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Glyphosate-resistant Palmer amaranth has become a major problem for cotton producers throughout much of the southern United States. With cotton producers relying heavily on glyphosate-resistant cotton, an alternative solution to controlling resistant Palmer amaranth is needed. A field experiment was conducted during 2009 and 2010 at Marianna, AR, in which a rye cover crop and no cover crop were tested in combination with deep tillage with the use of a moldboard plow and no tillage to determine the impact on Palmer amaranth emergence in cotton. To establish a baseline population, 500,000 glyphosate-resistant Palmer amaranth seeds were placed in a 2-m2 area in the middle of each plot and incorporated into the soil, and emergence was evaluated five times during the season. In 2009, both tillage and the cover crop reduced Palmer amaranth emergence in cotton, but the combination of the two reduced emergence 85%. In the second year, only the cover crop reduced Palmer amaranth emergence in cotton, a 68% reduction. Cover crops and deep tillage will not eliminate glyphosate-resistant Palmer amaranth; however, use of these tools will likely reduce the risks of failures associated with residual herbicides along with selection pressure placed on both PRE- and POST-applied herbicides. Additional efforts should focus on the integration of the best cultural practices identified in this research with use of residual herbicides and greater focus on limiting Palmer amaranth seed production and reducing the soil seedbank. Nomenclature: Glyphosate; Palmer amaranth, Amaranthus palmeri S. Wats.; cotton, Gossypium hirsutum L. ‘Stoneville 4554 B2RF'; rye, Secale cereale L. ‘Wrens Abruzzi'. El Amaranthus palmeri resistente a glyphosate se ha convertido en un gran problema para los productores de algodón a lo largo del sur de los Estados Unidos. Al depender los productores de algodón, fuertemente de algodón resistente a glyphosate, se necesita una solución alternativa para controlar A. palmeri resistente. Se realizó un experimento de campo durante 2009 y 2010 en Marianna, AR, en el cual se evaluó el centeno como cultivo de cobertura y la ausencia de cultivo de cobertura en combinación con labranza profunda con el uso de arado de vertedera y cero labranza, para determinar el impacto en la emergencia de A. palmeri en el algodón. Para establecer una población base se pusieron 500 000 semillas de A. palmeri resistente a glyphosate en un área de 2 m−2 en el centro de cada parcela y se incorporaron al suelo, y la emergencia fue evaluada cinco veces durante la temporada de crecimiento. En 2009, ambos sistemas de labranza y el cultivo de cobertura redujeron la emergencia de A. palmeri en algodón, pero la combinación de ambos redujo la emergencia en 85%. En el segundo año, solamente el cultivo de cobertura redujo la emergencia de A. palmeri en el algodón, con una reducción de 68%. Los cultivos de cobertura y la labranza profunda no eliminarán A. palmeri resistente a glyphosate. Sin embargo, el uso de estas herramientas probablemente reducirá el riesgo asociado a fallas en el control con herbicidas residuales, además de la presión de selección asociada a herbicidas PRE y POST. Esfuerzos adicionales deberían enfocarse en la integración de las mejores prácticas culturales identificadas en esta investigación con el uso de herbicidas residuales y un mayor énfasis en limitar la producción de semilla de A. palmeri y así reducir el banco de semillas.

