Unweeded Control Research Articles

Weed dynamics, energetic, yields and economics as influenced by sequential application of herbicides for weed management in direct seeded rice

This study quantifies the crop yield loss by weeds and management of hardy and prominent weeds. Uncontrolled weeds reduced grain yield of DSR by 68%. Pendimethalin 1.0 kg ha−1 pre-emergence (PE) followed by (fb) bispirbac-sodium 30 g ha−1 at 25 DAS fb fenoxaprop-p-ethyl 60 g ha−1 at 30 DAS, and pendimethalin 1.0 kg ha−1 (PE) fb azimsulfuron 25 g ha−1+fenoxaprop-p-ethyl 60 g ha−1 at 30 DAS significantly reduced weed density and weed dry matter, and recorded higher grain yield in DSR than other treatments. The pendimethalin 1.0 kg ha−1 (PE) fb bispyribac-sodium 30 g ha−1 at 30 DAS was statistically similar to stale seed-bed fb bispyribac-sodium 30 g ha−1 at 30 DAS and gave higher weed control efficiency and energy index compared to unweeded control and bispyribac-sodium 30 g ha−1 at 30 DAS. Pendimethalin 1.0 kg ha−1 (PE) fb bispyribac-sodium 30 g ha−1 at 25 DAS fb fenoxaprop-p-ethyl 60 g ha−1 30 DAS showed more promising in controlling tough weeds like L. chinensis and D. aegyptium and predominant weeds (Echinochloa colona, broad-leaved weeds and Cyperus species) in DSR.

A comparative study of drone and manual herbicide application for weed management in wet direct-seeded rice (Oryza sativa L.)

A field experiment was conducted at Tamil Nadu Agricultural University, Coimbatore, during the Navarai season (January-April) of 2024 to assess the efficiency of drone-based herbicide application in terms of weed control, energy use, and cost effectiveness in wet direct-seeded rice (Oryza sativa L.). The study compared the effectiveness of weed control using herbicide combinations applied as pre-emergence followed by early post-emergence, with both drone and knapsack sprayer. The treatments included the application of pretilachlor followed by early post-emergence bispyribac sodium, and pyrazosulfuron followed by penoxsulam + cyhalofop butyl, using both drone and knapsack sprayer. Additionally, weed-free and unweeded control plots were included. Results indicated that the application of pretilachlor followed by bispyribac sodium using a drone sprayer significantly reduced weed density and weed dry weight compared to the unweeded plot. This treatment also resulted in a higher grain yield (5286 kg ha-1). Moreover, drone application of pretilachlor followed by bispyribac sodium provided a higher net return (? 51631/ha), benefit-cost ratio (2.17), energy-use efficiency (9.53), and energy productivity (0.30 kg/MJ). The experiment concluded that drone-based spraying of pretilachlor followed by bispyribac sodium is an effective weed management strategy for wet direct-seeded rice, offering superior yield attributes, energy use efficiency, and profitability.

Growth, nutrient uptake and yield ofdirect seeded rice as influenced by weed management practices

A field experiment was conducted during the rainy (Kharif) seasons of 2018 and 2019 at the Kerala Agricultural University, Kerala, to evaluate the effect of herbicides and herbicide combinations on the weed management and growth, nutrient uptake and yield of direct seeded rice (DSR). The experiment was laid out in a randomized block design with three replications. Nine weed control treatments were used, including sole application of three herbicides (cyhalofop butyl @ 80 g/ha, bispyribac sodium @ 25 g/ha, fenoxaprop-p-ethyl@ 60 g/ha), five herbicidal combinations (penoxsulam + cyhalofop butyl commercial formulation @ 150 g/ha, cyhalofop butyl @ 80 g/ha + carfentrazone ethyl @ 200 g/ha, bispyribac sodium @ 25 g/ha + cyhalofop butyl @ 80 g/ha, bispyribac sodium @ 25 g/ha + fenoxaprop-p-ethyl @ 60 g/ha and stale seedbed followed by (fb) glyphosate @ 800 g/ha + oxyfluorfen @ 150 g/ha at 15-20 days after land preparation + cyhalofop butyl @ 80 g/ha + carfentrazone ethyl @ 200 g/ha), and hand weeding twice at 20 and 40 days after sowing. Weeds removed 27.72, 4.61 and 67.95 kg of N, P and K/ha respectively at 45 days after treatment application (DATA) under unweeded conditions in direct seeded rice. Herbicidal treatments enhanced grain yield by 23.89 to 58.84 % and herbicide combinations increased grain yield by 56 to 59 % compared to the unweeded control in direct seeded rice. Tank mix combination of bispyribac sodium @ 25 g/ha + fenoxaprop-p-ethyl @ 60 g/ha and bispyribac sodium @ 25 g/ha + cyhalofop butyl @ 80 g/ha and premix combination of penoxsulam + cyhalofop butyl @ 150 g/ha recorded higher nutrient uptake and grain yields (5.03, 4.76 and 4.79 t/ha, respectively) and were on par to hand weeding twice. Unweeded control recorded the lowest pooled grain yield (2.07 t/ha) and uncontrolled weed competition resulted in 59.95 % reduction in grain yield. Keywords: Crop competition, Herbicide combinations, Herbicide interactions, Nutrient removal, Nutrient uptake, Yield reduction

