumentar o retorno econômico com o uso de doses reduzidas de herbicidas, desde que aplicadas em conjunto com medidas de manejo integrado de plantas daninhas (Boström et al, 2000;Popp et al, 2000). Resultados similares foram relatados por Walker et al (2002), porém, neste caso, a redução da dose herbicida dependeu da densidade e do estádio das plantas daninhas.…”

Herbicidal strategies to control Phalaris brachystachys in a wheat-sunflower rotation: a simulation approach

“…Using management practices that increases crop competitiveness may reduce the negative effects associated with the use of low herbicide rates. Different studies have shown that control of sterile oat (Avena sterilis) and paradoxa grass (Phalaris paradoxa) populations can be improved by using competitive crop cultivars and high seeding rates (Walker et al, 2002;FernandezQuintanilla et al, 2006). Integrating these practices with the use of low herbicide rates may provide an agronomically viable and environmentally friendly solution for short-spiked canary grass control under semi-arid conditions.…”

A survey of management and economic impact of weeds in dryland cotton cropping systems of subtropical Australia

“…Walker et al (2001Walker et al ( , 2002 showed that control of wild oats and paradoxa grass was improved substantially with increased competition from winter cereals, and growers in the intensive cropping region of Darling Downs in Southern Queensland considered increasing crop density as an important weed control practice (Streit 1996). In contrast, only a few growers sowed their dryland cotton and rotational crops at higher seeding rates, and this option needs to be explored for summer crops in this environment, and more widely adopted for winter crops of the rotations.…”