Weed management in the organic Vidalia® sweet onion production system is largely dependent on multiple cultivations with a tine weeder. Earlier research suggested cultivation with a tine weeder did not predispose onion bulbs to infection during storage. Trials were conducted from 2012 through 2014 near Lyons, GA, to determine the interactive effects of cultivation, weed removal, and a biofungicide on weed densities, onion yield, grade, and diseases of stored onion. Cultivation twice or four times at biweekly intervals with a tine weeder reduced densities of cutleaf evening-primrose, lesser swinecress, and henbit compared with the noncultivated control, although weeds surviving cultivation were very large and mature at harvest. Cultivation generally improved onion yields over the noncultivated control, except in 2014, when baseline weed densities were high and weeds surviving cultivation were numerous. Weeds removed by hand weeding improved onion yields, but that effect was independent of cultivation. Four applications of a biofungicide derived from giant knotweed had no effect on onion yield. Cultivation had no effect on incidence of the fungal disease botrytis neck rot, with inconsistent effects on the bacterial diseases center rot and sour skin. Weed removal with hand weeding did not affect diseases of stored onion. The biofungicide had no effect on diseases of stored onion. These results demonstrate the limitations of cultivation when cool-season weed infestations are dense. With no interactions among main effects, weed control and onion yield response to cultivation and hand weeding are independent. Cultivation for weed control is much less costly than hand weeding. With no interaction between the cultivation and weed removal main effects, it is not necessary to supplement tine weeder cultivation with costly hand weeding. Nomenclature: Cutleaf evening-primrose, Oenothera laciniata Hill; giant knotweed, Reynoutria sachalinensis (F. Schm.) Nakai; henbit, Lamium amplexicaule L; lesser swinecress, Coronopus didymus (L.) Sm.; dry-bulb onion, Allium cepa L.

Interrow cultivation is a selective, in-crop mechanical weed control tool that has the potential to control weeds later in the growing season with less crop damage compared with other incrop mechanical weed control tools. To our knowledge, no previous research has been conducted on the tolerance of narrow-row crops to interrow cultivation. The objective of this experiment was to determine the tolerance of field pea and lentil to interrow cultivation. Replicated field experiments were conducted in Saskatchewan, Canada, in 2014 and 2015. Weekly cultivation treatments began at the 4-node stage of each crop, continuing for 6 wk. Field pea and lentil yield linearly declined with later crop stages of cultivation. Cultivating multiple times throughout the growing season reduced yield by 15% to 30% in both crops. Minimal yield loss occurred when interrow cultivation was conducted once at early growth stages of field pea and lentil; however, yield loss increased with delayed and more frequent cultivation events. Nomenclature: Field pea; Pisum sativum L.; lentil; Lens culinaris L.

Current awareness about the environmental impact of intensive agriculture, mainly pesticides and herbicides, has driven the research community and the government institutions to program and develop new eco-friendly agronomic practices for pest control. In this scenario, integrated pest management and integrated weed management (IWM) have become mandatory. Weeds are commonly recognized as the most important biotic factor affecting crop production, especially in organic farming and low-input agriculture. In herbaceous field crops, comprising a wide diversity of plant species playing a significant economic importance, a compendium of the specific IWM systems is missing, that, on the contrary, have been developed for single species. The main goal of this review is to fill such gap by discussing the general principles and basic aspects of IWM to develop the most appropriate strategy for herbaceous field crops. In particular, a 4-step approach is proposed: (i) prevention, based on the management of the soil seedbank and the improvement of the crop competitiveness against weeds, (ii) weed mapping, aiming at knowing the biological and ecological characteristics of weeds present in the field, (iii) the decision-making process on the basis of the critical period of weed control and weed thresholds and iv) direct control (mechanical, physical, biological and chemical). Moreover, the last paragraph discusses and suggests possible integrations of allelopathic mechanisms in IWM systems.

Core Ideas Cover crops can effectively suppress weeds after termination and up to early stage of crop growth. Use of cover crops for early season weed suppression did not affect grain crop yield, but improved yield of vegetable crops. Use of a single cover crop species provided early weed suppression similar to that of cover crop species mixtures. There were differences in cover crop and main crop management among studies that evaluated cover crop for weed suppression. Cover crops are gaining importance as their use has numerous benefits including improved soil health, reduced soil erosion, and weed suppression. Weeds are most competitive with crops at early growth stages, and a management strategy that ensures early season weed suppression in crops is crucial for crop growth, development, and yield. In this study, systematic and meta‐analytic reviews of published studies from 1990 to January 2017 were conducted to provide evidence on whether using cover crops can provide satisfactory weed suppression at termination of the cover crop and up to 7 wk after planting of the main crop. The impact of cover crops as a weed control input on main crop yield was also evaluated. A total of 46 relevant field studies were evaluated. Main crops were planted 1 to 3 wk after termination of the cover crops. Overall, our meta‐analysis results indicated that cover crops provided early season weed suppression comparable to those provided by chemical and mechanical weed control methods in cropping systems. The use of cover crops for early season weed suppression had no effect on main crop grain yields, but could increase vegetable crop yields when compared with no cover crop. Decisions about selecting cover crops species type (broadleaf or grass) or number (single or mixtures) were not as important as identifying cover crops with inherent characteristics that suppress weeds, such as high biomass productivity and persistent residue.

