Dynamics of weed growth in an apple orchard tree strip

The aim of this work is to visualise weed growth in an apple orchard tree-strip and how it develops under three different mulch treatments using a biological age modelling approach. Field data were obtained from a weed control experiment conducted in 2021 at the Kompetenzzentrum Obstbau Bodensee in Southwest Germany. A completely randomised experimental design with three different organic mulch treatments (grass clover silage, biodegradable spray or woodchips) and nine replicates used repeated time-series assessments to determine weed growth as weed area coverage (%), maximum height (cm) and mean height (cm). Assessments were conducted four times at monthly intervals from mid-May to early August. The weed growth rates estimated by the models were distinct for each treatment but common for all the assessed variables. Woodchip mulch was the best treatment to suppress weed growth, silage and spray mulch were less effective and gave similar results with a small benefit of the spray application. Typically, growth processes are non-linear across time and fitting a non-linear model can partition the existing biological variation in such a way that it forms a very good basis upon which to further explore repeated measures data. Given the very high variation in weed growth, field studies should be designed with a large number of repetitions (∼20) per treatment.