Critical Time for Weed Removal in Corn as Influenced by Planting Pattern and PRE Herbicides

Dejan Nedeljković,Sava Vrbničanin,Dragana Božić,Stevan Knežević

doi:10.3390/agriculture11070587

Dejan Nedeljković, Sava Vrbničanin + Show 2 more

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https://doi.org/10.3390/agriculture11070587

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Abstract

Determining the critical time for weed removal (CTWR) is essential for the development of an integrated weed management plan. Therefore, field experiments were conducted to evaluate the effects of two planting patterns (standard and twin-row) with and without PRE-applied herbicides on CTWR in corn. Experiments were laid out in a split-plot arrangement with two main plots: (i) standard row planting (SRP) that is 70 cm wide, and (ii) twin-row planting (TRP) with 50 cm distance between each set of double rows. Each main plot was divided into two sub-plots (with and without PRE herbicides). The sub-sub-plots consisted of seven weed removal timings for PRE herbicides, and tank mixes were utilized (S-metolachlor (1.44 kg a.i. ha−1) + terbutylazine (0.75 kg a.i. ha−1)). The CTWR without PRE herbicides was similar in both the SRP and TRP systems, where it was around the V1 to V2 (16 to 19 d after emergence (DAE)) growth stages. The use of PRE-applied herbicides delayed CTWR in SRP to the V4 to V10 (25 to 58 DAE) stages and up to the V11 (60 DAE) stage in TRP. These results clearly indicate that PRE herbicides are important for protecting corn yields regardless of the planting pattern. In more meteorologically favorable seasons (sufficient heat and precipitation) in both sowing systems, corn plants produce their biological maximum with the fact that over the number of plants per unit area (SRP = 80,000 plants ha−1, TRP = 93,900 plants ha−1) provide higher yields in variants with PRE herbicides, and thus the advantage of the TRP system can be justified.

Highlights

Corn (Zea mays L.) is one of the most important crops grown worldwide in a wide range of environments because of its greater adaptability [1]
In sub-plots with PRE herbicides, broadleaf weeds accounted for 57.2% in standard row planting (SRP) and 51.4% in twin-row planting (TRP), compared to grassy weeds (42.8 and 48.6%)
Other researchers reported that corn planted at higher plant populations and narrower rows (e.g., TRP) could make better use of the habitat by expediting canopy closure and light interception, which gave the crop a competitive advantage over weeds [47,48,49,50], In our study, the plots with PRE herbicides across years had a lower number of weeds compared to plots without PRE herbicides, due to the effectiveness of herbicides, which was confirmed in many studies [51,52,53]

Summary

Introduction

Corn (Zea mays L.) is one of the most important crops grown worldwide in a wide range of environments because of its greater adaptability [1]. One of the most important goals in corn production is to protect yield; this is not always easy due to many factors. Yield losses in corn can be highly impacted by competition from weeds [6,7,8] to as much as 90%. Harrison et al [16] reported a 13.6% yield loss in corn from a moderate weed density (1 plant 10 m−2), compared to 90% yield loss from higher weed densities. Other studies reported that 6 to 12 plants m−2 of Xanthium strumarium reduced corn yields by 28 to 45% [17,18,19]. Corn competitiveness can be improved by adjusting production practices such as reducing the row spacing, increasing the planting density, and planting more competitive cultivars that exhibit weedsuppressive potential [20]

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