Weed Science

Aquatic weeds are those unwanted vegetation which grow in water and hamper its use. Out of about 160 aquatic weeds, Eichhornia crrassipes, Ipomoea aquatica, Typha angustata, Ceratophyllum demersum, Salvinia molesta, Nelumbo nucifera, Alternanthera philoxeroides, Hydrilla verticillata, Vallisneria spiralis, Chara spp., Nitelia spp., Potamogeton spp. are of primary concern in India. Several irrigation and hydroelectric projects in the country like Nagarjuna Sagar project in Andhra Pradesh, Tungabhadra project in Karnataka and Kakki and Idikki reservoirs in Kerala are suffering with massive growth of  aquatic weeds. Weeds enhance rates of evaporation many folds through evapotranspiration than that of open surface, thus cause great loss of water. Water hyacinth makes water unfit due to eutrophication and slows down the flow rate of water besides causing many health associated problems. Aquatic weeds can be controlled by several methods like biological, chemical and physical. Each method has its benefits and drawbacks. There are several popular control mechanisms for preventing the spread or eradication of aquatic weeds. Physical methods are suitable only for small scale infestation but when applied in large water bodies become ineffective due to high cost and regrowth. Chemical control has been practiced against aquatic weeds since long time in India but it is not prevalent. Control of small infestations with herbicides has often been very effective, but is heavily dependent on skilled operators who maintain longterm vigilance for appearance of regrowth or seedlings. In recent decades, there has been a significant increase in the level of nutrients dumped into water from industrial and domestic sources as well as from land where fertilizers are used or where clearance has caused an increase in run-off. Successful attempts have been made to control water hyacinth and water fern by use of exotic weevil Neochetina spp. And Cyrtobagaus salvinae in different parts India but for several other aquatic weeds, suitable bioagents are not available. Some species of herbivorous fishes (Tilapia spp. and Ctenopharyndon idella) have been utilized to control some submerged weed especially Hydrilla spp. with varying degree of success. This paper describes the aquatic weed problems in India and the efforts made so far for their management by various methods.

Plant height, tillers/m row length, leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR) and dry matter accumulation in plants were significantly higher in plots getting weed free environment closely followed by pre-emergence application of butachlor 1.5 kg/ha fb 1 HW. However, yield attributes i.e. panicles/m2 and fertile grains/panicle and finally yield were significantly higher in weed free check with butachlor fb 1 HW closely on its heel. Among the nutrient concentration, it was only P in straw which was very marginally higher in weed free check and butachlor fb 1 HW. However, sowing date of 22nd June showed significantly higher N, P and K uptake by grain and straw. Weed population and weed dry matter were significantly higher in 12th July sown crop but least weed population, dry matter and good weed control efficiency were accounted with weed free check and butachlor fb 1 HW though the nutrient concentration were affected significantly both due to sowing date and weed management practices. Nutrient uptake due to weed was higher in 12th July sowing date. Amongst the weed management methods, the nutrient uptake of weeds were least in weed free check followed by butacholar fb 1 HW and Sesbania broadcast fb 2,4-D 0.5 kg/ha at 30 DAS. Similar results were also recorded in the case of gross return, net return and B :C ratio in case of 22nd June.

A field experiment was conducted during 2006-2008 to find out suitable dose of velper K4 60 WP for the control of weeds in spring planted sugarcane. Weed population and weed dry weight were reduced significantly due to different weed control measures. Cane yield increased significantly with all the measures over weedy check and was highest under weed free conditions (94.3 t/ha) though it was at par with hoeing at 30, 60 and 90 day after transplanting (DAT). Atrazine was the most effective herbicide reducing weed population and weed dry weight followed by Velpar. Weed growth in weedy plot caused 73.5% reduction in cane yield compared to weed free condition. Among herbicidal treatments, maximum cane yield of 82.4 t/ha was obtained in atrazine and no herbicide treatment was at par with this. Due to phytotoxicity reason Velpar K 60 WP resulted in lower cane yield, though it effectively controlled the weeds.

Several herbicides were evaluated for their possibility of use in the lac production system under Flemingia semialata in the Research Farm of Indian Institute of Natural Resins and Gums, Ranchi. Among several herbicides evaluated, application of glyphosate at 1.0 kg/ha in Flemingia semialata (vernacularly called bhalia) plantation at 10 days prior to lac insect inoculation, resulted in significant reduction in weed density and dry weight with 88.6% weed control efficiency (WCE). Glyphosate was found safe to lac insect and superior to other tested herbicides and resulted in 38.8% higher sticklac yield over control. The weed free treatment (manual, weeding twice) recorded the highest sticklac yield (239.7 g/bush or 1918 kg/ha) but was uneconomical in comparison to herbicide treatments.