The widespread use of herbicides in cropping systems has led to the evolution of resistance in major weeds. The resultant loss of herbicide efficacy is compounded by a lack of new herbicide sites of action, driving demand for alternative weed control technologies. While there are many alternative methods for control, identifying the most appropriate method to pursue for commercial development has been hampered by the inability to compare techniques in a fair and equitable manner. Given that all currently available and alternative weed control methods share an intrinsic energy consumption, the aim of this review was to compare methods based on energy consumption. Energy consumption was compared for chemical, mechanical, and thermal weed control technologies when applied as broadcast (whole-field) and site-specific treatments. Tillage systems, such as flex-tine harrow (4.2 to 5.5 MJ ha-1), sweep cultivator (13 to 14 MJ ha-1), and rotary hoe (12 to 17 MJ ha-1) consumed the least energy of broadcast weed control treatments. Thermal-based approaches, including flaming (1,008 to 4,334 MJ ha-1) and infrared (2,000 to 3,887 MJ ha-1), are more appropriate for use in conservation cropping systems; however, their energy requirements are 100- to 1,000-fold greater than those of tillage treatments. The site-specific application of weed control treatments to control 2-leaf-stage broadleaf weeds at a density of 5 plants m-2 reduced energy consumption of herbicidal, thermal, and mechanical treatments by 97%, 99%, and 97%, respectively. Significantly, this site-specific approach resulted in similar energy requirements for current and alternative technologies (e.g., electrocution [15 to 19 MJ ha-1], laser pyrolysis [15 to 249 MJ ha-1], hoeing [17 MJ ha-1], and herbicides [15 MJ ha-1]). Using similar energy sources, a standardized energy comparison provides an opportunity for estimation of weed control costs, suggesting site-specific weed management is critical in the economically realistic implementation of alternative technologies.

Weed control is necessary to ensure a high crop yield with good quality. Herbicide application and mechanical weeding are the most common methods worldwide. The use of herbicides has led to the increasing occurrence of herbicide-resistant weeds and unwanted contamination of the environment. Mechanical weed control harms beneficial organisms, increases the degradation of organic matter, may dry out the soil, and stimulate new cohorts of weed seeds to germinate. Therefore, there is a need to develop more sustainable weed control means. We suggest using small autonomous vehicles equipped with lasers as a sustainable alternative method. Laser beams are based on electricity, which can be produced from non-fossil fuels. Deep learning methods can be used to locate and identify weed and crop plants for targeting and delivery of laser energy with robotic actuators. Given the targeted nature of laser beams, the area exposed for weed control can be reduced substantially compared to commonly used weed control methods. Therefore, the risk of affecting non-target organisms is minimized, and the soil will be kept untouched in the field, avoiding triggering weed seeds to germinate. Small autonomous vehicles may have limited weeding capacity, and precautions need to be taken as reflections from the laser beam can be harmful to humans and animals. In this paper, we discuss the pros and cons of replacing or supplementing common used weed control methods with laser weeding. The ability to use laser weeding technology is relatively new and not yet widely practiced or commercially available. Therefore, we do not discuss and compare the costs of the various methods at this early stage of the development of the technology.

