Volume-52 | Issue-3(July-September)| Year 2020

Senna tora, Dermatitis, Islands, Parthenium, Zygogramma bicolorata

Parthenium (Parthenium hysterophorus L.) has traversed the oceans to reach Andaman & Nicobar and Lakshadweep Islands of India in early 21st century, nearly half a century after its first report in Maharashtra state in 1955. Its entry might be on account of contaminated movement of food grains and other materials with Parthenium seeds from mainland through ships and airplanes. The weed has established in wastelands and community lands in some of the islands, hence there is lurking threat of its further invasion in other islands and into croplands. Public were less aware of its harmful effects due its new occurrence in the region. Competitive plant Senna tora was noticed in the islands during survey, and was recommended for Parthenium management on the road side. Physical removal was done involving people participation and was recommended for its management due to ban on using of chemicals. Bioagent Zygogramma bicolorata was not found in Andaman & Nicobar Islands in spite of its introduction in 2005 and 2006 for its biological control.

CA-SYS platform, Cropping system, Evenness, Community, Yield loss

Reconciling crop productivity and biodiversity maintenance is one of the main challenges of agriculture worldwide. Weed management is recognized to be a key point for ecological intensification in agriculture because weeds can generate severe yield losses but also represent the base of agricultural trophic networks. Research in weed science has often opposed two different perceptions of weeds. Low within-field weed diversity and abundance has either been considered as a sign of efficient weed management or an erosion of the agroecosystem services provided by weeds. However, a recent study in grain-based systems in France highlighted the potential benefits of weed diversity in mitigating crop yield losses. Major yield losses may simply arise from the dominance of a few competitive species. A higher diversity of traits (characteristics) within the weed community should induce complementarity in resource use (light, water, nitrogen etc.) and alleviate weed:crop competition. Thus, weed scientists should try to confirm this relationship in different production situations (e.g. floristic contexts, pedoclimates, cropping systems) and then identify cropping systems which promote weed evenness, either from a taxonomic or functional point of view. Weeding operations should exclusively target competitive and dominant species. However, current weed control practices do not allow to target a specific species in a complex community. Therefore, future studies need to identify if weed diversity could rather be indirectly promoted by diversifying weed management tools, which ought to limit weed density/biomass. The CA-SYS platform (INRAE, Dijon, France) is a unique site in Europe to experiment biodiversity-based forms of agriculture, including a diversity of weed management strategies. The overarching objective of the CA-SYS platform is to design and test the feasibility and performances of pesticide-free agriculture which resorts to (cropped and wild) biodiversity in support of production.

Chinese sprangletop, Herbicides, Ready-mix combination, Tank mix combination, Weeds, Wet seeded rice

An experiment was conducted to evaluate the efficiency of various herbicides for the management of chinese sprangletop (Leptochloa chinensis) at Integrated Farming System Research Station, Karamana, Thiruvananthapuram of Kerala Agricultural University, India during Kharif (rainy season) 2018 and 2019. Grass weeds were the most dominant weed species followed by broad-leaf weeds and sedges during both the crop seasons. The present study revealed that fenoxaprop-p-ethyl at 60 g/ha was the most effective herbicide against L. chinensis followed by cyhalofop-butyl at 80 g/ha. Dry matter production of L. chinensis was lower in sole application of fenoxaprop-p-ethyl at 60 g/ha and cyhalofop-butyl at 80 g/ha compared to their tank mix combination with bispyribac-sodium at 25 g/ha during both the years. Ready-mix combination of penoxsulam + cyhalofop-butyl (6% OD) at 150 g/ha was very effective in managing the complex spectrum of weeds however, it was not effective in managing L. chinensis compared to other herbicidal treatments. Application of bispyribac-sodium alone at 25 g/ha was not effective in controlling L. chinensis resulted in lower weed control efficiency of 37 and 48% during 2018 and 2019, respectively. Tank mix application of bispyribac-sodium with fenoxaprop-p-ethyl (at 25 + 60 g/ha) or cyhalofop-butyl (at 25 + 80 g/ha) recorded the least total dry matter production of weeds. All the tested herbicides and the herbicide combinations increased the grain yield compared to unweeded control during both the years.

