Weed Science

Weed management practices in rice consisted of weedy check, hand weeding at 30 and 60 DAT, butachlorat 1.5 kg/ha and anilofos at 0.5 kg/ha. The experiment was part of a long term trial in rice – wheat cropping system conducted in a split plot design with three replications. Data on weed dry weight, crop growth and yield parameters were recorded at different growth stages. Herbicides were effective in reducing the growth of several weeds and improving the physiological status of the crop. Hand weeding twice recorded lowest weed dry weight at both 60 and 90 DAT during both the years (7.44 and 13.64g/m2, respectively). Butachlor and anilofos treatments recorded lower weed dry weight at 60 and 90 DAT as compared to weedy plot. Physiological parameters such as chlorophyll content and photosynthetic rate of the crop were higher in the herbicide treatments. 

The experiment comprising of twelve treatments was laid out in a randomized block design with three replications. Prominent weeds were Echinochloa colona and Digitaria sanguinalis among the grasses; Cyperus iria, among the sedges and Spilanthes acmella and Ludwigia parviflora among the broad-leaved weeds throughout the cropping period. Fenoxaprop-p-ethyl at 60 g/ha + metsulfuron-methyl + chlorimuron-ethyl at 4 g/ha at 25 DAT effectively controlled the grasses, broad-leaved and sedges at 50 DAT which was statistically at par with the azimsulfuron at 40 g/ha  at 20 DAT. The loss of grain yield of rice due to weed infestation was to the tune of 35-38%. Lower values of weed density, total weed dry weight and higher values of weed control efficiency, yield and net return of rice were registered with combined application of fenoxaprop-p-ethyl at 60 g/ha  + metsulfuron-methyl + chlorimuron-ethyl at 4 g/ha  at 25 DAT and was followed by sole application azimsulfuron at 40 g/ha  at 20 DAT. These treatments may be recommended for managing composite weed flora and obtaining higher yield and net return of transplanted Kharif (wet) rice in the lateritic belt of West Bengal, India.

Field and pot studies were conducted to identify the effective broad-leaf herbicides for wheat crop. In field study, pre-mix combination (1:4 w/w) of metsulfuron-methyl + carfentrazone-ethyl (Ally-express 50 DF) 22.5 to 25 g/ha with 0.2% (v/v) non-ionic surfactant (NIS) was better than without NIS and sole application of metsulfuron (4 g/ha), carfentrazone (20 g/ha) and 2,4-D-amine (750 g/ha). Carfentrazone was poor in controlling Lathyrus aphaca (meadow peavine), whereas metsulfuron was ineffective against Malva parviflora (little mallow) and Solanum nigrum (black nightshade). Metsulfuron-methyl + carfentrazone-ethyl effectively controlled these weeds, leading to increased wheat yield than metsulfuron and carfentrazone. In pot studies, growth regulator herbicide, 2,4-D-E was ineffective against S. nigrum and Physalis minima (groundcherry) but controlled by another growth regulator herbicide, dicamba. Carfentrazone 20 g, isoproturon 1000 g, metribuzin 250 g, dicamba 360 g and topramezone 50 g/ha effectively controlled S. nigrum and P. minima. Additional herbicides, effective against P. minima were metsulfuron 4 g, mesosulfuron + iodosulfuron 12 + 2.4 g/ha, pyroxsulam 18 g and sulfosulfuron 25 g/ha. Auxin herbicide, halauxifen-methyl-ester in combination with florasulam 12.76 (6.51 + 6.25) g/ha was also poor against S. nigrum and P. minima. Rumex dentatus control with 2,4-D (ester, amine and sodium) was poor, whereas, halauxifen + florasulam 12.76 g, metsulfuron 4 g and metsulfuron + carfentrazone 4 + 20 g/ha provided complete control.

