Adjuvants

Herbicide

Income

Input-use efficiency

Losses

Weeds 

Increasing incomes by reducing crop losses due to various pests and improving productivity and input-use efficiency, are some of the major recommendations of the report on Doubling Farmers’ Income by 2022. Weeds are unwanted intruders into agro-ecosystems that compete for limited resources and reduce crop yields and farmers’ income. It was estimated that on an average the weed control costs around INR 6000/ha (USD 92.42/ha) in rainy season crops and around INR 4000/ha (USD 61.61/ha) for winter crops, which accounts for around 33% and 22% of total cost of cultivation, respectively. Thus, efficient weed management can help in increasing the farmers’ income by reducing the losses caused by weeds, decreasing the cost of production, and increasing the productivity through efficient utilization of resources. The present paper deals with the importance of weeds in crop production and farmers’ income, and role of smart weed management practices in reducing cost of production, and improving input-use efficiency and crop productivity.

Direct-seeded rice

Grain yield

Herbicide

Weed control efficiency

Weed dynamics 

Effect of herbicide combinations were evaluated in Raipur (Chhattisgarh) on crop growth, weed suppression and rice yield in direct-seeded rice (DSR) system during 2014 and 2015. Results revealed that combination of pyrazosulfuron + pretilachlor provided wide spectrum weed control at 15 + 600 g/ha to 30 + 1200 g/ha (61.6 - 81.5%), which was comparable to two hand weeding at 15 and 30 days after sowing. Weed control efficiency was recorded to the tune of 40.0 - 89.9%, with highest in two hand weeding (84.6 - 89.9%) and lowest in pendimethalin and lowest dose of pyrazosulfuron + pretilachlor in 2014 (40.0%) and pyrazosulfuron alone in 2015 (48.5%). The crop growth parameters (tillers, total dry matter/hill and leaf area index), yield attributes (panicle length, panicle weight, filled grains/panicle) and grain yield were recorded highest in two hand weeding (2.69 t/ha in 2014 and 5.87 t/ha in 2015) followed by pyrazosulfuron + pretilachlor at 15 + 600, 16.88 + 675 and 30 + 1200 g/ha. However, the least rice grain yield was recorded under weedy plot (1.45 t/ha in 2014 and 2.17 t/ha in 2015). The results suggested that pyrazosulfuron + pretilachlor at 15 + 600, 16.88 + 675 and 30 + 1200 g/ha were the best broad spectrum effective herbicide in order to minimize the diverse weed flora in DSR system.

Azimsulfuron

Oxyflourfen

Tillage

Water regime

Weed management 

Field experiments were conducted during 2016 rainy and winter seasons to study the effect of tillage, water regimes and weed management methods on weeds and transplanted rice. The design was split plot with combinations of tillage and water regimes as main plot treatments and weed management methods as subplot treatments. The weed biomass was significantly reduced and the rice performance was superior under intensive tillage (three ploughings followed by (fb) puddling), when compared to the conventional farmers’ practice of land preparation. Among the water regimes, continuous deep water ponding (> 7.5 cm water) either till panicle initiation or grain filling stage suppressed weed growth better than that under the recommended practice of maintaining about 5 cm water level with intermittent drainage. Weed control efficiency (WCE) was maximum under azimsulfuron 35 g/ha applied at 15 days after transplanting (DAT), followed by pre-plant application of oxyflourfen fb one hand weeding at 20 DAT.

Direct-seeded rice

Grain yield

Propanil

Weeds

A field experiment was carried out at G.B. Pant University of Agriculture and Technology, Pantnagar, U.S. Nagar, Uttarakhand during rainy season of 2015 and 2016 to evaluate the efficacy of propanil 80% WG against mixed weed flora in direct-seeded rice. The most dominant weeds were: Echinochloa colona, Echinochloa crus-galli, Leptochloa chinensis, Eleusine indica and Digitaria sanguinalis among grassy weeds; Celosia argentea as broad-leaved weed and Cyperus spp. as sedge. Results revealed that propanil 4000 g/ha being on a par with 3000 g/ha was found most effective for controlling grassy as well as broad-leaved weeds as compared to other herbicidal treatments. The lowest weed biomass (11.9 g/m2) and the highest weed control efficiency (73.6%) were also recorded with this treatment. Propanil 4000 g/ha being on a par with 3000 g/h recorded maximum grain yield (4.6 t/ha) which was superior to rest of the herbicidal treatments.