Effect of chemical weed management on growth, yield and economics of drum seeded rice (Oryza sativa)

Field experiment was conducted at Periyanarkunam, Bhuvanagiri Taluk, Cuddalore District during Kuruvai 2021 and 2022 to study the effect of different herbicidal weed management on growth, yield and economics of drum seeded rice (Oryza sativa L.) variety ‘ASD 16’. The experiment was conducted in randomized block design with four replications. The treatments comprised of six weed management practices and are made up of a combination of herbicides (pre-emergence, early-post and post-emergence herbicides) with hand weeding, which was com- pared with unweeded control and twice hand weeding on 25 and 45 DAS. Application of bensulfuron methyl 0.6% + pretilachlor 6% GR @ 660 g a.i./ha PE fb metsulfuron methyl 10% + chlorimuron ethyl 10% WP @ 4 g a.i./ha PoE on 25 DAS fb hand weeding on 45 DAS recorded the highest weed control efficiency of 77.55 and 74.23% during Kuruvai 2021 and 2022 respectively, growth attributes at 60 DAS viz., plant height (96.82 and 91.79 cm), tillers/m2 (367 and 343) and dry matter production (8.01 and 7.78 t/ha), yield attributes like productive tillers/m2 (319 and 312), filled grains/panicle (100.64 and 98.42), grain yield (6.19 and 6.11 t/ha) and benefit cost ratio (2.78 and 2.49) during Kuruvai 2021 and 2022, respectively over bispyribac sodium 10% SC @ 25 g a.i./ha PoE on 20 DAS fb hand weeding on 45 DAS (farmers practice). Hence, it is an efficient weed management practice and an economically feasible method for achieving the maximum growth, yield and economics of drum seeded rice.

Selectivity of new generation herbicide ‘Tembotrione’ under conservation agriculture-based maize (<i>Zea mays</i>) in maize-wheat-mungbean cropping system

An experiment was conducted at the ICAR-Indian Agricultural Research Institute in New Delhi during the rainy (Kharif) seasons of 2021–22 and 2022–23. The study aimed to evaluate the weed control efficiency of low dose new generation herbicide: tembotrione (34.4% SC) as a component of integrated weed management (IWM), on zero-till (ZT) and conventional till (CT) maize (Zea mays L.). The treatments were comprised of conventional tillage maize (M1: CT-M), conventional tillage maize with green manure from preceding green gram (M2: CT-M+GM), zero tillage maize with residue retention at 3 t/ha (M3: ZT-M+R), zero tillage maize with Sesbania co-culture as brown manuring (cover crop) (M4: ZT-M+BM) in the main plot and five weed control treatments, viz S1: Un- weeded check, S2: Pre +1 HW, S3: Pre + Post (tembotrione) @120g/ha, S4: Pre+ Post (Premix of Mesotrione+ Atrazine) @120 g/ha, S5: Weed free check (WFC) in the sub-plots were evaluated in split-plot design. It was ob- served that ZT-M+BM caused a considerable reduction in the population of broad-leaf weed, narrow leaf weed with sedges and total weeds (28.4% reduction at 60 days after sowing) compared to M1. The results also revealed that the sequential application of atrazine @750g/ha+pendimethalin @750g/ha(pre) followed by (fb.) tembotrione (34.4% SC) @120 g/ha (post) among the herbicide options reduced the weeds population (78.5%) and dry weight (81.3%) significantly than the un-weeded control (UWC). Maize yield attributes were higher in ZT with Sesbania co-culture (ZT-M+BM) than conventional-tilled treatments (CT-M). The application of atrazine @750g/ ha+pendimethalin @750g/ha (pre) fb. tembotrione @120 g/ha (post) combined with ZT-M+BM resulting in higher maize yield (6.88 t/ha) which was comparable with that in weed-free check (WFC). The post emergence (PoE) ap- plication of tembotrione (34.4% SC) @120 g/ha recorded highest weed control efficiency (86.2%), weed control in- dex (88.1%) and lowest value of weed index (7.04) when applied in the ZT-maize with sesbania as a cover crop. Therefore, combining zero tillage (ZT) with brown manure (Sesbania), along with atrazine and pendimethalin (@750g/ha each) as pre-emergence herbicides, and tembotrione (@120g/ha) as a post-emergence herbicide is recommended for effective weed control and high maize productivity in the North-Western Indo-Gangetic plains (IGP).

