A field experiment was conducted for two consecutive rainy seasons of 2010 and 2011 at Varanasi (U.P.) to evaluate the effect of nitrogen application and weed management on transplanted rice and associated weeds. Puddled transplanting recorded significantly reduced weed density and heigher weed control efficiency at 60 days after transplanting (DAT) as compared to unpuddled transplanting. Butachlor 1.5 kg/ha followed by cono-weeding at 20 and 40 DAT recorded significantly higher plant height, no. of tillers/hill, dry matter accumulation, leaf area index, 1000-grain weight, no. of panicles/hill, grains/panicle and grain yield as compared to pretilachlor 0.75 kg/ha followed by azimsulfuron 35 g/ha at 15 DAT,  and butachlor 1.5 kg/ha followed by azimsulfuron 35 g /ha at 15 DAT. Significantly higher yield components and rice grain yield were recorded with the application of 1/4 at 10 DAT, 1/2 at tillering and 1/4 N at panicle initiation as compared to conventional scheduling of nitrogen application.

A field experiment was conducted in strip-plot design with three crop establishment techniques and six weed management practices to study the effect of crop establishment and weed management on weeds and yield of lowland rice at Coimbatore during Rabi 2011-12 and 2012-13. The field was dominated by Echinochloa colona, Cyperus difformis, Eclipta alba, Marselia quadrifoliata and Ammania baccifera. The results revealed that  machine planting (30 x 20 cm) and subsequent cono-weeding at 10, 20, 30 and 40 days after transplanting (DAT) registered lower density and biomass of sedges, grasses, broad-leaved and total weeds resulting in higher grain yield than other treatments. Weed control efficiency  (93.2 and 90.8% in 2011-12, and 2012-13, respectively) was higher with this treatment compared with the other treatments. Next best treatment was the machine planting with pretilachlor (0.75 kg/ha at 3 DAT) + bispyribac-sodium (20 g/ha at 15 DAT) + cono-weeding at 40 DAT.

Invasion by problematic weed species is one of the major contributors in the loss of potential yield in rice cultivation. Therefore, weed flora associated with rice crop in Kashmir Valley was investigated. Based on extensive field surveys carried out during 2010-2013, the present study revealed that 40 plant species were growing as weeds in rice fields of Kashmir Valley, which belonged to 27 genera in 19 families. The actual weeds of rice (40 species) and the weeds (58 species) growing along raised bunds and in between undulated lands of rice fields were recorded. Six species have been reported for the first time as rice weeds. For each weed species, crucial data on growth form, life span, flowering and fruiting months, breeding and dispersal mechanisms were obtained. Weed species growing commonly in the rice fields of Kashmir Valley, as well as those growing rarely were identified. Though weed species were distributed throughout the region, the overall taxonomic diversity of weed flora in rice fields were drastically declined from North to South in Kashmir Valley. Based on the data obtained on diversity and distribution of weed flora, the paper also discusses long-term weed management in the rice fields of Kashmir Valley.

Studies on the impact of long-term fertilizer application on changes in weed community composition are important and likely to provide insight into the effects of prolonged fertilizers on weed community structure and infestation. Nine treatments of long term fertilizers experiment, viz. (i) control (plots which did not receive NPK fertilizers or farm yard manures (FYM) (ii) 50% of recommended doses of NPK (iii) 100% NPK (recommended dose of fertilizers) (iv) 150% NPK, (v) 100% NPK + hand weeding (No herbicides application in jute, rice and wheat (vi) 100% NPK + Zn (vii) 100% NP, (viii) 100%N (ix) 100% NPK+FYM 10 t/ha/year before sowing of jute with four replication were included in the present investigation. A total of 12 weed species were recorded under different fertilizer treatments. Significantly higher total weed density (733/m2) was recorded in 100% NPK + FYM treatments compared to other treatments. Significant variation in weed species was also recorded in different fertilizers treatment. Cyperus rotundus density was comparatively higher in control, 50% NPK and 100% NPK + Hand weeding plot. Echinochloa colona density was higher in 150% NPK, 100% NPK + Zn and 100% NP. Comparatively higher broad-leaved weed density were recorded in 100% NPK + FYM. The highest Shannon-weiner index (H’=2.02), Simpson diversity index (D’=0.81) and weed species evenness (E’=0.81) were recorded in 100% NPK + FYM and the lowest (H’=1.0, D’=0.62 and E’=0.5) in control plot. Thus, weed management strategies in FYM applied jute field should be given highest priority for getting higher fibre yield.

