Bioefficacy, Phytotoxicity and Economics of Post-emergence Herbicides in Moth Bean (Vigna aconitifolia) in Hot Arid Regions

Background: Weed infestation is the major cause of yield loss to Kharif pulses in arid regions. Post-emergence herbicide application is a promising weed management option for pulses in these areas. Therefore, the current study was aimed to find an effective and economic post-emergence herbicide molecule for weed control in moth bean. Methods: A field experiment was conducted during 2017-2019 with different herbicides, hand weeding, weed-free and unweededs in Kharif mung bean in a randomized complete block design with three replications. Result: Among the herbicide treatments, post-emergence application of propaquizafop + imazethapyr @ 125 g a.i. ha-1 being statistically at par with clodinafop-propargyl + sodium acifluorfen @ 312.5 g a.i. ha-1 and hand weeding recorded the highest reduction in total weed dry matter (73.9%), highest weed control efficiency (73.8%) and lowest weed persistence index (1.03) compared to the unweeded. The reduction in seed yield in unweeded compared to weed-free and hand weeding was 50.8% and 42.1%, respectively. As the imazethapyr-containing herbicides caused crop phytotoxicity, significantly higher crop dry weight (513 g m-2), seed yield (5.53 q ha-1), stover yield (18.0 q ha-1), gross returns and net benefits of moth bean were recorded with clodinafop-propargyl + sodium acifluorfen (312.5 g a.i. ha-1) over other herbicide treatments. Clodinafop-propargyl + sodium acifluorfen (@312.5 g a.i. ha-1) registered the minimum value of weed index (20) and highest values of herbicide efficiency index (3.9) and crop resistance index (4.70).

Differences in Germination of ACCase-Resistant Biotypes Containing Isoleucine-1781-Leucine Mutation and Susceptible Biotypes of Wild Oat (Avena sterilis ssp. ludoviciana)

Herbicide resistance can affect seed germination and the optimal conditions required for seed germination, which in turn may impose a fitness cost in resistant populations. Winter wild oat [Avena sterilis L. ssp. ludoviciana (Durieu) Gillet and Magne] is a serious weed in cereal fields. In this study, the molecular basis of resistance to an ACCase herbicide, clodinafop-propargyl, in four A. ludoviciana biotypes was assessed. Germination differences between susceptible (S) and ACCase-resistant biotypes (WR1, WR2, WR3, WR4) and the effect of Isoleucine-1781-Leucine mutation on germination were also investigated through germination models. The results indicated that WR1 and WR4 were very highly resistant (RI > 214.22) to clodinafop-propargyl-contained Isoleucine to Leucine amino acid substitution. However, Isoleucine-1781-Leucine mutation was not detected in other very highly resistant biotypes. Germination studies indicated that resistant biotypes (in particular WR1 and WR4) had higher base water potentials than the susceptible one. This shows that resistant biotypes need more soil water to initiate their germination. However, the hydrotime constant for germination was higher in resistant biotypes than in the susceptible one in most cases, showing faster germination in susceptible biotypes. ACCase-resistant biotypes containing the Isoleucine-1781-Leucine mutation had lower seed weight but used more seed reserve to produce seedlings. Hence, integrated management practices such as stale seedbed and implementing it at the right time could be used to take advantage of the differential soil water requirement and relatively late germination characteristics of ACCase-resistant biotypes.

Effect of Irrigation and Herbicides on Most Tenacious Weed Cyperus rotundus in Wheat

To manage the Cyperus rotundus (Purple nut sedge.) is a troublesome, economically damaging weed, widely naturalized in the tropical and subtropical regions of the world. A field experiment was done at Students Instructional Farm of Chandra Shekhar Azad University of Agriculture & Technology, Kanpur (U.P).The study was conducted to investigate the competitive effects of C. rotundus in wheat (Triticum aestivum L.) under varying irrigation regimes and herbicides in field conditions at Kanpur during Rabi 2017-18 and 2018-19 in a split plot design. The experiment was laid out in split-plot design with four irrigation schedule viz. irrigation at CRI and active tillering stage (I1), irrigation at CRI + jointing + booting (I2), CRI + active tillering + booting + flowering stage (I3) and irrigation at CRI + jointing + booting + flowering + milking stage (I4) were assigned to main plots and weed management practices viz. W1-weedy check, W2-two hand weeding at 20 and 40 DAS, W3-sulfosulfuron @25 g/ha , W4- pendimethalin (pre emergence) fbWCPL-15(clodinafop- propargyl 15 %) @400 g/ha , W5- carfentrazone ethyl 20% + sulfosulfuron 25%WG @ 100 g/ha , W6- halauxafen + penxasulam 23.5% @ 75 g/ha , W7- halauxafen - methyl 1.21% w/w + fluroxypyr @ and W8- clodinafop- propargyl 15% + metsulfuron 1% @ 400 g/ha were allocated to sub plots. Application of two irrigations at CRI and active tillering stage (I1) significantly reduced the density of C. rotundus and their fresh and dry weight with highest weed control efficiency (WCE) over irrigation at CRI+ jointing+ booting+ flowering+ milking stage (I4), irrigation at CRI + active tillering + booting + flowering stage (I3) and irrigation at CRI + jointing + booting (I2). However, maximum yield was recorded with the application of five irrigation at CRI+ jointing+ booting+ flowering+ milking stage (I4). Among herbicidal treatments, lowest density, fresh and dry weight of C. rotundus with the highest WCE resulted in higher yield of wheat was recorded with the application of carfentrazone ethyl 20% + sulfosulfuron 25%WG as post emergence (35 DAS) at 100 g/ha as compared to other treatments. However, none of the herbicidal treatments as effective as hand weeding twice at 20 and 40 DAS.