A field experiment was carried out at Norman E. Borlaug Crop Research Centre of G.B.P.U.A&T, Pantnagar during Rabi seasons of 2010-11 and 2011-12 to test the efficacy of different dosses of metribuzin 42% + clodinafop propargyl 12% WG against weeds in wheat. 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 at 500-600 g/ha were as effective as two hand weeding at 30 and 50 DAS in reducing the weed density of Phalaris minor and Chenopodium album, Cornopus didymus, Melilotus spp., Rumex spp. and Fumaria parviflora at 30 and 60 days after application as compared to rest treatments. Maximum grain yield was recorded in metribuzin + clodinafop-propargyl WG 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-leaved weeds in wheat.

A field experiment was conducted during 2013-14 and 2014-15 at Jabalpur to assess the effect of conservation tillage and weed management practices on the total bacteria, fungi, actinomycetes and dehydrogenase activity under soybean - wheat cropping system in vertisols. The results of the investigation revealed that tillage systems to influence significantly the microbial population. Among the tillage treatments, zero tillage + crop residue (soybean) fb zero tillage + crop residue (wheat) had higher bacterial, fungal population and dehydrogenase activity during both the seasons. But actinomycetes population was higher in zero tillage + crop residue (soybean) fb zero tillage (wheat) during both seasons. However, there was no adverse effects of herbicides use in soybean-wheat cropping system on microbial population during both crop seasons except Rabi season 2014 -15 in which bacterial population was reduced by 27.3% when mesosulfuron (12 g/ha) + iodosulfuron (2.4 g/ha) mixture was applied in wheat following application of pendimethalin (750 g/ha) fb imazethapyr (100 g/ha) in preceding  soybean crop.

Pinoxaden 50 g/ha alone and as tank mixture with and before metsulfuron-methyl 4 g/ha, carfentrazone ethyl 20 g/ha and 2, 4-D 500 g/ha was compared to isoproturon + 2, 4-D, clodinafop fb 2, 4-D, weed free and weedy check for nutrient depletion by weeds and wheat. Phalaris minor and Anagallis arvensis were the major weeds constituting 60.8 and 21.4% of total weed population, respectively. Pinoxaden fb metsulfuron-methyl (50 fb 4 g/ha) remaining at par with pinoxaden + metsulfuron-methyl (50 + 4 g/ha) and pinoxaden + 2,4-D (50 + 500 g/ha) resulted in significantly lower total weed dry weight over rest of the herbicidal treatments. Pinoxaden + metsulfuron-methyl (50 + 4 g/ha) and pinoxaden fb metsulfuron-methyl (50 fb 4 g/ha) were as effective as weed free in reducing N, P and K uptake by weeds. Weeds in weedy check removed 37.4 kg/ha N, 6.9 kg/ha P and 46.8 kg/ha K. Weed free remaining at par with pinoxaden + metsulfuron-methyl (50 + 4 g/ha), pinoxaden fb metsulfuron-methyl (50 fb 4 g/ha) and pinoxaden fb 2, 4-D (50 fb 500 g/ha) resulted in significantly higher wheat dry matter accumulation over rest of the treatments. Weed free gave highest grain yield. However, pinoxaden + metsulfuron-methyl (50 + 4 g/ha), pinoxaden (50 g/ha), pinoxaden + carfentrazone-ethyl (50 + 20 g/ha), pinoxaden fb metsulfuron-methyl (50 fb 4 g/ha), isoproturon + 2, 4-D (1250 + 500 g/ha), clodinafop fb 2, 4-D (60 fb 1000 g/ha), pinoxaden + 2, 4-D (50 + 500 g/ha), pinoxaden fb carfentrazone-ethyl (50 fb 20 g/ha) and pinoxaden fb 2, 4-D (50 fb 500 g/ha) were as good as weed free.