Crop establishment methods, Herbicides, Rice, System of rice intensification, Weed management

A field experiment was conducted during Kharif (rainy) seasons of 2017 and 2018 at Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Wadura, Jammu and Kashmir. The treatments comprised of three crop establishment methods, viz. transplanting, direct seeding (DSR), System of Rice Intensification (SRI) in main plots and seven weed management practices, viz. butachlor (1500 g/ha), penoxsulam (22.5g/ha), pyrazosulfuron-ethyl + pretilachlor (15 and 600g/ha), bensulfuron methyl + pretilachlor (60 and 600         g/ha), twice conoweeding/hand weeding, weed free and weedy check in sub-plots replicated thrice in a split plot design. The results revealed that significantly lowest weed density and weed dry weight were recorded with transplanted method as compared to SRI and DSR. Application of penoxsulam 22.5 g/ha recorded significantly the lowest weed population and weed dry matter depicting higher weed control efficiency. SRI had resulted in significantly higher yields over DSR and transplanted rice. Penoxsulam (22.5      g/ha) produced significantly higher grain and straw yields. SRI proved to be better method of crop establishment than transplanting and DSR whereas, application of penoxsulam 22.5 g/ha proved superior to other herbicide treatments used.

Direct-seeded rice, Post–emergence herbicide, Weed control efficiency

A field experiment was conducted during Kharif 2017 and 2018 at I.G.K.V, Raipur, Chhattisgarh to study the effect of existing herbicides in managing weeds in direct-seeded rice (Oryza sativa L.) and to assess their residual effect on succeeding crops. Application of bispyribac-sodium 2% (BS) + 2,4-D sodium salt 54.3% SP (DSS) with adjuvant (WA) (30.0 + 814.5 g/ha), BS + 2,4-DSS (WA) (25.0 + 678.75 g/ha), BS+ 2,4-DSS (30.0 + 814.5 g/ha) and BS + 2,4-DSS (WA) (20.0 + 543.0 g/ha) was at par to weed free in terms of grain yield. BS + 2,4- DSS (WA) (30.0 + 814.5 g/ha) controlled the weeds more effectively throughout the crop growth period and recorded higher weed control efficiency (97.5% at 30 DAS and 92.4% at 60 DAS), herbicide efficiency index (47.1 and 13.2), reduction of weed density (88.1 and 80.6%) and weed biomass (97.5 and 92.4%) and lower weed persistence index (0.2 and 0.4) during both the years. The phytotoxicity effect was observed with higher doses of BS + 2,4-DSS, alone and with adjuvant at 25.0 + 678.8 g/ha and 30.0 + 814.5 g/ha, however it was recovered quickly. There was no phytotoxicity and carryover effect of these herbicides tested on chickpea + linseed intercrop, grown as succeeding crop. Application of BS + 2,4-DSS (WA) (30.0 + 814.5 g/ha) recorded highest net returns ( 65444 and 76762/ha) and B:C ratio (2.2 and 2.6) during 2017 and 2018, respectively

Oxadiargyl, Post-emergence herbicide, Pyribenzoxim, Rice, Weed

A study was conducted at Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh during Kharif 2017 and 2018 to evaluate the efficacy of pyribenzoxim herbicide in dry direct-seeded rice. Among the herbicidal treatments, pyribenzoxim 5% EC 60 g/ha was the most suitable for controlling weeds, followed by oxadiargyl 80% WP 100 g/ha, though hand weeding treatment showed lowest weed infestation and maximum grain yield (4.55 t/ha). Weed density and weed dry weight had strong negative correlation with grain yield (r = -0.982** and -0.983**, respectively). Total weed population and biomass was the lowest in manually weeded plots followed by pyribenzoxim 5% EC 60     g/ha. The highest weed control efficiency (70.0, 86.7 and 88.3% at 30, 45 and 60 DAS, respectively), weed control index (82.9, 85.5 and 86.4% at 30, 45 and 60 DAS, respectively) and herbicide efficiency index (43.4%) were found with pyribenzoxim 5% EC 60 g/ha. The pyribenzoxim 5% EC 60 g/ha at 15 DAS was found the most remunerative with benefit-cost ratio of 2.42.

