Efficacy of Herbicides against Broad-spectrum Weed Floras and Their Effect on Non-target Soil Micro-organisms and Productivity in Sugarcane (Saccharum sp.)

Weeds pose a major challenge at the initial stages of sugarcane and when uncontrolled cause high yield losses. This study was undertaken to define a better and cost-effective weed management strategy. Field experiment was carried out at District Seed Farm (C Unit) of Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India (22°97'N latitude and 88°43'E longitude with the 9.75 meters above the mean sea level) under natural weed infestations in sugarcane in 2017–2018 and 2018-19. The objective was to evaluate the efficacy of herbicides on weed floras, non-target soil organisms and productivity of sugarcane (cv. CoS 98231). The pattern of nutrient uptake by weed species was also itemized. The treatments were comprised of four doses of Atrazine 50% WP (1.0, 2.0, 3.0 and 4.0 kg a.i. ha-1), Trifloxysulfuron-Na (10% OD) 30 g a.i. ha-1 and weedy check within a randomized complete block design, replicated four times. The results revealed that among the tested herbicides, the utmost dose of Atrazine was most efficient against grassy as well as broadleaf weeds. The higher weed control efficiency (> 60%) and cane yield (85.41 t ha-1) were recorded from treatment received Atrazine 4000 g a.i. ha-1 followed by its lower doses. Owing to an efficient controller of diversified weeds same herbicide treated plot removed the least amount essential primary nutrients irrespective of all weed species. Herbicides did not show any phytotoxicity symptoms on sugarcane throughout the observation period. Based on overall performance, the Atrazine 50% WP (4000 g a.i. ha-1) may be considered as the best substitute for others post-emergent herbicide against the complex weed floras in sugarcane.