A field study was carried out at the Punjab Agricultural University, Ludhiana for two seasons to study the weed control in three canola gobhi sarson cutlivars and tolerance of these cultivars to different herbicides. Three canola gobhi sarson cultivars ‘GSC 5’, ‘GSC 6’ and ‘Hyola PAC 401’ in main plots and five weed control treatments -fluchloralin at 0.75 and 1.5 kg and trifluralin at 0.75 and 1.5 kg/ha and hand weedings in sub-plots were evaluated in a split plot design. Fluchloralin and trifluralin at 0.75 and 1.5 kg/ha recorded effective control of annual weeds and recorded canola seed yield similar to hand weeded control. All the three cultivars of canola gobhi sarson tolerated both the herbicides at 0.75 and 1.5 kg/ha. The study indicated that fluchloralin and trifluralin could safely be used to control weeds in canola gobhi sarson cultivars ‘GSC 5’, ‘GSC 6’ and ‘Hyola PAC 401’

A total of eight treatments were evaluated in a randomized block design (RBD) with three replications. The treatments consisted of pre-emergence application of pendimethalin (30.0% EC) at 1.0 kg/ha + 1 hoeing on 45 DAS, post-emergence application of quizalofop-ethyl 50 g/ha (30 DAS) + 1 hoeing, pendimethalin at 1.0 kg/ha fb quizalofop-ethyl 50 g/ha + 1 hoeing on 45 DAS, post-emergence application of pyrithiobac-sodium 62.5 g/ha (30 DAS) + 1 hoeing on 45 DAS, combination of pyrithiobac-sodium 62.5 g/ha + quizalofop-ethyl 50 g/ha + 1 hoeing on 45 DAS, glyphosate 1.0 kg/ha (45 DAS) as directed spray and control plots of weed free check and unweeded check. The results revealed that application of pre-emergence herbicide pendimethalin at 1.0 kg/ha at 3 DAS followed by post-emergence herbicide (quizalofop-ethyl 50 g/ha at 30 DAS) + one hoeing or combined post-emergence application of pyrithiobac-sodium + quizalofop-ethyl + one hoeing on 45 DAS recorded lesser weed population and weed dry weight and higher weed control efficiency with lower weed index. These treatments were also comparable with pre-emergence application of pendimethalin + 1 hoeing. Higher yield attributes, viz. number of sympodia per plant, number of bolls per plant and boll weight and seed cotton yield were also registered by these treatments. The yield reduction due to weeds accounted 44.8 and 80.3%  during 2012-13 and 2013-14, respectively The economic analysis indicated that higher total income, net income and benefit–cost ratio were associated with pre-emergence application of pendimethalin followed by post-emergence application of quizalofop-ethyl + one hoeing, combined post-emergence application of pyrithiobac-sodium + quizalofop-ethyl + one hoeing and pre-emergence application of pendimethalin + 1 hoeing in both the years of study.

A field experiment was conducted during the Rabi season of 2008-09 and 2009-10 on sandy loam soils of research farm of Regional Station, Bathinda to find out response of different varieties of barley and various combinations of herbicides on growth, weed dry matter and grain yield of barley under semi arid conditions of Punjab. The experiment was laid out in split plot design with two varieties in main plots and 12 different herbicide combinations in sub plots. The grain yield had no significant difference with respect to two varieties but it varied significantly with various combinations of herbicides. The maximum mean grain yield i.e. 3.46 t/ha was recorded in pinoxaden + metsulfuron 50 + 4 g/ha (T4) followed by metsulfuron fb pinoxaden 4 + 50 g/ha, metsulfuron fb pinoxaden 4 + 45 g/ha and lowest (2.31 t/ha) in control. The dry weight of weed flora was significantly higher in control plots as compared to other treatments during both the years and no significant difference was observed in both the varieties with respect to dry weight of weed flora.