A field experiment was carried out at Pantnagar during Rabi season of 2010-11 and 2011-12 to test the efficacy of different doses of metribuzin 42% + clodinafop-propargyl 12% WG in wheat and associated weeds. The soil of the experimental field was clay loam in texture, medium in organic carbon (0.67%), available phosphorus (29.6 kg/ha) and potassium (176.4 kg/ha) with pH 7.2. Results revealed that metribuzin + clodinafop-propargyl 500 g/ha was significantly at par with its higher dose at 600g/ha, and two hand weedings at 30 and 50 DAS recorded the lowest density of Phalaris minor and Chenopodium album, Coronopus didymus, Melilotus spp., Rumex spp. and Fumaria parviflora at 30 and 60 days after application as compared to rest of the treatments. Maximum grain yield was recorded in metribuzin 42%+ clodinafop-propargyl at 600 g/ha, which was statistically at par with its lower dose of 500 g/ha due to effective control of grassy and broad-leaf weeds in wheat.

Weeds are one of the most important factors that impose a great threat to crop yield. In order to alleviate weed infestation in wheat (Triticum aestivum L.), efficacy of various doses of ACM 9 were tested during Rabi 2010 to 2011 at Norman E. Borlough Crop Research Center, Pantnagar, Uttarakhand. Results revealed that ACM 9 applied at 1000 and 1200 g/ha severely reduced total density and dry weight of weeds as compared to control, while poor weed control was achieved using clodinafop 400 g/ha and metribuzin 300 g/ ha. Highest grain yield of wheat was recorded with ACM 9 at 1200 g/ha (4.09 t/ha) during 2010 while in 2011, it was with ACM 9 at 1000 g/ha (4.16 t/ha). Post-emergence application of ACM 9 at 1200 and 1000 g/ha caused increase in wheat yield (18.2 and 97.4% during 2010 and 2011, respectively) over control. Highest number of spike and grains per spike were obtained from plots treated with ACM 9 at 1200 and 1000 g/ha as post-emergence. Based on the depressed wheat yield obtained, clodinafop 400 g/ha and metribuzin 300 g/ha can be said to be phytotoxic to crop plants.

A field experiment was conducted with eight treatments comprising individual application of isoproturon 0.75 and 1.00 kg/ha and tank mix application of isoproturon 0.75 and 1.00 kg/ha with metsulfuron 0.004 kg/ ha each and isoproturon 1.00 and 1.25 kg/ha with 2,4-D 0.50 kg/ha each including hand weeding twice and a weedy check. All herbicidal treatments resulted in significant reduction of count and dry matter of total weeds, thereby giving significantly higher grain yield of barley over weedy check. Application of isoproturon + metsulfuron 1.00 + 0.004 kg/ha and isoproturon + 2,4-D 1.25 + 0.5 kg/ha was statistically similar to hand weeding twice with significant reduction of weed count and dry matter resulting in higher weed control efficiency. Tank mix application of all combinations gave significantly higher grain yield of barley. However, isoproturon + metsulfuron 1.00 + 0.004 kg/ha recorded similar higher grain yield of 1.72 t/ha as comparable to hand weeding twice (1.72 kg/ha), which was 8.6 to 27.3 % higher over remaining herbicide treatments. Highest net returns due to weed control and marginal benefit cost ratio of Rs 4661/ ha and 2.32, respectively was obtained with isoproturon + metsulfuron 1.00 + 0.004 kg/ha followed by isoproturon + metsulfuron 0.75 + 0.004 kg/ha with corresponding values of Rs 3560/ha and 1.86.

