Volume-50 | Issue-4(October-December)| Year 2018

Bispyribac-sodium

Herbicide residue

Pyrazosulfuron-ethyl

Rice

Weed biomass

A field experiment was conducted on a silty clay loam soil at Palampur, Himachal Pradesh during Kharif 2016 and 2017 to assess pyrazosulfuron-ethyl as an alternative herbicide to manage weeds in transplanted rice. Ten treatments comprised of company released sample of pyrazosulfuron-ethyl at 10, 15, 20 and 30 g/ha was compared to its market sample at 10 and 15 g/ha, bispyribac- sodium at 20 and 40 g/ha, hand weeding twice and weedy check. Pyrazosulfuron-ethyl and bispyribac-sodium effectively reduced the biomass of Echinochloa colona, Echinochloa crusgalli and Cyperus difformis. These herbicides also suppressed the growth of Ammannia baccifera, but not to the extent as hand weeding twice. Pyrazosulfuron-ethyl curtailed Eclipta alba, but lower dose of bispyribac-sodium was not effective against it. In 2016, pyrazsulfuron-ethyl 20 g/ha gave significantly higher yield while in 2017, pyrazsulfuron-ethyl 30 g/ha  gave significantly higher yield of rice over other weed control treatments. Every gram weed biomass increase per square metre caused 5.6 kg/ha yield reduction of transplanted rice. Samples of pyrazosulfuron-ethyl obtained directly from the industry had an edge over the market samples. Weed persistence index was found to be decreased and crop resistance index increased corresponding to increase of dose of pyrazosulfuron-ethyl and bispyribac-sodium. The minimum weed index was under company’s pyrazosulfuron-ethyl at 20 g/ha followed by 15 g/ha, 30 g/ha and market’s sample at 15 g/ha. Cost of weed control was 3.0 to 4.7% of the total cost with pyrazosulfuron-ethyl and 6.1 to 9.8% with bispyribac-sodium. Company procured pyrazosulfuron-ethyl at 15 and 20 g during 2016 and at 20 and 30 g/ha during 2017 had higher net returns and marginal benefit cost ratio (MBCR). Eighty per cent of applied pyrazosulfuron-ethyl got degraded within 5 days of its application. Residues of pyrazosulfuron-ethyl in grain and straw at the time of harvest were below detectable level (BDL) irrespective of treatments.

Ecosystem

Entrapped

Oxadiargyl

Rice

Slow release

Field experiments were carried out in two locations, viz. Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai and ICAR-Central Island Agricultural Research Institute, Port Blair, Andaman and Nicobar Islands during Kharif, 2016 and 2017 respectively to study the effect of entrapped pre-emergence oxadiargyl herbicide on the growth and yield of rice under various agro ecosystems. Weed control measures significantly reduced the density and dry weight of weeds in both the ecosystems. In mainland ecosystem, at 20 DAT, the highest reduction in weed density (61.8%) was noticed with the application of oxadiargyl encapsulated with starch which was comparable with the application of butachlor at 1.25 kg/ha on 3 DAT fb hand weeding on 40 DAT (60.8%). Whereas, under island ecosystem, the lowest total weed density (78.2%) was observed with the application of oxadiargyl loaded in zeolite which entrapped herbicides have increased sorption and decreased the dissipation of herbicide in soil which helps to release herbicide slowly through entire season for effective weed control. Application of butachlor at 1.25 kg/ha on 3 DAT fb hand weeding on 40 DAT recorded significantly higher number of productive tillers/m2 followed by the application of oxadiargyl loading with zeolite on 3 DAT. Weed free check has recorded significantly higher grain and straw yield in both ecosystems. The increase in grain yield with weed control treatment was ranged from 1.22 to 2.97 t/ha and 1.07 to 3.15 t/ha in main and island ecosystem, respectively compared to weedy check. The highest straw yield of 59.3 and 72.4% was recorded under weed free check as compared to weedy check in main and island ecosystem, respectively.

