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Weed infestation is one of the most damaging biotic factors to limit crop production by competing with the crop for space, water, and nutrients. Different conventional approaches are being used to cope with weed infestation, including labor intensive manual removal and the use of soil-degrading, crop-damaging, and environment-deteriorating chemical herbicides. The use of chemicals for weed control has increased 2-fold after the green revolution and their non-judicious use is posing serious threats to mankind, animals, and biodiversity. The detrimental effects of these approaches have shifted the researchers' attention from the last two decades towards alternate, sustainable, and eco-friendly approaches to cope with weed infestation. The recent approaches of weed control, including plant and microbial allelopathy have gained popularity during last decade. Farmers still use conventional methods, but the majority of farmers are very passionate about organic agriculture and describe it as a slogan in the developed world. The effectiveness of these approaches lies in host specificity by selective bacteria and differential response towards weeds and crops. Moreover, the crop growth promoting effect of microorganisms (allelopathic bacteria) possessing various growth promoting traits, that is, mineral solubilization, phytohormone production, and beneficial enzymatic activity, provide additional benefits. The significance of this review lies in the provision of a comprehensive comparison of the conventional approaches along with their potential limitations with advanced/biological weed control approaches in sustainable production. In addition, the knowledge imparted about weed control will contribute to a better understanding of biological control methods. [ABSTRACT FROM AUTHOR]

Aromatic and medicinal plants release volatile allelochemicals which influence the organisms in their environment. A pot culture experiment was conducted to determine the phytotoxic activity of essential oil emulsions (EOEs) of Mentha piperita L., Chrysopogon zizanioides L., Mentha arvensis L. and Pelargonium graveolens L. with two herbicides (clodinafof-propargyl 15 % WP and sulfo sulfuran 75 % WG) on growth and physiological parameters of Avena fatua L. (wild oat) and on soil enzyme activities. Post-emergence application of EOEs and chemical herbicide were applied on 5-week old A. fatua plants. We found that several EOEs with varying concentrations and chemical herbicides reduced (p ≤ 0.05) the A. fatua plant growth (shoot length, root length, fresh and dry weight of plant), physiological parameters and also affected the post-harvest soil enzyme activities and soil microbial biomass carbon (SMBC). Chlorophyll content was considerably decreased, but increased proline accumulation and electrolyte leakage in A. fatua plants indicating membrane rupture and loss of integrity. Since essential oils interfere with plant growth and physiological processes and have exceptional inhibitory effects on the A. fatua plant, the allelochemicals present in these donor plants may be used as active ingredients to develop natural herbicides. [ABSTRACT FROM AUTHOR]

Weeds are a permanent component of anthropogenic ecosystems. They require strict control to avoid the accumulation of their long-lasting seeds in the soil. With high crop infestation, many elements of crop production technologies (fertilization, productive varieties, growth stimulators, etc.) turn out to be practically meaningless due to high yield losses. Intensive use of chemical herbicides (CHs) has led to undesirable consequences: contamination of soil and wastewater, accumulation of their residues in the crop, and the emergence of CH-resistant populations of weeds. In this regard, the development of environmentally friendly CHs with new mechanisms of action is relevant. The natural phytotoxins of plant or microbial origin may be explored directly in herbicidal formulations (biorational CHs) or indirectly as scaffolds for nature-derived CHs. This review considers (1) the main current trends in the development of CHs that may be important for the enhancement of biorational herbicides; (2) the advances in the development and practical application of natural compounds for weed control; (3) the use of phytotoxins as prototypes of synthetic herbicides. Some modern approaches, such as computational methods of virtual screening and design of herbicidal molecules, development of modern formulations, and determination of molecular targets, are stressed as crucial to make the exploration of natural compounds more effective. [ABSTRACT FROM AUTHOR]

