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Jabran, Khawar/0000-0001-8512-3330; Mahajan, Gulshan/0000-0002-9423-9893; Chauhan, Bhagirath/0000-0003-1540-4668 WOS: 000397372500001 Weeds represent a significant challenge to successful crop production. Highly effective and sustainable weed control is required in order to meet global food demand. In this context, excessive use of herbicides has resulted in serious environmental and ecological issues. There are several weed control options which neither harm the environment nor require a significant increase in cost of production. Improving crop competition is particularly important and attractive among such options, which can be achieved by using crop cultivars possessing a competitive advantage over weeds, and manipulating the seed rate and direction of crop rows. Crop cultivars possessing traits such as fast germination, quick growth, high biomass, and large leaf area have a competitive advantage over weeds. Sowing such cultivars has been shown to suppress weeds in various crops. The use of high seed rates and narrow row spacing, if properly manipulated, can cause a significant decrease in weed proliferation in the crops. These techniques (cultivar, seed rate, row spacing, and row direction) are under-exploited as weed control methods, and offer considerable potential for achieving environmentally benign weed management. This special issue on "Eco-friendly Weed Management" will address the role of crop competition in managing weeds in different crops as well as in different countries. (C) 2016 Elsevier Ltd. All rights reserved.

This review provides an overview on the most common rice weed species of the world. It shows that a few generalists have established in rice independent from sites, crop management systems, and local climatic conditions. Cosmopolitan weeds are even constant elements where rice cultivation started just a century ago. Local differences may be explained by cultivation methods, growing seasons, or special weed management. Some general changes in weed spectra have been observed globally in recent years. Weedy rice ( Oryza sativa L.) and herbicide resistance have become general global problems within the last decades. Some global key weed genera such as Echinochloa , Cyperus , Scirpus , or Fimbristylis species are, however, still dominating rice fields despite the decade long use of well performing herbicides. On the other side, general species shifts as a result of resistance have not been observed yet. Leptochloa species started to become major problems in Asia in the end of the last century and now in Europe also. Several modern herbicides allow the control of perennial weeds, such as Cyperus rotundus L. or Eleocharis kuroguwai Ohwi which makes them no longer serious threats. Some genera in rice such as Echinochloa and Oryza (weedy rice) are characterized by an enormous germplasm variability which makes species definitions difficult. The fact that weeds in rice have to adapt to wet or aquatic conditions reduces the biodiversity range in comparison to other arable crops. Water management has a considerable impact on weed spectra. The increase of rice acreages with reduced irrigation may end up in higher weed infestations. Long term results of weed surveys in rice as they exist for other crops are, however, not available. This makes predictions on biodiversity changes in this crop quite difficult.

Wheat (Triticum aestivum L.) production is vital to global food security. Climate change is threatening sustainable wheat production not only with direct negative effects on crop growth but also with a profound impact on pest biology and management. This review presents a critical analysis of the impact of key climate change elements, including drought, high temperature and increased atmospheric carbon dioxide levels on biology, ecology and behaviour of wheat pests. Climate change is expected to favour the growth, virulence, multiplication, persistence and range expansion of most serious wheat pests. Rapid climatic changes are opening new geographic windows for disease outbreaks, insect attacks and weed infestations in wheat crops across the globe. Wheat–pest interactions are also favourable for pests in most cases where one or more climate change elements come into play. Existing pest management options are not successful under these circumstances. Climate change has a direct negative effect on the efficacy of existing control options, which increases pest virulence and their competitive ability, pest resistance to pesticides and pest–environment interactions, leading to inadequate pest control and substantial crop yield losses. Integrated pest management approaches, based on innovative and traditional pest control strategies, may be more appropriate in the changing climate. Proactive measures, including early detection and eradication by frequent pest-scouting, preventive control, and forecasting of potential outbreaks or new introductions by predictive modelling, could help in this regard. A better understanding of the changing pest biology, interactions and management strategies presented here is inevitable for successful pest management and sustainable wheat production under the changing climate.

In many parts of the world, sawdust is a common wood industrial waste that is either wasted or used as fuel. Sawdust has low weight, good drainage and is inexpensive. This study assesses the potential of wood sawdust to be used as a viable substrate for soilless garlic production. In two experiments, garlic (Allium sativum) was grown in plastic bags containing six different types of sawdust substrates made of Azadirachta indica (neem), Mangifera indica (mango), Morus alba (mulberry), Acacia nilotica (gum arabic), Eucalyptus albens (eucalyptus), Bombax ceiba (cotton tree) and in clay loam soil (control). We found that A. nilotica and M. alba sawdust significantly decreased the leaves number, plant height, leaf area, relative water content, bulb diameter, number of cloves bulb−1, shoot dry weight and bulb dry weight of garlic. Moreover, the use of these two substrates apparently increased the number of days to seed clove emergence and the chlorophyll content index of garlic. However, A. indica sawdust did not affect the number of days to seed clove emergence, number of leaves plant−1, plant height, leaf area, relative water content, bulb diameter, number of cloves bulb−1, shoot dry weight and bulb dry weight. Therefore, A. indica sawdust may have potential to be used as a cheap alternative substrate to garlic soilless cultivation.