Bispyribac-sodium

Hand weeding

Nitrogen

Pretilachlor

Pendimethalin

Rice

Weed control efficiency

A field experiment was conducted during Kharif seasons of 2014, 2015 and 2016 with an objective to assess the feasibility of weed and nutrient management in direct-seeded rice. The experiment was laid out in a factorial RBD with eighteen treatment combinations including six weed management treatments, viz. pretilachlor, pendimethalin, pretilachlor followed by (fb) bispyribac-sodium, pendimethalin fb bispyribac-sodium, weed free and weedy check and three nitrogen (N) levels, viz. 80, 100 and 120 kg N/ha with three replications. Significantly lower weed biomass was recorded with weed free which [2 hand weedings (HW) at 20 and 40 days after seeding (DAS)] was at par with pendimethalin 1.0 kg/ha pre-emergence treatment (PE) fb bispyribac-sodium 0.04 kg/ha, post-emergence treatment (PoE). Similarly, the highest weed control efficiency (WCE, 73.0%) and the lowest weed index (WI) were also recorded with weed free treatment, followed by pendimethalin 1.0 kg/ha fb bispyribac sodium 0.04 kg/ha (WCE, 71.2%).  Rice growth and yield attributes, viz. plant height, effective tillers, panicles length, grains/panicle were improved significantly under combine application of  PE  and  PoE herbicides either pendimethalin 1.0 kg/ha or pretilachlor  0.75 kg/ha (PE) fb  bispyribac 0.04 kg/ha (PoE) and weed free [2 HW at 20 and 40 DAS]. Further, weed free treatment as well as pendimethalin 1.0 kg/ha fb bispyribac 0.04 kg/ha were found equally effective and recorded significantly higher rice grain and straw yield and nutrient use efficiency (NUE) with higher net returns compared to rest of treatments. Application of 120 kg N/ha significantly increased the plant height, effective tillers/plant, panicle length, grain/panicle, grain and straw yield, N content and NUE % over rest of the treatments in all aspects of yield and yield attributes. It was concluded that 2 HW at 20 and 40 DAS or application of pendimethalin 1.0 kg/ha fb bispyribac-Na 0.04 kg/ha for weed control appeared to be a viable strategy along with 120 kg N/ha for achieving higher and profitable yield of direct-seeded rice.

Green manuring

Herbicides

Transplanted rice

Weeds

A field study was conducted at Dr. Balasdaheb Sawant Konkan Krishi Vidyapeeth, Dapoli (Maharashtra) during Kharif 2011 to 2014 to evaluate the effect of green manuring with Sesbania rostrata and different herbicide on complex weed flora in transplanted rice. The experimental field was infested with Ludwigia octovalis, Cloem viscosa, Cyperus iria, Amaranthus sessils, Isachne globosa and Eriocaulon hexangularis. Four year pooled data revealed that green manuring did not influence the dry matter of monocots and BLWs at all the stages of observation. Green manuring significantly influenced the grain and straw yields of rice and produced significantly higher grain and straw yields (3.86 grain and 3.87 straw t/ha) as compared to without green manuring. Pre-emergence application of pretilachlor-S 0.75 kg/ha at 3-7 DAT recorded the highest weed control efficiency (36.40% at 30 DAT and 48.18% at 50 DAT) and rice grain yield (3.54 t/ha).

Conventional tillage

Dehydrogenase

Phosphatase

Sesbania

Urease

Zero till

Intensive tillage in the rice-wheat system affects soil microbial health by use of agrochemicals, particularly herbicides for control of weeds. Tillage and crop rotation also affects microbial immobilization of soil nutrients. Tillage and agrochemical load directly or indirectly affect the performance of different soil microbial health and its functions which supports the soil health, plant growth and ultimately crop performance. Thus, learning about the interaction of different conservational practices and weed management in terms of soil biological properties is extremely necessary. Hence, the present study was conducted at N.E. Borlaug Crop Research Centre of Govind Ballabh Pant University of Agriculture & Technology, Pantnagar (Uttarakhand) during 2015-16 to 2016-17 with 5 establishments methods of rice and 3 weed management practices under strip plot design with three replications. Conventional Agricultural practices with weed management practices had a significant impact on soil biological properties i.e. dehydrogenase activity, acid, and alkaline phosphatase activity, during both the years. The value of dehydrogenase, acid, and alkaline phosphatase activity was higher in zero till rice and wheat with retention of residues followed by Sesbania brown manuring in summers (ZTR+R-ZTW+R-ZTS) with a weedy check, during both the years of study.