Chemical weed management in chickpea (Cicer arietinum) under Vertisols of Eastern Plateau Plain zone of India

A field experiment was conducted during the winter seasons of 2020–21 and 2021–22 at Instructional-cumResearch farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh to study the effect of various herbicides and their combinations on weed dynamics and performance of chickpea. A total of 14 treatment combinations including hand weeding and unweeded control were laid out in a randomized block design with three replications. The results revealed that significantly lower weed density and dry matter production, weed index and higher weed control efficiency were observed under two hand weedings at 20 and 40 DAS which was found at par to oxyfluorfen 150 g/ha (PE) fb topramezone 20.6 g/ha (PoE) and metribuzin 350 g/ha (PE) fb topramezone 20.6 g/ ha (PoE). The higher dry matter accumulation, crop growth rate, number of pods/plant, number of seeds/pod, seed index, seed yield (1.78 t/ha) and stover yield (2.70 t/ha) of chickpea were obtained with oxyfluorefen 150 g/ha (PE) fb topramezone 20.6 g/ha (PoE). Application of oxyfluorefen 150 g/ha (PE) fb topramezone 20.6 g/ha (PoE) controlled complex weeds flora effectively and fetched maximum net returns (`63.1 × 103/ha) and benefit-cost ratio (3.02).

Efficacy of Sequential Applications of Pendimethalin 500 EC (Pendimight®) and Oxyfluofen 240 EC (Harris®) for Weed Control in Direct Seeded Onion (Allium cepa L.) in Sudan

A field study was carried out to evaluate the efficacy of pendimethalin 500 EC (trade name: Pendimight®) and oxyfluorfen 240 EC (trade name: Harris®) to control weeds in direct-seeded onion (Allium cepa L.). Pendimethalin and oxyfluorfen were applied solely at reduced rates (1.35 and 0.17 kg a.i. ha-1), and at the recommended rates (1.8 and 0.25 kg a.i. ha-1) as pre-and post-emergence herbicides, respectively. Both herbicides were also applied sequentially at the same doses. Ten weeks after sowing (WAS), the application of pendimethalin alone provided better weed control (62% - 65%) than oxyfluorfen alone (33% - 43%) when they were applied at the lower and recommended rates, respectively. Sequential applications of the two herbicides as pre-and post-emergence herbicides, outperformed applications of the two herbicides alone, and resulted in the best weed control (79% to 85%), lowest weed dry weight (18.35 to 35.60 g.m-2), significantly increased plant height and the number of leaves per plant, and resulted in a ten-fold higher onion yield (24.64 to 26.37 t. ha-1) compared with the Un-weeded control (2.27 t. ha-1). There were no significant differences observed between the treatments on the emergence (%) of onion seeds and the survival of onion seedlings. Sequential applications of pendimethalin and oxyfluorfen is a promising techniques for weed control in direct-seeded onions in Sudan.

Conservation agriculture and weed management effects on weed community and crop productivity of a rice-maize rotation

In recent years, an increase in weed infestation, which is adversely affecting crop growth and productivity has been a major challenge facing the farmers of South Asia. The adoption of a permanent bed in combination with residue retention-based crop management practices may reduce weed abundance and increase crop productivity. In a two-year field study, we evaluated the responses of different organic weed management practices with contrasting tillage and residue (R) management strategies to weed dynamics and crop productivity under rice-maize rotation. The main plot treatments consisted of zero-tillage direct seeded rice and zero-tillage maize (ZTR fb ZTM); ZTDSR and maize both on permanent raised beds with residue (PBDSR + R fb PBDSM + R); PBDSR and PBM without residue (PBDSR-R fb PBDSM-R) and conventional tillage puddled transplanted rice and conventional tillage maize (CTR fb CTM). The subplots comprised unweeded control; vermicompost mulch; P- enriched vermicompost mulch; live mulch with Sesbania spp. in rice and Pisum sativum in maize and weed-free. Total weed density and biomass in rice and maize at 30 days after sowing (DAS) were minimum for PBDSR + R fb PBDSM + R compared to remaining tillage and residue management practices in both years. Apart from weed-free treatment, the highest weed control index was found with live mulch. Yield of rice and maize were found higher in permanent beds along with residue retention-based practices. In rice, the weed-free treatment showed the highest grain yield and live mulch reported 9.8 and 6.8 % higher grain yield than vermicompost mulch and P-enriched vermicompost mulch respectively. Our study shows that conservation agriculture practices under rice-maize rotation is one of the ways to reduce weed density and improve crop productivity in South Asia and other similar agro-ecologies.