A field experiment was conducted at the Product Testing Unit, JNKVV, Jabalpur during Kharif season 2013 and 2014 to adjudge the efficacy of propaquizafop and imazethapyr mixture against weeds in soybean. Grassy weeds were predominant (76.25%) in the experimental field compared with broadleaved weeds (23.75%). However, Echinochloa colona (33.90%) and Dinebra retroflexa (23.90%) were predominant in soybean but, other weeds (Cyperus rotundus, Cynodon dactylon, Alternanthera philoxeroides, Eclipta alba and Mollugo pentaphylla) were also present. Post-emergence application of propaquizafop (75 g/ha) alone curbed only grassy weeds. However, its efficacy was improved when applied in combination with imazethapyr being higher under propaquizafop + imazethapyr mixture applied at 53 + 80 g/ha or higher rate (56 + 85 g/ha). Yield attributing characters and yield were superior under propaquizafop + imazethapyr mixture applied at 56 + 85 g/ha followed by 53 + 80 g/ha which were comparable to hand weeding twice at 20 and 40 DAS.

A field experiment was conducted during Kharif, 2005 and 2006 at the Pulses and Oilseeds Research Substation, Beldanga, Murshidabad, West Bengal to evolve an integrated weed management (IWM) practice in blackgram. Cynodon dactylon, Dactyloctenium aegyptium, Cyperus rotundus, Cleome viscosa and Physalis minima were the dominant weeds. Pre-emergence application of pendimethalin either at lower dosage (0.75 kg/ha) along with one hand weeding at 40 days after sowing or at higher dosage (1.0 kg/ha) without any integration with hand weeding proved to record higher seed yield (1.09 and 1.03 t/ha, respectively. In addition, use of 30% higher seed rate than the normal rate of 22.0 kg/ha was found to effectively suppress the weeds and further enhance the yield level. Season-long weed competition caused an average yield reduction of 26.4% as compared to IWM in blackgram.

A field experiment was conducted during Kharif season of 2009 and 2010 to study t-he effect of pre- and post-emergence herbicides on weeds, growth, symbiotic traits and grain yield of greengram. Postemergence application of imazethapyr at 75 g/ha 17 days after sowing was found to be effective for controlling sedges, grassy and broad-leaf weeds as well as in improving grain yield of greengram and net returns whereas imazethapyr at lower doses (25 and 40 g/ha), did not control weeds effectively. Weed free and two hand weeding treatments gave higher grain yield than the other treatments during both the year. Imazethapyr at 25, 40 and 75 g/ha and pendimethalin at 0.75 and 1 kg/ha had negative effect on different symbiotic parameters such as nodule number, dry weight and leghaemoglobin content as compared to two hand weeding.

A field experiment was carried out at Pantnagar, Uttarakhand during 2009-10 and 2010-11 to study the effect of rates of herbicide ethoxysulfuron for the control of Cyperus rotundus and other weeds in sugarcane. Ethoxysulfuron at 60 g/ha effectively reduced the density of Cyperus rotundus as well as Trianthema monogyna, Digera arvensis, Cleome viscosa and Ipomoea spp. The highest cane yield was obtained with hand weeding thrice at 30, 60 and 90 days after planting. Among the herbicides, ethoxysulfuron at 60 g/ha being at par with ethoxysulfuron at 56.25 g/ha recorded significantly higher cane yield than 2,4-D at 1000 g/ha.