Field and pot studies were conducted to determine the efficacy of sulfosulfuron and ready mixture, sulfosulfuron + carfentrazone- 45 (25+20) WDG at different surfactant doses against complex weed flora of wheat. The weed control, particularly the grass was significantly poor, when sulfosulfuron or its ready mix combination with carfentrazone was applied without surfactant compared with surfactant. The grass (Avena ludoviciana, Echinochoa crusgalli, Phalaris minor and Polypogon monspeliensis) weed control with sulfosulfuron or ready mixture (RM) of sulfosulfuron + carfentrazone- 45 WDG was similar at surfactant doses of 625, 750 and 1250 ml/ha indicating the possibility of reducing the surfactant doses by 40-50% from the present recommendation of 1250 ml/ha in India. The optimum dose of RM, sulfosulfuron + carfentrazone was 45 (25+20) g/ha with 625-750 ml/ha surfactant. This combination was superior over sulfosulfuron, due to the control of Rumex dentatus, thereby increased the wheat yield by 7.6% on an overall mean basis. The RM, sulfosulfuron + carfentrazone with surfactant was similar to ready mixtures, Total (sulfosulfuron 75 + metsulfuron 5)-80 WDG at 32 (30+2) g/ha and Atlantis (mesosulfuron + iodosulfuron) at 14.4 (12+ 2.4) g/ha in controlling weeds and producing wheat yield. The carry over effect of sulfosulfuron involving treatments (sulfosulfuron, sulfosulfuron + metsulfuron, sulfosulfuron + carfentrazone) was observed on succeeding maize (Zea mays L.) crop. At 2X dose of sulfosulfuron + carfentrazone (50+40 g/ha), the reduction in maize biomass was 62.6-73.0% in comparison to weed free check.

A field experiment was conducted on sandy clay loam soil of Andhra Pradesh during kharif and rabi seasonsics of rice-zero till maize cropping system. The results showed that the rejuvenation of rice stubbles in the sequence crop of rabi maize were more in early harvested than late harvested rice varieties and reverse was the trend in weed growth. Among herbicide treatments, use of paraquat as pre-emergence application for controlling rejuvenation of rice stubbles in zero-till maize was superior to pre-emergence application of atrazine and no-herbicide treatment. On the other hand pre-emergence application of atrazine was more effective in controlling first flush of weeds than paraquat and no-herbicide treatment. Herbicide treatments, consequent to termination of rice stubble and weed competition, promoted plant growth, dry matter production, nutrient uptake, yield structure and yield of maize and consequently productivity and economics of the system as compared to no-herbicide treatment. Rice-zero till maize irrespective of the herbicide supplementation gave higher rice equivalent yield, net returns and benefit of cost when compared to existing rice-pulse sequence. However, soil fertility status and microbial status of the rice-maize cropping system was no match to the existing system of rice-pulse sequence and herbicide treatments did not exhibit any detrimental effect on microbial population. of 2006-07 and 2007-08 on the effect of weed management practices on the productivity and economy.

The experiment was conducted to evaluate the efficacy of post emergence applications of imazethapyr on weed control and soybean yield. The field was infested with grassy weeds (51.6%), broad leaf weeds (34.1%) and sedges (13.2%). Application of imazethapyr XL 10% SL at 150 g/ha as post emergence significantly reduced the density of all grassy, broad leaf weeds sedges and their dry weight, and provided maximum number of branches/plant, pods/plant, seeds/pod and seed yield as compared to weedy check and imazethapyr 10% at 50 g/ha. Infestation of weeds throughout the growth period caused 57.2% reduction in seed yield of soybean. Maximum seed yield (1075 kg/ha) and weed control efficiency of grasses (86.9%), broad leaf (88.4%) and sedges (73.0%) was obtained with 2 hand weeding at 20 and 40 days after sowing closely followed by imazethapyr XL 10% at 150 g/ha (957 kg/ha). Application of imazethapyr XL 10% SL at 100 g/ha recorded significantly higher net return (Rs 14,237/ha) and B : C ratio (1.68) followed by imazethapyr XL 10% at 150 g/ha over weedy check and imazethapyr XL 10% at 50 g/ha.