Brown manuring in maize (Zea mays): Effects on weed interference and crop productivity

A field experiment was undertaken during rainy (kharif) season 2017 at ICAR-Indian Agricultural Research Institute, New Delhi to study the effects of brown manuring on weeds and maize (Zea mays L.) productivity. Season-long weed infestation (~unweeded control) resulted in the highest reduction (~41%) in grain yield of maize. Among the brown manuring (BM) treatments, growing of 1:1 mixture of Sesbania bispinosa (12.5 kg seed/ha) + Crotalaria juncea L. (12.5 kg seed/ha) supplemented with 2,4-D 0.5 kg/ha applied at 35 DAS, resulted in the highest reduction in weed density (~93%) and dry matter (~94.4%). This BM, in these regards, was comparable with the atrazine + hand weeding (HW) at 35 days after sowing (DAS) and weed-free control treatments. All BM treatments suppressed noxious weed Cyperus rotundus, which was poorly or not controlled by the recommended tank-mixture of atrazine and pendimethalin. Weed-free control resulted in the highest values of maize plant dry-matter (~210.6 g/plant), cob weight (~155.9 g/cob), and grain yield (~6.0 t/ha). The atrazine + HW, Sesbania + Crotalaria (12.5 + 12.5 kg/ha) mixture applied with 2,4-D 0.5 kg/ha at 25 DAS, Sesbania 25 kg/ha with 2,4-D 0.5 kg/ha at 25 DAS, and pendimethalin 0.75 kg/ha + atrazine 0.75 kg/ha treatments were comparable with weed-free control on maize grain yield.

Weed and nitrogen management effects on weed flora and productivity of transplanted rice (Oryza sativa) in North-Eastern region of India

A field study was conducted during rainy (kharif) season of 2017 at Barapani, Meghalaya, to find out the effects of weed and nitrogen management on weed flora and yield of transplanted rice (Oryza sativa L.) in North-Eastern region of India. The experiment was taken in split-plot design with 3 replications. In the main plot, 4 weed management practices, viz. unweeded control; oxadiargyl 0.08 kg/ha followed by (fb) bispyribac-Na 0.02 kg/ha; oxadiargyl 0.08 kg/ha fb hand weeding (HW) at 40 days after transplanting (DAT), and 2 HW at 20 and 40 DAT was taken, while 4 N levels, viz. 0, 30, 60 and 90 kg N/ha were taken in sub-plots. At 60 DAT, total weed population and weed density were remained at par in HW at 20 and 40 DAT, oxadiargyl 0.08 kg/ha fb HW at 40 DAT and oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha. The grain yield also followed the same trend and remained at par in HW at 20 and 40 DAT, oxadiargyl 0.08 kg/ha fb HW at 40 DAT and oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha. However, in terms of net returns, application of oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha recorded the highest followed by oxadiargyl 0.08 kg/ha fb HW at 40 DAT. Application of N at higher level reduced the total weed population at 60 DAT and a reverse trend was found with weed dry weight. Application of 90 kg N/ha recorded higher grain yield, net returns and benefit: cost ratio. It may be concluded that oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha with 90 kg N/ha could be an alternative for HW to enhance the productivity in transplanted rice for North-Eastern region of India.

Comparison of Straw Mulching and Herbicide Levels for Control of Various Weed Species in Maize (Zea mays L.)

Weed management in maize is one of biggest concerns for growers. To reduce dependence on chemicals and chances of herbicide resistant weeds, and to improve soil status, thus straw mulching was added as cultural component with chemicals for improving weed management in maize. Field experiments were conducted at two locations (Punjab Agricultural University, Ludhiana, and Regional Research Station, Gurdaspur) during kharif season to find out the influence of different paddy straw mulch and herbicides for control of various weeds species in maize. The results showed that application of paddy straw mulch 6.25 t/ha effectively controlled Eleusine indica, Cynodon dactylon, Commelina benghalensis, Eragrostis tenella, Digitaria sanguinalis, Echinochloa colona, Trianthema portulacastrum, Portulaca oleracea, Phyllanthus niruri, Euphorbia hirta, Conyza stricta and Cyperus compressus over no mulching. In addition to above weed species, paddy straw mulch 9.0 t/ha also effectively reduced density of Dactyloctenium aegyptium, Acrachne racemosa, Digera arvensis, Mollugo nudicaulis, Alternanthera philoxeroides, Amaranthus viridis and Veronica agrestis and Cyperus rotundus as compared to 6.25 t/ha and no mulch treatment. Atrazine pre emergence at 1.0 kg/ha controlled Eleusine indica, Echinochloa crusgalli, Eragrostis tenella, Digitaria sanguinalis, Echinochloa colona, Trianthema portulacastrum, Mollugo nudicaulis, Alternanthera philoxeroides, Digera arvensis, Amaranthus viridis and Cyperus compressus compared to its lower dose (0.8 kg/ha) and control at all stages. Post emergence application of tembotrione reduced the density of all weed species compared to atrazine and unweeded control.