Complex weed flora

Rice-wheat cropping system

Penoxsulam

Transplanted rice 

Weed flora

Field experiments were conducted to evaluate the efficacy of penoxsulam 1.02% w/w (1.0% w/v) + cyhalofop-butyl 5.1% w/w (5.0% w/v) as post-emergence (PoE) in transplanted rice at CCS Haryana Agricultural University, Regional Research Station, Karnal during kharif 2010 to 2011, along with its phyto-toxicity on rice crop (Kharif 2010 to 2012), residual phyto-toxicity on wheat crop (Rabi 2010-11 to 2012-13), its residual studies in soil, straw and rice grains in lab (2017) and also multi-locational adaptive trials on rice during Kharif 2017. Penoxsulam + cyhalofop 135 g/ha reduced the density and dry weight of Echinochloa crusgalli and other aerobic grassy weeds (0.0- 3.3/m2 and 0.0-26.3 g/m2) and broad-leaf weeds (30.7-36.7/m2 and 0.0-4.7 g/m2) over its lower doses (105 and 120 g/ha) and was at par with its higher dose (150 g/ha), and it provided almost complete control of sedges during both the years. There was no significant effect of herbicidal treatments on the plant height and panicle length of the crop during both the years. Penoxsulam + cyhalofop 135 g/ha resulted in significantly higher number of effective tillers/ mrl (49.0 in 2010 and 53.3 in 2011) than cyhalofop 80 g/ha (33.8.0 in 2010 and 49.8 in 2011) and weedy check (27.0 in 2010 and 32.5 in 2011), and penoxsulam + cyhalofop 105 g/ha during 2011 (46.5 in 2010 and 51.5 in 2011). The grain yield in plots treated with penoxsulam + cyhalofop 135 g/ha (5.46 t/ha in 2010 and 5.53 t/ha in 2011) was higher than its lower doses (105 and 120 g/ha) and at par with higher dose (150 g/ha) during both the years. Penoxsulam + cyhalofop 135 g/ha provided grain yields similar to penoxsulam 22.5 g/ha, pretilachlor 750 g/ha, butachlor 1500 g/ha and weed free check; and higher than cyhalofop 80 g/ha, bispyribac-sodium 20 g/ha and weedy check during both the years. Weeds growing throughout the crop season caused 68.8% and 45.8% reduction in the grain yield during 2010 and 2011, respectively. Penoxsulam + cyhalofop 135 g/ha provided net returns (` 24945-29325/ha) and B-C ratio (1.80-1.91) almost similar/ higher to recommended PoE application of penoxsulam 22.5 g/ha (` 23756-29368/ha; 1.79-1.95). There was no phyto-toxicity of penoxsulam + cyhalofop even up to 600 g/ha on transplanted rice as well as succeeding wheat crop. Residues of penoxsulam + cyhalofop applied at 135 and 270 g/ha were below detectable level in soil, straw and grains of rice at harvest during 2010-11 to 2012-13. Penoxsulam + cyhalofop 135 g/ha applied at 15-20 DAT in rice (scented as well as coarse rice varieties) at 12 locations provided 92-97% control of weeds and average grain yield of 4.13 t/ha as compared to 3.83 t/ha in check herbicide bispyribac-sodium 25 g/ha. Penoxsulam + cyhalofop 135 g/ha resulted in average total monetary gain of ` 9665/ha and a net returns of ` 8465/ha. 

