Sequential Herbicide Application Boost Yield and Economics in Spring Maize Cultivation

Weed infestations represent a critical threat to global food security, particularly in maize cultivation, where fierce competition for essential resources such as light, water, and nutrients can drastically reduce crop productivity. This study investigated the efficacy of various weed management strategies—including manual weeding and the sequential application of pre- and post-emergence herbicides—on the weed dynamics, grain yield, and overall economic viability of spring maize. Conducted over two years in spring 2024 and spring 2025 at the Maize, Sorghum and Millet Field of the Crop Sciences Institute (CSI), National Agricultural Research Centre (NARC), Islamabad, Pakistan, the research aimed to identify a highly effective and scalable solution to enhance maize productivity in large-scale agricultural settings. The experimental design utilized a randomized complete block design (RCBD) with three replications, testing eight distinct treatments against a no-weeding control (T0).

The treatments included manual weeding at 15 and 30 days after sowing (T1), and several herbicide combinations. These combinations involved two primary active ingredients: atrazine combined with s-metolachlor, and atrazine paired with mesotrione. Specific treatments included single applications (pre-emergence or post-emergence) and sequential applications. Notably, the most complex treatment, T8, involved the sequential application of atrazine + s-metolachlor as a pre-emergence spray followed by atrazine + mesotrione as a post-emergence spray. The study utilized the NARC-3 maize variety, which possesses a 120-day duration and a potential yield of 7400 kg/ha, ensuring that the results reflected performance under specific, high-potential agronomic conditions. Soil analysis indicated a pH of 7.8 and 0.4% organic matter, providing a stable environment for the tested crop and weed interactions.

The impact of weed management was profound across all measured parameters. In terms of plant growth, the days required to reach 50% tasseling and silking, as well as morphological traits like tassel and cob height, were significantly affected by the weed control strategies. The no-weeding control plot (T0) exhibited the longest duration to reach 50% tasseling (67.83 days) and 50% silking (70.5 days), indicating delayed maturity. Conversely, the manual weeding plot (T1) recorded the shortest days to 50% tasseling (58.83) and 50% silking (62.17). The sequential herbicide application (T8) also showed a rapid progression, closely following the manual weeding treatment. Furthermore, T1 resulted in the highest recorded tassel height (170 cm) and cob height (93 cm), while T8 demonstrated substantial benefits, increasing tassel height by 20% and cob height by 21% compared to the control, showcasing the physical advantages of effective weed suppression.

The results concerning crop yield metrics provided compelling evidence for the superiority of active weed management. While the number of cobs per plant remained largely unaffected across treatments, significant improvements were observed in cob length, number of grains per cob, and thousand-grain weight. The manual weeding treatment (T1) achieved the highest grain yield at 5114.7 kg ha⁻¹, accompanied by a harvest index (HI) of 34.41%. Critically, the percentage increases compared to the control were substantial: manual weeding increased grain yield by 79% and HI by 32%, whereas the sequential herbicide application (T8) increased grain yield by 76% and HI by 28%. These figures underscore the immense potential for weed control to unlock latent yield capacity in maize.

The study also provided detailed insights into the weed dynamics themselves. Various weed species were identified, including broad-leaf weeds such as Chenopodium album, Convolvulus arvensis, Fumaria indica, and Rumex dentatus, alongside narrow-leaf weeds like Cynodon dactylon and Cyperus rotundus. Theweed density and biomass were dramatically reduced by the treatments. The no-weeding control (T0) recorded the highest densities across all species, with Cynodon dactylon reaching a density of 74.08 m⁻². Manual weeding (T1) and the sequential herbicide treatment (T8) were the most effective in reducing density. For instance, manual weeding decreased the density of Chenopodium album by 90%, while the sequential herbicide application (T8) lowered the density of Chenopodium album by 86%. Furthermore, the fresh and dry weights of weeds were significantly minimized in T1 and T8 compared to T0, confirming that both physical and chemical methods successfully curtailed weed competition for vital soil resources.

From an economic perspective, the findings suggest that while manual weeding provides excellent biological results, the chemical approach offers superior economic returns. The economic analysis revealed that the sequential application of atrazine + s-metolachlor (pre-emergence) followed by atrazine + mesotrione (post-emergence) yielded the highest net returns at Rs. 366,300 ha⁻¹. This significantly outperformed the no-weeding control (Rs. 213,262 ha⁻¹) and the manual weeding treatment (Rs. 358,675 ha⁻¹). This economic advantage is crucial for large-scale agricultural adoption, as the labor-intensive nature of manual weeding, despite its high biological efficacy, presents logistical and cost barriers in modern commercial farming.

The mechanism behind the success of the sequential herbicide strategy (T8) is rooted in its sophisticated approach to weed management. The combination of atrazine, a photosystem II (PSII) inhibitor, with HPPD inhibiting herbicides like mesotrione, can lead to synergistic weed control. HPPD inhibition depletes plastoquinone, which subsequently enhances the binding and efficacy of atrazine at the PSII D1 protein. This dual action is particularly effective against challenging and potentially herbicide-resistant weeds. Furthermore, the sequential application strategy addresses the temporal nature of weed emergence. The pre-emergence mixture effectively suppresses grass weeds, while the post-emergence application targets broadleaf weeds that may have survived the initial treatment. This strategy prolong the weed-free period, allowing the maize crop to establish a competitive canopy and maintain its yield potential without succumbing to the continuous pressure of weed competition.

In conclusion, the research definitively establishes that weed control is the primary constraint limiting maize growth and yield. While manual weeding is highly effective, the sequential application of atrazine + s-metolachlor (pre-emergence) followed by atrazine + mesotrione (post-emergence) emerged as the most effective and economically viable strategy. This approach not only achieves a yield increase of 78% over the control but also provides a practical, scalable solution for maximizing maize grain production and enhancing overall farm profitability, thereby offering a robust pathway toward improved maize productivity in large-scale cultivation.

Subject of Research: Efficacy of sequential pre- and post-emergence herbicide application on weed control, maize yield, and agricultural economics.

Article Title: Efficacy of pre- and post-emergence herbicides on weed dynamics, grain yield and economics of spring maize

Article References: Hussain, T., Khan, M. A., Raza, A., Ahmed, Z., Raheem, H., & Sarwar, M. A. (2026). Efficacy of pre- and post-emergence herbicides on weed dynamics, grain yield and economics of spring maize. Discover Agriculture, 4(1), Article 327. https://doi.org/10.1007/s44279-026-00815-w

Image Credits: AI Generated

DOI: 10.1007/s44279-026-00815-w

Keywords: Maize cultivation, Herbicide efficacy, Weed management, Agronomy, Sequential application, Grain yield, Agricultural economics, Efficacy, pre-, post-emergence, herbicides, weed