Weeds compete with crops for water and nutrients and can adversely affect crop growth and yield, so it is important to research effective weed control methods. This paper provides an overview of the impact of weeds on crop yield and describes the current state of research on weed management in field herbaceous crops. Physical weed control mainly refers to thermal technologies represented by flame weed control and laser weed control, which can efficiently and accurately remove weeds. Mechanical weed control requires a combination of sensor technologies, machine vision technology, and high-precision navigation to improve weed control accuracy. Biological weed control relies heavily on plant extracts and pathogens to create herbicides, but it is costly, and some can be toxic to mammals. Chemical weed control is a common method, resulting in environmental pollution and weed resistance. To reduce the use of chemical herbicides, scholars have proposed integrated weed management strategies, which combine biological control, control of the seed bank, and improve crop competitiveness. Integrated weed management strategies are considered to be the future direction of weed management. In conclusion, physical, mechanical, biological, and chemical weed control methods are commonly used in weed management. Each method has its applicable scenarios, and the implementation of integrated weed management strategies can lead to better weed control, improving crop yield and quality. The main objective of this review is to organize the research progress on weed management methods for herbaceous crops in the field and to provide a reference for the agricultural sector to develop weed control strategies. Specifically, this paper categorizes weed management methods into four groups, discusses and presents the advantages and disadvantages of the aforementioned weed control methods, and discusses future research directions.

AbstractIntegrated weed management encourages long-term planning and targeted use of cultural strategies coherently combined at the cropping system scale. The transition towards such systems is challenged by a belief of lower productivity and higher weed pressure. Here, we hypothesize that diversifying the crop sequence and its associated weed management tools allow long-term agronomic sustainability (low herbicide use, efficient weed control, and high productivity). Four 6-year rotations with different constraints (S2: transition from reduced tillage to no-till, chemical weeding; S3: chemical weeding; S4: typical integrated weed management system; S5: mechanical weeding) were compared to a reference (S1: 3-year rotation, systematic ploughing, chemical weeding) in terms of herbicide use, weed management, and productivity over the 2000–2017 period. Weed density was measured before and after weeding. Crop and weed biomass were sampled at crop flowering. Compared to S1, herbicide use was reduced by 46, 65, and 99% in S3, S4, and S5 respectively. Herbicide use in S2 was maintained at the same level as S1 (− 9%), due to increased weed pressure and dependence to glyphosate for weed control during the fallow period of the no-till phase. Weed biomass was low across all cropping systems (0 to 5 g of dry matter m−2) but weed dynamics were stable over the 17 years in S1 and S4 only. Compared to S1, productivity at the cropping system scale was reduced by 22% in S2 and by 33% in S3. These differences were mainly attributed to a higher proportion of crops with low intrinsic productivity in S2 and S3. Through S4’s multiperformance, we show for the first time that low herbicide use, long-term weed management, and high crop productivity can be reconciled in grain-based cropping systems provided that a diversified crop rotation integrating a diverse suite of tactics (herbicides included) is implemented.

The increasing public concern about food security and the stricter rules applied worldwide concerning herbicide use in the agri-food chain, reduce consumer acceptance of chemical plant protection. Site-Specific Weed Management can be achieved by applying a treatment only on the weed patches. Crop plants and weeds identification is a necessary component for various aspects of precision farming in order to perform on the spot herbicide spraying or robotic weeding and precision mechanical weed control. During the last years, a lot of different methods have been proposed, yet more improvements need to be made on this problem, concerning speed, robustness, and accuracy of the algorithms and the recognition systems. Digital cameras and Artificial Neural Networks (ANNs) have been rapidly developed in the past few years, providing new methods and tools also in agriculture and weed management. In the current work, images gathered by an RGB camera of Zea mays, Helianthus annuus, Solanum tuberosum, Alopecurus myosuroides, Amaranthus retroflexus, Avena fatua, Chenopodium album, Lamium purpureum, Matricaria chamomila, Setaria spp., Solanum nigrum and Stellaria media were provided to train Convolutional Neural Networks (CNNs). Three different CNNs, namely VGG16, ResNet–50, and Xception, were adapted and trained on a pool of 93,000 images. The training images consisted of images with plant material with only one species per image. A Top-1 accuracy between 77% and 98% was obtained in plant detection and weed species discrimination, on the testing of the images.