Conservation tillage

Pendimethalin

Weed management

Yellow mustard 

Zero tillage

A field experiment was conducted during 2015-16 and 2016-17 at Agriculture Farm, Institute of Agriculture, Visva-Bharati, Sriniketan, West Bengal to study the effect of tillage and weed management practices on weed growth and productivity of yellow mustard in direct-seeded rice - yellow mustard - greengram cropping system. The experiment was laid out in a strip plot design with four horizontal tillage strips and three vertical weed management strips replicated thrice. Results revealed that conservational tillage (zero tillage + residue) along with recommended herbicide (RH) (pendimethalin at 0.75 kg/ha) + one hand weeding (HW) recorded the lower values of total weed density (6.20 and 6.43 no/m2) and dry weight (1.22 and 1.42 g/m2) and higher values of seed yield (1.20 and 1.46 t/ha) in first and second year, respectively. In second year, conservational tillage even with RH alone registered at par values of total weed density and dry weight with conventional tillage + RH + 1 HW and it also recorded 10.2% higher seed yield than conventional tillage + RH + 1 HW. Thus, conservation tillage along with recommended herbicide alone in yellow mustard appeared to be a promising technique with respect to weed suppression and productivity of yellow mustard in conservation agriculture based rice-mustard sarson-greengram cropping system.

Herbicide residue

Pre-emergence and post-emergence

Weed control efficiency

Wheat fodder

Wheat grain yield

Weeds are the biological constraints to increase wheat productivity in Asia. A field experiment was conducted during the Rabi seasons of 2015-16 and 2016-17 to evaluate the efficacy of pendimethalin, pinoxaden, metsulfuron, sulfosulfuron, clodinafop under sole, mixture and their sequential application against control of mixed weed flora in dual purpose wheat at area of farm CCS HAU Hisar (Haryana). The season-long growth of weeds reduced wheat yield up to 55.4 and 59.3% during 2015-16 and 2016-17, respectively. Before cutting of wheat for fodder, among herbicidal treatments, pre-emergence (PE) application of pendimethalin 1500 g/ha significantly reduced grassy (P. minor) and broad-leaf weeds dry weight at 25 and 55 days after sowing (DAS) during both the years. After cutting, weed dry weight at 85, 115 DAS and at harvest was significantly reduced under sequential application of pendimethalin 1500 g/ha fb pinoxaden + metsulfuron (50 + 4) at 2 week after cutting (WAC) at 55 DAS, pendimethalin 1500 g/ha fb sulfosulfuron + metsulfuron (30 + 2) at 2 WAC and pendimethalin 1500 g/ha fb clodinafop + metsulfuron (60 + 4) at 2 WAC as compared to alone application of post-emergence (PoE). Among herbicidal treatments, significantly higher weed control efficiency, plant height, total tillers, grain yield and B:C ratio was observed under sequential application of herbicides than alone application of herbicides during both the years of study. Wheat fodder could be used safely for livestock as no residue was reported.

Clodinafop

Herbicide resistance

Phalaris minor

Wheat 

The field efficacy of pre- and post-emergence herbicides and rotational use of different group of herbicides were tested against Phalaris minor in wheat on farmers’ fields during the year 2015-16  and 2016-17. Clodinafop is being used by 64% farmers at Makowal and 44% at village Mallu Nangal from the last five years. None of the farmer was using pre-emergence herbicide. The higher herbicide dose (76% at site I and 80% at site II) coupled with hallow cone nozzle and less quantity of water (200-225 l/ha) resulted in poor control of P.minor. At site I, continuous use of clodinafop resulted in poor weed control efficiency (58.7%) with lower grain yield (4.46 t/ha). Sequential application of pre-emergence herbicide pendimethalin followed by post-emergence application of clodinafop provided effective control of P.minor (WCE 76.8%) and significantly higher yield (5.1 t/ha) over the existing farmers’ practices (2 sprays of clodinafop at 45 and 65 DAS). At the second site,compared to clodinafop with pendimethalin, mesosulfuron + iodosulfuron, fenoxaprop + metribuzin or sulfosulfuron resulted into higher yield with effective weed control efficiency. Highest yield was recorded with spray of mesosulfuron + iodosulfuron (5.1          t/ha) which was statistically at par with pendimethalin (5.06 t/ha), fenoxaprop+ metribuzin (5.01 t/ha) and sulfosulfuron at 15 DAS (4.98 t/ha).