Bio-efficacy, Ready-mix, Triticum aestivum L., Weed, Weed control index, Yield

A field experiment was conducted during 2015-16 and 2016-17 at Rajasthan College of Agriculture, Udaipur, India with the objective to assess bio-efficacy potential of the ready-mix herbicides against complex weed flora in wheat. The experiment consisting of fifteen treatments, was laid out in a randomized block design with four replications. The results indicated significant reduction in population and growth of weeds by ready-mix application of sulfosulfuron + metsulfuron (32.0 g/ha) and mesosulfuron + iodosulfuron (14.4 g/ha) followed by clodinafop + metsulfuron (64.0 g/ha), pinoxaden + metsulfuron (64.0 g/ha) over other weed control treatments. However, two hand weeding (30 and 45 DAS) registered maximum decline in density and dry biomass of all the weeds. Moreover, herbicides combination sulfosulfuron + metsulfuron and mesosulfuron + iodosulfuron attributed to greater value of weed control index (WCI) with maximum reduction of weed density and dry biomass. At 60 DAS, the array of WCI ranged from 9.19 to 95.01 and 57.48 to 97.01% for monocots and dicots, respectively and resulted into higher grain yield (34.3 and 20.5% more), net returns (49.1 and 47.7% more) and B-C ratio (2.34 and 2.32) over the unweeded control. The study concluded that the use of sulfosulfuron + metsulfuron (32.0 g/ha) and mesosulfuron + iodosulfuron (14.4 g/ha) as post-emergence at 5 WAS provided efficacious control of all sorts of weeds in wheat with higher yield and net returns.

Herbicide mixture, pendimethalin, Phalaris minor, pinoxaden, pyroxasulfone, wheat, cross resistance

Field experiment was conducted at CCS Haryana Agricultural University during Rabi 206-17 and 2017-18 to evaluate bio-efficacy of different herbicides and their combination against cross resistant P. minor in wheat, and to study the phytotoxic effects on the crop, if any. The treatments included application pre-emergence herbicides pendimethalin 1500 g/ha and its mixture with metribuzin 175 g/ha alone, pendimethalin + pyroxasulfone  Tank mix (TM) at 1500 + 102 g/ha alone and their sequential application with post-emergence herbicides application (PoE) of mesosulfuron + iodosulfuron ready mix (RM) 14.4 g/ha and pinoxaden 60 g/ha along with weedy check treatment. The minimum density of P. minor, weed biomass and the highest wheat grain yield was observed with pendimethalin + pyroxasulfone TM fb mesosulfuron+ iodosulfuron RM (1500 + 102 fb 14.4 g/ha). All the herbicides significantly reduced the weed biomass as compared with the control but maximum reduction in the weed biomass was achieved with pendimethalin + pyroxasulfone TM fb mesosulfuron+ iodosulfuron RM. Pinoxaden at 60 g/ha did not control Rumex dentatus and Chenopodium album. Only pre-emergence application of metribuzin, pendimethalin + metribuzin (before sowing), pinoxaden + metribuzin TM caused toxicity of up to 5% at 10 days after treatment (DAT). The wheat recovered from toxicity by 20 DAT without any yield penalty. On-farm demonstrations of pyroxasulfone at 127.5 g/ha PE in Haryana revealed 88.3 % control of multiple herbicide resistant P. minor. Its integration with pendimethalin at 1.5 kg/ha (PE) and post-emergence herbicides at 35 DAS has improved control of P. minor to 92.1%.

