Evaluation of two patch spraying systems in winter wheat and maize

Abstract

Gutjahr C, Sökefeld M & Gerhards R (2012). Evaluation of two patch spraying systems in winter wheat and maize. Weed Research52, 510–519.SummaryFifteen field experiments were conducted in winter wheat and maize to analyse the spatial distribution of weed species and to evaluate two systems of site‐specific weed control. Fields were divided into cells and weed densities for all weed species were counted in each cell. Weed species were then grouped into annual broad‐leaved species, grass weeds and Galium aparine in winter wheat and annual broad‐leaved species, grass weeds and perennials in maize. Weed control thresholds were set for each group of weed species and different herbicides were sprayed in cells where the weed control threshold was exceeded. All three weed species groups were distributed heterogeneously within and between the fields, with densities ranging from 0 to more than 2000 plants m−2. Site‐specific weed control was realised with a GPS‐controlled multiple‐tank sprayer, containing three separate spray lines for each of the three application maps. In winter wheat, site‐specific weed control using a multiple‐tank sprayer resulted in 70% untreated area compared with uniform applications across the whole field. Simulated site‐specific weed control using a conventional sprayer with a tank mixture only resulted in 37% untreated area. In maize, 47% of the area remained untreated using the multiple‐tank sprayer and 6% using a conventional sprayer and tank mixtures. Efficacy of site‐specific weed control was good in all fields. The results demonstrate the need for combining weed mapping and new application technologies for patch spraying.