Weed flora of experimental field was dominated with Echinochloa colona during Kharif 2012 and Trianthema portulacastrum during Kharif 2013. Post-emergence application of imazethapyr at 70 g/ha and its ready mixture with imazamox at 60-80 g/ha although provided excellent (80-90%) control of weeds but caused 23-35% injury to greengram in initial stages in terms of yellowing of leaves and stunted crop growth up to 7 DAT which mitigated to 5-7% up to 45 DAS, without any yield reductions. Pre-emergence application of pendimethalin+ imazethapyr (ready mix) at 1000 g/ha provided season long control (75-82%) of weeds in greengram. During both years, seed yield was maximum (1.50 and 1.58 t/ha, respectively) in weed free treatment which was at par with post-emergence application of imazethapyr at 50 and 70 g/ha and imazethapyr + imazamox (ready mix)  at 60 g/ha in 2012 but significantly higher than all herbicide treatments in 2013. Imazethapyr and its ready mix combination irrespective of dose did not cause any injury to succeeding mustard crop after harvest of greengram.

A field experiment was conducted during Kharif 2010, 2011 and 2012 at Agricultural Research Station, Gadhinglaj under rainfed condition in sub-montane zone of Maharashtra. The experiment consisting of eight treatments, viz. two pre-emergence and one post-emergence herbicides alone and in combination with one hoeing and one weeding with weed free and weedy check was laid out in randomized block design with three replications. The predominant weed flora observed in the experimental field was dicot weeds. The result revealed that pre-emergence application of pendimethalin + 1 hoeing + 1 hand weeding recorded minimum weed density, weed biomass and weed index as compared with all treatments. Gross and net returns were significantly higher with pendimethalin + 1 hoeing + 1 hand weeding which was at par with butachlor + 1 hoeing +1 hand weeding and superior over rest of treatments. Higher weed control efficiency and B: C ratio were recorded by the same treatments.

Field experiments were conducted during Kharif 2012-13 and 2013-14 at the Research farm of Rajendra Agricultural University Bihar, Pusa to find out effective and economical approaches for weed management in turmeric. The grassy weeds present in the experimental field were Cynodon dactylon, Echinocloa colona and Dactyloctenium aegyptium. Cyperus rotundus was only sedge and Chenopodium album, Cannabis sativa, Parthenium hysterophorus, Phyllanthus niruri and Caesulia auxillaris were the broad-leaved weeds. The lowest weed count, weed dry weight and the highest number of tillers per plant, number of leaves per plant and rhizome yield of turmeric were recorded by the weed free (hand weeding at 25 and 45 DAS). The highest rhizome yield (52.05 t/ha) was recorded under weed free which was statistically at par with atrazine 0.75 kg/ha fb fenoxaprop 67 g/ha+ metsulfuron 4 g/ha (50.65 t/ha). The highest weed control efficiency (84.62%) was recorded under the treatment weed free which was closely followed by atrazine 0.75 kg/ha fb fenoxaprop 67 g/ha+ metsulfuron 4 g/ha (78.9%) and pendimethalin 1.0 kg/ha fb fenoxaprop 67 g/ha + metsulfuron 4 g/ha (78.6%). The highest B:C ratio was recorded with application of atrazine 0.75 kg/ha fb fenoxaprop at 67 g/ha + metsulfuron 4 g/ha, which was statistically at par with weed free, pendimethalin 1.0 kg/ha fb fenoxaprop at 67 g/ha + metsulfuron 4 g/ha and metribuzin 0.7 kg/ha fb fenoxaprop at 67 g/ha + metsulfuron 4g/ ha.

