Effect of Maize (Zea mays L.) and Legume Intercropping Systems on Weed Dynamics

The field experiments were conducted during two consecutive seasons of kharif (June to October), 2016 and 2017 at the Experimental Research Farm, ICAR Research Complex for NEH Region, Nagaland Centre, Medziphema, Nagaland, India. The treatments consisted of four planting geometries i.e. maize+black gram (1:1), maize+black gram (2:2), maize+soybean (1:1) and maize+soybean (2:2) and three weed management practices i.e. weedy check, pre-emergence application of pendimethalin @ 1.0 kg a.i. ha-1+one hand weeding (1HW) at 30 DAS and two hand weedings (2HW) at 20 and 40 DAS. The experiment was laid out in Randomized Block Design with two factors comprising twelve treatment combinations and replicated three times. The results revealed that among the planting geometry, maize+soybean (2:2) recorded the highest weed control efficiency (WCE) and reduced the weed population, fresh weight and dry weight of monocot and dicot weed at 60 DAS and gave the maximum maize equivalent yield (4374.96 kg ha-1). Among the weed management, 2HW at 20 and 40 DAS recorded the lowest weed population, fresh weight, dry weight and the highest weed control efficiency (WCE) of monocot and dicot weed at 60 DAS and the maximum maize equivalent yield as 4591.10 kg ha-1 which was at par with the pre-emergence application of pendimethalin @ 1.0 kg a.i. ha-1+1HW at 30 DAS as 4461.80 kg ha-1. The highest net return (` ha-1), return per rupee invested and B: C ratio were recorded from the pre-emergence application of pendimethalin @ 1.0 kg a.i. ha-1+1HW at 30 DAS with ` 36624.05 ha-1 which was closely followed by 2HW at 20 and 40 DAS with Rs. 35428.81 ha-1.

Optimization of Spray Fluid for Herbicide Application for Drones in Irrigated Maize (Zea mays L.)

A field experiment was conducted in a randomized complete block design to screen the optimum spray fluid of herbicide application for drone based on visual toxicity and weed control efficiency in maize (Zea mays L.) during the summer season (March 2021) at eastern block farms of Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu. Three herbicide treatments namely Atrazine, Tembotrione and 2, 4-D with recommended dosages, 75% and 125% as pre-emergence herbicides applied on 3 days after, early post-emergence herbicides applied on 15 days after sowing and post-emergence applied on 25 days after sowing respectively. Totally thirty treatments with different spray fluids such as 500, 400, 300, 200, 100, 80, 60, 40, 30 L ha-1 and 20 L ha-1 were replicated three times. The study revealed that T5- Recommended dosage of pre emergence Atrazine – early post emergence Tembotrione – post emergence 2, 4-D (spray fluid 100 L of water ha-1),T6- Recommended dosage of pre emergence Atrazine – early post emergence Tembotrione–post emergence 2, 4-D (spray fluid 80 L of water ha-1), T7- Recommended dosage of pre emergence Atrazine – early post emergence Tembotrione – post emergence 2, 4-D (spray fluid 60 L of water ha-1) and T8- Recommended dosage of pre emergence Atrazine – early post emergence Tembotrione – post emergence 2, 4-D (spray fluid 40 L of water ha-1) produced the best results with respect to phytotoxicity and weed control efficiency. Based on the results it was concluded that the application of spray fluid 80 L ha-1 was optimum for herbicide application through drones with recommended dosage pre emergence Atrazine 1 kg a.i ha-1 on 3 days after sowing – early post emergence Tembotrione 120 g a.i ha-1 on 15-20 days after sowing - post emergence 2, 4-D 1 kg a.i ha-1 on 30 - 35 days after sowing.

Efficacy of Pre and Post Emergence Application of Imazethapyr and its Ready Mix Herbicides on Growth, Weed Dynamics and Productivity of Chickpea (Cicer arietinum L.)

Background: Weeds are major constraints in chickpea production. This crop is highly susceptible to weed competition owing to slow initial growth thus weeds cause up to 75% yield loss. Methods: Treatments comprised of imazethapyr 50 g/ha as PE (pre emergence), imazethapyr 70 g/ha as PE, imazethapyr 50 g/ha as PoE (post emergence), imazethapyr 70g/ha as PoE, imazethapyr + imazamox ready mix (RM) 50 g/ha as PE, imazethapyr + imazamox (RM) 70 g/ha as PE, imazethapyr + imazamox (RM) 50 g/ha as PoE, imazethapyr + imazamox (RM)70 g/ha as PoE, pendimethalin 1 kg/ha PE, imazethapyr + pendimethalin (RM) 1 kg/ha PE, hoeing at 20 and 40 DAS and weedy check. Result: Application of imazethapyr + pendimethalin (RM) 1 kg/ha as pre emergence recorded maximum plant dry matter accumulation at 60, 90, 120 DAS and at maturity stage and also higher CGR at 60-90, 90-120 and120 DAS - maturity of crop. Application of imazethapyr + pendimethalin (RM) 1 kg/ha as pre emergence was most effective in producing higher seed yield (1749 kg/ha), weed control efficiency (87.28%), net return (` 77,136), reduced weed management index 5.15 and 3.90 at 30 and 60 DAS respectively.