An experiment was conducted during rabi seasons of 2006 and 2007 at Pulses Research Sub-Station Samba, SKUAST-Jammu to study the efficacy of pre and post emergence herbicides in controlling weed flora of urd bean (Vigna mungo L.) under rainfed subtropical conditions of Jammu. The weed free treatment produced the highest seed yield and was at par with imazethapyr 250 ml/ha (post-emergence) after 15-20 days sowing. However, among the other treatments, pendimethalin (pre-emergence) 1.0 kg/ha fb 1 HW at 30 DAS was found superior in controlling the weed flora and increasing the seed yield. Unweeded check produced the lowest seed yield.

A field experiment was conducted to evaluate the efficiency of herbicide mixture of almix (metasulfuron methyl + chlorimuron ethyl) and butachlor to control both grassy and broad leaved weeds. Application of almix 0.004 kg/ha mixed with butachlor 0.938 kg/ha at three days after transplanting (DAT) was at par with hand-weeding twice at 20 and 40 DAT in controlling weeds and higher grain yield. This application increased the grain yield by 45.1% over the unweeded check. There was a negative linear relationship between weed dry weight and grain yield.

Water hyacinth (Eichhornia crassipes) is one of the most predominant, persistent and troublesome aquatic weeds. Periodical surveys of various water bodies in and around Jabalpur were under taken with the objective to isolate and evaluate the indigenous strains of fungal pathogens as myco-herbicides to manage water hyacinth. Three fungal pathogens, viz., Fusarium oxysporum, Curvularia lunata and Alternaria alternata were isolated. Efficacy studies of the pathogens were done by inoculating water hyacinth plants, either directly or after creating wounds. Artificial injury created in the plants by pin pricks before inoculation of the pathogens aided in the entry of the pathogens there by resulting in the better infection of the plants. Among the three pathogens, Fusarium oxysporum was found to be the best resulting in the killing of inoculated water hyacinth in about 15 days.

Persistence of pendimethalin and oxyfluorfen in an alfisol and vertisol was studied at three moisture levels (at saturation, Field Capacity and 50 % Field Capacity) and at two temperature levels (10 2 C and 27+ 20C) for 137 days in the laboratory. Degradation of pendimethalin and oxyfluorfen was more rapid at high temperature and moisture levels. The disappearance curve / semi logarithmic plot followed first order kinetics with two distinct pathways, an initial faster rate followed by a slower and more gradual disappearance. Half life values for pendimethalin varied from 35.45 to 108.28 in alfisol and from 28.28 to 91.84 in vertisol ; for oxyfluorfen half life values varied from 97.60 to 192.50 in Alfisols and 90.05 to 147.44 in vertisols.

A total of 11 weeds were collected and screened for their antimicrobial activity against plant and human pathogens. Antimicrobial compounds of weeds were extracted with three different solvent viz. methanol, chloroform and petroleum ether of varying polarity. The results revealed that the petroleum ether extract of Lucas aspera was most effective against the Fusarium oxysporum, Colletotricum falcatum and C. capsici. The methanol extract of Phyllanthus niruri was showing highest antimicrobial activity against the human pathogens such as Entrococcus coli, Bacillus subtilis, Bacillus licheniformis, Bacillus amylovorus. Similarly, chloroform extract of L. aspera recorded the highest inhibition zone against the Vibrio cholerae and Salmonella typhi. Among the 11 weeds, L. aspera and P. niruri were found having more antimicrobial activity against most of the selected plant and human pathogens.

A field experiment was conducted during rabi season of 2007-08 and 2008-09 on the mollisols of Pantnagar (Uttrakhand). Twelve treatments consisted of two tillage practices (zero and conventional), two varieties (small seeded-Pant L-4 and bold seeded- Pant L-5) and three levels of weed management (weedy check, hand weeding, (HW) 30 DAS and pendimethalin 1 kg/ha as PRE) were set out in split plot design keeping tillage practices and variety in the main plot and weed management practices in sub plots with four replications. Results revealed that zero tillage recorded higher weeds density viz, Cyperus rotundus and total dry matter of weeds per unit area than that of conventional tillage. Weed density and dry weight remained unaffected under both the varieties. Hand weeding done at 30 DAS controlled the weeds more effectively than PRE application of pendimethalin 1 kg/ha. Conventional tillage out yielded zero tillage. Most of the yields attributing characters were higher in conventional tillage. Small seeded variety Pant L-4 gave significantly higher grain yield than that of bold seeded Pant L-5 during both the years. HW 30 DAS and PRE application of pendimethalin 1 kg/ha being on par produced significantly more grain yield of lentil than weedy check during the first year at 30 DAS out yielded remaining weed management practices.