In two glasshouse experiments, range of herbicides was applied as pre- or post-emergence to examine their effect in controlling Italian ryegrass (Loluim multiflorum) grown with barley. In experiment 1, treatment by one of the three herbicides named, chlorotoluron, controlled Italian ryegrass (L. multiflorum) \significantly (P<0.01). However, the three herbicides differed significantly (P<0.05) in their dose. Chlorotoluron gave effective control of L. multiflorum at dose of 2 kg/ha with less than 10% of mean of ryegrass plants/pot survived and only a slight damage on barley was observed. Isoproturon and methabenzthiazuron were less effective in controlling the weed as more than 30% of L. multiflorum plants survived at different doses applied while barley plants were not affected significantly by the chemicals. In experiment 2, two herbicides diclofop-methyl or pendimethalin were applied as post-emergence treatment. The herbicide diclofop-methyl achieved an effective control of Italian ryegrass associated with barley even at rates as low as 0.25 kg/ha. Mean of ryegrass numbers and fresh weight (20 plants)/pot were decreased significantly and only few plants of L. multifloruim survived at 1 kg/ha, however, they were very small in size and badly damaged. Barley plants were not damaged by diclofop-methyl treatments at all applied doses. Pendimethalin created a significant effect (P=0.05) on ryegrass numbers/pot or fresh weight (20 plants/pot) at doses, 0.125 or 0.25 kg/ha. However, at 1 kg/ha there was about 40% reduction in weed numbers/pot and its fresh weight (20 plants/pot), which indicate low control effect of this chemical. There was no evidence of damage to barley plants by pendimethalin at all tested rates.

Ten field experiments were conducted at Viswavidyalaya farm during 2004 - 14 in system intensification methodology on SRI rice (Oryza sativa), groundnut (Arachis hypogea), soybean (Glycine max), rapeseed (Brassica campestris), sesame (Sesamum indicum), greengram (Vigna mungo) and blackgram (Vigna aureus) crops grown in inceptisols following annual planning of weed management to find out the efficacy of botanical extracts. In all experiments varied treatments 5-12 numbers were used in RBD with 3-5 replications in plot size 3-4 x 5 m. The botanical extracts (BE) of different plants with 0.25% Tween 80 surfactants were used at 5, 10 and 100% at pre-emergence (PE) in moist soil along with two mechanical weeding (MW) at 20 and 40 DAP. Weedy check (WC), hand weeding (HW) at 20 and MW at 40 days after planting (DAP), pre-emergence (PE)  herbicides at 1-2 DAP pretilachlor at 500 g/ha, alachlor at 1500 g/ha or pendimethalin at 750 g/ha + MW at 30 DAP and post-emergence (POE) herbicides quizalofop-ethyl or fenoxaprop-p-ethyl at 50 g/ha at 20 DAP + MW at 40 DAP were also used in different crops as standard check. The experiments on rapeseed and soybean during 2004-05 showed PE Eucalyptus leaf extract attributed 11.2% higher seed yield over WC besides two HW and pendimethalin. During 2010-11 in experiment on SRI rice, the grain yield was 6.35 t/ha in HW, 5.35 t/ha in CC, 5.16 t/ha in Tectona methanol extract while 3.44 t/ha in WC. In another experiment during 2010-11 on sesame, green and blackgram, the botanical extract of Ageratum conyzoides recorded higher growth and yield in sesame and blackgram while Ocimum sanctum extract among the botanicals in greengram exhibited higher harvest index, oil content and also soil nutrient status. In groundnut during 2012, average pod yield of botanical treatments was 32.5% (summer) and 42.5% (Kharif) which was higher than WC. Experiment on SRI rice during 2012-13 revealed that maximum WCE was obtained from HW (91%) followed by chemical control CC (84%) and BE (78%) compared to three MW (67%), two MW (53%) over WC. The mean grain yield data showed that HW recorded 88% followed by CC (79%), BE (76%), three MW (67%) and two MW (36%) over control. The maximum WCE was obtained from HW (91%) followed by CC (84%) and BE (78%) compared to 3 MW 67% and 2 MW 53%.