A field experiment was carried out to find out the effect of some chemical herbicides (Crash and U46), and Datura leaves extract (4 leaf age) on the companion weed of two barley cultivars (IPA 265 and IPA 99) and the yield and components of these two cultivars. The results showed the superiority of the two weed spraying (T1) and the extract (T2) treatments by giving the best results, as they recorded the lowest number of weeds after 30 days of spraying with 2.83 and 10.17 plants m-2. Besides, the highest control percentage was 96.11% and 86.27% for the two treatments, respectively, compared to the control treatment (T3; weedy), which gave the highest number of weeds after spraying 73.50 plants m-2, while the lowest control percentage of 0.00%. Moreover, T1 was superior by giving the best grain yield of 1.99 ton ha-1 and the highest weight of 1000 grains (48.88 g) as well as the highest number of grains per spike (43.57 grain spike-1). T1 exhibited a significant difference with T2, which recorded a lower yield of 1.34 ton ha-1 and weight of 1000 grains (46.78 g), as well as the number of grains (33.17 grain spike-1) and a number of spikes (313.3 spike per m2). In comparison, the control treatment (T3) recorded the lowest grain yield and the lowest weight of 1000 grains along with the lowest grain per spike, and the lowest number of spikes (1.00 ton ha-1) as well as 36.72 g, 25.60 grain spike-1 and 269.7 spikes m-2, respectively. The two cultivars called IPA 99 and IPA 265, recorded a control percentage of 64.07% and 57.52%, respectively. There was a significant interaction in specific traits understudy for the two factors of the study, so that, T1 and T2 were superior with cultivars IPA 265 and IPA 99 by giving the best interaction in reducing the number of weeds after 30 days of spraying plant m-2, coupled with the control percentage. Since, the cultivar IPA 99 and T1 achieved the lowest number of weeds, i.e., 2.33 plant m-2 and the best control percentage reached 96.79%. However, the cultivar IPA 265 and T1 achieved the best grain yield of 2.113 ton ha-1. It can be concluded from this that spraying barley weeds with Datura leaves extract eliminated the weed, gave good control percentages, and increased the yield of barley grains and their components, with results close to what was achieved by the addition of the two herbicides.

A field experiment was carried out to evaluate the efficiency of selected weed herbicides in controlling the growing weed with barley. The experiment was carried out using randomized complete block design, by split plots arrangement with three replicates. The results showed the superiority of the mixture of herbicides (U 46 1 L.ha-1) + (Axial 1.5 L.ha-1) (H1) by giving the best weed control, where this treatment reduced the number of weeds in the experiment to give 0.00 plant.m-2. It also gave the best control percentages by 100% that was reflected in giving the best grain yield of 1.57 ton.ha-1, whose results were close to the treatment of hand weeding. Besides, the variety Iba 265 achieved the best results compared to the other varieties used in the study, as it gave the highest grain yield of 1.82 ton.ha-1 compared to the control treatment which gave the lowest grain yield amounted to 0.98 ton.ha-1. [ABSTRACT FROM AUTHOR]

The study was undertaken to prime a strain of Lasiodiplodia pseudotheobromae (C1136) as a mycoherbicidal agent against Amaranthus hybridus L. (pigweed) utilizing various agricultural wastes for its production. The rate of mortality and dry weight reduction of the target weed was determined in both the greenhouse and field conditions. The mycoherbicidal efficacy of the highly virulent isolate (strain C1136) was established based on the influence of the dew period, temperature, and inoculum concentration as well as plant growth stages. A dew period of 72 h was observed to be the highest time period necessary to obtain 90.6% mortality rate while there was no death observed at 0- and 12-h dew period treatments, respectively. Maximum disease development and mortality rate was observed at 25 °C on the target weed. It was observed that the inoculum concentration at 4 × 106 CFU/ml had the highest dry weight reduction of 98.60% and mortality rate of 89.4%. Groundnut husks gave comparatively the best spore yield (9.8 × 107 CFU/g), and yam peels gave the least (1.1 × 107 CFU/g). Greenhouse and field trials showed that the strain C1136 had a strong antagonistic effect on the test weed. This study therefore confirms the suitability of the strain C1136 as a potentially effective bioherbicidal agent that is eco-friendly. Furthermore, the cheap strain's observed responses to the environmental parameters assessed in the study affirmed its sustainability and possibility as a permanent substitute for synthetic herbicides in agrosystems' practices for effective weed management. [ABSTRACT FROM AUTHOR]