Herbicides, Nitrogen levels, Nitrogen uptake, Weed control, Weed management, Wheat 

A field experiment was conducted during Rabi seasons of 2015-16 and 2016-17 to study the effect of nitrogen and weed control on wheat yield, nitrogen uptake and economics of wheat. The treatments comprised of 4 levels of nitrogen, viz. 90, 120, 150 and 180 kg/ha, and 5 weed control methods, viz. weedy check, hand weedings at 30 and 60 days after seeding (DAS), clodinafop + metsulfuron (60 + 4 g/ha), fenoxaprop + metsulfuron (120 + 4 g/ha) and sulfosulfuron + metsulfuron (25 + 4 g/ha). Weed density was reduced with increased rate of nitrogen from 90 to 180 kg/ha. Crop fertilized with180 kg N/ha was at par with 150 kg N/ha but produced significantly higher weeds biomass than the rest of the nitrogen levels. The uptake of nitrogen by weeds was significantly higher with 180 kg/ha than the other N-levels. Post-emergence spray of clodinafop + metsulfuron (60 + 4 g/ha) recorded significantly the lowest weed population followed by sulfosulfuron + metsulfuron (25 + 4 g/ha) and fenoxaprop + metsulfuron (120 + 4 g/ha). Hand weeding twice (30 and 60 DAS) recorded the significantly lowest weeds biomass, followed by clodinafop + metsulfuron (60 + 4 g/ha). Weedy check recorded significantly maximum amount of nitrogen uptake by weeds. Nitrogen applied at 180 kg/ha recorded the highest wheat grain yield (3.82 and 3.98 t/ha), crop nitrogen uptake (96.81 and 99.69 kg/ha), gross returns ( 73700/ha), net returns ( 49600/ha) and B:C ratio (2.06).

Organic, Soil solarization, Soybean-gram, Stale seed bed, Weed management

The significantly lower weed density and biomass, at 40 days after seeding (DAS) was recorded in weed free plots followed by soil solarization with 25 μ polythene mulch during summer + one hand weeding at 25 DAS in soybean and gram during both the years. Among the weed management practices, combination of stale seedbed + reduced spacing + mulching with wheat straw (2 t/ha) + one HW at 25 DAS recorded higher soybean equivalent yield. Higher net returns and benefit: cost ratio was observed in soybean + sun hemp incorporation after 35-40 DAS in Kharif and gram + safflower (2:1) intercropping in Rabi season, followed by stale seedbed + reduced spacing + mulching with wheat straw (2 t/ha) + one HW at 25 DAS. Application of two hand weeding (20-25 and 45-50 DAS) recorded higher values of yield attributes.

Haulm, Herbicides, Weed dry weight

A field experiment was conducted during two consecutive summer season of 2018 and 2019 in loamy sand soil at  B. A. College of Agriculture, Anand Agricultural University, Anand to study the effect of integrated weed management in summer groundnut. Results indicated that pre-emergence application of oxyfluorfen 180 g/ha PE fb interculturing (IC) + hand weeding (HW) at 40 DAS found to be effective for controlling weeds, and higher pod yield (3.99 t/ha) of groundnut, followed by oxyfluorfen 180 g/ha PE fb imazethapyr 100 g/ha PoE, IC fb HW at 20 and 40 DAS, oxyfluorfen 180 g/ha PE fb imazethapyr + imazamox 70 g/ha PoE (pre-mix) and fluazifop-p-butyl  + fomesafen 250 g/ha ePoE (pre-mix) fb IC + HW at 40 DAS.

Conservation tillage, Mustard, Productivity, Weed flora, Weed management

The effects of tillage and weed management practices were evaluated for four years (2014-15 to 2017-18) in pearlmillet-mustard-cowpea cropping system. The results revealed that conventional tillage during Kharif (rainy) and Rabi (winter) seasons and zero tillage with previous crop residue application significantly increased the grain yield by 36 and 15% and reduced the total weed biomass by 57 and 26%, respectively compared to zero tillage without residue application. Among different weed flora, conventional tillage during Kharif and Rabi season fb the zero tillage with previous crop residue reduced the population of P. minor by 24.6 and 16%, C. arvensis and M. hispida by 50 and 29% and C. rotundus  by 42 and 10% with weed control efficiency of 79 and 65%, respectively at 60 DAS over zero tillage without residue application. However, among different weed management practices, the pre-emergence application of oxyfluorfen 0.23 kg/ha with one hand weeding at 30-35 DAS resulted in significant reduction of total weed biomass, highest grain yield, weed control efficiency and net returns. The integrated weed management approach reduced the narrow-leaved weeds by 75%, broad-leaved weeds by 86% and sedges by 90% as compared to the weedy check.