Dry-seeded rice

Herbicides

Planting methods 

Weed management

Yield

A field experiment was conducted to evaluate the effect of planting methods and weed management in direct dry-seeded rice during summer season of 2012 and 2013 at Agricultural Research Farm, Institute of Agricultural Sciences Banaras Hindu University, Varanasi (Uttar Pradesh). The treatment comprised of five rice planting treatments, viz. conventional tillage normal spacing [row to row (R × R) -18 cm], conventional tillage square planting (R×R-20 cm, plant to plant (P × P)-20 cm),  conventional tillage paired row (9-27-9 cm), reduced tillage paired row (9-27-9 cm), reduced tillage square planting (R × R -20 cm, P×P-20 cm) in main plot and sub-plot consisted of four weed management treatments, viz. weedy, two hand weeding, pendimethalin 1.0 kg/ha fb azimsulfuron 17.5 g/ha + bispyribac 25 g/ha (tank mixed) at 15 DAS fb one hand weeding (HW), oxadiargyl 50 g/ha fb metsulfuron-methyl 2 g/ha + chlorimuron-ethyl 2 g/ha (ready mix) at 20 DAS fb 1 HW. Significant reduction in weed density and biomass was recorded in two hand weeding fb pendimethalin 1.0 kg/ha fb azimsulfuron 17.5 g/ha + bispyribac 25 g/ha (tank mixed) at 15 DAS fb 1 HW which resulted in improved growth and yield attributes and yield of rice. Amongst rice planting methods, conventional tillage normal spacing (R × R -18 cm) and conventional tillage paired row (9-27-9 cm) were able to compete with weeds more as compared to other rice planting methods resulting in lower weed density and weed biomass, enhanced rice growth and yield attributing characters and yield.

Morphological characterisation

Morphometric character

Morphotypes

Qualitative traits

Quantitative characters

Seed bank

Weedy rice

Yield

Weedy rice (Oryza sativa f. spontanea) has emerged as a major threat to global rice production and has already established in the major rice growing tracts of Kerala, viz. Palakkad, Kuttanad and Kole lands. The main objective of the study was to compare the morphological characteristics of weedy rice morphotypes across the state so as to chalk out morphometric relationship between the weedy and cultivated rice at different stages of plant growth. Different morphotypes of weedy rice were collected from the major rice tracts of the state and characterization was done, both for qualitative and quantitative (morphometric) traits. The study revealed similarity in most of the qualitative traits observed for weedy and cultivated rice. The morphometric characters that varied significantly between weedy and cultivated rice during the initial stages of growth included thickness of culm and length of ligule. Most striking difference observed was in the number of tillers/plant with 87 per cent of weedy rice morphotypes recording higher tiller number (ranged from 11 to 20) compared to cultivated rice (10 and 9 for ‘Jyothi (Ptb-39) and ‘Uma-MO-16, respectively). Studies also revealed that weedy rice plants were lanky, taller (105 to 115.67 cm) with more round culm, with or without anthocyanin pigmentation at the nodal region, short ligule, early flowering compared to cultivated rice, more number of tillers per plant and mostly with awned grains. Similarities between weedy and cultivated rice were found to increase after every cultivating season due to the repeated back crossing and gene flow between the two plant types as evident from compact panicles and awnless grains observed among the morphotypes. As weedy rice invasion reduces crop yield substantially (40-70 percent), its management is an urgent need of the hour. Some of the morphological adaptations exhibited by the morphotypes in response to the prevailing ecological situations clearly indicated the possibility of weedy rice becoming a persistent threat to rice cultivation. Morphological characterization could help in identifying the competitive traits of weedy rice morphotypes which can be used in advanced breeding programmes for developing ecofriendly weedy rice management strategies.