A field experiment was conducted during 2008-09 and 2009-10 at the Agricultural Research Farm of C.C.R. (P.G.) College Muzaffarnagar (U.P.) to study the integration of chemical and cultural weed management practices in spring planted sugarcane. The experiment consisted of ten treatments laid out in randomized block design with three replications. Cyperus rotundus, Cynodon dactylon and Sorghum halepense were observed as major weeds in both the year. All the weed management practices led to significant reduction in density and dry matter of weeds when compared to weedy check. Hoeing done at 30, 60, 90 DAP recorded lowest weed density (23.77 and 22.07/m2) and dry matter (8.71 and 8.34 g/m2) with mean WCE of 57.0% and was found at par with the application of glyphosate 1.0 kg/ha as pre-emergence + atrazine 2.0 kg/ha after 1st irrigation + one hoeing at 90 DAP (density 24.14 and 23.29/m2, dry matter 10.99 and 10.61 g/m2 and WCE 45.5%). The mean reduction in cane yield ranged from 39.0% under weedyconditions to 8.0% with the crop received 03 hoeing at 30, 60 and 90 DAP and it was closely followed by the glyphosate 1.0 kg/ha as pre-emergence + atrazine 2.0 kg/ha after 1st irrigation + one hoeing at 90 DAP and atrazine 2.0 kg/ha as pre-emergence + one hoeing at 60 DAP. Further, the cane yield was recorded highest (88.8 t/ha) when crop raised with 3 hoeing at 30, 60, 90 DAP which was closely followed (87.9 t/ ha) by glyphosate 1.0 kg/ha as pre- emergence + atrazine 2.0 kg/ha after 1st irrigation + one hoeing at 90 DAP.

Ten weed control treatments viz. metribuzin (700 g/ha) or pendimethalin (1000 g/ha) each followed by (fb) hoeing twice; metribuzin (700 g/ha), pendimethalin (1000 g/ha) or atrazine (750 g/ha) each followed by i) fenoxaprop (670 g/ha) + metsulfuron-methyl (4 g/ha) or ii) straw mulch fb hoeing; weed free (hand weeding thrice) and weedy check] were evaluated for weed control in turmeric on a silty clay loam soil at Palampur during 2012 and 2013. Treatment constituting of fenoxaprop + metsulfuron-methyl were phytotoxic. Pendimethalin fb hoeing and pendimethalin /metribuzin /atrazine fb mulch fb hoeing were comparable to weed free in reducing population of Echinochloa colona, Digitaria sanguinalis, Panicum dicotomiflorum, Cyperus iria and Aeschynomene indica. Metribuzin fb mulch fb hoeing significantly reduced the count of Ageratum conyzoides and Galinsoga parviflora upto 60 DAS. Metribuzin/pendimethalin fb hoeing and pendimethalin/ metribuzin/ atrazine fb mulch fb hoeing resulted in significantly higher plant height, leaves per plant, number of shoots per plant, plant dry matter accumulation, rhizome weightperplant and fresh rhizome yield over other treatments. Atrazine/ pendimethalin/metribuzin fb mulch fb hoeing increased fresh rhizome yield by 1.54-1.68 times over weed free. Metribuzin fb mulch fb hoeing resulted in highest gross and net returns due to weed control. Marginal benefit cost ratio (MBCR) was highest under pendimethalin fb mulch fb hoeing (54.67) followed by atrazine fb mulch fb hoeing (50.73), metribuzin fb mulch fb hoeing (46.2) and pendimethalin fb hoeing (24.86). Weeds in weedy check reduced rhizome yield by 78.2% over metribuzin fb mulch fb hoeing.

A long-term trial was conducted in the coconut plantation at Thrissur, Kerala, India from July 2008 to June 2013. Time series analysis was performed with monthly weed count data to determine seasonality of selected weeds of a coconut garden. A multiplicative model was assumed for the time series and the seasonal index was worked out for each weed species. The results revealed that Axonopus compressus, Biophytum sensitivum and Mimosa pudica dominated during the South West monsoon season while Curculigo orchioides and Desmodium gangeticum were seen germinating during the North East monsoon period from September– October and were predominant in the field till February. Hemidesmus indicus and M. pudica were the weed species seen throughout the year. However, their predominance was the field was between November to April and July to November, respectively.