A study was conducted on modelling and forecasting the time series data of total herbicide consumption in India. Among many time series methodology, Box-Jenkins Autoregressive Integrated Moving Average (ARIMA) model was used for modelling and forecasting purposes using data from 1990 to 2010. Before the modelling, stationarity of the data was checked using Augmented Dicky Fuller test. Best model was chosen using two criterion viz. Akaike information criterion and Schwarz’s Bayesian criterion. ARIMA (0, 1, 1) model was found to the best among many models from ARIMA family. Forecasting was done using the best model and prediction for total herbicide consumption in India was made for next three year (2011, 2012, 2013) as 6624, 6581 and 6562 tonnes respectively.

his study identifies the utilization of common weed Chenopodium murale as raw material for vermiculturing. Growth and cocoon production in each mixture was recorded weekly for 18 weeks. Significant variations in food preference were observed in worm when the cattle dung was mixed with weed in different combination. The present study revealed that addition of weed in cow dung not only enhanced the growth of the worm but also increased cocoon production thus providing a possible tool towards proper utilization of weed for production of value added product.

Among the weed control treatments, herbicidal combinations of pre-emergence application of pendimethalin 1000 g/ha fb post-emergence application of bispyribac-sodium 25 g/ha and post-emergence application of readymix of penoxsulam + cyhalofop-butyl 135 g/ha were found most effective in controlling weed infestation with the highest weed control efficiency and grain yield.

The Floristic composition of weeds in five different rice field around Vanur taluk of Villupuram district, Tamil Nadu, India was studied from November 2010 to April 2011. A total of 56 weed species belonging to 23 families was identified. Out of this 37 species in Kiliyanur, 38 species in Konthamur, 45 species in Thensiruvallur, 30 species in Thailapuram, and 32 species in Aadhanapattu were identified. An important value index for each weeds species was calculated to find dominance. Bergia capensis, Cynodon dactylon, Cyperus difformis, Eclipta alba, Echinochloa colona, Marsilea quadrifolia were dominant weeds species. Considering species diversity, Thensiruvallur village rice field was highly diverse of weed species compared to other fields. From the six month observations, it was found that weed growth occurs within forty one days after rice sowing. The perennial weeds created the most serious problem in rice fields.

The field experiment was conducted during Rabi season of 2012-13 at Faizabad to study the bio-efficacy of clodinafop-propargyl + metsulfuron-methyl and some other new herbicide molecules against complex weed flora in wheat. Significant reduction density was recorded at different stages of crop growth due to effect of different treatments. As far as the narrow leaved (P. minor) and BLWs were concerned, both type of weeds were effectively controlled by application of clodinafop-propargyl + metsulfuron-methyl 400 g/ha at 32 DAS which was proved superior with respect to number of effective shoots/m2 (0.32) and grain yield (3.95 t/ha) of wheat over rest of the other herbicidal treatments. Lower value of weed index was calculated in clodinafop-propargyl + metsulfuron-methyl 400 g/ha (1.45%) followed by other herbicidal treatments.

Wheat fields of three agro-climatic zones, viz. submontane zone (districts Roopnagar and Hoshiarpur), central zone (Jalandhar, Kapurthala, Shaheed Bhagat Singh Nagar, Ludhiana and Moga) and arid irrigated zone (districts Bathinda, Muktsar and Faridkot) were surveyed for recording weed flora during the month of March in 2014 and 2015. The major weed flora included four broad-leaf weeds Cannabis sativa, The most noteworthy change was increase in the frequency of C. sativa over two years. C. sativa which was earlier a weed of non-cropped areas has started infesting wheat fields also. The frequency of C. sativa in districts Ludhiana, Kapurthala, Jalandhar and Hoshiarpur increased from 30.8-54.6% in 2014 to 45.6-83.6% in 2015. In districts Roopnagar, Shaheed Bhagat Singh Nagar and Moga, the frequency of this weed increased from 0-10.6% in 2014 to 11.9-19.8% in 2015. The survey indicated that C. sativa is likely to become a major weed of wheat in near future in four districts viz., Ludhiana, Kapurthala, Jalandhar and Hoshiarpur.