Bispyribac-sodium 

Direct-seeded rice

Integrated weed management

Pedimethalin

A field experiment was conducted during summer 2014 and 2015 at Agriculture and Horticultural Research Station, Kathalagere Davanagere district (Zone-7, Southern Transition Zone, Karnataka), to study the effect of various weed management practices on weed density, weed dry weight, yield and economics of direct seeded rice. The experiment consists of ten treatments replicated thrice in a randomized complete block design. Among the various treatments, three hand weeding (20,40 and 60 DAS) recorded significantly higher rice grain (4.04 t/ha and 3.64 t/ha) and straw (6.3 t/ha and 6.52 t/ha) yields in 2014 and 2015, respectively and it was found at par with pendimethalin 1.0 kg/ha at 2 DAS fb bispyribac sodium 25 g/ha fb manual weeding (3.87 t/ha, 6.0 t/ha in 2014 and 3.5 t/ha and 6.4 t/ha in 2015, respectively). Higher net returns and benefit: cost ratio of ` 28965 and 2.0 and ` 41402 and 2.4 in 2014 and 2015, respectively were obtained with pendimethalin 1.0 kg/ha fb bispyribac sodium 25 g/ha as post-emergence with manual weeding.

Penoxsulam

Transplanted rice

Soluble concentrate

Weed control

Field investigations were carried out at wetland farm, Agriculture College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, during rainy seasons (June to October) of 2014 and 2015 to evaluate penoxsulam on weed control and yield of rice and its residual effect on microorganisms and succeeding greengram crop. Two years of field experimentation, revealed that pre-emergence application of penoxsulam at 22.5 g/ha resulted in significantly lower total weed density, weed biomass and higher weed control efficiency at all the stages. Application of new formulation of penoxsulam (21.7% SC) at 22.5 g/ha as pre-emergence herbicide kept the weed density and biomass below the economic threshold level and increased the grain yield as 5.20 and 5.04 t/ha in 2014 and 2015, respectively in rice. Succeeding greengram crop sown immediately after the rice harvest was not affected by the residue of new formulation of penoxsulam at all tested doses.

Herbicide combination

Phalaris minor

Residual effects

Weed control

Wheat

A field experiment to evaluate the efficacy of a pre-mix herbicide pinoxaden 2.53% + clodinafop 2.53% w/w (Traxos 5% EC) against grassy weed Phalaris minor in wheat was conducted during winter season 2011-12 and 2012-13 at CCS Haryana Agricultural University, Regional Research Station, Karnal. Density and dry weight of P. minor under pinoxaden + clodinafop 60 g/ha was at par to pinoxaden 50 g/ha but lower than clodinafop 60 g/ha and fenoxaprop 120 g/ha. However, the differences with clodinafop in respect of dry weight of P. minor were not significant. Pinoxaden + clodinafop 60 g/ha provided control of P. minor as good as weed free check, and resulted in higher number of effective tillers than its lower dose (40 g/ha), fenoxaprop 120 g/ha and weedy check. This ready mix provided grain yield of wheat similar to pinoxaden 50 g/ha, clodinafop 60 g/ha and weed free check but higher than fenoxaprop 120 g/ha during both the years, and there was no phyto-toxicity on wheat. There was also no phyto-toxicity of pinoxaden + clodinafop up to 120 g/ha on succeeding rice crop.

Economics

Lentil

Nutrient uptake

Quality

Weed dynamics

Weed management 

The field experiment was conducted at research farm of Tirhut College of Agriculture, Dholi of Dr. Rajendra Prasad Central Agricultural University, Pusa, Bihar during winter seasons of 2012-13 and 2013-14 to find out the suitable herbicides and their combinations for controlling weeds and improving yield of rainfed lentil (Lens culinaris). Study comprised post-emergence application of quizalofop-ethyl 50      g/ha or imazethapyr 37.5 g/ha, pre-plant application of chlorimuron-ethyl 4 g/ha, pre-emergence (PE) application of pendimethalin 300 g/ha, pendimethalin 154 g/ha + imazethapyr 10.5 g/ha (ready-mix), ready-mix pendimethalin 205 g/ha + imazethapyr 14 g/ha (ready-mix), pendimethalin 300 g/ha + hand weeding at 40 DAS, hand weeding twice at 20 and 40 DAS and weedy check. Hand weeding twice at 20 and 40 days after sowing caused the highest reduction (84.6%) in weed population (75.9 and 93.3% in monocot and dicot weeds, respectively) and registered the lowest nutrient depletion (13.6 kg/ha) by weeds. The highest seed yield (1.83 t/ha) obtained with hand weeding twice was 117.4% higher as compared to weedy check. The yield obtained under this treatment was at par with the combined application of pendimethalin 300 g/ha + hand weeding at 40 days after sowing (1.73 t/ha). However, the maximum B: C ratio (3.42) was obtained with application of pendimethalin 205 g/ha + imazethapyr 14 g/ha as PE followed by (fb) their lower dose (pendimethalin 154 g/ha + imazethapyr 10.5 g/ha as PE). The chemical weed control was found economically better than hand weeding and weedy check.