Weed seedbank as influenced by tillage and herbicide in direct seeded rice‐mustard cropping sequence in lateritic soil of eastern India

AbstractThe above‐ground community dynamics of weeds represent the soil weed seedbank in an agro‐ecosystem. Hence, understanding the seedbank will offer an idea for future weed management tactics. We aimed to determine the density of weed seedbank and emergence of major weeds in direct seeded rice (DSR) (Oryza sativa L.)—mustard (Brassica campestris L. var. yellow sarson) cropping sequence under varied tillage and herbicide combinations. The present study on weed seedbank was conducted using seedling emergence method after collecting the soils at the harvest of mustard at the completion of 2 years field experimentation. The experiment was conducted in split‐plot design with two tillage practices [zero tillage (ZT) and conventional tillage (CT)] in main plot and eight weed management practices in DSR [oxadiargyl followed by (fb) bispyribac‐sodium, penoxsulam + cyhalofop‐butyl, oxadiargyl fb penoxsulam + cyhalofop‐butyl, fenoxaprop‐p‐ethyl + ethoxysulfuron, oxadiargyl fb fenoxaprop‐p‐ethyl + ethoxysulfuron, pendimethalin fb bispyribac‐sodium, unweeded control, and weed free check] as subplot. The carry‐over effect of tillage and weed management practices were recorded in mustard crop. Seed emergence study revealed that ZT reduced the emergence of grassy weeds (by 13.7%) and total weed emergence (19.5%) in comparison to the CT (p < 0.05). However, emergence of broadleaf weeds was 24.5% higher in ZT than in CT. The higher infestation was recorded for Ludwigia parviflora (Jacq.) Raven under penoxsulam + cyhalofop‐butyl, fenoxaprop‐p‐ethyl + ethoxysulfuron, Cyperus iria (L.) under fenoxaprop‐p‐ethyl + ethoxysulfuron, and Eleusine indica (L.) Gaertn. under pendimethalin fb bispyribac‐sodium, oxadiargyl fb bispyribac‐sodium. Sole application of post‐emergence (POE) herbicide decreased the total weed emergence by 22.2%–28.1% than unweeded control (p < 0.05). Whereas, sequential application of PRE + POE herbicides decreased the total weed emergence by 32.8%–36.9% than unweeded control (p < 0.05). Notably, sedge weeds such as Cyperus iria (L.) and Fimbristylis miliacea (L.) Vahl were lower in ZT than in CT under herbicide treated plots (by 66.6%–84.3%) than unweeded control. Thus, ZT with oxadiargyl 90 g a.i. ha−1 fb fenoxaprop‐p‐ethyl + ethoxysulfuron (90 + 15 g a.i. ha−1) as tank‐mix can be effectively used to lower the weed seedbank density vis‐à‐vis managing complex weed flora in DSR and rice‐mustard cropping sequence.

Effect of Drone Application of Pendimethalin on Microbial Population, Nodulation, Weed Control and Yield of Green Gram (Vigna radiata L.)

A field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Tiruchirappalli, during Winter, 2023 to study the effect of pendimethalin application using drone on soil microbial population, nodulation, weed control and yield of green gram. The experiment was laid out in RBD with 12 treatments and 3 replications. The treatments consisted two levels of pendimethalin dosage (0.75 and 1.0 kg ha-1), five levels of spray fluids (40, 50, 60, 70 and 80 litres ha-1) for drone spray compared with manual spray of pendimethalin at 1.0 kg ha-1 with 500 litres ha-1 spray fluid and control. The results revealed that significantly higher microbial population such as bacteria (17.60 × 106 cfu/g of soil), fungi (14.90 × 103 cfu/g of soil), actinomycetes (42.60 × 104 cfu/g of soil) and rhizobium (21.30 × 105 cfu/g of soil) were recorded with no herbicide application (unweeded control) at 30 DAS than pendimethalin 1.0 kg ha-1 application either manual or drone. The lower dose of pendimethalin 0.75 kg ha-1 with spray fluid of 60 litres ha-1 was on par with no herbicide application treatment. Significantly higher root nodules per plant-1 (17.56 and 22.51) at 30 and 45 DAS was registered under drone spray of pendimethalin 0.75 kg ha-1 with spray fluid of 60 litres ha-1. Higher weed control efficiency (72.6 %) and grain yield (747 kg ha-1) were statistically superior under drone spray of pendimethalin 1.0 kg ha-1 with spray fluid of 60 litres ha-1 over 40 or 80 litres ha-1 spray fluids and was comparable with lower dose of pendimethalin (0.75 kg ha-1) with 60 litres ha-1. Thus, it can be inferred that pendimethalin at 0.75 kg ha-1 with spray fluid of 60 litres ha-1 was considered as ideal dose and spray fluid for drone application to get better soil microbial population, nodulation, weed control efficiency and grain yield of green gram.