Weed management is one of the most important aspects in successful crop production, and with the passage of time, ecological and biological aspects are becoming more significant. Echinochloa crus-galli (L.) Beauv. is among the most noxious weeds in the world due to its superior biology and tremendous ecological adaptations. It causes substantial yield losses in different field crops, especially rice. It is widespread in different countries, infesting numerous cropping systems due to its invasive nature. It has a strong allelopathic potential, which aids resource competition to exert notable yield losses. Herbicide resistance evolution in E. crus-galli is a serious threat to agricultural productivity. This review covers all the aspects on the interface of ecology and biology of E. crus-galli in order to generate useful information for better understanding of the weed behavior. Management scenario of E. crus-galli is also presented with reference to its eco-biological interference. Some cultural strategies like preventive measures, hand weeding, irrigation management, the use of competitive cultivars, and mechanical control are still trustworthy but in integration with other means. Although little research has been done on biological control, it may be helpful under sustainable systems. The use of allelopathy for the management of E. crus-galli is another encouraging domain. Herbicides are inevitable but they must be used in rotations and combinations along with other non-chemical tools to avoid the expansion of herbicide resistance. This review provokes an insight about understanding E. crus-galli biology for better management. This weed is noxious in terms of productivity and profit losses and it should be managed through integrated approaches, keeping in view its interference, ecological procession, biological mechanisms, and evolution.

Weeds are a hidden foe for crop plants, interfering with their functions and suppressing their growth and development. Yield losses of ∼34% are caused by weeds among the major crops, which are grown worldwide. These yield losses are higher than the losses caused by other pests in the crops. Sustainable weed management is needed in the wake of a huge decline in crop outputs due to weed pressure. A diversity in weed management tools ensures sustainable weed control and reduces chances of herbicide resistance development in weeds. Allelopathy as a tool, can be importantly used to combat the challenges of environmental pollution and herbicide resistance development. This review article provides a recent update regarding the practical application of allelopathy for weed control in agricultural systems. Several studies elaborate on the significance of allelopathy for weed management. Rye, sorghum, rice, sunflower, rape seed, and wheat have been documented as important allelopathic crops. These crops express their allelopathic potential by releasing allelochemicals which not only suppress weeds, but also promote underground microbial activities. Crop cultivars with allelopathic potentials can be grown to suppress weeds under field conditions. Further, several types of allelopathic plants can be intercropped with other crops to smother weeds. The use of allelopathic cover crops and mulches can reduce weed pressure in field crops. Rotating a routine crop with an allelopathic crop for one season is another method of allelopathic weed control. Importantly, plant breeding can be explored to improve the allelopathic potential of crop cultivars. In conclusion, allelopathy can be utilized for suppressing weeds in field crops. Allelopathy has a pertinent significance for ecological, sustainable, and integrated weed management systems.

Weed management is the major challenge to the success of dry-seeded rice (DSR). A field study was conducted during the dry seasons of 2013 and 2014at the International Rice Research Institute to evaluate the performance of herbicides combined with mechanical weeding in DSR. The lowest weed density and biomass were found in the treatment oxadiazon followed by (fb) fenoxaprop+ethoxysulfuron fb 2,4-D fb mechanical weeding (MW) at 42 days after sowing (DAS). However, this treatment had similar weed density and biomass to the treatments oxadiazon fb bispyribac-sodium fb fenoxaprop+ethoxysulfuron fb 2,4-D,oxadiazon fb bispyribac-sodium fb 2,4-D, and oxadiazon fb MW (28 DAS) fb MW (42 DAS). The highest weed density and biomass were recorded in the treatment oxadiazon fb MW (28 DAS) and oxadiazon fb 2,4-D. Higher grain yield (5.3-5.8tha-1) was produced in the plots that received oxadiazon fb fenoxaprop+ethoxysulfuron fb 2,4-D fb MW(42 DAS) and oxadiazon fb bispyribac-sodium fb fenoxaprop+ethoxysulfuron fb 2,4-D. The results of this study provide sustainable weed management options to farmers growing DSR.

Crop yield potential with conservation agriculture (CA) in rainfed systems is often greater than with conventional tillage (CVT) systems, particularly where sub-optimal rainfall limits yield. However, the full potential is rarely achieved because of various biotic and abiotic constraints. Analysis of 25 experiments found a slight increase in CA crop yields over time relative to CVT, indicating that CA can compete with CVT on a purely crop production basis and also has well-established environmental benefits. Evolved weed resistance to herbicides remains one of the greatest challenges to CA yields and long-term sustainability, yet there are some successful management stories. Worldwide adoption of CA is increasing; however, uptake in some regions is slow or non-existent. A lack of information on the effects and interactions of minimal soil disturbance, permanent residue cover, planned crop rotations and integrated weed management, which are key CA components, can hinder its adoption. This is because these interactions can have positive and negative effects depending on regional conditions. The positive impacts should be exploited through systems research to enhance CA crop yields. A greater focus on the influence of residue and weed management components as well as breeding for varieties adapted to biotic and abiotic stresses often associated with CA is required.