A Study on Influence of Different Weed Management Practices on Yield and Economics of Rabi Groundnut in Telangana State

An experiment was conducted to study the effect of different high efficiency herbicides as pre and post-emergence application on the economics of groundnut at College of Agriculture, Professor Jayashankar Telangana State Agricultural University, Hyderabad, during rabi 2020-21. The experiment consisted of ten treatments laid out in randomised block design (RBD) replicated thrice. Treatments are diclosulam 84% WDG 26 g ha-1 PE fb intercultivation at 20 DAS, imazethapyr 2% EC + pendimethalin 30% EC 960 g ha-1 PE fb intercultivation at 20 DAS, pyroxasulfone 85 % WDG 127.5 g ha-1 PE fb intercultivation at 20 DAS, propaquizafop 2.5% + imazethapyr 3.75% w/w ME 125 g ha-1 PoE fb intercultivation at 40 DAS, imazethapyr 35% + imazamox 35% WG 70 g ha-1 PoE fb intercultivation at 40 DAS, sodium acifluorfen 16.5% EC + clodinafop propargyl 8% EC 250 g ha-1 PoE fb intercultivation at 40 DAS, imazethapyr 10% SL 100 g ha-1 PoE fb intercultivation at 40 DAS, intercultivation (20 and 40 DAS), intercultivation fb hand weeding (20 and 40 DAS) (Weed-free) and Unweeded control. The findings also conveys that, among all the weed management practices, higher gross returns were realized with intercultivation fb hand weeding at 20 and 40 DAS and among the herbicides, diclosulam 26 g ha-1 PE fb intercultivation at 20 DAS and imazethapyr + pendimethalin 960 g ha-1 PE of fb intercultivation at 20 DAS recorded higher returns. However the net returns and B: C ratio was significantly highest with diclosulam 26 g ha-1 PE fb intercultivation at 20 DAS and imazethapyr + pendimethalin at 960 g ha-1 PE fb intercultivation at 20 DAS.

Economical Efficacy of Weed Management Options in Groundnut + Pigeonpea Relay Intercropping System

Aims: To evaluate the effect of different weed management options on the economics in groundnut + pigeonpea relay intercropping on medium black clayey soils of Junagadh . Study Design: Field experiment was conducted at Junagadh during kharif 2019-20 and 2020-21 in Randomized Block Design with three replications to evaluate the effect of different weed management options on the economics in groundnut + pigeonpea relay intercropping on medium black clayey soils. The treatments comprised of: pendimethalin 0.9 kg ha-1 as PE fb interculturing and hand weeding at 45 DAS, pendimethalin 0.45 kg ha-1 + oxyfluorfen 0.09 kg ha-1 as PE fb interculturing and hand weeding at 45 DAS), interculturing and hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as POE, interculturing and hand weeding at 15 DAS fb quizalofop p ethyl 40 g ha-1 at 45 DAS as POE, interculturing and hand weeding at 15 DAS fb propaquizafop 70 g ha-1 at 45 DAS as POE, pendimethalin 0.9 kg ha-1 as PE fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as POE, pendimethalin 0.9 kg ha-1 as PE fb quizalofop p ethyl 40 g ha-1 at 45 DAS as POE, pendimethalin 0.9 kg ha-1 as PE fb propaquizafop 70 g ha-1 at 45 DAS as POE (T8), weed free, and unweeded control (T10). Place and duration of the study: Instructional Farm, Department of Agronomy, College of Agriculture, Junagadh Agricultural University, Junagadh during kharif seasons of 2019-20 and 2020-21. Methodology: on the basis of prevailing local charges. The gross realization in terms of rupees per hectare. A net return of each treatment was calculated by deducting the total cost of cultivation from the gross returns. Result: Significantly higher amount of gross returns were recorded with the weed free treatment (T9), which was closely followed by interculturing and hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as PoE (T3). Statistically higher net returns and higher net returns and B:C ratio were registered with interculture and hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as PoE (T3).