An indigenous fungal culture, isolated from diseased water hyacinth, in Bolpur, Santiniketan, West Bengal, India, was found to be causing severe blight and dieback disease on water hyacinth, under laboratory and field conditions. It was subjected to morphological and molecular characterization by amplification of 18S RNA gene fragment from genomic DNA using 18S gene universal primers. Subsequently with sequencing, GenBank database comparisons and phylogenetic analysis, the fungus was determined as Alternaria japonica Yoshii. Further the pathogen was evaluated for its host specificity to be developed as mycoherbicidal agent against this invasive weed. Host range of A. japonica was screened against 48 plant species in 42 genera representing 22 families in pot experiment. Water hyacinth was the only species strongly susceptible to spore suspension (5 × 105 conidia/ml) of A. japonica. Minor infection was observed on goosefoot which is not only a weed but also ecologically separated from water hyacinth. Thus, the use of this pathogen in the biological control of water hyacinth would be safe for plants of economic and ecological significance in India. The secondary metabolite produced by A. japonica was sprayed on the test plants but phytotoxic symptoms were produced on nine out of 48 plants tested, demonstrating that phytotoxin produced by the fungus is not host specific. Further field tests needs to ascertain its efficacy under more natural conditions.

Impact on soil chemistry of Calyptocarpus vialis Less., (Straggler daisy), Chromolaena odorata (L.) King and Robinson (siam weed) and Parthenium hysterophorus L. (congress weed) invaded and uninvaded sites were studied during 2014-2015 in selected sites of GKVK, Bengaluru and Mysore district of Karnataka (India). Two soil cores (5 and 10 cm depth, litter discarded) were collected and subjected for analysis of pH, OC, available P K, Zn, Cu, Fe and Mn content. In C. vialis, siam weed and congress grass infested sites at surface soil (5 cm depth) and subsoil layer (10 cm depth) pH, C, P and K were less when compared to the uninvaded sites. Soil ions Zn, Cu, Fe and Mn in C. vialis and C. odorata invaded sites were more at 5 and 10 cm depth. Whereas in P. hysterophorus invaded soil, Cu, Fe ions were less at 5 and 10 cm depth and Zn was more at 5 cm and less at 10 cm depth. Mn ion was less at 5 and more at 10 cm depth. Phosphorus was less available at surface layer and more at subsoil layer in all the three weeds infested sites. Whereas, in the uninvaded sites, there was sufficient availability of P. The same is the case for K. Since the form and availability of P and K is highly pH dependant, the low pH had affected the solubility of P and K. A high variability in response to invasion was observed. Results reflected that soil chemistry was disturbed by the presence of C. vialis, C. odorata and P. hysterophorus to some extent with regard to soil pH, C, P and K contents at 5 and 10 cm depth and micronutrients Zn, Cu, Fe and Mn were increased only in the presence of C. vialis and C. odorata.

Increasing reliance of present day intensive agriculture on herbicide use has led to certain concerns about their eco-toxicological effects influencing various microbial populations and associated enzymatic activities, which may serve as indicators of soil quality. The effect of herbicides (cyhalofop butyl, isoproturon, butachlor and clodinafop) on soil microbial population of beneficial and other organisms was assessed over a period after 13 years in a Rabi and Kharif season. In the present study, herbicide application resulted in transient suppression of population of beneficial microorganisms including fungi. The microbial population regained its number by the time of harvesting of crops

Groundnut (Arachis hypogaea L.) is cultivated in diverse agro-climatic environments characterized by spatial and temporal variation in rainfall, temperature and soils of varying water holding capacity under rainfed as well as irrigated conditions. The productivity of early Kharif groundnut is very low due to lack of suitable variety and optimum plant population coupled with heavy weed infestation as the crop is grown under irrigation. Groundnut crop is highly sensitive to weed competition and yield reduction up to 70% have been observed (Americanos 1994). Varieties differ not only in their production potential, but also differ in competitive ability of weeds on account of variation in rapid development of foliage and formation of close canopy during early growth stage (Bussan et al. 1997). Different crop geometry also imparts competing ability of crop plants to weeds (Singh and Bhan 2002). It was concluded that groundnut ‘Kadin-6’ had the highest weed suppressing ability, whereas the highest pod yield was recorded with variety Dharani’. A plant population of 0.66 m/ha was optimum for weed suppression.

