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La depredación de semillas de malas hierbas es un claro ejemplo de cómo la conservación de la biodiversidad de los sistemas agrarios redunda en un beneficio, tanto para el agricultor como para la sostenibilidad del sistema. Roedores, pájaros e insectos han sido descritos como los depredadores más abundantes y los que muestran mayores consumos de semillas y, por tanto, son los que pueden tener un impacto mayor en el control de las poblaciones de malas hierbas de los cultivos. De hecho, se ha estimado que los depredadores de semillas pueden consumir entre el 26 y el 83 % de las semillas producidas anualmente por estas plantas. A diferencia de los sistemas naturales, los agro-ecosistemas son sistemas alterados en los que el manejo puede determinar en gran medida el grado de diversidad presente y su funcionalidad. Este artículo revisa el papel que el laboreo, la cobertura del suelo y el paisaje pueden tener sobre los distintos tipos de depredadores de semillas y sus tasas de depredación, y esboza qué estrategias pueden ser las más idóneas para conservar este servicio ecosistémico con el objetivo de disminuir la dependencia de los herbicidas para el manejo de la flora arvense.

Background: Using cover crops in organic vineyards can provide many advantages, including weed suppression. However, their effectiveness may depend on the weed community, the cover crop species and the termination method. The most common practice for cover crop termination is shredding, but rapid residue decomposition can allow noxious species like Cynodon dactylon to proliferate during summer and compete with the vines. The use of roller-crimpers as an alternative method can be effective in some cropping systems, but no studies have focused on their use in the inter-row of vineyards. The objective of this study was to evaluate the effectiveness of seven cover crops (spontaneous, Avena strigosa, Hordeum vulgare, Lolium multiflorum, Phacelia tanacetifolia, Sinapis alba and X Triticosecale) and two termination methods (shredding or roller-crimper) in managing C. dactylon during summer., Results: In 2020, rolled A. strigosa, P. tanacetifolia and the spontaneous flora limited the coverage of C. dactylon more than shredding (increases of 3% and 18% in C. dactylon cover from July to September in rolled and shredded cover crops, respectively), while in 2021, rolling was better than shredding for all cover crop species in September (5% and 18% increases, respectively)., Conclusion: Roller-crimping cover crops was an effective method to control C. dactylon in vineyard inter-rows but it did not consistently work for all cover crops in both years. Our study is one of the first to test the efficacy of roller-crimpers to manage summer weeds in vineyards. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Cover crop mixtures can provide multiple ecosystem services but provisioning of these services is contingent upon the expression of component species in the mixture. From the same seed mixture, cover crop mixture expression varied greatly across farms and we hypothesized that this variation was correlated with soil inorganic nitrogen (N) concentrations and growing degree days. We measured fall and spring biomass of a standard five-species mixture of canola (Brassica napus L.), Austrian winter pea (Pisum sativum L), triticale (x Triticosecale Wittm.), red clover (Trifolium pratense L.) and crimson clover (Trifolium incarnatum L.) seeded at a research station and on 8 farms across Pennsylvania and New York in two consecutive years. At the research station, soil inorganic N (soil iN) availablity and cumulative fall growing degree days (GDD) were experimentally manipulated through fertilizer additions and planting date. Farmers seeded the standard mixture and a "farm-tuned" mixture of the same five species with component seeding rates adjusted to achieve farmer-desired services. We used Structural Equation Modeling to parse out the effects of soil iN and GDD on cover crop mixture expression. When soil iN and fall GDD were high, canola dominated the mixture, especially in the fall. Low soil iN favored legume species while a shorter growing season favored triticale. Changes in seeding rates influenced mixture composition in fall and spring but interacted with GDD to determine the final expression of the mixture. Our results show that when soil iN availability is high at the time of cover crop planting, highly competitive species can dominate mixtures which could potentially decrease services provided by other species, especially legumes. Early planting dates can exacerbate the dominance of aggressive species. Managers should choose cover crop species and seeding rates according to their soil iN and GDD to ensure the provision of desired services., Competing Interests: The authors have declared that no competing interests exist.