Clodinafop 60 g/ha and metsulfuron methyl 4 g/ha + surfactant 0.02% alone, combinations of clodinafop and metsulfuron + surfactant at the similar and double dose and isoproturon + 2, 4-D were evaluated against complex weed flora in wheat during 2007-08 and 2008-09. Phalaris minor, Avena ludoviciana and Lolium temulentum were the major grassy weeds. Vicia sp., Anagallis arvensis and Lathyrus aphaca were among the broad-leaved weeds found growing in association with wheat crop. All the herbicidal treatments significantly reduced the dry weight of weeds. Tank mixture of clodinafop 60 g/ha + metsulfuron 4 g/ha and clodinafop 120 g/ha + metsulfuron 8 g/ha with and without 0.2% surfactant provided excellent control of weeds and produced significantly higher grain yield of wheat. Weeds caused 55.7% reduction in wheat grain yield.

Field and laboratory experiments were conducted to study the persistence and dissipation of pretilachlor in soil, straw and flood water. In soil, pretilachlor at 0.75 kg/ha dissipated to below detectable level (BDL) within 30 days after application (DAA) when applied along with green leaf manure, while in other treatments viz., pretilachlor at 0.75, 1.5 kg/ha alone and gypsum + pretilachlor at 1.5 kg/ha persisted up to 45 DAA (DAA). In the case of plant, pretilachlor at 0.75 kg/ha dissipated to below detectable limit at 30 DAA, while 1.5 kg/ha persisted up to 60 DAA. Irrespective of the treatments, pretilachlor dissipated to below detectable limit at 10 DAA in flood water. The half-life of pretilachlor varied from 3.9-10.0, 3.4- 8.5, 0.87-1.52 days for soil, rice plant and flood water, respectively.

The experiment consisted of five planting geometry viz., sole maize, sole blackgram, maize + blackgram (1:1), maize + blackgram (2:1) and maize + blackgram (2:2) and four weed management practices viz., weedy check, hand weeding (HW) at 30 DAS, alachlor 2.0 kg/ha as pre emergence (PRE) and alachlor 1.5 kg/ha as PRE + HW at 40 DAS. These treatments were evaluated under split plot design with three replications. At harvest of maize (105 DAS), weed population and nitrogen removals of all species of weeds were significantly highest under sole maize. However, the highest nitrogen removal by weeds was recorded under weedy check by all the weed species, while the lowest removal of nitrogen was in alachlor 1.5 kg/ha + HW at 40 DAS. Among the planting geometry, the grain yield, productivity rating index (PRE), production efficiency (PE) and weed control efficiency (WCE) were highest under maize + blackgram (2:1) for maize, however weed smothering efficiency of maize was highest under maize + blackgram (1:1). The same parameters were highest under sole blackgram. At harvest stages of blackgram (75 DAS) and maize (105 DAS), dry weight of weeds was lowest with the application of alachlor 1.5 kg/ha + HW at 40 DAS. This treatment produced maximum grain yield, PRI and PE of maize and blackgram, along with higher WCE.

Water hyacinth (Eichhornia crassipes) is the most gregariously growing aquatic weed of India. An attempt was made to control water hyacinth from a village pond of about one hectare through integration of herbicides and bio-agents. One thousand bioagent weevils of Neochetina spp. were released as initial inoculation in the pond over an area of 3000 m2 for further population build up. Three herbicides namely 2,4-D (1.5 and 2.0 kg/ha), glyphosate (2.0 and 2.5 kg/ha) and paraquat (0.7 and 1.0 kg/ha) were applied in adjoining area after 15 days of bioagent inoculation in an area of 10 x30 m2 in three replicates for each dose. Population samples of water hyacinth and bioagent were taken after spray and release, respectively. On appearing new growth of water hyacinth in treated area, 15% of the total pond was again sprayed with the herbicides after 6 months. 2,4-D (2.0 kg/ha) proved the best herbicide to control water hyacinth (98.20%) followed by glyphosate 2.5 kg/ha (95.85 %) and paraquat 1.0 kg/ha (93.48 %). After initial control, highest regrowth was recorded in paraquat treated replications followed by 2,4-D and glyphosate. Population sampling of bioagants revealed spread and increase in number of the weevil in the entire pond. Bioagents also invaded re-growth rapidly resulted after herbicide spray. Neochetina spp. Adult population was found increased in the adjoining area treated with herbicides. After 9 months of biological and chemical integration, the first cycle of complete control was achieved. This early collapse of weed within a period of 9 month could be possible due to integration of herbicide and bioagents which would otherwise have taken minimum 24-36 month by the bioagents alone. After some time, again water hyacienth population increased due to new germination from buried seeds or from the left stolons of water hyacinth. This second wave of water hyacinth was again collapsed in 21 months due to integration of one spray of herbicides after one month of regrowth.

