Weed Control Practices Research Articles

A Review of Non-Chemical Weed Control Practices in Christmas Tree Production

Weeds interfere with Christmas tree growth at any time and at any stage of production. Growers mostly rely on mechanical mowing and applications of herbicides for weed control in their fields. However, herbicides can be phytotoxic to non-target plants, can cause environment-related issues, and their repeated application can even cause herbicide-resistant weeds. The main objective of this manuscript is to provide a review of non-chemical weed control strategies in Christmas tree production and identify areas where current practices could potentially be improved or in which further research is required. Preventing the introduction of weed seeds requires controlling weeds along farm roads, maintaining clean equipment, and eliminating new weeds before they start seeding. Mowing helps to reduce the number of seeds produced by the weeds and can significantly reduce competition with trees. Shropshire sheep are well suited for grazing Christmas tree plantations as they prefer grazing on grasses and weeds rather than on coniferous trees. Weeds can also be controlled around Christmas trees by mulching. Organic mulch can improve soil moisture, maintain soil temperatures, enhance root establishment and transplant survival, and improve plant establishment and overall growth. Incorporating cover crops into Christmas tree plantations may improve tree growth, quality, and soil fertility and can supplement conventional nitrogen fertilizers. However, if cover crops are not properly managed, they can be highly competitive with the trees. Flaming can cause suppression of many annual weed species but is less effective on larger weeds and needs to be applied with caution. Several insects have been used as biological agents to control selective weed species. However, further research is required to focus on several potential biological agents, different types and depths of mulches, on cover crops types and their competition with different species of Christmas trees and their effects on seedling survival and growth.

Sustainable alternatives to chemicals for weed control in the orchard - a Review

This review is designed to address various alternative weed-control practices and their possibilities in the fruit orchard in terms of sustainability. Correct weed management and maintenance of adequate orchard biodiversity are crucial for sustainable orchard soil management. The key is to practice an alternative weed-management approach (single or integrated) rather than to use possibly harmful chemicals only. Integration of modern equipment with a shallow tillage system can provide effective weed control in tree rows, including optimised tree performance and soil biodiversity. Living mulch suppresses weeds and enhances orchard biodiversity, while selection of less competitive and less pest-attracting species is crucial. Plastic covers offer long-term weed control, but additional nutrient amendments are required to maintain the balanced fertility of the soil. Wood chip mulch is suggested where the materials are available on or near the farm, and where there is lower incidence of perennial weeds. High pressure water and robotic systems are still in their infancy for fruit orchards, and required more research to confirm their efficiency.

Spatial Distribution of Weed Seed Banks in the Agricultural Field and Anthropized Cerrado

Characterization of the seeds bank is an essential tool for decision making on weed control and management practices and the study and maintenance of the ecological dynamics of natural areas. In this context, the present study aimed to characterize the spatial variability of the seeds bank in an experimental agricultural field and an anthropized cerrado area, using the ordinary kriging geostatistical technique. Sampling was carried out on 10x10 regular grids in two different environments. Area 01 consisted of an experimental agricultural field of annual crops (soy and corn); area 02 represented the anthropized cerrado. The sample grids consisted of 25 points collected at a depth of 0.00-0.20 m. The soil samples were placed in 6.38 dm3 and 0.05 m² plastic containers. Spatial distribution maps of the species found have been drawn up, grouped in dicotyledonous, monocotyledonous, and total density, in addition, the density of three weeds most found in each area. The weed seed bank present strong spatial variability to 01 and 02, which indicates behavior in spots or in patches for both dicotyledonous and monocotyledonous plants, especially Mollugo verticillata L. and Eleusine indica (L.) Gaertn. in the experimental field, and for Richardia scabra L. and Eleusine indica (L.) Gaertn. in the anthropized cerrado. The ordinary kriging technique made it possible to map the weed seed bank and, therefore, it may work as an efficient tool in controlling weeds in agricultural fields, especially in its pre-emergence phase. Furthermore, it can assist in the recovery of native anthropized vegetation.