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A field investigation was carried out at Eastern Block farm, Tamil Nadu Agricultural University, during winter season of 2011-12 to evaluate the new formulation of potassium salt based glyphosate (Roundup Crop Shield 460 SL) on seed cotton yield and quality parameters in winter irrigated cotton. Experimental results revealed that higher seed cotton yield was obtained with POE glyphosate at 1800 g/ha at 35 and 70 DAS with + IC at 45 and 55 DAS which was comparable with PE pendimethalin at 750 g/ha + IC at 45 and 55 DAS. While comparing, intercultural operation carried out treatments performed better and recorded more seed cotton yield than the treatments without intercultural operation, Cotton fibre quality in glyphosate applied plots was showed similarity with hand weeding, hand weeder weeding and power weeder weeding, shows that POE glyphosate application did not affect the quality parameters.

Topramezone + atrazine at 25.2 + 250 g/ha + methylated seed oil MSO (adjuvant) or tembotrione + atrazine at 105 + 250 g/ha + stefes mero (adjuvant) as post-emergence, atrazine at 1.0 kg/ha followed by intercultivation at 30 DAS and intercropping of maize with cowpea and pendimethalin at 1.0 kg/ha as pre-emergence reduced the weed density and weed biomass significantly at 20 DAS.

Imperata cylindrica was the dominant grass weed (42-46%) followed by Cynodon dactylon (10%) and Cyperus rotundus (8-12%). Weed infestation throughout growing season of ramie reduced the fibre yield up to 51%. Significant reduction in weed density and dry weight was recorded in both quizalofop-ethyl at 40 g/ha and quizalofop-ethyl at 60 g/ha with weed control efficiency of 72-77% and weed index of 11-15%. The highest fibre yield was recorded in weed free treatment (470-504 kg/ha/cut) which was statistically at par with that of quizalofop-ethyl at 40 g/ha and quizalofop-ethyl at 60 ml/ha treatments (400-447 kg/ha/cut), respectively. Significant reduction of plant height of ramie was observed in ethoxysulfuron at 20 g/ha at initial growth stage. Quizalofop-ethyl at 40 g/ha or quizalofop-ethyl at 60 g/ha followed by one hand weeding may be applied for effective weed control in ramie.

To characterize the phytotoxic potential, a laboratory experiment was conducted by considering some prominent wasteland weeds like Parthenium hysterophorus, Croton bonplandianum, Cassia occidentalis, Cassia obtusifolia, Calotropis procera, and Tephrosia purpurea. Aqueous leachates of leaf and root of different concentrations (50 and 100%) were tested against seed germination and seedlings growth of wheat and barley, as test plants. High concentration (100%) of leaf leachates showed remarkable inhibition on seed germination, radicle and plumule length and decreased biomass respectively, closely followed by the 50% concentration of leaf leachates. Maximum inhibition (> 70.00%) was recorded in 100% concentration of P. hysterophorus, C. occidentalis and C. obtusifolia leaf leachates as compared to root leachates (< 65.00%) except P. hysterophorus and similar trend of inhibition in radicle, plumule length and biomass was recorded. Root leachates showed least inhibitory effects at 50% concentration whereas 100% root leachates were comparatively more effective than 50% leaf leachates. A statistically significant interaction between leachates, concentrations and plants (P < 0.001) was observed; hence a significant inhibition was seen at higher concentration of leaf leachates. Inhibition potential of considered weeds clearly indicates the presence of phytotoxic chemicals in their tissues that supports them in establishment, competing and replacement of surrounding flora.

A study was conducted during 2014-2015 in College of Horticulture, Vellanikkara, Thrissur to understand response of the Isachne miliacea to common herbicides. Sensitivity of the weed to pre-and post-emergence herbicides were tested using seed and whole plant bioassay techniques, respectively. The pre-emergence herbicides butachlor and oxyfluorfen gave the best results. Among post-emergence herbicides, effective control was observed for azimsulfuron, cyhalofop-butyl and fenoxaprop-p-ethyl. The weed was found to be resistant to pyrazosulfuron. Regrowth was observed after two weeks for bispyribac sodium and penoxsulam. All the non-traditional rice herbicides tested, viz. glyphosate, diuron, paraquat, glufosinate ammonium gave excellent control of the weed.