A field experiment was conducted during 2011 at Anand, Gujarat to study the bio-efficacy of different herbicides against weeds of blackgram grown in Kharif season. Density and dry weight of weeds were significantly reduced by twice hand weeding carried out at 20 and 40 DAS than that of recorded in other treatments except pre-emergence application of pendimethalin 500 g/ha fb IC + HW at 30 DAS, quizalofop-ethyl 38 g /ha as POE fb IC + HW at 30 DAS, imazethapyr 50 g/ha as POE fb IC + HW at 30 DAS, oxyfluorfen 100 g/ha as PE fb IC + HW at 30 DAS) and fenoxaprop-p-ethyl 50 g/ha as POE fb IC + HW at 30 DAS. Twice hand weeding treatment was found superior to other treatments in respect of reducing the density and dry weight of weeds and recording higher seed and haulm yields.

A field experiment was conducted to study the effect of integrated weed management practices on growth, yield, quality of clusterbean and nutrient uptake by crop and weeds at Bikaner during Kharif 2013. Higher yield were recorded under weed-free treatment. Weed biomass was reduced significantly by pendimethalin 0.75 kg/ha as pre-emergence as well as imazethapyr and imazethapyr + imazamox as post-emergence. The highest total uptake of N (88.2 kg), P (17.9 kg) and K (70.8 kg/ha) by the crop was recorded under weed-free conditions.

A field experiment was carried out during rabi 2012-13 to study the effect of integrated weed management in isabgol (Plantago ovata Forsk). Twelve treatments of weed control i.e., oxyfluorfen 50 g/ha post-emergence at 20 DAS, oxyfluorfen 50 g/haat 15 DAS + interculturing followed by hand weeding at 30 DAS,oxyfluorfen 75 g/ha postemergence at 20 DAS, oxyfluorfen 75 g/ha postemergence at 15 DAS + interculturing followed by hand weeding at 30 DAS, isoproturon 500 g/ha as pre-emergence, oxadiargyl 80 g/ha at 20 DAS, oxadiargyl 80 g/ha at 15 DAS + interculturing followed by hand weeding at 30 DAS, oxadiargyl 100 g/ha at 20 DAS, oxadiargyl 100 g/ha at 15 DAS + interculturing followed by hand weeding at 30 DAS, interculturing followed by hand weeding at 20 and 40 DAS, unweeded and weed free were evaluated in randomized block design with three replications. Results revealed that, crop in weed free condition recorded significantly higher growth parameters, yield attributes, swelling factor (14.0 ml/g), seed (1.22 t/ha) and straw (2.93 t/ha) yields, which were statistically at par to the physical method i.e. interculturing followed by two hand weedings at 20 and 40 DAS and integrated weed management practices i.e. oxadiargyl 100 g/ha at 15 DAS + interculturing followed by hand weeding at 30 DAS.

Phyto-sociological analysis of weed flora in Kharif and Rabi season of 2009-2010 conducted in Purulia, Bankura and Birbhum districts of West Bengal, India revealed that rice field was infested with 35 (8 grasses, 22 broad-leaved and 5 sedges), 24 (9 grasses, 10 broad-leaved and 5 sedges) and 45 (11 grasses, 28 broad-leaved and 6 sedges) weed species in Purulia, Bankura and Birbhum districts, respectively. In rapeseed-mustard 16 (4 grasses, 11 broad-leaved and 1 sedges), 9 (3 grasses, 5 broadleaved and 1 sedges) and 20 (3 grasses, 16 broadleaved and 1 sedge) weed species were observed in\ Purulia, Bankura and Birbhum districts, respectively. The wheat field of Purulia and Birbhum districts was infested with 12 (3 grasses, 8 broad-leaved and 1 sedges) and 20 (3 grasses, 14 broad-leaved and 3 sedges) weeds. A total of 13 (3 grasses, 9 broadleaved and 1 sedge) and 23 (4 grasses, 16 broadleaved and 3 sedges) weed species were observed in potato field of Bankura and Birbhum districts, respectively. Ludwigia parviflora recorded the highest values of frequency, dominance and importance value index in rice field of all the districts Whereas, the dominant weed species in rapeseedmustard, wheat and potato fields was Cynodon dactylon followed by Echinochloa colona and Digitaria sanguinalis among grasses, and Cyperus rotundus among sedges.