Weedy plants pose a major threat to food security, biodiversity, ecosystem services and consequently to human health and wellbeing. However, many currently used weed management approaches are increasingly unsustainable. To address this knowledge and practice gap, in June 2014, 35 weed and invasion ecologists, weed scientists, evolutionary biologists and social scientists convened a workshop to explore current and future perspectives and approaches in weed ecology and management. A horizon scanning exercise ranked a list of 124 pre-submitted questions to identify a priority list of 30 questions. These questions are discussed under seven themed headings that represent areas for renewed and emerging focus for the disciplines of weed research and practice. The themed areas considered the need for transdisciplinarity, increased adoption of integrated weed management and agroecological approaches, better understanding of weed evolution, climate change, weed invasiveness and finally, disciplinary challenges for weed science. Almost all the challenges identified rested on the need for continued efforts to diversify and integrate agroecological, socio-economic and technological approaches in weed management. These challenges are not newly conceived, though their continued prominence as research priorities highlights an ongoing intransigence that must be addressed through a more system-oriented and transdisciplinary research agenda that seeks an embedded integration of public and private research approaches. This horizon scanning exercise thus set out the building blocks needed for future weed management research and practice; however, the challenge ahead is to identify effective ways in which sufficient research and implementation efforts can be directed towards these needs.

Weed management is a critically important activity on both agricultural and non-agricultural lands, but it is faced with a daunting set of challenges: environmental damage caused by control practices, weed resistance to herbicides, accelerated rates of weed dispersal through global trade, and greater weed impacts due to changes in climate and land use. Broad-scale use of new approaches is needed if weed management is to be successful in the coming era. We examine three approaches likely to prove useful for addressing current and future challenges from weeds: diversifying weed management strategies with multiple complementary tactics, developing crop genotypes for enhanced weed suppression, and tailoring management strategies to better accommodate variability in weed spatial distributions. In all three cases, proof-of-concept has long been demonstrated and considerable scientific innovations have been made, but uptake by farmers and land managers has been extremely limited. Impediments to employing these and other ecologically based approaches include inadequate or inappropriate government policy instruments, a lack of market mechanisms, and a paucity of social infrastructure with which to influence learning, decision-making, and actions by farmers and land managers. We offer examples of how these impediments are being addressed in different parts of the world, but note that there is no clear formula for determining which sets of policies, market mechanisms, and educational activities will be effective in various locations. Implementing new approaches for weed management will require multidisciplinary teams comprised of scientists, engineers, economists, sociologists, educators, farmers, land managers, industry personnel, policy makers, and others willing to focus on weeds within whole farming systems and land management units., (© 2016 by the Ecological Society of America.)

Background/aims: To define if a new function improves the capability of the scanning laser polarimetry with variable corneal compensation (GDx-VCC) nerve fiber analyzer in detecting preperimetric glaucoma using 12 retinal nerve fiber layer (RNFL) peripapillary sectors., Methods: Data were obtained in a cross-sectional, hospital-clinic-based study in which 478 eyes from 478 glaucoma suspects were enrolled. All of them underwent ophthalmological examination, static automated perimetry (Humphrey 24-2 Swedish interactive threshold algorithm), optic nerve stereoscopic photography, red-free digital RNFL photography and GDx-VCC examination. The overall intake included 391 normal eyes and 60 preperimetric glaucoma eyes with defects in the fiber layer photographs., Results: The mean values of inferior average, temporal-superior-nasal-inferior temporal average, superior average and the number (nerve fiber indicator) were significantly lower in the eyes with RNFL defects than in the control group, when compared with the obtained linear discriminating function. The area under the curve values for receiver-operating characteristics analysis of the new parameter were 5% better than the best GDx-VCC standard values., Conclusions: Our results confirm that the new function has a better diagnostic reliability in preperimetric glaucoma and confirms the usefulness of morphological diagnosis between normal and early damaged RNFLs., ((c) 2009 S. Karger AG, Basel.)