A field experiment under on farm trials programme of KVK, was conducted in farmers field during rabi 2005-06 and 2006-07 on wheat (Tricitum aestivum L.) crop cv. GW-273 to evaluate the efficiency of two herbicide 2,4-D and isoproturon and their tank mixture. Phalaris minor among the monocot weeds and Lathyrus aphaca among dicot were the major weeds in the demonstration fields, Post emergence application of 2,4-D 0.75 kg/ha + isoproturon 1.0 kg/ha at 25-30 days after sowing (DAS) gave maximum grain yield (3646 kg/ha) followed by the alone application of isoproturon 1.0 kg/ha at 25-30 DAS with gain yield (3222 kg/ha) and 2, 4-D 0.75 kg/ha at 25-30 DAS (2910 kg/ha). The application of 2,4-D + isoproturon increased the grain yield by 35.4% over control and 19% and 26.8% over individual application of 2,4-D and isoproturon, respectively. The application of 2,4-D + isoproturon also resulted higher weed control efficiency (80.4%).

The twelve different weed management practices were laid out in randomized block design with three replications. Rice variety “MTU-1010” was grown as a test crop. Rice was transplanted with a spacing of 20 x 20 cm and fertilized with 90, 60 and 40 kg/N, P and K/ha, respectively. At later period of growth, maximum panicle length, number of seeds/panicle, WCE, weed density, dry matter accumulation under post-emergence fb post-emergence application of fenoxaprop-p-ethy (60 g/ha) + ethoxysulfuron (15 g/ha) favoured significant enhancement in seed yield which was at par with hand weeding. Application of postemergence fb post-emergence application of fenoxaprop-p-ethyl (60 g/ha) + ethoxysulfuron (15 g/ha) gave higher net return (Rs 3,4249.72/ha) and benefit: cost ratio (1.72)

A total of 13 microorganisms viz., Aspergillus niger, A. flavus, A. fumigatus, Chaetomium globosum, Corynespora cassicola, Curvularia lunata, Curvularia sp., Eurotium chavelari, Fusarium oxysporum, F. moniliforme, Monilia sp. Rhizopus stolonifer and Trichoderma harzianum was isolated from the Parthenium infested soils of Tamil Nadu with various degree of distribution. Among them, A. niger and R. stolonifer had 100% distribution followed by A. flavus, T. harzianum, C. lunata and F. moniliforme.

An investigation was carried out to identify the ability of locally available weeds for metal removal at polluted soils along various roads in Jabalpur and adjoining areas. It was found that among weed species, the highest lead and manganese accumulation ratio was observed in Vetiveria zizinoides (17.9, 6.38), Arundo donax (12.5, 6.06) Calotropis procera (5.35, 3.03) and S. indicus (2.73, 4.69). Thus, having higher metal extraction ability, weeds such as V. zizinoides and A. donax can be applied for phytoremediation of lead and manganes contaminated sites.

In experimental field, weed species Eleusine indica (87/m2) was the most dominant weed, while Digitaria sanguinialis was second in order (84/m2 ) followed by Dactyloctenium aegyptium, Phyllanthus niruri. Boerhavia repanda, Digera arvensis, Cyperus iria and Cyperus rotundus. Significantly higher number of fruit yield was recorded in pre-emergence application of pendimethalin 1000 g/ha ƒb hand weeding at 30 DAS which was at par with interculturing + hand weeding carried out at 30 and 60 DAS and post-emergence application of quizalofop-ethyl 75g/ha ƒb hand weeding at 30 DAS.