A field experiment was carried out to find out the effect of some chemical herbicides (Crash and U46), and Datura leaves extract (4 leaf age) on the companion weed of two barley cultivars (IPA 265 and IPA 99) and the yield and components of these two cultivars. The results showed the superiority of the two weed spraying (T1) and the extract (T2) treatments by giving the best results, as they recorded the lowest number of weeds after 30 days of spraying with 2.83 and 10.17 plants m-2. Besides, the highest control percentage was 96.11% and 86.27% for the two treatments, respectively, compared to the control treatment (T3; weedy), which gave the highest number of weeds after spraying 73.50 plants m-2, while the lowest control percentage of 0.00%. Moreover, T1 was superior by giving the best grain yield of 1.99 ton ha-1 and the highest weight of 1000 grains (48.88 g) as well as the highest number of grains per spike (43.57 grain spike-1). T1 exhibited a significant difference with T2, which recorded a lower yield of 1.34 ton ha-1 and weight of 1000 grains (46.78 g), as well as the number of grains (33.17 grain spike-1) and a number of spikes (313.3 spike per m²). In comparison, the control treatment (T3) recorded the lowest grain yield and the lowest weight of 1000 grains along with the lowest grain per spike, and the lowest number of spikes (1.00 ton ha-1) as well as 36.72 g, 25.60 grain spike-1 and 269.7 spikes m-2, respectively. The two cultivars called IPA 99 and IPA 265, recorded a control percentage of 64.07% and 57.52%, respectively. There was a significant interaction in specific traits understudy for the two factors of the study, so that, T1 and T2 were superior with cultivars IPA 265 and IPA 99 by giving the best interaction in reducing the number of weeds after 30 days of spraying plant m-2, coupled with the control percentage. Since, the cultivar IPA 99 and T1 achieved the lowest number of weeds, i.e., 2.33 plant m-2 and the best control percentage reached 96.79%. However, the cultivar IPA 265 and T1 achieved the best grain yield of 2.113 ton ha-1. It can be concluded from this that spraying barley weeds with Datura leaves extract eliminated the weed, gave good control percentages, and increased the yield of barley grains and their components, with results close to what was achieved by the addition of the two herbicides. [ABSTRACT FROM AUTHOR]

Weeds are a permanent component of anthropogenic ecosystems. They require strict control to avoid the accumulation of their long-lasting seeds in the soil. With high crop infestation, many elements of crop production technologies (fertilization, productive varieties, growth stimulators, etc.) turn out to be practically meaningless due to high yield losses. Intensive use of chemical herbicides (CHs) has led to undesirable consequences: contamination of soil and wastewater, accumulation of their residues in the crop, and the emergence of CH-resistant populations of weeds. In this regard, the development of environmentally friendly CHs with new mechanisms of action is relevant. The natural phytotoxins of plant or microbial origin may be explored directly in herbicidal formulations (biorational CHs) or indirectly as scaffolds for nature-derived CHs. This review considers (1) the main current trends in the development of CHs that may be important for the enhancement of biorational herbicides; (2) the advances in the development and practical application of natural compounds for weed control; (3) the use of phytotoxins as prototypes of synthetic herbicides. Some modern approaches, such as computational methods of virtual screening and design of herbicidal molecules, development of modern formulations, and determination of molecular targets, are stressed as crucial to make the exploration of natural compounds more effective.

The objective of this study was to control the Darnel weed Lolium temulentum, using the chemical herbicides Pallas, Atlantis and biological herbicides represented by organic solvent leaves extracts (ethyl alcohol, ethyl acetate and hexane) of the Clerodendrum inerme in several concentrations while the water spraying was considered as a control treatment. Some characteristics of vegetative growth were measured such as length of plant height, length of the root and number of branches, during different time periods 40 and 50 days from the time of the treatment. The results of the experiment showed the Atlantis herbicides superiority on the pallas as well as the rest of the factors at the highest concentration reached 16.80, 7.80 and 30.20 respectively of length of plant height, length of the root and number of branches compared with 72.6, 33.5 and 77.8 respectively in the control treatment after 50 days. [ABSTRACT FROM AUTHOR]