Faktor Lingkungan dan Teknik Budi daya terhadap Epidemi Penyakit Mati Meranggas pada Pohon Pala di Aceh Selatan

Faktor budi daya yang sangat penting dalam perkembangan penyakit tanaman ialah lingkungan dan teknik budi daya. Kedua faktor tersebut merupakan salah satu dasar dalam menentukan strategi pengendalian penyakit. Oleh karena itu, analisis faktor tersebut perlu dilakukan untuk penyakit yang tergolong baru. Penelitian ini bertujuan untuk mengidentifikasi faktor lingkungan terhadap epidemi penyakit mati meranggas pada tanaman pala di Aceh Selatan. Pengamatan lapangan untuk mengukur insidensi penyakit dilakukan di 36 kebun sampel pada Kecamatan Labuhan Haji, Meukek, Sawang, Samadua, Tapak Tuan, dan Pasie Raja yang merupakan sentra pala di Aceh Selatan. Selain itu, cara bercocok tanam dan kondisi lahan dari petani pemilik kebun contoh didata. Data lingkungan terkait dengan kondisi cuaca diperoleh dari Badan Metereologi, Klimatologi dan Geofisika setempat. Berdasarkan pengamatan di lapangan, insidensi penyakit tertinggi muncul pada saat umur tanaman berumur di atas 50 tahun dengan pola tanam monokultur serta tanpa pengendalian gulma. Faktor lingkungan sebagai pemicu terjadinya insidensi penyakit mati meranggas pala di Aceh Selatan adalah curah hujan dan bulan basah yang semakin menurun serta perbedaan topografi.

Influence of different weed management practices on weed dynamics, yield attributes and economics of black gram

A field experiment was conducted at Birsa Agricultural University, Ranchi, Jharkhand during rainy & winter seasons of 2015-16 and 2016-17. The experiment was laid out in randomized block design with 12 treatments i.e. haloxyfop 81 g/ha, haloxyfop 108 g/ha, haloxyfop 135 g/ha, haloxyfop 270 g/ha, fenoxaprop-p-ethyl 61.9 g/ha, quizalofop-ethyl 43.8 g/ha, imazethapyr 100 g/ha each applied at 20 DAS, pendimethalin 1000 g/ha, oxyfluorfen 100 g/ha each applied at 3 DAS, two mechanical, two hand weeding each performed at 25 and 45 DAS and weedy check, replicated thrice. Black gram var. Birsa Urd-1 was sown at 30 cm using 30 kg seed/ha fertilized with recommended level of nutrients N:P2O5:K2O:Si.e. 25:50:25:25 kg/ha. Mustard var. Pusa-Bold was sown at 30 cm using 5 kg seed/ha fertilized with recommended level of nutrients N:P2O5:K2O:S i.e. 80:40:20:20 kg/ha. The experimental field was mainly infested with Eleusine indica, Echinocloa spp. Commelina spp., Alternanthra sessilis and Cyperus species. Two hand weeding at 25 & 45 DAS recorded higher number of pods/plant, 1000-seed weight, seed yield and harvest index to the extent of 28.90, 16.10, 104.09 and 38.87 per cent, respectively as compare to weedy check i.e. 10.72 pods/plant, 33.80 g, 621 kg/ha and 19.15 per cent, respectively. However, application of haloxyfop 108 g/ha at 20 DAS recorded ` 10,513 and ` 13,878/ha higher net return compared to conventional practice of weed control i.e. two hand weeding at 25 & 45 DAS (` 26,789/ha) and two mechanical weeding at 25 & 45 DAS (` 23,421/ha), respectively and also recorded maximum B: C ratio (1.56).