Herbicide resistance, Metsulfuron-methyl, Rumex dentatus, Wheat

Over-reliance and continuous use of similar mode of herbicides lead to increase in selection pressure which resulted in evolution of herbicide resistance in weeds. Metsulfuron-methyl is used for the control of broad-leaf weeds in wheat since 1990s. There are reports of failure of control of Rumex dentatus with metsulfuron from farmers’ fields in North-Western India. Pot studies were conducted at Punjab Agricultural University, Ludhiana during winter (Rabi) 2018-19 and 2019-20 to quantify the status and level of herbicide resistance in R. dentatus in Punjab and Haryana. Rumex populations were collected from farmers’ fields in both years. Fifty six and 33 biotypes of R. dentatus from farmers’ fields of Haryana and 6 and 19 biotypes from Punjab were collected in first and second year, respectively. Biotypes were screened using recommended dose of metsulfuron-methyl (5 g/ha) along with unsprayed in pot study. Results revealed that 38 out of 56 biotypes of R. dentatus collected from Haryana in first year were found resistant to metsulfuron whereas only one biotype showed resistance from Punjab. Further, 23 biotypes out of 33 biotypes collected in second year were found resistant from Haryana whereas 14 biotypes out of 19 were found resistant in Punjab. This indicated that R. dentatus has evolved resistance against metsulfuron-methyl in different regions of Punjab and Haryana.

ACCase inhibitors, ALS inhibitors, Multiple herbicide resistance, Phalaris minor

Phalaris minor is seriously affecting wheat productivity and profitability in Haryana. The menace of P. minor has worsened after it evolved resistance to herbicides. For rational recommendation and implementation of management strategies, it is imperative to assess and quantify the level of resistance in P. minor populations. In dose-response assay, it was found that P. minor populations ‘Naggal’ and ‘Kalvehri’ exhibited multiple resistance to herbicides from different chemical families. ‘Naggal’ was 13-, 18-, 26- and 22-fold resistant to clodinafop, pinoxaden, sulfosulfuron and mesosulfuron + iodosulfuron, respectively and ‘Kalvehri’ was 15-, 29- and 16-fold resistant to pinoxaden, sulfosulfuron and mesosulfuron + iodosulfuron, respectively. All tested populations were resistant to ACCase inhibitors with more number of populations being highly resistant to clodinafop than pinoxaden. However, majority of the populations were susceptible to ALS inhibitors particularly mesosulfuron + iodosulfuron. The evolution of multiple herbicide resistance in P. minor is a big challenge for scientists and farmers alike.

Indole acetic acid content, Net photosynthesis, Nitrate reductase enzyme activity, Proline content, Soluble protein content

The experiment was conducted at Agricultural Research Station, Mannuthy in the year 2018 with the rice variety ‘Jyothi’. The experiment was laid out in RBD with three replications. Treatments included recommended and double the recommended doses of 2,4-D, metsulfuron-methyl + chlorimuron-ethyl and penoxsualm and two controls (hand weeded and unweeded). Herbicides were sprayed at 20 days after sowing (DAS). Biochemical parameters were estimated at one week after herbicidal application and at the time of flowering. Biochemical parameters such as soluble protein, total amino acid and nitrate reductase enzyme activity showed a decline in herbicide treatments compared to hand weeded control. Proline content and catalase enzyme activity showed an increase with herbicide application while other physiological parameters like Indole acetic acid (IAA) content, chlorophyll content, stomatal conductance and net photosynthesis showed a decline. Double the recommended dose of herbicides affected these parameters more adversely as compared to the recommended dose of herbicides. Even though double the recommended dose of herbicide exhibited higher weed control efficiency, it reduced the yield of rice plant.