Native AMF consortium

Striga asiatica

Sugarcane

Weed control

The control of Striga is difficult to achieve because of its high fecundity and asynchronous seed germination. Thus, an attempt was made to control Striga in its subterranean stage of development using native arbuscular mycorrhizal fungi (AMF) spp.  In this investigation, 16 AMF spp. were isolated, grouped and mass multiplied according to their morphological differences from the Striga suppressive soil of sugarcane growing area. Further, these 16 native AMF isolates (coded as UASDAMF), native AMF consortium (including 16 native AMF spp.), standard AMF consortium and uninoculated control- UIC (without AMF spp.) were tested against Striga under pot experiment. Significant inhibition of Striga emergence was observed with standard AMF consortium, native AMF consortium, UASDAMF-2, UASDAMF-5, UASDAMF-9 and UASDAMF-12.  While, the UIC recorded highest number of Striga infestation.  Chlorophyll content in sugarcane leaves (43.36 and 42.72 at 90 and 120 DAP respectively) were recorded highest with native AMF consortium. The physiological parameters such as photosynthetic rate and stomatal conductivity of sugarcane also recorded highest (18.16 and 0.55 µmol/m2/sec respectively) with native AMF consortium. The results indicated that the native AMF can efficiently compensate the negative effect of Striga infestation on sugarcane plants. An overall improvement in the biochemical and physiological attributes of the Striga-susceptible sugarcane variety CO86032 upon AMF colonization, clearly suggests the biocontrol and growth promotional potential of AMF consortium.

Barley

Surfactant

Weed control efficiency

Field experiment was conducted at Agricultural Research Farm, Banaras Hindu University during winter seasons of 2014-15 and 2015-16 to evaluate the effect of herbicides alone or as mixture with or without nonionic surfactant on broad-leaf weeds in barley (Hordeum vulgare L.). Post-emergence application of premix formulation of metsulfuron-methyl + carfentrazone-ethyl at 25 g/ha + surfactant at 0.2% proved most effective against Anagalis arvensis L., Chenopodium album L., Melilotus alba L., Solanum nigrum L. and Rumex dentatus L. Maximum reduction in population and dry weight of weeds, and higher weed control efficiency (63.2%), yield attributes and yield (3.5 t/ha) of barley were recorded in metsulfuron-methyl + carfentrazone-ethyl at 25 g/ha + surfactant at 0.2% applied as post-emergence.

Biodiversity

Domestication

Invasive weeds

Weed ecology

Weed survey 

Weed monitoring and survey was conducted to detect appearance of new weed species during decade of 2008-2017. Ten new weed species namely Galium spurium Linn. (family Rubiaceae), Geranium nepalense Sweet  (family Geraniaceae), Lamium amplexicaule Linn. (family Lamiaceae),  Evolvulus nummularius (family Convolvulaceae), Euphorbia thymifolia Linn.(family Euphorbiaceae), Oenothera laciniata Hill (family Onagraceae),  Soliva anthemifolia (Juss.) R. Brown (family Asteraceae), Verbesina encelioides (Cav.) Benth. and Hook. f. ex A. Gray (family Asteraceae), Nicotiana plumbaginifolia Viv. (family Solanaceae) and Portulaca oleracea L. (family Portulacaceae) have been recorded in the last decade from different places of Punjab State. Out of these, weed species namely, O. laciniata, L. amplexicaule, S. anthemifolia and G. nepalense were mainly observed inhabiting the crop fields. Three weed species namely, G. spurium, N. plumbaginifolia and V. encelioides were observed growing along roadsides, wastelands, canal banks and uncultivated areas. P. oleracea and E. thymifolia were observed growing on bunds of agricultural fields. E. nummularius is a serious weed of lawns and landscapes. These weeds have now domesticated in the studied ecological niche and may potentially harm the biodiversity of those areas.