Tillage and weed control effect on weeds and wheat productivity

A 3-year study was conducted to assess the impact of tillage and weed control practices on weed flora and wheat productivity. Experiments were conducted during Rabi season of 2012–13 to 2014–15 at GBPUA&T, Pantnagar, with clayloam soil. There were five crop establishment methods, viz. Transplanted rice (conventional tillage) (TPR)- wheat (conventional tillage) (CTW) (TPR-CTW), Transplanted rice (conventional tillage)- wheat (zero tillage)-Sesbania green manuring (S) (TPR-ZTW-S), Direct-seeded rice (conventional tillage)-wheat (conventional tillage)-Sesbania incorporation (S) (DSR-CTW-S), Directseeded rice (zero tillage)-wheat (zero tillage)-Sesbania brown manuring (S) (ZTR-ZTW-S) and Direct-seeded rice (zero tillage) + residue retention-wheat (zero tillage) + residue retention-Sesbania brown manuring (S) (ZTR + R-ZTW+R-ZTS) and three weed control methods [(weedy check, recommended herbicide (Recommended ready-mix herbicide clodinafop 15% + MSM 1% (60 + 4 g/ha) and integrated weed management i.e., clodinafop 15% + MSM 1% 60 + 4 g/ha fb manual weeding at 45 days after seeding (DAS)]. Continuous zero-till cropping system along with residue retention and brown manuring of Sesbania has resulted in the lowest total weed biomass at 60 DAS and greatly reduced the density of Phalaris minor, Medicago denticulata, Polygonum plebeium and Coronopusdidymus. However, density of C. didymus, Rumex acetosella and Vicia sativa was reduced under conventionally tilled wheat. Ready mix application of clodinafop 15% + MSM 1% supplemented with one hand weeding at 45 DAS greatly reduced the density and biomass of weeds. The maximum wheat grain (4.5 t/ha) and straw (6.3 t/ha) yields was achieved under zero-tilled wheat with rice residue retention and Sesbania as brown manure. The integration of clodinafop 15% + MSM 1% with 1 HW at 45 DAS resulted in an increase in grain and straw yields by 45.5% and 30.8%, respectively, over weedy check. It may inferred that in wheat cultivation conventional tillage could be replaced with zero-tillage along with residue retention by growing of Sesbania and the application of 2,4-D at 30 days stage to attain sustainability of ricewheat cropping system.

Variety and weed management effects on organic chickpea stand establishment and seed yield

AbstractThe need for organic produce is increasing worldwide but weed control remains a critical problem for organic crop production. Three types of weed control practices were evaluated for two organic chickpea (Cicer arietinum L.) varieties at the Western (Corvallis) and Eastern (Sidney) Agricultural Research Centers of Montana State University. Treatments included two chickpea varieties (Black and CDC Orion chickpeas), two seeding rates (standard seeding rate or 1× at 43 seeds m−2 and 50% increase over the standard rate or 1.5×), and two pre‐emergent weed control practices (flame weeding and shallow tillage). Results revealed that Black chickpea was associated with greater stand densities and grain yield with lower weed biomass than CDC Orion. Increasing seeding rate for Black chickpea improved crop density and increased grain yield to the extent of 26% compared with the standard seed rate. Flaming increased chickpea grain yield only at Corvallis in 2016. The combined effects of shallow tillage and increased seeding rates resulted in reduced weed biomass. Shallow tillage can be successfully integrated to improve yields and reduce weed pressure in organic chickpea. However, precaution must be taken for the tillage timing to avoid damage to emerging chickpea seedlings. More research is needed to select chickpea varieties that have improved vigor and are more competitive to weed pressure commonly seen in organically managed fields.

On-Farm Evaluation of Conservation Agriculture Practice on Weed Control and Yield of Wheat in Northern Bangladesh

On account of rural labour shortages, smallholder farms in South Asia are seeking labour saving strategies for planting and weed control. To overcome this challenge, conservation agriculture practices involving mechanized planting and crop residue retention together with the application of herbicides are being developed. But their effectiveness for weed control is still uncertain. The present study was undertaken to determine the effectiveness of residue retention relative to herbicides and hand weeding for weed control and yield of wheat in strip planted soil in northern Bangladesh. The on-farm experiment was conducted during November-March in 2014-2016, with wheat cv. BARI Wheat 26 grown after monsoon rice under two tillage types combined with the six weed control practices [P1: conventional tillage (CT)+three hand weedings (HW) (Control), P2: Glyphosate (Gly)+strip planting (SP)+one HW, P3: Gly+SP+pre-emergence (PE) herbicide, P4: Gly+SP+post-emergence (PO) herbicide, P5: Gly+SP+PE+PO, P6: Gly+SP+weed-free (WF); and two levels of rice residue retention, R0: no-residue and R50: 50% residue (by height). The CT consisted of two primary tillage operations by a two-wheel tractor, anwhiled SP had done by a Versatile Multi-crop Planter in a single-pass process. A pre-plant herbicide (glyphosate), a PE herbicide (pendimethalin) and PO herbicide (carfentrazon-ethyl) was applied at recommended doses. The combination of applied glyphosate, SP, followed by sequential application of PE and PO herbicides and the retention of 50% of rice straw achieved the highest weed control efficacy. Furthermore, this practice produced the 24% higher yield and 40% higher economic returns relative to control without exerting any phyto-toxicity in wheat.