A field study was carried out to determine the critical period of crop weed competition in cotton (Gossypium hirsutum. L.) during the summer season (Febuary to July) of 2007. Twelve treatments consisting of weed free and weedy periods at 20, 40, 60, 80 and 100 DAS and at harvest along with a weedy and weed free check were arranged in randomized block design with three replications. The predominant weed species in the experimental field were Echinochola colona, Leptochloa chinensis, Cyperus rotundus, Trianthema portulacastrum, Rotala densiflora, Eclipta alba and Phyllanthus maderaspatensis. Seed cotton yield loss increased in the duration of competition and maximum loss (96.5%) occurred due to full season competition. Seed cotton yield increased significantly with the increase in initial duration of weed free condition upto 80 DAS. Beyond 80 DAS, seed cotton yield was reduced considerably due to lower boll setting percentage. Critical period of weed competition was found to be 20 to 60 days after sowing

Allelopathic effect of aqueous extract of Parthenium hysterophorus (L). were studied on seed germination and seedling emergence of some cultivated crops like Triticum aesticum (L)., Zea mays (L), Sorghum vulgare Pers., Gossipium hirsutum (L) and Glycine max (L). Seed germination of Z. mays was completely inhibited at 2% leaf extract of P. hysterophous and of T. aesticum. It gradually reduced the seed germination up to concentration of 10% while in Sorghum vulgare, it was inhibited at 6%. At 4% aqueous extract, the maximum inhibition occurred in Glycine max and G. hirsutum. The aqueous extract of Parthenium showed strong inhibitory effect on the growth of root and shoot development of crops except T. aesticum.

Study revealed that drum seeding + green manure method of seedling establishment and pre-emergence application of pretilachlor + safener at the rate of 0.45 kg/ha on 5 days after sowing (DAS) fb hand weeding (HW) at 45 DAS registered lowest weed density, weed biomass, highest weed control efficiency (WCE), zero per cent weed index (WI), lowest depletion of NPK nutrient by weeds and highest grain yield of crop and B: C ratio

Among the treatments, weedy and butachlor plots had higher population of weeds. Weed population was lower at all the doses of rice straw incorporated with the lowest in 500 g/m2 rice straw treatment. Data on weed dry weight recorded at 60 DAT revealed a significant decrease in all the plots where rice straw was incorporated as compared to weedy and butachlor treated plots. Grain yield was also higher at all the doses of rice straw incorporation while it was lowest (2658 kg/ha) in the weedy treatment (Table 3). Highest grain yield (3,925 kg/ha) was obtained, irrespective of cultivars, in the treatment with the highest rice straw incorporation (500 g/m2). A total of 17 compounds were recorded in the straw. Among these, four compounds could be identified after comparing with phenolic standards. These were gallic acid, phydroxy benzoic acid, ferulic acid and vanillic acid.

The experiment was conducted in the fields of 10 farmers as 'On farm trial' in adopted villages of Krishi Vigyan Kendra (KVK), Rewa. Population and dry matter accumulation of Phalaris minor were significantly reduced with post emergence application of sulfosulfuron (25 g/ha), mesosulfuron+ iodosulfuron (12+2.4 g/ha) and pinoxaden (50 g/ha) when compared with unweeded control during both the years of investigations. Significantly more grain yield was recorded in all herbicidal treatments as compared to unweeded control.

An experiment was conducted during kharif season of 2006 and 2007 in Jammu to study the efficacy of pre and post emergence herbicides for controlling weeds of mung bean under limited moisture conditions of Kandi belt of Jammu. Hand weeding twice at 20 and 40 DAS produced the highest average seed yield (697.8kg/ha) which was at par with metolachlor (PE, 0.75kg/ha fb one hand weeding at 20 DAS) (691.6kg/ha). Among the other herbicidal treatments, pendimethalin (PE 1.0 kg/ha fb 1HW at 30 DAS) was superior in controlling weeds and increasing the seed yield.

The study was undertaken in Shahdol District of Madhya Pradesh to determine the impact of different types of weeder in SRI. Twenty SRI trained farmers, were selected for practicing SRI trained before Jawahar paddy plant marker for line marking at equi-distance among plant to plant and row to row in the grids of 25 x 25 cms and cono weeder, rotary weeder and twin wheel hoe for weeding. It was observed that average productivity was 555 kg/ha as compared to farmers practice 275 kg/ha. Cono weeder and rotary weeder were found suitable for weeding in wet condition and twin wheel hoe in dry condition of SRI fields.