Purpose: To evaluate the magnification characteristics of an Optical Coherence Tomograph (STRATUS OCT 3000) used to measure optic disc size., Methods: An eye model was designed, built and used to measure changes in the magnification of the Optical Coherence Tomograph (OCT) with variation in the axial length of the eye and OCT correction lenses. Theoretical calculations using ray-tracing were used to compare the experimental and theoretical results., Results: OCT-performed fundus measurements have a magnification that depends on two factors: eye axial length and optical correction with the focusing dial of the OCT. Theoretical calculations showed that the size of the optic disc image for greater axial lengths of the eye model (myopic eye) was less than that for smaller axial lengths (hyperopic eye). The disc diameter measurements of the image obtained with the OCT did not agree with the real disc size. By focussing with the focusing dial of the OCT, the power of the optics can be varied from -12.0 D to +12.0 D and the image size is decreased for all axial lengths. The maximum variation of the disc area was 2.1%. Differences in area measured at intervals of 2.0 D after correcting the eye refraction for measurements with the OCT were equivalent to the repeatability error at that point., Conclusions: Our results confirm that any variation in the optical system of the eye, in the OCT, and/or in the distance between them, induces a change in the magnification of the tomograph images. These variations will affect the measurements of any of the structures in the retinal plane.

Purpose: To evaluate the capability of the GDx VCC nerve fiber analyzer to detect preperimetric glaucoma across 12 retinal nerve fiber layer (RNFL) peripapillary sectors., Methods: Data were obtained in a cross-sectional, hospital clinic-based study; 699 eyes from 699 glaucoma suspects were enrolled in this protocol. All subjects underwent ophthalmologic examination, static automated perimetry [Humphrey 24-2 Swedish interactive threshold algorithm (SITA) Standard], optic nerve stereoscopic photographs, red-free digital RNFL photographs and GDx VCC examination. Group S included 283 normal eyes and 39 preperimetric glaucoma eyes with RNFL superior or diffuse defects in the fiber layer photographs. Group I included 324 normal subjects and 24 with preperimetric glaucoma eyes with RNFL inferior or diffuse defects in fiber layer photographs., Results: Mean values of the area under the curve (AUC) for receiver operating characteristic analysis for inferior average (Inf Avg), temporal-superior-nasal-inferior temporal average (TSNIT Avg), superior average (Sup Avg), and the nerve fiber indicator were significantly less in the eyes with RNFL defects than the control group compared with the AUC for thickness at hour 12 and at hour 6 calculated from the RNFL sector density. The AUC for receiver operating characteristic analysis of the new parameters improved by 12% with respect to the best GDx VCC standard values., Conclusions: Our results confirm that the 12 sector divisions of the GDx VCC have better diagnostic reliability in preperimetric glaucoma, and are able to improve the discrimination capability between normal and early damaged RNFLs.

Schematic eye models have typically been used to explain the average monochromatic and chromatic imaging properties of the eye. Both monochromatic aberrations and transverse chromatic aberration are known to vary widely across subjects. However, to our knowledge, the ability of schematic eye models to predict these individual variations has not been tested experimentally. We used a spatially resolved refractometer to measure the monochromatic aberrations and the optical transverse chromatic aberration (oTCA) in a group of 15 eyes. By recording the 1st and 4th Purkinje images for five directions of gaze, we also estimated the tilt, misalignment of ocular surfaces (front surface of the cornea and back surface of the lens) and off-axis position of the fovea (angle alpha), as well as pupil centration. We conclude that, contrary to expectations none of those factors are major contributors to the variability in monochromatic aberrations and oTCA in this group of eyes. Simulations show that corneal curvature and corneal conicity are also unlikely to account for the observed relation between monochromatic aberrations and oTCA. Our results suggest an important contribution of corneal irregularities to those aberrations.