Mimosa bush (Vachellia farnesiana) is an invasive woody weed widely distributed in Australia. While it can be controlled using several mechanical and chemical techniques, this study evaluated a novel herbicide delivery mechanism that minimizes the risk of spray drift and potential non-target damage. This method, developed by Bioherbicides Australia, involves the implantation of encapsulated granular herbicides into the stem of intact plants or into the stump after cutting off plants close to ground level (cut stumps). Trials were implemented near Moree (New South Wales, Australia) on intact (two experimental runs) plants and cut stumped (two experimental runs) plants. For each trial, an untreated control plus the conventional basal bark application of a liquid formulation of triclopyr + picloram mixed with diesel was included for comparison. Encapsulated glyphosate, aminopyralid + metsulfuron-methyl, hexazinone and clopyralid were also tested in all trials. In addition, encapsulated triclopyr + picloram, and metsulfuron-methyl were included in one of the intact plant trials. Aminopyralid + metsulfuron-methyl was consistently most effective on cut stump and intact plants, whilst clopyralid provided highest mortality when applied to cut stumps and single-stemmed intact plants. Particularly for multi-stemmed intact plants, clopyralid should be applied to each stem. Overall, the highest efficacy was achieved on single stemmed plants, but with further refinement of the technique, it should be possible to achieve similar results for multi-stemmed individuals. This method resulted in a reduction in the use of herbicide and environmental contamination while significantly improving speed of treatment.

Olive groves represent an important economic, agro-ecological, and cultural resource in the Mediterranean Basin. Weed management plays a fundamental role in their sustainable management. The aim of this work was to characterize and assess the plant diversity associated with different weed control practices, in a homogeneous olive-dominated landscape in the South-East of Italy. Sixty-five vegetation plots were sampled in orchards treated with different weed control practices: mowing, tillage, and use of chemical herbicides. The multi-response permutation procedure was used to test the hypothesis of no difference among the treatments. The relationships between plots were visualized by means of non-metric multidimensional scaling ordination. A generalized linear mixed model was used to analyze the relationships between weed control practices and life forms, chorotypes, and diversity indexes. The results showed that the three weed control practices determined slightly different plant communities. Chemically weeded orchards showed an impoverished floristic composition and the lowest diversity, whereas mowing and tillage yielded similar values. These latter two treatments differed for the percentages of hemicryptophytes and therophytes. Moreover, different from other studies, we did not find plant species of particular concern for biodiversity conservation. We hypothesize that this result is due to the monotonous structure of the agro-landscape we investigated, where natural elements are almost lacking. From this point of view, a correct management of agro-districts should consider both the agronomic practices at the level of the individual olive groves and the structure of the agro-landscape.

Moldavian balm is an annual herbaceous plant and its lemon-scented leaves contain essential oil. However, weeds adversely affect its growth by release of allelochemicals, and/or direct competition for nutrient, moisture, light and space. Current experiment was conducted to evaluate the different weed control methods including preventive approach (soil pasteurization), mechanical methods (one hand weeding, two hand weeding, and successive hand weeding for weed free condition), and chemical control by synthetic herbicides (haloxyfop-R-methyl and trifluralin). Results revealed that stem diameter, quantity of secondary branches, flower-bearing branches and leaves were significantly affected by weed control treatments; the highest lateral growth was obtained by successive mechanical weed control and two hand weeding method, respectively. This trend was also observed in canopy spread and chlorophyll content. Pre-emergence control by trifluralin considerably accelerated the initiation of flowering in Moldavian balm. However, observation of qualitative traits showed that the highest essential oil content and oil yield was obtained when the plants grew in weed free soil which was pasteurized. Considering the recognized essential oils, the most responsive composition was including Geranial, Geranyl acetate, Neral and Geraniol. The lowest amount of Neral was recorded in postemergence control performed by means of haloxyfop-R-methyl herbicide.

Introduction. Weeds are an important factor in determining production in the agricultural sector. Currently, weeds have been managed by employing synthetic weedicides chemicals. These chemicals have a negative impact on the environment through accumulation in soil and water, in addition to their effect on biological diversity. Materials and method. A study was undertaken to evaluate the activity of the aqueous extract of leaves from; Nerium (Nerium oleander L), olives (Olea europaea L) and castor (Ricinus communis L) on the control of Cyperus rotundus L. The study comprised of two components: three plant species, and the uses of three planta extracts concentration (5%, 7.5% and 10%) and their impact on germination and inhibition of seedling growth. Results. The results from using Nerium extract in comparison with Tibenuron and the two other plants extracts gave 90% inhibition at concentrations of 5% and 10%, while the concentration of 2.5% gave the lowest inhibition rates for germination of all plant extracts under study. The second experiment carried out using 10% concentration of the Nerium extract gave complete inhibition (100%), compared with the same concentrations of other plants extract and weedicides. Conclusions. The current study indicates the possibility of using natural products of plant origin as alternatives to chemical herbicides as one of the means of biological control to reducing environment pollution. [ABSTRACT FROM AUTHOR]