Brown manuring, Herbicides, Sequential application, Weed dynamics

The study was carried out in rainy season in 2015 at Ludhiana, India. Present study evaluated the effect of timing of brown manuring with Sesbania aculeata alone and its integration with herbicides on weed incidence and rice grain yield. Sesbania seed was broadcasted at time of rice sowing and brown manured using 2,4-D at 580 g/ha at 4- and 5-weeks age. BM plots had significantly lower weed density and biomass than without BM (sole rice). BM at 4 weeks was more effective in suppressing weeds than BM at 5 weeks age. Among weed control methods, sequential application of pendimethalin and bispyribac gave best weed control and highest rice grain yield. Combination treatments of BM (4 weeks) with pendimethalin and, sole rice with pendimethalin and bispyribac gave similar rice grain yield. It was concluded that BM has weed control potential equivalent to one post-emergence herbicide, however, for getting the highest rice productivity it must be used in combination with pre- and post-emergence herbicides.

Biochar, Dry direct-seeded rice, Weed, Yield

Field experiment was conducted during rainy season (Kharif) 2018 to study the bio-efficacy of pre-emergence herbicides in dry direct-seeded rice. The treatments were weedy check, weed free, pendimethalin applied as pre-emergence at 1.0, 1.5 and 2.0 kg/ha fb post-emergence application of bispyribac-sodium at 0.025 kg/ha with amendment of biochar at 4.0 t/ha and without amendment of biochar. Total weed dry matter accumulation was maximum at 60 DAS. The highest grain yield was obtained in weed free treatment which was 7.38% higher than pendimethalin as pre-emergence at 1.5 kg/ha followed by bispyribac-sodium at 25 g/ha under biochar condition. Recommended dose of pendimethalin (1.0 kg/ha) along with biochar had 7.5% less yield compared to 1.0 kg/ha pendimethalin without biochar amendment. Higher dose of pendimethalin reduced grain, straw and biological yield, setback on yield was more pronounced in non-biochar amended soil. Addition of biochar decreased the B:C compared to without biochar treatments.

Blackgram, Critical period, Yield loss, Weed competition

A field experiment was carried out at Pandit Jawaharlal Nehru College of Agriculture and Research Institute, Karaikal, U.T. of Puducherry, India during rainy season (Kharif) of 2019 with ten treatments replicated thrice in a randomized block design to study the critical period of crop-weed competition in irrigated blackgram in deltaic coastal ecosystem. The weed spectrum comprised of Echinochloa colona (L), Dactyloctenium aegyptium (L.), Trianthema portulacastrum (L.), Cleome viscosa (L.), Eclipta prostrata (L.) and Cyperus rotundus (L.). The density and dry weight of weeds significantly increased when crop-weed competition was prolonged from 15 days after sowing (DAS) to the maturity of the crop. The highest seed yield (706.5 kg/ in coastaha) was obtained when blackgram was maintained weed free till harvest closely followed by weed free till 60 DAS (652.1 kg/ha) and weedy condition till 15 DAS (608.6 kg/ha). The critical period of crop-weed competition was found to be 17 to 50 DAS. Weedy condition upto 15, 30, 45, 60 DAS and throughout crop growth resulted in a yield loss of 9.66, 39.19, 59.13, 75.87 and 86.30%, respectively.

Economics, Greengram, Herbicides, Imazethapyr, Oxyfluorfen, Pendimethalin, Trianthema portulacastrum