Impact of weed control practices on weed suppression and crop performance in boro rice

Impact of weed control practices on weed suppression and crop performance in boro rice

Comparative Efficacy of Weed Control Practices for Parthenium Weed and Sunflower Crop under Varying Tillage Systems

Comparative Efficacy of Weed Control Practices for Parthenium Weed and Sunflower Crop under Varying Tillage Systems

Integrating machine vision-based row guidance with GPS and compass-based routing to achieve autonomous navigation for a rice field weeding robot

Autonomous weeding robots are a productive and more sustainable solution over traditional, labor-intensive weed control practices such as chemical weeding that are harmful to the environment when used excessively. To achieve a fully autonomous weed control operation, the robots need to be precisely guided through the crop rows without damaging rice plants and they should be able to detect the end of the crop row and make turns to change rows. This research attempted to integrate GNSS, compass and machine vision into a rice field weeding robot to achieve fully autonomous navigation for the weeding operation. A novel crop row detection algorithm was developed to extract the four immediate rows spanned by a camera mounted at the front of the robot. The extracted rows were used to determine a guide-line that was used to precisely maneuver the robot along the crop rows with an accuracy of less than a hundred millimeters in variable circumstances such as weed intensity, growth stage of plants and weather conditions. The GNSS and compass were used for locating the robot within the field. A state-based control system was implemented to integrate the GNSS, compass and vision guidance to efficiently navigate the weeding robot through a pre-determined route that covers the entire field without damaging rice plants. The proposed system was experimentally determined to deliver good performance in low weed concentrations with an accuracy of less than 2.5° in heading compensation and an average deviation from the ideal path of 45.9 mm. Though this accuracy dropped when the weed concentration increased, the system was still able to navigate the robot without inflicting any serious damage to the plants.

Elicitation of the Allelopathic Potential of Rice by Methyl Salicylate Treatment

Weed infestation is one of the most severe problems affecting rice production worldwide. Current weed control practices are either costly or pose a threat to the environment. The use of competitive rice genotypes seems to be a promising strategy. The aim of our study was to improve the allelopathic potential of three selected rice genotypes by foliar application of methyl salicylate (MeSA), a signaling molecule eliciting the plant defense response. Aqueous extracts of the shoots and roots of two competitive (UPR 2962-6-2-1 and Govind) and one non-competitive (UPR 2992-17-3-1) rice genotypes treated with MeSA solution at different concentrations (1 mM, 2 mM, and 3 mM) showed phytotoxic effects on the growth of the weed Echinochloa colona. Specifically, shoot and root extracts obtained from the competitive rice genotypes similarly decreased both the E. colona germination rate (9% to 44.5%) and the length of its roots and shoots (11% to 48%). Extracts of the non-competitive rice genotype showed a similar trend but lower effects, inhibiting the E. colona germination up to 32% and reducing the growth of the weed roots and shoots by 6–23.5% and 7–28%, respectively, according to the increasing MeSA concentrations. High-performance liquid chromatography (HPLC) analysis demonstrated an increase in different allelopathic phenolic acids in the three rice genotypes in response to MeSA treatments. Among the detected compounds, vanillic and protocatechuic acids showed the greatest differences compared to controls with values up to 2.1-fold higher in shoots of the two competitive UPR-2962-6-2-1 and Govind rice genotypes, while their roots were characterized by the greatest increases of 8-hydroxyquinoline (8.2-fold) and protocatechuic acid (1.7-fold). Differently, non-competitive genotype UPR 2992-17-3-1 showed the highest increase for gallic acid (2.2-fold) in shoots and for p-hydroxybenzoic acid (2.4-fold) in roots. Lastly, MeSA was found to improve the competitiveness of rice genotypes without any detrimental effect on the host plant.