Effect of Herbigation on Weed Control and Yield of Drip Irrigated Cotton

A field experiment was conducted during Summer, 2023 at Anbil Dharmalingam Agricultural College and Research Institute, Tamil Nadu Agricultural University, Tiruchirappalli to study the effect of herbigation on weed control and yield of drip irrigated cotton. The experiment was laid out in randomized block design with nine treatments and replicated thrice. The treatments consisted of herbigation of pre emergence (PE) herbicides (Pendimethalin 1.0 kg ha-1 and Oxyfluorfen 0.2 kg ha-1) combined with hand weeding at 45 DAS or manual spray or herbigation of post emergence (PoE) herbicide (Pyrithiobac Sodium + Quizalofop Ethyl 75 g ha-1 on 25 DAS) compared with recommended practice of manual spray of PE pendimethalin 1.0 kg ha-1 + HW at 45 DAS, HW twice on 20 and 40 DAS and unweeded control. The results revealed that among the different weed management practices manual spray of PE pendimethalin 1.0 kg ha-1 + HW at 45 DAS registered significantly lower total weed density (12.63 m-2), total weed dry weight (8.23 g m-2) and higher weed control efficiency (77%) at 20 DAS. This was followed by herbigation of PE pendimethalin 1.0 kg ha-1 + manual spray of PoE pyrithiobac sodium + quizalofop ethyl 75 g ha-1 on 25 DAS. Among the herbigation treatments, herbigation of PE pendimethalin 1.0 kg ha-1 + manual spray of PoE pyrithiobac sodium + quizalofop ethyl 75 g ha-1 on 25 DAS obtained lower total weed density (12.13 m-2), total weed dry weight (9.19 g m-2) and higher WCE (86%) at 40 DAS. This was followed by herbigation of PE oxyfluorfen 0.2 kg ha-1 + manual spray of PoE pyrithiobac sodium + quizalofop ethyl 75 g ha-1 on 25 DAS. At 60 DAS, application of manual spray of PE pendimethalin 1.0 kg ha-1 + HW at 45 DAS recorded lower total weed density (18.07 m-2), total weed dry weight (16.03 g m-2) and higher weed control efficiency (85%). However, this was comparable with herbigation of PE pendimethalin 1.0 kg ha-1 + manual spray of PoE pyrithiobac sodium + quizalofop ethyl 75 g ha-1 on 25 DAS and HW on 20 and 40 DAS. The highest seed cotton yield (2109 kg ha-1) was obtained with manual spray of PE pendimethalin 1.0 kg ha-1 + HW at 45 DAS and it was on par with herbigation of PE pendimethalin 1.0 kg ha-1 + manual spray of PoE pyrithiobac sodium + quizalofop ethyl 75 g ha-1 on 25 DAS and HW on 20 and 40 DAS. Hence, considering the labour scarcity, herbigation of PE pendimethalin1.0 kg ha-1 on 3 DAS followed by manual spray of PoE pyrithiobac sodium + quizalofop ethyl 75 g ha-1 on 25 DAS could be recommended for better weed control in drip irrigated cotton.

Mesotrione: A New Herbicide for Productivity and Profitability of Maize (Zea mays L.)

The field experiment was conducted at Zonal Agricultural Research Station, University of Agricultural Sciences, GKVK, Bengaluru during summer 2021 to evaluate the effect of new generation mesotrione herbicide on growth and yield of maize (Zea mays L.). The experiment consists of application of different doses of mesotrione herbicide as early post emergent (EPoE) and weed free check and unweeded control were replicated thrice in RCBD. Major weeds observed were Alternanthra sessilis, Borreria articularis, Euphorbia geniculata, Cynodon dactylon, Dactyloctenium aegyptium, Echinochloa colonum, Eleusine indica and Cyperus rotundus. Post-emergent application of mesotrione 48% SC @ 120 ml ai. ha-1 recoded higher kernel yield, stover yield of maize and BC ratio (6273 kg ha-1, 7583.7 kg ha-1 and 2.94 respectively) and it was on par with mesotrione 48% SC @ 144 ml a.i. ha-1 (6075 kg ha-1, 7430 kg ha-1 and 2.79 respectively). Weedy check recorded a kernel yield (3090.7 kg ha-1), lower stover yield (4096.3 kg ha-1) of maize and lower BC ratio (1.03) compared to other treatments.