Field experiments were conducted to select suitable pre- and post-emergence herbicides for the control of Trianthema portulacastrum in greengram. Treatments were consisted of pre-emergence (PE) herbicides, viz. pendimethalin (1.0 kg/ha), oxyfluorfen (100 and 200 g/ha) with one hand weeding at 30 days after sowing (DAS), post-emergence (PoE) imazethapyr 50 g/ha at 15 DAS, combinations of PE and PoE herbicides and hand weeding (HW) twice at 15 and 30 DAS and control. Significantly lesser weed density (137/m2) and dry weight (30.4 g/m2) and higher weed control efficiency (89.6%) were recorded with application of pendimethalin 1.0 kg/ha at 3 DAS + imazethapyr 50 g/ha at 30 DAS than other treatments at 45 DAS. Significantly higher dry matter production (1.34 t/ha), more number of pods per plant (38.4) and seeds per pod (9.8) were recorded with application of pendimethalin1.0       kg/ha + imazethapyr 50 g/ha 30 DAS than other treatments. Application of pendimethalin 1.0 kg/ha on 3 DAS followed by imazethapyr 50 g/ha on 30 DAS recorded significantly higher mean grain yield of 461 kg/ha, mean net returns (  14443/ha) and benefit cost ratio (2.09) over other treatments. Thus, it could be concluded that application of PE herbicide pendimethalin 1.0 kg/ha on 3 DAS followed by PoE herbicide imazethapyr 50g/ha on 30 DAS controlled the Trianthema portulacastrum effectively and produced higher productivity and profitability of greengram in irrigated condition.

Blackgram, Economics, Weed

An on farm testing (OFT) was conducted in the farmer’s field of Daloda Rail village, Mandsaur district, Madhya Pradesh in kharif season of 2014, 2015 and 2016 to assess the effect of integrated weed management treatments on weed management and yield of blackgram (Vigna mungo L.). Application of imazethapyr 75 g/ha at 18 days after seeding (DAS) and hand weeding at 40 DAS gave 36.91% mean higher blackgram grain yield as compare to farmer’s practice (0.88 t/ha). Further, this treatment also resulted in significantly higher blackgram plant height, pods/plant, net return and B:C ratio as compared to all other tested treatments and significantly reduced the weed density and biomass as recorded at 45 DAS as compared to all other treatments tested.

Plant extracts, Weed dry weight, Weed control efficiency, Yield

Sorghum (NJ-2647), sunflower (NDSH-1012) and rice (NLR-34449) were grown up to physiological maturity and harvested for preparing plant extracts during Kharif 2017 at Sri Venkateswara Agricultural College, Tirupati, Andhra Pradesh. Plant parts of Parthenium hysterophorus, Lantana camera and Cyperus rotundus were collected from the non-cropped area at flowering. The chopped material of above plants were soaked separately in distilled water for 24 hours at room temperature of 210C at a ratio of 1:10 (w/v) and the same was filtered through 10 and 60 mesh sieve separately. A field experiment was conducted during Rabi 2017-18 in a randomized block design with 10 treatments to evaluate the performance of different plant extracts each applied at 15 L/ha at 15 and 30 DAS and rice straw mulch 5 t/ha for weed management in groundnut. The application of rice straw mulch 5 t/ha was found to be the best followed by sunflower extract spray for obtaining higher pod yield and maximum net returns, besides effective control of weeds in groundnut in view of sustainability and reduce the load of herbicides in the soil, however pre-emergence application of pendimethalin 1.0 kg/ha + HW at 30 DAS produced higher pod yield and net returns.

Dehydrogenase enzyme activity, Diclosulam, Enzyme activity, Imazethapyr, Nodules

Impact of integrated weed management practices involving stale seedbed, mulching with dried banana leaves, herbicides, viz. pre-emergence (PE) diclosulam, post-emergence (PoE) quizalofop-p-ethyl and imazethapyr and manual weeding on nodulation in bush cowpea and enzyme activity in soil was studied. Stale seedbed recorded significantly higher number of total nodules per plant. Dehydrogenase enzyme activity was also higher in stale seedbed however, urease enzyme activity did not have any significant effect at 15 and 30 DAS. Treatments with imazethapyr recorded lesser number of total nodules than treatments with diclosulam and quizalofop-p-ethyl. Among the herbicide treatments at 15 DAS, PE diclosulam registered significantly higher urease and dehydrogenase enzyme activity than weedy check and comparable activity with hand weeding treatment. Post-emergence imazethapyr showed a reduction in dehydrogenase and urease enzyme activity at 30 DAS compared to 15 DAS. However, PoE quizalofop-p-ethyl registered higher dehydrogenase and urease enzyme activity at 30 DAS compared to 15 DAS and values were comparable or higher than that of hand weeding treatment.