Junglerice (Echinochloa colona) and feather fingergrass (Chloris virgata) seed production and retention at sorghum maturity

AbstractIn Australia, junglerice and feather fingergrass are problematic weeds in sorghum. The high seed production potential of these weeds increases their seedbank in the soil and makes weed control practices more difficult and expensive, particularly when weeds have evolved resistance to herbicides. A study was conducted to evaluate the seed production and seed retention behavior of junglerice and feather fingergrass at sorghum crop maturity following four transplanting times: 0, 2, 4, and 6 wk after sorghum emergence. Averaged across years, junglerice and feather fingergrass produced 4,060 and 5,740 seeds plant-1, respectively,when they were transplanted with the emergence of a sorghum crop. Seed retention ranged from 42% to 56% for junglerice and 67% to 75% for feather fingergrass when these weeds were transplanted from 0 to 4 wk after crop emergence. A positive correlation (r = 0.75 for junglerice; r = 0.44 for feather fingergrass) was found between seed production and weed biomass in both weeds, indicating that larger plants produced more seeds than smaller plants. However, no correlation was found between weed biomass and seed retention for junglerice. A weak positive correlation (r = 0.44) was found between feather fingergrass biomass and percent seed retention, indicating that seed retention was greater in larger plants compared with smaller plants. Our results suggest that feather fingergrass is a good candidate for harvest weed seed control (HWSC) tactics if crop harvest is timely. There is limited opportunity to use HWSC tactics for targeting junglerice seeds in sorghum crops, because most seeds dispersed before crop maturity. Additional research is required to evaluate seed retention levels of these weeds in other summer crops such as corn and soybean to determine the potential for HWSC for management of these species.

Herbisit dayanıklılığını anlamak: Domates ve patatesteki AHAS (asetohidroksiasit sentetaz) genlerinin biyoinformatik analizleri

The identification of enzymes’ mutable sites is important to the development of herbicide resistant crops and for weed control practices. The objective of this study was to provide insights into mutable residues causing resistance to the acetohydroxyacid synthase enzyme (AHAS, EC 2.2.1.6) inhibitor herbicides in the tomato (SlAHAS) and potato (StAHAS) through bioinformatics approaches. The results showed AHAS proteins investigated in this study were highly conserved but differed in length. Mutation analyses showed that Lys541 and Val542 in SlAHAS were mutable sites for preservation of the enzyme activity. While Ala, Phe, Arg, and Val residues were found to be substitutable with Lys541, Ile was exchangeable for Val542. Similarly, Ile124, Met266, and Leu272 in StAHAS were identified as protein stabilizing residues. In this respect, Lys and Arg were substitutable residues for Ile124, whereas Leu was for Met266 and Ala, Pro and Ser were suitable residues for Leu272 regarding enzyme stabilization. The docking analyses displayed that the best binding affinities were obtained for Ser387, Arg235, and His341 for chlorosulfuron (CS) and Phe11, Ala40, and His341 have the highest binding score for imazaquin (IQ) in SlAHAS. As for StAHAS, Lys232, Asn123, and Arg53 residues were found to bind with CS whereas Lys405, Lys489, and Arg268 amino acids were identified as sites where IQ bound. His341 and Gln478 were binding residues for both CS and IQ in SlAHAS whereas both ligands were found to bind with Val61 and Arg366 in StAHAS. Arg366 was identified as a binding site in SlAHAS for IQ as well.