Above Ground Emergence and Floristic Composition of Weeds in Relation to Tillage and Weed Management Practices in Maize and Cowpea

Background: Weeds are one of the most important elements influencing crop productivity. Tillage practices have a significant effect on the weed seed bank and the appearance of weeds, both of which have a direct impact on farm productivity. Different tillage strategies based on ploughing depth, as well as weed control practices, change the dynamics of weed seeds in the soil. This research will aid in the development of integrated weed control methods by investigating the interaction between tillage and weed management practices. Methods: Field trials were carried out in two seasons, Summer and Kharif 2022, using a split-plot design with three tillage methods and four weed management practices. The treatments were replicated three times. Result: Among the different tillage treatments Mouldboard plough fb Cultivator fb Rotovator recorded the lowest weed density. With respect to weed management methods, pre- and post-emergence herbicide application and hand weeding at 20 and 40 DAS recorded the lower weed density. Interaction effects of tillage and weed management practices resulted in lower weed density in Mouldboard plough fb Cultivator fb Rotovator with herbicide application and Mouldboard plough fb Cultivator fb Rotovator with hand weeding. Highest weed density was recorded under Cultivator fb Rotovator in unweeded control. With respect to relative density, among the broad-leaved weeds (BLW) Trianthema portulacastrum and Dactyloctenium aegyptium in grasses dominated among the weed species in 30 and 60 DAS respectively. From the present study it was concluded that the Mouldboard plough fb Cultivator fb Rotovator with hand weeding twice or herbicide application reduces the weed emergence from the soil weed seed bank.

Effect of spacing and weed management practices on yield parameters and yield of direct-seeded rice

Background: Field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Thiruchirappalli, Tamil Nadu during the rabi season of 2022-23 to evaluate the effect of spacing and weed management practices of yield parameters and yield of direct seeded rice under sodic soil using three levels of spacing and seven weed management strategies. Methods: The main plots were spacing of 20 x 15 cm, 20 x 20 cm, and 25 x 25 cm. Sub plot consisted of weed management practices in direct seeded rice viz., PE pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS + PoE bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS, PE pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS + cono weeding on 20 DAS + hand weeding (HW) on 40 DAS, PE pyrazosulfuron Ethyl 10% WP at 20 g a.i ha-1 on 3 DAS + cono weeding on 20 DAS and 40 DAS, PE pyrazosulfuron ethyl 10% WP at 20 g a.i ha-1 on 3 DAS + PoE bispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS + cono weeding on 40 DAS, PE pyrazosulfuron Ethyl 10% WP at 20 g a.i ha-1 on 3 DAS + PoEbispyribac sodium 10% SC at 25 g a.i ha-1 on 20 DAS + HW on 40 DAS, Hand weeding at 20 and 40 DAS, and unweeded control. The field experiment was laid out in split plot design with three replications. Results: The results indicated that lower total weed density (40.39 no. m-2), dry weight of weeds (85.52 g m-2) and higher WCE (77.5%) were registered under 20 × 15 cm which was on par with spacing of 20 × 20 cm. The higher number of productive tillers m-2 (389), number of grains panicle-1 (192), number filled grains panicle-1 (187), grain yield (4546 kg ha-1) and straw yield (6714 kg ha-1) were observed under spacing of 20 × 20 cm. Application of pyrazosulfuron ethyl 20 g ha-1 at 3 DAS + bispyribac sodium 25 g ha-1 at 20 DAS + cono weeding at 40 DAS possessed the lowest total weed density (7.67 no. m-2), dry weight of weeds (12.63 g m-2), higher WCE (97.0) at 45 DAS and significantly improved the yield parameters and yields compared to unweeded control. The highest grain and straw yields were recorded from interaction between 20 × 20 cm and pyrazosulfuron ethyl 20 g ha-1 at 3 DAS + bispyribac sodium 25 g ha-1 at 20 DAS + cono weeding at 40 DAS.

Assessment of Post Emergence Herbicide Efficacy for Drone Spraying in Transplanted Rice (Oryza sativa L.)

A field experiment was conducted at Rice Research Centre, Agriculture Research Institute, Rajendranagar, Hyderabad during kharif, (2022) to assess the post emergence herbicide efficacy for drone spraying in transplanted rice (Oryza sativa L.). The experiment was laid out in randomized block design with 7 treatments and replicated thrice. Results revealed that among different doses of herbicidal treatments, post emergence application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 180 g a.i ha-1using drone recorded highest number of tillers at harvest, plant height at harvest, number of panicles at harvest, grain yield and low weed dry matter at 60 DAT. It was statistically on par with application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 120 g a.i ha-1 using knapsack sprayer, application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 150 g a.i ha-1 using drone, and application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 120 g a.i ha-1 using drone followed by application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 90 g a.i ha-1 using drone followed by unweeded control.