Bispyribac-sodium + metamifop

Broad-leaved weeds

Direct-seeded rice

Grasses

Penoxsulam + cyhalofop-butyl

Sedges

Weed seed bank

To study the effect of post-emergence applied herbicide mixtures, viz. bispyribac-sodium + metamifop and penoxsulam  + cyhalofop-butyl on soil weed seed bank, weed seed bank assay were carried out at College of Agriculture Vellayani, Thiruvananthapuram during rainy season 2014 and winter season 2014-15. Weed seed bank assay results revealed a significant reduction in the emergence of sedges, broad-leaved weeds (BLW) and grasses from the soil treated with herbicide mixtures compared to individual application of bispyribac-sodium at 25 g/ha and penoxsulam at 22.5 g/ha. The results also revealed that penoxsulam + cyhalofop-butyl was more effective in reducing the weed seed bank than bispyribac sodium + metamifop. The higher doses of penoxsulam + cyhalofop-butyl (135, 130 and 125 g/ha) were found to be more effective than its lower dose of 120 g/ha.  Among the tested doses of bipyribac-sodium + metamifop, its higher doses (90 and 80 g/ha) performed better than lower doses (60 and 70 g/ha) in reducing the soil weed seed bank. Hence, post-emergence application of penoxsulam + cyhalofop-butyl either at 125 or 130 or 135 g/ha or bispyribac-sodium + metamifop at 80 or 90 g/ha at 15 DAS (days after sowing) can be recommended for the effective management of weed seed bank in wet direct-seeded rice.

Adoption level

IWM practices

Profile characteristics

This study explored the adoption level towards integrated weed management (IWM) practices and the associated relationship with various profile characteristics of 108 farmers from 12 villages of 6 blocks of Jabalpur district of Madhya Pradesh with an ex-facto sampling design. A list of various IWM practices in major crops suited to the study area and recommended by ICAR-Directorate of Weed Research, Jabalpur, was prepared after consultation with experts in the area. It was found that majority of the respondents had medium extent of adoption of IWM practices with reference to rice (56%), soybean (49%), greengram (50%) and wheat (55%). A positive and significant correlation between level of adoption of respondents on overall IWM practices with other variables viz. age, education, farm size, training, extension contact, mass media exposure, input availability and innovativeness were noticed.

AG 1-IB

Rhizoctonia solani

Pathogenicity

Rhizoctonia solani Kuhn is a soil borne fungal plant pathogen, infecting several crops. Many weeds act as collateral hosts of this pathogen and help in spreading this. Pathogenicity of R. solani AG 1-IB isolate was tested on 47 common weeds of Meghalaya. Incubation period on all the common weeds was 2-3 days except 6 days on Cyperus iria with R. solani AG 1-IB isolate. Minimum days for sclerotia formation was 4 days on Crassocephalum crepidioides, Galinsoga parviflora and Tridax procembens. Maximum sclerotia production (16 nos.) was observed on Lantana camara. The weed Emilia sonchifolia was most susceptible to isolate R. solani AG 1-IB based on area under disease progress curve criteria. Highly susceptible weeds identified in this study should be avoided for mulching purpose since this will increase the inoculum load of this pathogen

Herbicides, Weeds, Weed management, Wheat, Yield

Sulfosulfuron + metsufuron-methyl  30 + 2 g/ha application as post-emergence recorded significantly less weed biomass and higher weed control efficiency followed by clodinafop 60 g/ha compared to the rest of the herbicidal treatments. The highest (65.8 g/m2) weed biomass was recorded with weedy check conditions. Post-emergence application of sulfosulfuron + metsulfuron-methyl 30 + 2 g/ha recorded significantly less weed biomass and higher weed control efficiency, number of effective tillers, grain yield which were at par with weed free check and clodinafop 60 g/ha.