Tillage

Nutrient

Weed, Weed seed bank

Nutrient uptake 

Yield

Weeds are major threats for loss of yield in any cropping system. Especially in conservation tillage systems, it is a basic necessary requirement to keep the weed population below their threshold levels to realize optimum grain yields. Managing weeds in conservation tillage systems are very essential to optimize crop production. Hence, to study the effect of conservation tillage practices on weed dynamics, soil weed seed bank and their distribution, a field experiment was conducted under rainfed finger millet (Eleusine coracana (L.) Gaertn.) on Alfisols for two consecutive seasons during 2014 and 2015 at All India Coordinated Research Project on Dryland Agriculture, University of Agricultural Sciences, GKVK, Bengaluru, India under split-plot design with three main plots (different tillages) and five sub-plots (different nutrient management). Conventional tillage has recorded significantly higher grain and straw yield of finger millet (3.04 and 4.69 t/ha, respectively) due to effective control of weeds as evidenced by lower total weed density and dry weight observed (13.7 no./m2, 8.0 g/m2 at 30 DAS and 23.9 no./m2, 9.0 g/m2 at 60 DAS) along with higher weed control efficiency (92.5-93.2% in 2014 and 93.3-93.8% in 2015) and lower weed index (7.6-10.3%) due to lower number of weed seeds observed during 2014 (12.3, 19.5 and 4.6/kg soil at 15, 30 and 60 days, respectively) and 2015 (11.3, 17.6 and 4.1/kg soil at 15, 30 and 60 days, respectively as compared to minimum tillage (2.60 and 4.03 t/ha, respectively). Whereas, zero tillage has recorded significantly lower grain and straw yield (2.09 and 3.24 t/ha, respectively) due to poor weed control as observed by higher soil weed seed bank. Among different nutrient management practices application of 100% recommended NPK + 7.5 t FYM/ha yielded significantly higher grain and straw yields (3.03 and 4.68 t/ha, respectively) over other nutrient management practices. Wherein, the soil weed seed bank was not significantly influenced by nutrient management practices and their interactions with the tillage.

Morphology

Physiology

Tembotrione

Yield traits 

A field experiment was conducted in spring 2016 and 2017 at G.B.P.U.A&T, Pantnagar to evaluate the effect of different weed management practices on the morphological and physiological parameters of sweet corn (Zea mays L. var. ‘Sugar 75’), which determines the yield directly or indirectly. The experiment was comprised of twelve treatments. Effect of weed management practices were studied over several growth characters viz. plant height, crop dry matter accumulation, leaf area index, Fv/Fm value, crop growth rate, leaf chlorophyll content, yield, harvest index and nutrient uptake by crop. At 45 DAS, maximum crop height (57.5 cm), crop dry matter (776.5 g/m2), CGR (26.1 g/m2/day), LAI (6.71) and SPAD (60.4) records were obtained from twice hand weeding at 20 and 40 DAS. Fv/Fm value remained unaffected by weed interferences. A significant positive correlation of weed control efficiency was found with all the growth parameters However, weed dry matter accumulation and weed density impacted morpho-physiological characters and ultimate yield in a negative way.

Rainfed, Blackgram, Weeds, Herbicides, Weed Control Efficacy, Yield

A replicated field experiment was conducted during 2016 and 2017 for selecting suitable herbicide for weed management in rainfed blackgram at Krishi Vigyan Kendra Farm, Ashokenagar, West Bengal, India. Among the herbicides tested, pre-emergence application (PE) of pendimethalin 1.0 kg/ha fb post-emergence application (PoE) quizalofop-ethyl 50 g/ha 25 days after seeding (DAS) resulted in lower weed density and higher weed control efficiency (92.10%) with an average seed yield of 0.82 t/ha, which was 48.35% grain yield over the control. Pendimethalin (PE) 1.0 kg/ha fb quizalofop-ethyl 50 g/ha (PoE) could be used for effective and economic weed control in blackgram in rainfed conditions.