Physiological Parameters and Yield of Green Gram As Influenced By Weed Management Practices

A field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Tiruchirappalli during Summer, 2021 to evaluate the weed management practices in green gram. The study comprised of eleven weed management practices with different combination viz., pre emergence (PE) application of Diclosulam at 17.5 g/ha, Pendimethalin + Imazethapyr 1 kg/ha, post emergence (POE) application of Fluazifop-p-butyl + Fomesafen 313 g/ha, Acifluorfen sodium + Clodinofop propargyl 187.5 g/ha, PE Diclosulam 17.5 g/ha fb POE Fluazifop-p-butyl + Fomesafen 313 g/ha , PE Pendimethalin + Imazethapyr 1 kg/ha fb POE Fluazifop-p-butyl + Fomesafen 313 g/ha, PE Diclosulam 17.5 g/ha fb POE Acifluorfen sodium + Clodinofop propargyl 187.5 g/ha, PE Pendimethalin + Imazethapyr 1 kg/ha fb POE Acifluorfen sodium + Clodinofop propargyl 187.5 g/ha, PE Pendimethalin1 kg/ha fb HW on 30 DAS, HW on 20 and 40 DAS and unweeded control (UWC) in green gram. The results revealed that the highest plant height, number of branches plant-1, DMP, LAI, CGR, RGR and NAR were registered in PE Pendimethalin + Imazethapyr at 1 kg ha-1 fb POE Fluazifop-p-butyl + Fomesafen at 313 g ha-1. The grain and haulm yields were also higher in PE Pendimethalin + Imazethapyr at 1 kg ha-1 fb POE Fluazifop-p-butyl + Fomesafen at 313 g ha-1 and it was on par with PE Pendimethalin + Imazethapyr at 1 kg ha-1 fb POE Acifluorfen sodium + Clodinofop propargyl at 187.5 g ha-1. Hence, application of PE Pendimethalin + Imazethapyr at 1 kg ha-1 fb POE Fluazifop-p-butyl + Fomesafen at 313 g ha-1 was found to be the most viable option for getting higher growth and yield in green gram.

Weed management with Triafamone herbicide in transplanted rice ecosystem

Field experiments were conducted during Rabi 2018-19 (September to January) and Kharif 2019 (May to September). Medium duration rice cv. CO(R) 51 was used as a test variety at Tamil Nadu Agricultural University, Coimbatore, India to study the effect of Triafamone on broad spectrum weed control in transplanted rice. Triafamone was applied at two times. First set of treatments (30, 40,50 and 100 g/ha) applied two to three leaf stage of weeds and second set treatments imposed (30, 40,50 and 100 g/ha) at three days after transplanting of the rice crop. These treatments were compared with Pyrazosulfuron ethy 10% WP @ 15 g/ha, Pretilachlor 5% EC @ 750 g/ha, hand weeding @ 20 and 40 days after transplanting and unweeded control. The major grasses were Echinochloa crus-galli (L.) and E. colonum (L.) while the sedge weed included Cyperus nutans (L.). Among the broad leaved weeds Eclipta alba (L.) and Bergia ammanioides were the dominant species. In both the seasons of the study, lesser population of grass was recorded with the pre and early post emergence application of triafamone herbicide 40 g a.i. ha-1 (1.41 and 1.41 per m-2 at 28 and 42 DAA for both the seasons respectively) and it was closely followed by application of triafamone herbicide 50 g a.i. ha-1 and application of PE Pretilachlor at 0.75 kg a.i. ha-1 and EPOE Pyrazosulfuron ethyl at 15 g a.i. ha-1. The same trend was observed for broad leaved weeds and their weed dry weights. Application of triafamone herbicide at 40 g a.i. ha-1 as pre emergence and early post emergence application recorded highest weed control efficiency of 100, 97.7 and 99.6 % and 97.8% at 42 DAA during both years of experimentation and also resulted in higher grain yield (8052 and 8182 kg ha-1 during rabi 2018-19 and 9018, 9175 kg ha-1 during Kharif 2019). Further, it is noticed that, there was no residual toxicity of herbicide to the succeeding crops. Hence, application of Triafamone 40 g a.i. ha-1 either pre or early post emergence herbicide has higher productivity and no residues in transplanted rice ecosystem.
 Key words: Triafamone, efficacy, weeds and transplanted rice ecosystem