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Herbicide mixture is a widely used weed control practice in many agricultural areas. However, interactions between the herbicide mixture and soil may alter the soil dynamics. This research evaluated the effect of the physicochemical properties of the soils in the application of diuron alone and in a mixture with hexazinone, by means of sorption-desorption Freundlich isotherms. 14C-diuron sorption (isolated and mixed) was evaluated by batch equilibration at five concentrations of diuron (0.14, 0.16, 0.19, 0.26 and 0.39 μg mL-1) and hexazinone (0.03, 0.06, 0.13, 0.19 and 0.26 μg mL-1), corresponding to the recommended field dose (D) of D/4, D/2, D, 2×D and 4×D, respectively, in five soils cultivated with sugarcane. The sorption of the diuron applied separately and in mixture presented Freundlich sorption coefficient (Kf) values in the range of 1.47 to 5.08 and 0.59 to 3.77 µmol(1-1/n) L1/n kg-1, respectively. The lowest desorption values were found for Clay-1 soil (72.5% clay), with 6.01 and 5.87% for diuron isolated and blended, respectively. Diuron sorption was slightly higher when applied alone rather than in the herbicide mixture, and this sorption correlated positively with the clay content of the soils, regardless of the application form. The disponibility of diuron improved in mixture of hexazinone in soil, which can increase its absorption and control efficiency; on the other hand, the transport of herbicide can rise. Future researches about the transport, runoff or leaching are required for complete information of the behavior of this mixture of herbicides in soil. Key words: Retention process, sorption kinetics, hysteresis, commercial mixture.

Studies on integrated weed management practices in maize-A review

Worldwide yield losses in maize due to weeds are estimated to be around 37%. Weeds reduce crop yield by competing for light, water, nutrients and CO2, interfere with harvesting and increase the cost of cultivation. The predominant weed flora were Echinochloa crusgalli L. and Cynodon dactylon L. among monocots; Cyperus rotundus L. among sedges; and Amaranthus viridis L., Digera arvensis L., Portulaca oleracea L., Alternenthara sessili L. and Trianthema spp. among dicots in India. The infestation of these weeds is increasing day by day in the maize growing belt of the state especially where the farmers are using atrazine year after year. New herbicides with broad spectrum of weed control are highly essential for effective control of grasses, sedges and broad leaved weeds. So, in order to widen the weed control spectrum, it is desirable to use tank mix combinations of two herbicides having different mode of action and integrated weed management practices for better weed control.

Inefficiency of manual weeding in rainfed rice systems affected by parasitic weeds

AbstractManual weeding is the predominant weed control practice and the most labor‐consuming activity in smallholder, rainfed rice systems in sub‐Saharan Africa. This study investigates the technical inefficiency of weeding labor, other labor, and overall inputs, and identifies sources of technical inefficiency of weeding labor in the context of parasitic weed infestation. The analysis applies a two‐stage approach. First, a directional input distance function DEA approach was used to compute input‐specific technical inefficiencies. Second, sources of technical inefficiency of weeding labor were identified using a truncated bootstrap regression. Data from 406 randomly selected smallholder farmers from Benin (n = 215) and Côte d'Ivoire (n = 191) were used. The technical inefficiency of weeding labor was high in both countries (58% in Côte d'Ivoire and 69% in Benin). This implies that a substantial fraction of weeding labor could be saved without reducing rice productivity or increasing the use of other inputs. A decrease in the technical inefficiency of weeding labor with an increase in production scale was observed. In addition, weeding regime and education level were each associated to significant changes in the technical inefficiency of weeding labor.

Available plant nutrients in soil as influenced by planting methods and herbicidal treatments