Herbicides

Sugarcane

Weed control efficiency

Weeds management

An experiment was conducted at Agricultural Research Station, Dhadesugur, UAS, Raichur, Karnataka during 2015-16 and 2016-17 to study the effect of weed control practices on growth and yield of sugarcane and its associated weeds. Dominant weeds were Echinochloa spp. (E. crus-galli and E. colona), Dactyloctenium aegyptium, Eleusine indica, Brachiaria spp. (B. mutica and B. ramosa) and Digitaria sanguinalis among grasses, Eclipta alba, Chenopodium album, Physalis minima, Ageratum conyzoides, Parthenium hysterophorus and Portulaca oleracea as broad-leaf weeds and Cyperus spp. (C. rotundus and C. iria) as sedges. Among the herbicidal treatments, pyrazosulfuron-ethy + metribuzin + 2,4-D sodium salt WDG (3000 g/ha) recorded significantly higher millable cane yield (119.5 t/ha) as compared to other treatments due to lower weed biomass (42.7 and 47.0 g/m2 at 45 and 75 DAP, respectively) and higher weed control efficiency at 45 and 75 DAP (86.4 and 85.5% at 45 and 75 DAP, respectively) during 2015-16. Similar trend was observed in 2016-17.

Cotton

Herbicide

Weed dynamics

Weed control efficiency

A field experiment was carried out for two consecutive years at the Research farm of Regional Agricultural Research Station, Nandyal during Kharif 2016-17 and 2017-18 with an objective to find out the effective and economic method of weed control in Bt cotton. Among different herbicide applications, pendimethalin 1.0 kg/ha as pre-emergence fb glyphosate 1.0 kg/ha as directed spray at 2-4 leaf stage weed + one hoeing at 50 DAS were significantly superior in reducing weed density and dry weight of weeds. The crop growth parameters (plant height, no of sympodia per plant), yield attributes (no. of bolls/m2 andboll weight) and seed cotton yield were recorded highest in weed free check (4.18 t/ha in 2016 and 3.23 t/ha in 2017) and was comparable with pendimethalin 1.0 kg/ha as pre-emergence fb glyphosate 1.0 kg/ha as directed spray at 2-4 leaf stage weed + one hoeing at 50 DAS. However, the lowest seed cotton yield was recorded under weedy check plot (1.62 t/ha in 2016 and 1.64 t/ha in 2017). Among weed control treatments, highest B:C ratio was recorded with application of pendimethalin 1.0 kg/ha as pre-emergence fb glyphosate 1.0 kg/ha as directed spray at 2-4 leaf stage weed+ one hoeing at 50 DAS closely fb weed free check.

AWL

BPDS

Heart rate

ODR

Oxygen consumption

Weeding efficie

Human labour is a single costliest input in farming operations. Most of agricultural equipment designers regarded the operator as only another part of man-machine system and neglected their comfortness. Manually operated weeders are of push/pull type weeders, operated by application of force in dynamic motion. But, the existing dryland weeders designed based on static force exertion, even though they are in dynamic nature and require higher amount of force application than static ones. Hence, weeders of straight blade (apex angle 1800) and V blade (apex angle 900) were developed for dryland conditions based on the dynamic strength optimized under laboratory conditions. The ergonomical and field performance evaluation was conducted for developed weeders along with one existing twin wheel hoe. The developed weeders showed an increased field performance in terms of field capacity, weeding efficiency and performance index with minimum physiological responses over twin wheel hoe. There was an increase in weeding efficiency, field capacity and performance index by 5, 21 and 7 percent and 4, 21 and 6 percent for straight and V blade weeders, respectively over twin wheel hoe. Further, the physiological responses such as heart rate, oxygen consumption, energy expenditure, acceptable work load (AWL), limit of continuous performance (LCP), overall discomfort rating (ODR) and body part discomfort score (BPDS) were reduced by 5, 7, 8, 8, 9, 11 and 6 percent for straight blade and 5, 7, 8, 9, 10, 13 and 10 percent for V blade respectively over twin wheel hoe.