Response of Cowpea [Vigna unguiculata (L.) Walp.] as Succeeding Crop to Residual Effect of Extreme Levels of Atrazine Administered in Preceding Maize (Zea mays L.)

Background: Globally, grain legumes are the paramount family of agricultural crops following cereals. Generally, sequence cropping has manifested effectual in increasing farm productivity and profitability. However, sometimes herbicides administered in previous crop may be associated with phytotoxic effects that can later cause damage to the succeeding crops. The present study aimed to understand the residual effect of extreme levels of atrazine on succeeding cowpea under maize-cowpea cropping system. Methods: Field experiments were conducted during Kharif and rabi season of 2019-20 and 2020-21 in a randomized block design with eleven treatments, replicated thrice. Result: Residual effect of pre-emergence atrazine at 0.50 kg a.i. ha-1 followed by tembotrione at 120g a.i. ha-1 as post-emergence at 25 DAS recorded the lowest total weed density (4.41), total weed dry weight (9.81 g m-2) and highest weed control efficiency (39.25%) during rabi 2019-20 while during rabi 2020-21 lowest total weed density (5.03), total weed dry weight (10.68 g m-2) and highest weed control efficiency (39.65%) were noticed in pre-emergence atrazine 50% WP at 2.00 kg a.i. ha-1. Highest seed yield (788.67 and 842.33 kg ha-1) was obtained in weed free treatment.

Effect of Pre and Post-Emergence Herbicides on Yield, Economics and Weed Control in Linseed (Linum usitatissimum L.) Under Irrigated Medium Land Condition of Jharkhand

Linseed (Linum usitatissimum L.) production is affected by several factors, out of which weed is one of the most important factors responsible for causing tremendous loss in yield. An experiment was conducted during rabi season of 2018-2019 and 2019-2020 at Research Farm of Birsa Agricultural University, Kanke, Ranchi, Jharkhand to study the effect of pre and post-emergence herbicide on yield, economics, weed count, weed dry matter and weed control efficiency in linseed. The treatments comprised of weed management practices viz., T1-Weedy Check, T2-Hand weeding twice at 30 and 60 DAS, T3-Metribuzin 250 g/ha + Oxyflourfen 125g/ha (Pre.), T4-Pendimethalin 1 kg/ha (Pre.) fb. metsulfuron methyl 4 g/ha (Post.), T5-Imazethapyr 75 g/ha (Post.), T6-Oxyflourfen125 g/ha (Pre.), T7-Metsulfuron methyl 4 g/ha (Post.), T8-Clodinafop 60 g/ha (Post.), T9-Clodinafop 60 g/ha + metsulfuron methyl 4 g/ha (Post.) and T10-Oxadiargyl 80 g/ha (Pre.), and were replicated thrice. The research outcomes revealed that Hand Weeding twice at 30 and 60 DAS resulted in maximum seed yield (14.26, 15.66 and 14.96 q/ha), net return (Rs. 41635, 45907 and 43771/ha), in 2018-19, 2019-20 and pooled data respectively while among weed parameters hand weeding recorded minimum total weed count at 30 DAS (1.19 and 1.22 /m2) and 60 DAS (3.04 and 3.19 /m2), minimum total weed dry matter at 30 DAS (1.17 and 1.18 g/m2) and at 60 DAS (3.43 and 3.57 g/m2) and maximum weed control efficiency at 30 DAS (97.08 and 96.97%) and at 60 DAS (80.66 and 79.24%) in 2018-19 and 2019-20 respectively.

Influence of Pre and Post Emergence Herbicides on Weed Dynamics, WCE and Yield of Pigeon Pea under Rainfed Conditions

A field experiment was conducted at ICAR-KVK, Kalaburgi, during Kharif seasons of 2018-19 and 2019-20 to adjudge the efficacy of pre and post emergence herbicides against diverse weed flora in pigeonpea ecosystem. The experiment was laid out in RCBD with 11 treatments comprising of different pre-emergent herbicides viz., Pendimethalin, Pendimethalin 30 EC + Imazethapyr 2 EC and post-emergence premix product herbicides such as Imazamox 35 WG + Imazethapyr 35 WG, Propaquizafop 2.5% + Imazethapyr 3.75%w/w ME and their different dosages with cultural methods were compared with weed free check and weedy check treatments. Among the different pre and post emeregent herbicides tested against different weed flora, post emergent application of Propaquizafop 2.5% + Imazethapyr 3.75% w/w ME @ 2000 ml ha-1 at 20-25 days recorded significantly lower weed density, weed dry weight, highest weed control efficiency (91.36%) and lowest weed index (8.78%) and higher grain yield (1209 kg ha-1 ), net returns (` 43,036 ha-1) and benefit cost ratio (2.35) followed by Propaquizafop 2.5% + Imazethapyr 3.75% w/w ME @ 1500 ml ha-1 at 20-25 DAS, Imazamox 35 WG + Imazethapyr 35 WG at 100 g ha-1 at 20-25 DAS and HW at 20 and IC 40 and 60 DAS.

