Weed interference in Marandu palisade grass pastures under renewal or maintenance conditions

ABSTRACT The presence of weeds as a consequence of pasture degradation is one of the main problems facing livestock worldwide. Thus, knowing the interference aspects and the appropriate time for weed management is essential for applying a particular control measure. This research aimed to study the weed interference on the morphostructural and nutritional quality of the Marandu palisade grass in conditions of renewal or maintenance of pasture. The experiments were conducted in a randomized block design, with four replicates and treatments consisted of eight growth periods of coexistence between Marandu palisade grass and weeds (0, 15, 30, 45, 60, 75, 90, and 120 days). Forage grass was characterized at the end of the experimental period, corresponding to 120 days of coexistence, and the main morphostructural and nutritional components were determined. Under the renewal or maintenance process, the weeds interfere in the morphostructural and nutritional quality of pasture areas with Marandu palisade grass. In vitro organic matter digestibility of Marandu palisade grass is negatively influenced by weeds, suggesting that control measures for renewal or maintenance areas should be adopted within 24 and 18 days of coexistence, respectively.

Normalized difference vegetation index for desiccation evaluation with glyphosate + 2,4-D in magnetized spray solution

Water magnetization and geoprocessing are increasingly utilized tools in weed management. Our objective was to study the influence of water magnetization on herbicide efficiency and to verify whether there is a relationship between control scores and the normalized difference vegetation index (NDVI). In the laboratory experiment, water was subjected to magnetization and evaluated with respect to four characteristics. In the field experiment, plots of Brachiaria grass were subjected to treatments in a factorial scheme (6 × 2 + 1). Six herbicidal factors (doses of glyphosate and glyphosate + 2,4-D) and the magnetization or absence of magnetization of the spray solution were evaluated and compared against the control treatment (without spraying). Weed control assessments were carried out six times. Images were obtained using an embedded multispectral camera to determine the NDVI values. Data related to water characteristics were analyzed using the t test. Weed control and NDVI data were subjected to analysis of variance and are presented in regression graphs. Dispersion analysis of NDVI data was performed according to the control scores. The magnetization process decreased the pH of the water and increased the surface tension, but it did not influence the control scores or the NDVI. As the glyphosate dose was increased, the control scores were higher and the NDVI values were lower. Magnetized water did not affect the biological efficiency of the herbicides, and there was a strong correlation between the control scores and the NDVI values.

Exploring the Effects of Different Stubble Tillage Practices and Glyphosate Application Combined with the New Soil Residual Herbicide Cinmethylin against Alopecurus myosuroides Huds. in Winter Wheat

Effective control of Alopecurus myosuroides Huds. (blackgrass) solely with a chemical treatment is not guaranteed anymore because populations exhibit resistance to almost all herbicide modes of action. Integrated weed management (IWM) against blackgrass is necessary to maintain high weed control efficacies in winter cereals. Four field experiments were conducted in Southwest Germany from 2018 to 2020 to control A. myosuroides with a combination of cultural and chemical methods. Stubble treatments, including flat, deep and inversion soil tillage; false seedbed preparation and glyphosate use, were combined with the application of the new pre-emergence herbicide cinmethylin in two rates in winter wheat. Average densities of A. myosuroides in the untreated control plots were up to 505 plants m−2. The combination of different stubble management strategies and the pre-emergence herbicide cinmethylin controlled 86–97% of A. myosuroides plants at the low rate and 95–100% at the high rate until 120 days after sowing. The different stubble tillage practices varied in their efficacy between trials and years. Most effective and consistent were pre-sowing glyphosate application on the stubble and stale seedbed preparation with a disc harrow. Stubble treatments increased winter wheat density in the first year but had no effect on crop density in the second year. Pre-emergence application of cinmethylin did not reduce winter wheat densities. Multiple tactics of weed control, including stubble treatments and pre-emergence application of cinmethylin, provided higher and more consistent control of A. myosuroides. Integration of cultural weed management could prevent the herbicide resistance development.

Yield and Seed Quality of Summer Green Gram as Influenced by Weed Management under Zero Tillage

Background: Weeds are primary factors that adversely affect growth, yield and seed quality of summer green gram, which can be minimized with adoption of proper weed management practices. This field experiment was conducted to find out the effective weed management practice in summer green gram (Vigna radiata) under zero tillage condition. Methods: In this field-laboratory investigation conducted during summer season 2019 on different herbicides were applied to manage weeds in summer green gram. Eight treatments were applied based on various application windows. In the field and laboratory, the collected samples were determined for growth parameters, nutrient uptakes, seed yield and seed quality of summer green gram. Result: The result revealed that weed free treatment recorded higher growth parameters like, plant height, number of branch/plant, number of leaves/plant and root biomass which was statically at par with Shaked (Propaquizafop + Imezathyper) as post-emergence (POE) at 20 DAS and Pendimethalin as pre-emergence (PE) followed by one hand weeding 20 DAS. Same trends were also observed in seed yield, nutrient content and uptake by seeds. Seed quality parameters like germination per cent (98.00), shoot (25.63 cm) root (14.20 cm) and seedling length (39.83 cm), seedling dry weight (0.16 g), vigour index I (3903.33) and vigour index II (14.96) was higher under weed free followed by Shaked (Propaquizafop + Imezathyper) and Pendimethalin as (PE followed by one hand weeding 20 DAS over weed check.

Weed Management in Sorghum

This publication provides information on weed control options in sorghum. Written by J. A. Ferrell, G. E. MacDonald, B. J. Brecke, and P. Devkota, and published by the UF/IFAS Agronomy Department, revised January 2022.