System of Rice Intensification (SRI), Weed management, Weed control efficiency, Yield, Economics

A field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Thiruchirappalli during Rabi season 2014-15 to evaluate the weed management practices in system of rice intensification contisted 8 treatments with three replication. Pre-emergence (PE) application of bensulfuron-methyl 60 g/ha + pretilachlor at 600 g/ha on 3 days after transplanting (DAT) fb early post-emergence application of bispyribac-sodium at 25 g/ha on 20 DAT registered the minimum total weed density (6.6, 8.8 and 14.3/m2 at 30, 45 and 60 DAT, respectively) along with higher weed control efficiency (WCE). The highest grain and straw yields of 5.72 and 8.36 t/ha, respectively and net returns and BCR of ` 55436/ha and 2.44, respectively were obtained in application of the same treatment

Organic farming

Scented rice

Weed control efficiency

Weed index

A field experiment on evaluation of weed management practices in scented rice under organic production system was conducted during 2017-18 at All India Coordinated Research Project on Farming System, College of Agriculture, Rewa (M.P.). Fimbristylis dichotoma was the most dominating weed in rice field followed by Jussia suffurusticosa. Incorporation of mustard oil cake at 5 t/ha along with one hand weeding gave maximum weed control efficiency (68%). Growth and development of rice was better with incorporation of mustard oil cake 15 days before sowing 5 t/ha + 1 hand  weeding (HW) followed by two HW at 20 and 40 days after transplanting (DAT) and locally available weed mulch Saccharum spontaneam at 3 t/ha + 1 hand weeding . These treatments gave 34 to 56% higher grain yield as compared to farmer’s practice of weed control as mulching with mango leaves. Net profit of ` 62061/ha was maximum in mulching with locally available weeds + 1 hand  weeding followed by ` 56695/ha in two HW at 20 and 40 DAT.

Bensulfuron-methyl + pretilachlor

Ethoxysulfuron 

Hand weeding

Penoxsulam

Perennial sedge

Rock bulrush

Wet-seeded rice

Field experiment was conducted at the College of Agriculture, Vellayani during 2017- 2018 to assess the efficacies of pre-emergence, early post-emergence and post-emergence herbicides for managing rock bulrush Schoenoplectus juncoides (Roxb.) Palla, an emerging sedge weed in the lowland paddy fields of Kerala. A pre-emergence spray of bensulfuron-methyl + pretilachlor 60+ 600 g/ha at 4-7 days after sowing (DAS) was effective till 30 DAS with 93.3% reduction in weed count. At 45 and 60 DAS, lower weed density (2.09 and 3.15 no./m2, respectively) and weed dry weight (0.13 and 1.83 g/m2, respectively) were recorded for ethoxysulfuron 15 g/ha at 15 DAS fb HW at 40 DAS. Higher weed control efficiencies of 99.8% and 98.1% were obtained in plots treated with ethoxysulfuron 15 g/ha at 15 DAS fb HW at 40 DAS during critical stages of crop-weed competition (45 and 30DAS). Penoxsulam 22.5 g/ha at 15 DAS and ethoxysulfuron 15 g/ha at 15 DAS both fb HW at 40 DAS were on a par at 45 and 60 DAS in terms of weed control efficiency (99.1% and 97.9%, respectively. The weed removal of N, P and K (8.61, 3.13 and 10.95 kg/ha, respectively) were also lower with ethoxysulfuron 15 g/ha at 15 DAS fb HW at 40 DAS. The study revealed that rock bulrush could be effectively controlled by ethoxysulfuron 15 g/ha or penoxsulam 22.5 g/ha both at 15 DAS fb HW at 40 DAS.

Carfentrazone-ethyl, Herbicides, Weeds, Wheat, Toxicity

Effects of different broad-leaf herbicides against complex weed flora in wheat and carryover effect on succeeding sorghum were evaluated at Agronomy Research Farm, CCS Haryana Agricultural University, Hisar during 2017-18. Application of different herbicides significantly reduced the dry weight of weeds compared to weedy check at different growth stages of crop. At 30 days after treatment (DAT), weed control efficiency (WCE) was higher with carfentrazone 20 g/ha (91.8%) compared to carfentrazone 10 g/ha (78.9%). Carfentrazone at different doses provide better control of weed as compared to 2,4-D amine at 60 DAT and at harvest. Number of tillers/m2 (401) and grain yield (6.11 t/ha) were recorded significantly higher with carfentrazone at 20 g/ha than carfentrazone at 10 g/ha (372 and 5.62 t/ha), 2,4-D amine at 500 g/ha (366 and 5.26 t/ha) and metsulfuron at 4 g/ha (389 and 5.79 t/ha), respectively. Also, there were no residual effect different herbicides on succeeding sorghum.