Inhibitory effect of Cassia occidentalis L. (CO) on Parthenium hysterophorus L. (PH) was assessed under various biochemical parameters like chlorophyll, nitrogen and protein percentage. Chlorophyll content, nitrogen and protein percentage of one month old Parthenium plants were observed after treatment with aqueous leachates of the shoots of C. occidentalis and compared with control sets treated with distilled water. The allelochemicals released from Cassia inhibited the chlorophyll, nitrogen and percentage of Parthenium to the tune of 84.9, 96.4 and 96.4%, respectively. The results indicated the possible suppressive effect of allelochemicals present in C. occidentalis L. (CO) on P. hysterophorus.

Parthenium is an invasive weed in many parts of the world. In Pakistan, this has now become dominant weed in wastelands, forests and other natural areas and is also becoming a problematic weed in other situations such as irrigated and rain-fed cropping systems, pasture lands. In this preliminary study we investigated the impact of this weed on the soil seed bank of a riparian habitat. The impact of Parthenium weed upon below ground soil seed bank was assessed in the invaded and non-invaded sites along the canal near district Lahore, Pakistan. In the invaded site, the average number of Parthenium weed seeds in the soil was found to be 4,434/m2. The average numbers of seed/m2 and species diversity were lowest in the invaded site while it was highest in weed-free sites. A number of important native plant species such as, Saccharum spontaneum, Eleusine indica and Solanum nigrum were found to be declining in the invaded sites. The long-term presence of Parthenium weed at these sites poses a serious threat to native plant diversity in these habitats.

A field experiment was conducted to evaluate The weed control efficiency and time saving on weeding operation of different manually operated weeders in irrigated maize. Among the manually operated weeders evaluated, wheel hoe registered an yield increase of 154% over control, took less time (71.4 hr/ha), covered maximum area with minimum cost of operation (` 714.3/ ha) and also required less number of mandays to complete the weeding operation (5.46 man days/ha). Among the mechanical weeders, the highest grain yield of 4.8 t/ha was recorded with wheel hoe weeding twice on 25 and 45 DAS and on par with pre-emergence application of atrazine 0.5 kg/ha on 3 DAS followed by one hand weeding on 45 DAS.

A laboratory soil column experiment was conducted to study the leaching behavior of atrazine and metribuzin in red sandy soil and clayey soil type of TCRS, Yethapur. In atrazine applied plot, chlorotic patches were observed in all the seedlings raised from 0 - 40 cm depths (0 – 5, 5–10,10-15, 15-20, 20 -30 and 30- 40 cm. Chlorosis was not observed in the seedlings raised in the soil depths of 40 - 50 cm and 50 -60 cm.This showed that atrazine traces are found in a depth of 0-40 cm. Application of metribuzin showed chlorosis in all the depths and also showed tip burning in blackgram. From this study, it can be recommended that metribuzin should not be applied in red sandy soil and clayey loam soil (loose soil texture) as this would result in poor weed control efficiency since they are subjected to leaching in deeper layers.

The study was carried out to document the density, survival and seed production potential as seed rain, through a single value, of important weeds under different cropping systems at the districts Bankura, Birbhum and Burdwan representing lateritic belt of West Bengal during 2011-12 and 2012-13. Twenty four weed species under 22 genera and 14 families were studied in 9 crops. Highest density was recorded in Mollugo stricta in rice under rice – rice system, in Oldenlandia corymbosa in rice under rice – wheat/mustard/ vegetables system, whereas Digitaria sanguinalis recorded highest density in winter and pre-Kharif crops. Highest survival per cent was recorded in Commelina nudiflora and seed rain in Spergula arvensis.