Uticaj vremena uklanjanja korova i pre-em primene herbicida na rast useva soje

Abstract

Field studies were conducted in 2017 at Concord in northeast Nebraska to evaluate how timing of weed removal and application of pre-emergence (PRE) herbicides influences the growth of soybean. The studies were laid out in a split-plot arrangement of 14 treatments (2 herbicide regimes and 7 weed removal timings) with four replicates. The 2 herbicide regimes were: No PRE and PRE application of a premix of sulfentrazone plus imazethapyr (140 plus 28 g ai ha-1). The 7 weed removal timings were: V1, V3, V6, R2 and R5 soybean growth stages, as well as weed free and weedy season long. Soybean growth parameters (leaf area and dry matter) were collected at R6 growth stage. Delayed timing of weed removal significantly influenced the soybean growth by reducing leaf area and dry matter. Without the application of PRE herbicides, a 5% reduction in soybean leaf area and dry matter occurred when weed removal was delayed until 100 growing degree days after emergence (GDD; equivalent to V1 soybean stage or 10 days after emergence [DAE]). Meanwhile, the use of PRE herbicide prevented the same level of reduction until 382 GDD (V5 soybean stage; 34 DAE). The practical implication is that the use of PRE herbicides protected soybean growth and delayed the need for post-emergence application of herbicides by three weeks after soybean emergence.