Cotton, Fluazifop-p-butyl, Grassy weeds, Blackgram, Residual effect

A field experiment was conducted during rainy seasons of 2010-11 and 2011-12 at Guntur, Andhra Pradesh, India to evaluate the bio-efficacy of fluazifop-p-butyl against grassy weeds in cotton and its residual effect on succeeding crop of blackgram during the winter season. Results revealed that among different doses of fluazifop-p-butyl, post-emergence application of fluazifop-p-butyl 167 g/ha reduced grassy weed growth and recorded higher crop dry weight, yield components and seed cotton yield (1915 kg/ha) over its lower doses (100 and134 g/ha) but was on par with the highest dose of 335 g/ha in both the years. None of the doses of fluazifop-p-butyl including the highest dose (335 g/ha) did not cause any injury to cotton. In a field experiment, residual carry over effect of fluazifop-p-butyl at different doses of 100 to 335 g/ha was studied using blackgram as a succeeding crop. Differences were non-significant on plant population, plant height, crop dry weight and seed yield of blackgram indicating that there was no residual effect of fluazifop-p-butyl in the soil after harvesting of the cotton crop. It was concluded that the post- emergence application of fluazifop-p- butyl 167 g/ha was effective in controlling grassy weeds in cotton without any crop injury and residual effect on succeeding crop.

Metribuzin

Dissipation

Herbicide residue

Half life

Field study was carried out to determine the dissipation of metribuzin and its residues in soil and chilli. Vermicompost (2 t/ha) was used as organic amendments to enhance the degradation. Metribuzin was applied at single and double the dose of 500 and 1000 g/ha. The chilli variety ‘Krishna Jolokia’ was grown with a recommended practices. The recoveries obtained for untreated soil and chilli were in acceptable range of (80.6–85.7%) and (86.8–92.2%) of the metribuzin standards and spiked samples. The limit of detection (LOD) – 0.003 µg/g and the limit of quantification (LOQ) – 0.01µg/g in soil and chilli. The metribuzin residue level ranged 0.153 – 0.356 µg/g on the day of application of metribuzin and further degraded to 0.023 – 0.087 µg/g on the 21st day of application. However, the half-life of metribuzin was observed to be 7 and 10 days with single and double the dose of application of metribuzin. Metribuzin residues did not persisted in soil beyond 30 days after application and in fruits.

Atrazine

Integrated weed management

Metsulfuron-methyl

Sorghum

Weed control efficiency

A field experiment was conducted at College Farm, Navsari Agricultural University, Navsari (Gujarat) during summer season 2016 to study the effect of integrated weed management practices on weed density, weed dry weight and economics in sorghum. The experiment was laid out in randomized block design with three replications and ten treatments with pre- and post-emergence herbicides (atrazine, 2,4-D and metsulfuron-methyl) alone or combination of these herbicides followed by hand weeding and inter-culturing operation. That two hand weeding and inter-culturing operations at 20 and 40 DAS significantly reduced weed density and dry weight of broad-leaved, grassy and sedge weeds. Weed control efficiency was recorded to the range of 52.50 - 97.00%, with the highest value in two hand weeding and inter-culturing operations at 20 and 40 DAS and lowest in atrazine 0.50 kg/ha as pre-emergence fb metsulfuron-methyl 6 g/ha as post-emergence. Higher net return of ` 54623/ha was obtained with two hand weeding and inter-culturing operations at 20 and 40 DAS followed by ` 50179/ha with atrazine 0.50 kg/ha as pre-emergence fb atrazine 0.50 kg/ha as post-emergence at 25 DAS.