Maize, Intercropping, IWM, Rotary hoeing, Weed management, Yield

Field experiments were conducted to study the effect of intercropping and integrated weed management practices on weeds experiment was conducted at Agricultural College and Research Institute, Madurai (Tamil Nadu) during winter 2013.  The experiment was laid out in a split plot design and replicated thrice. The main plots were assigned with three cropping systems, viz. maize, maize + blackgram, maize + cowpea and six weed management practices, Application of pendimethalin at 0.75 kg/ha followed by one rotary hoeing on 35 DAS recorded the highest weed control efficiency (85.9) and reduced weed populations and weed dry matter production at 60 DAS. The maize + cowpea system resulted increased plant height, LAI and dry matter production of maize at 30, 60 and 90 DAS respectively. Application of pendimethalin at 0.75 kg/ha followed by one rotary hoeing on 35 DAS resulted in the highest grain and straw yield of maize 6.05 and 18.15 t/ha, respectively.

Haloxyfop-p-methyl

Herbicides

Imazethapyr

Nutrient uptake

Weed management

A field experiment was conducted at College of Agriculture, PJTSAU, Rajendranagar, Hyderabad (Telangana) during rainy season 2015-16 on sandy loam soil to study the weed growth, yield and nutrient uptake in greengram under different early post-emergence herbicide treatments. Lower density and dry matter of weeds was recorded with hand weeding at 20 and 40 DAS followed by haloxyfop-p-methyl 135 g/ha + imazethapyr 75 g/ha at 12-15 DAS as early post-emergence, which remained at par with quizalofop-ethyl 50 g/ha + imazethapyr 75 g/ha at 12-15 DAS. Hand weeding twice at 20 and 40 DAS showed the highest uptake of N, P and K, which was comparable with haloxyfop-p-methyl 135 g/ha + imazethapyr 75 g/ha at 12-15 DAS and quizalofop-ethyl 50 g/ha + imazethapyr 75 g/ha at 12-15 DAS. Significantly higher seed yield was observed with hand weeding at 20 and 40 DAS (1.09 t/ha) which remained at par with haloxyfop-p-methyl 135 g/ha + imazethapyr 75 g/ha at 12-15 DAS (1.03 t/ha) and quizalofop-ethyl  50 g/ha + imazethapyr 75 g/ha at 12-15 DAS (1.01 t/ha).

Chickpea

Clodinafop

Imazethapyr

Pendimethalin

Weed Density

In a study on chickpea at Uttar Pradesh, two hand weeding done in weedy check and weed free plot results indicated that weed control treatments significantly reduced the density of weeds. Maximum weed control efficiency (100%) was recorded with weed free plot. Among herbicides, maximum WCE (95.0%) was recorded in pre-emergence of pendimethalin1000 g/ha followed by combined PoE application of imazethapyr 75 g + quizalofop-ethyl 60 g/ha at 35 DAS and lowest WCE was recorded in weedy check. Among herbicides, the lowest number of plants (20.7/m2), plant height (33.4 cm) and number of pods/plant (22.4) at harvest stage of chickpea were recorded in PE application of pendimethalin 750 g/ha followed by combined PoE application of quizalofop-ethyl 60 g + oxyfluorfen 200 g/ha at 30 DAS. Maximum net monetary returns ` 53588/ha was recorded with pre-emergence application of pendimethalin 1000 g and PoE application of clodinafop 60 g/ha at 35 DAS.

Imazethapyr

Imazemox, Mothbean

Pendamethalin

Vigna aconitifolia

A field experiment was conducted at College of Agriculture, S K Rajasthan Agricultural University, Bikaner during rainy season 2015 to find out the efficacy of herbicides for control of weeds in mothbean (Vigna aconitifolia). The experiment comprised of 16 treatment combinations. Application of imazethapyr + imazamox 50 g/ha  (20 DAS) + hand weeding at 35 DAS were significantly superior in reducing weed density and dry weight of both broad-leaved and grassy weeds. Weed free, pendimethalin 0.75 kg/ha + hand weeding at 25 DAS and pendimethalin 0.75 kg/ha PE alone, imazethapyr + imazamox 50 g/ha + hand weeding at 35 DAS and imazethapyr + imazamox 30 g/ha + hand weeding at 35 DAS registered 844, 827, 805, 801 and 781 kg/ha seed yield, respectively as against the seed yield of 427 kg/ha in weedy check. Among the weed control treatments, maximum net returns of ` 50529/ha was recorded under weed free treatment while highest B:C ratio was recorded with pendimethalin 0.75 kg/ha (2.48) closely followed by imazethapyr + imazamox 50 g/ha  + hand weeding at 35 DAS (2.47)