A field experiment was conducted in maize during kharif season 2013 on sandy loam soil at Crop Research Centre, Chirori of Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut (U.P.), to evaluate the various integration of chemical Herbicides on weed management and yield of kharif maize (Zea mays L.). The experiment was conducted in R.B.D with three replications comprising eleven treatments of weed management (weedy, weed free, Alachlor @ 1500 and 1000 g a.i. ha-1, Atrazine @ 1000 g a.i. ha-1, Metribuzin @ 750 and 250 g a.i. ha-1, Alachlor + Metribuzin @ 750 + 375 g a.i. ha- 1, Atrazine + Pendimethalin @ 750 + 500 g a.i. ha-1, Atrazine +2, 4-D @ 500 + 500 g a.i. ha-1 and Sesbania (BC) @ 20 kg ha-1 + 2, 4-D @ 500 g a.i. ha-1). The results indicated that chemical methods of weed control significantly reduced the weed population and their dry weight effectively over weedy check. The maximum number of grains cob-1, weed control efficiency, nutrient uptake by crop and highest grain yield (49.3 q ha-1) were recorded with the application of Atrazine + Pendimethalin @ 750 + 500 g a.i. ha-1 and established its superiority over rest of the herbicides. Similarly, this treatment also resulted into higher gross return, net return and B: C ratio. These values were very close to weed free treatment. The per cent increase in grains and stover yield was to the tune of 107.14 and 57.26 as compared to weedy check. [ABSTRACT FROM AUTHOR]

Mimosa bush (Vachellia farnesiana) is an invasive woody weed widely distributed in Australia. While it can be controlled using several mechanical and chemical techniques, this study evaluated a novel herbicide delivery mechanism that minimizes the risk of spray drift and potential non-target damage. This method, developed by Bioherbicides Australia, involves the implantation of encapsulated granular herbicides into the stem of intact plants or into the stump after cutting off plants close to ground level (cut stumps). Trials were implemented near Moree (New South Wales, Australia) on intact (two experimental runs) plants and cut stumped (two experimental runs) plants. For each trial, an untreated control plus the conventional basal bark application of a liquid formulation of triclopyr + picloram mixed with diesel was included for comparison. Encapsulated glyphosate, aminopyralid + metsulfuron-methyl, hexazinone and clopyralid were also tested in all trials. In addition, encapsulated triclopyr + picloram, and metsulfuron-methyl were included in one of the intact plant trials. Aminopyralid + metsulfuron-methyl was consistently most effective on cut stump and intact plants, whilst clopyralid provided highest mortality when applied to cut stumps and single-stemmed intact plants. Particularly for multi-stemmed intact plants, clopyralid should be applied to each stem. Overall, the highest efficacy was achieved on single stemmed plants, but with further refinement of the technique, it should be possible to achieve similar results for multi-stemmed individuals. This method resulted in a reduction in the use of herbicide and environmental contamination while significantly improving speed of treatment. [ABSTRACT FROM AUTHOR]

Olive groves represent an important economic, agro-ecological, and cultural resource in the Mediterranean Basin. Weed management plays a fundamental role in their sustainable management. The aim of this work was to characterize and assess the plant diversity associated with different weed control practices, in a homogeneous olive-dominated landscape in the South-East of Italy. Sixty-five vegetation plots were sampled in orchards treated with different weed control practices: mowing, tillage, and use of chemical herbicides. The multi-response permutation procedure was used to test the hypothesis of no difference among the treatments. The relationships between plots were visualized by means of non-metric multidimensional scaling ordination. A generalized linear mixed model was used to analyze the relationships between weed control practices and life forms, chorotypes, and diversity indexes. The results showed that the three weed control practices determined slightly different plant communities. Chemically weeded orchards showed an impoverished floristic composition and the lowest diversity, whereas mowing and tillage yielded similar values. These latter two treatments differed for the percentages of hemicryptophytes and therophytes. Moreover, different from other studies, we did not find plant species of particular concern for biodiversity conservation. We hypothesize that this result is due to the monotonous structure of the agro-landscape we investigated, where natural elements are almost lacking. From this point of view, a correct management of agro-districts should consider both the agronomic practices at the level of the individual olive groves and the structure of the agro-landscape. [ABSTRACT FROM AUTHOR]