Site Specific Weed Control in Winter Wheat

Abstract

There is much documentation in the scientific literature (e.g. Clay et al. 1999, Hamouz et al. 2006, Gerhards et al. 2012) that weeds are distributed in a patchy manner throughout agricultural fields. An aggregated distribution pattern of weed populations provides opportunity to reduce the herbicide application if site-specific weed management is adopted. Gerhards et al. (2002) achieved herbi-cide savings of 60% and 92% for dicotyledonous and monocotyledonous weeds, respectively, in spring barley (Hordeum vulgare L.) cultivation, and savings of 11% and 81% were achieved for the same weed groups for maize (Zea mays L.). In two winter wheat fields, Häusler et al. (1998) found that herbicide applications were necessary for 24% and 35% of the area for Galium aparine L., for 25% and 31% for other dicotyledonous weeds and for 55% and 7.5% for grasses. Using a simulation , Christensen and Heisel (1998) estimated a 40% reduction of herbicide consumption, and Nordmeyer and Häusler (2000) calculated the need for herbicide application from 7% to 64% of the total area in various fields. Site-specific weed management is based on the threshold concept: the aim is to adjust the intensity of management practices to the actual degree of weed infestation, with only those areas having a weed density exceeding the predefined control threshold typically being treated. However, site-specific weed management requires the precise setting of control thresholds for effectiveness and reliability. Furthermore, both areas that are treated superfluously and unsprayed areas that will show increases in weed infestation should be ABSTRACT An aggregated distribution pattern of weed populations provides opportunity to reduce the herbicide application if site-specific weed management is adopted. This work is focused on the practical testing of site-specific weed management in a winter wheat and the optimisation of the control thresholds. Patch spraying was applied to an experimental field in Central Bohemia. Total numbers of 512 application cells were arranged into 16 blocks, which allowed the randomisation of four treatments in four replications. Treatment 1 represented blanket spraying and the other treatments differed by the herbicide application thresholds. The weed infestation was estimated immediately before the post-emergence herbicide application. Treatment maps for every weed group were created based on the weed abundance data and relevant treatment thresholds. The herbicides were applied using a sprayer equipped with boom section control. The herbicide savings were calculated for every treatment and the differences in the grain yield between the treatments were tested using the analysis of variance. The site-specific applications provided herbicide savings ranging from 15.6% to 100% according to the herbicide and application threshold used. The differences in yield between the treatments were not statistically significant (P = 0.81). Thus, the yield was not lowered by site-specific weed management.

An on-farm approach to quantify yield variation and to derive decision rules for site-specific weed management

“…Site-specific weed management, based on weed distribution maps, can reduce treatment costs as well as herbicide loading in the environment. Several studies on site-specific weed control have shown that this practice is reasonable and it has been applied successfully to various crops, resulting in a considerable reduction of herbicide use and consequently benefits to the environment (Cousens 1987;Thompson et al 1991;Johnson et al 1995;Gerhards et al 1997;Gerhards and Christensen 2003). The German plant protection law requires the use of economic weed thresholds, i.e, critical values above which herbicide treatments are economically viable.…”

Geïntegreerde bestrijding van knolcyperus : Resultaten van een literatuurstudie naar alternatieven voor monam

“…Het ruimtelijke patroon van de plantensoort vormt hierbij een belangrijk onderdeel van de beschrijving (Cardina et al, 1997), zeker voor knolcyperus. Onkruidpatronen hebben veelal een plekkerig karakter (Cardina et al, 1997;Gerhards et al, 1997;Heijting et al, 2007  Er mag een maximale oppervlakte van 1 hectare behandeld worden, met minimaal 150 meter afstand tussen behandelde velden.  Dek de behandelde grond direct na toepassing af met VIF (Virtually Impermeable Film) folie gedurende een periode van tenminste 14 dagen.…”

Soil Electrical Conductivity as One Possible Tool for Predicting of Cirsium Arvense Infestation Occurrence

“…Of course, there is a chance for herbicide savings by using site specific herbicide application. The results of Gerhards et al (1997) demonstrated that the site specific weed management was technically feasible but further investigations are needed to verify and evaluate site specific weed control methods. The site-specific herbicide application presumes, that the herbicide spray can be omitted at certain areas within the field with no or low weed infestation.…”