Abstract Rice (Oryza sativa L.)-wheat (Triticum aestivum L.) is the predominant cropping system of North Indian region. Due to continuous following of rice-wheat cropping system every year, weed infestation particularly in wheat, has emerged a major problem resulting in reduced wheat yield and nutrient mining. Integration of suitable planting methods, along with effective weed control measures, can reduce the weed infestation and nutrient mining from the soil and can enhance available plant nutrients in the soil. To evaluate the influence of different planting techniques and weed control practices in wheat on available plant nutrients in soil, a field study was conducted at the department of Agronomy, Punjab Agricultural University, Ludhiana (India) for two consecutive years. The treatments comprised of five planting techniques: conventional tillage, zero till sowing without rice stubbles, zero till sowing in standing rice stubbles , zero till sowing after partial burning of rice stubbles and bed planting and five weed control treatments i.e. clodinafop 60 g/ha, clodinafop 60 g/ha fb 2, 4-D 0.5 kg/ha, sulfosulfuron 25 g/ha, mesosulfuron + iodosulfuron 12 g/ha and unweeded (control). The experiment was conducted in split plot design with planting methods in the main plot and herbicidal treatments in the sub plot with three replications. The results of the study showed that zero till sowing of wheat in standing rice stubbles observed significantly higher soil organic carbon, available nitrogen, phosphorus and potassium than conventional till wheat sowing after removal of rice residues. Although partial burning of rice stubbles also showed positive trend in soil organic carbon, available nitrogen, phosphorus and potassium but retort was less distinct than rice stubbles without burning. Further, zero tillage alone also showed improvement in soil organic carbon and available nitrogen, phosphorus and potassium over conventional tillage. Application of herbicides did not diverge soil organic carbon, but significantly improved the available nitrogen, phosphorus and potassium content in soil than the unweeded (control).

Weed management effect to increase grain yield in dry direct-seeded rice

An experiment was conducted during Kharif 2016 and 2017 at Agricultural Research Station, Dhadesugur, University of Agricultural Sciences, Raichur, Karnataka, India, to study the bio-efficacy of weed control practices on weeds and grain yield of dry-seeded rice. The dominant grassy weeds in fields were Echinochloa sp. Panicum repens, Cynodon dactylon, Bracharia mutica, Digitarias sanguinalis, Commelina communis and Leptochloa chinensis. Broad-leaf weeds were Eclipta alba, and Ludwigia parviflora and Cyperus sp. as sedge. Results revealed that, pre-emergence application of pretilachlor + pyrazosulfuron-ethyl (600 + 15 g/ha) recorded significantly lower weed dry weight at 15, 30 and 45 DAS during Kharif 2016 and 2017, higher weed control efficiency at 15, 30 and 45 days after sowing (DAS) (82.6, 80.2 and 80.6% during Kharif 2016 and 82.1, 82.7 and 80.2%, respectively during Kharif 2017, respectively) and higher rice grain yield (4.92 and 4.98 t/ha during Kharif 2016 and 2017, respectively) and which was at a par with twice hand weeding at 20 and 40 DAS.

Winter weeds and its control in the medicinal plants in Egypt: a survey study

Weed control is the main obstacle in the production of medicinal plants, especially in organic farming where the growers cannot use synthetic herbicides. For understanding the impact of weeds on the productivity of medicinal plants, the common weeds and weed control practices of more than 20 cultivated medicinal plants were evaluated in eight regions in Egypt with several of climatic conditions and soil types. All tested farms that have applied the organic farming systems and their products are mainly for export. The large-scale weed surveys have shown that the most problematic weed species in medicinal plant crops is Senecio desfontainei because it is content of pyrrolizidine alkaloid plants. The dominant weeds associated with the medicinal plant fields were Malva parviflora (16.8%), Chenopodium album (12.4%), Medicago intertexta (8.8%), Anagallis arvensis (8.8%), Sonchus oleraceus (6.2%), Beta vulgaris (5.3%) Brassica kaber (5.3%), Cichorium pumilum (3.5%), Melilotus indica (3.5%), Euphorbia geniculata (3.5%), S. desfontainei (1.8%), Emex spinosus (0.9), Solanium nigrum (0.9%), and Conyza linifolia (0.9%). The narrow-leaf weeds are Lolium multiflorum (7.1%), Avena fatua (6.2%), Phalaris minor (2.7%), and Polypogon monspeliensis (1.0%). The perennial broad-leaf and narrow-leaf weeds were Convolvulus arvensis (3.5%) and Cyperus rotundus (0.9%). The results of the survey indicated that the crop type and location had a significant effect on weed species and their frequencies and abundances. The common practice for weed control in the medicinal plants is hand weeding, mulch, acetic acid, presowing false irrigation, and mechanical weeding (in limited area). The efforts must be taken regarding search for safe, new, and nontraditional weed control methods to apply in the medicinal plant fields.