Imazethapyr, Metribuzin, Pendimethalin, Sesame, weed management

Pendimethalin, imazethapyr, metribuzin, oxyfluorfen, imezemox were evaluated as pre-emergence herbicides in sesame during summer season of 2013 and 2014 at ICAR-Directorate of Weed Research, Jabalpur. All the herbicides reduced the weed population significantly as compared with weedy check but delayed the germination of sesame and caused sesame injury. Among all the herbicides, pendimethalin alone and in combination with lower dose of imazethapyr caused less injury to the sesame and produced higher sesame yield. None of the herbicides surpassed the yield what was achieved with 2 HW.

Abundance

A/F ratio

Importance value index

Phytosociology

Phytosociological association of the weeds in the plantation of Jatropha curcas L. was studied in pre-monsoon and monsoon season at Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal. In pre-monsoon and monsoon period, 15 and 31 weed species were found, respectively. In both the seasons, the dominant family was Poaceae followed by Compositae, Araceae and Cyperaceae. Among the life forms, herbs were found to be dominant followed by grasses, shrubs and climbers. Digitaria violascens (54.32) and Torenia thouarsii (3.29) had the highest and lowest IVI, respectively, in pre–monsoon period, while Oplismenus burmani (68.63) and Cyperus rotundus (1.49) recorded maximum and minimum IVI, respectively, in monsoon period. Highest and lowest abundance frequency (A/F) ratio   was found with  Ludwigia octavolvis (0.75) and Kyllinga bulbosa, respectively,  in pre–monsoon period and Cyperus rotundus (0.03); and Axonopus compressus (1.05) and Mikania micrantha (0.05), respectively, in monsoon period.

Orobanche solmsii

Polarity

Stimulant

Root extract

The seed germination of Orobanche is initiated by the stimulants present in the root exudates of host plants. Therefore, in order to find out the polarity nature of germination stimulants, root extract of tomato, tobacco and brinjal plants were assayed through different organic solvents of varying polarity by the flow chart method. Hexane and ethyl acetate fractions of root extract of tobacco, tomato and brinjal induced better germination than any other solvent tested. Tobacco root extract fractions isolated in ethyl acetate induced the highest germination compared to hexane. Tomato root extract fractions in different solvents also produced similar results. The performance of root extract of brinjal was more or less similar to that of tobacco and tomato root extracts except that the percentage of germination in both the solvents was greater than in other two host plants. The polarity of one form of stimulants matches with that of hexane (1.89) and polarity of   another form with that of ethyl acetate (6.02).

Crop, Host range

Lepidoptera

Preference

Spodoptera litura

Weeds

A study was conducted to determine the preference and host range of a polyphagous lepidopteron, Spodoptera litura, collected during a search for biocontrol agent of Trianthema portulacastrum L.  Culture of S. litura was maintained on T. portulacastrum leaves at 26 ±2 0C and 70 ±5% RH. The experiment was done using 10 days old larvae of S. litura obtained from the laboratory reared nuclears culture. Forty five plant species of crops and weeds belonging to 21 families were used for host preference study. In each replication, 10 larvae were placed on bouquet of various crop and weed plants  in well aerated large size containers (2x3x2 ft). Out of the 45 crop and weed plants tested, larvae of S. litura showed high, moderate, low and nil preference for 15, 12, 7 and 9 plant species, respectively. Among the crop plants, maximum preference was observed on Lycopersicon esculentum Mill., Spinacea oleracea L., Brassica oleracea L. var. capitata and Trifolium alexandrium L. Among the 25 weed plants tested, high feeding preference was observed on Alternanthera philoxeroides Mart., Euphorbia hirta L., Eichhornia crassipes Mart., Trianthema portulacastrum L., Parthenium hysterophorus L., Cichorium intybus L., Rumex obtusifolius L. Chenopodium album L.,  and Ipomoea fistulosa Mart.