Dynamics of Clomazone Formulations Combined with Sulfentrazone in Sugarcane (Saccharum spp.) Straw

Herbicide formulations can alter the herbicide performance, affecting the application safety and weed control efficiency. Thus, the objective of this work was to compare the dynamics of clomazone herbicide applied single and combined with sulfentrazone on sugarcane (Saccharum spp.) straw. Laminated polypropylene containers filled with sugarcane straw (10 t ha−1) were subjected to two clomazone formulations (microencapsulated and conventional formulations; 1200 g ha−1) applied single or combined with sulfentrazone (600 g ha−1) with four replications, and the experiment was duplicated. The application was performed indoors with an automated sprayer. After application, accumulated rainfall depths (0, 5, 10, 20, 50, and 100 mm) on the treated containers were simulated soon after the herbicide applications, and the percolated waters were subsequently collected for herbicide quantification by chromatography and mass spectrometry (LC-MS/MS). The microencapsulated formulation of clomazone applied single or combined with sulfentrazone enabled the recovery of higher quantity of clomazone (>80%), with the advantage that a large percentage remained encapsulated (>70%), thus decreasing losses and increasing the product efficiency. The 30 mm simulated rainfall efficiently carried the clomazone herbicide when its microencapsulated formulation was applied, whereas its conventional formulation required higher rainfall depths (60 mm). Sulfentrazone was easily carried through the sugarcane straw by the rainfall depths when it was combined with clomazone, regardless of the clomazone formulation. The clomazone formulation affect the percolation dynamics of this herbicide through the sugarcane straw.

Influence of integrated weed management on growth and yield of Kharif maize (Zea mays L.)

A field experiment entitled, “Integrated weed management in Kharif maize (Zea mays L.)” was conducted during Kharif, 2020 at Post Graduate Research Farm, RCSM College of Agriculture, Kolhapur. The experiment was laid out in Randomized Block Design (RBD) having three replications and twelve treatments. The soil of the experimental plot was medium black clay (vertisol) with 90 cm depth, low in available N (250 kg ha-1), high in available P2O5 (30.60 kg ha-1) and medium in available K2O (290.67 kg ha- 1). The status of organic carbon content (0.34%) was low. The electrical conductivity and pH values were 4.2 dSm-1 and 7.10, respectively.Weed free check and tank mixure application of Tembotrinone 42 SC @ 120gm a.i.ha-1 + Atrazine 50 WP @ 500 gm a.i.ha-1 + surfactant @ 2ml/l of water EPoE At 20-25 DAS + fb hand weeding at 40 DAS were on par with each other and recorded significantly the higher growth and yield contributing characters viz., plant height (cm), number of functional leaves plant-1, leaf area plant-1(dm2), dry matter plant-1(g), length of cob (cm), diameter of cob(cm), number of grains, weight of grains cob-1and test weight resulting into significant increase in grain and straw yields of maize as compared to remaining weed management treatments. Tank mixure application of Tembotrinone 42 SC @ 120gm a.i.ha-1 + Atrazine 50 WP @ 500 gm a.i.ha-1 + surfactant @ 2ml/l of water EPoE At 20-25 DAS + fb hand weeding at 40 DAS recorded minimum dry weight of weed, highest weed control efficiency (86.94 %) and lowest weed index (1.79%).Significantly lowest values for growth, yield and yield attributes as well as weed control efficiency was observed in weedy check treatment.

Efficacy of tank mixture glufosinate ammonium and indaziflam for weed control in oil palm

The apprehension among oil palm farmers on the toxicity of glyphosate necessitated the need for an alternative herbicide for weed control in oil palm. Thus, a study was conducted at the Ni­gerian Institute for Oil Palm Research (NIFOR) to determine the efficacy of tank mixture of glu­fosinate ammonium (Basta) + indaziflam (Alion) for weed control in oil palm. The treatments consisted of glyphosate at 1.5 kg a.i ha-1, glyphosate + diuron at 1.5+2.0 kg a.i. ha-1, glufosinate ammonium at 0.4 kg a.i. ha-1, glufosinate ammonium at 0.5 kg a.i. ha-1, tank mixture of glufos­inate ammonium + indaziflam at 0.4 + 0.04 kg a.i. ha-1, tank mixture of glufosinate ammonium + indaziflam at 0.5 + 0.04 kg a.i. ha-1and weedy control. The results showed that tank mixture of glyphosate + diuron at 1.5 + 2 kg a.i ha-1, glufosinate ammonium + indaziflam at 0.4 + 0.04 kg a.i. ha-1 and glufosinate ammonium + indaziflam at 0.5 + 0.04 had the best weed control efficiency of 78.5%, 78.6% and 78.3% respectively up to 20 weeks. The study concluded that tank mixtures of glufosinate ammonium + indaziflam were as good as glyphosate + diuron for weed control in oil palm.