Automatic Identification and Monitoring of Plant Diseases Using Unmanned Aerial Vehicles: A Review

Disease diagnosis is one of the major tasks for increasing food production in agriculture. Although precision agriculture (PA) takes less time and provides a more precise application of agricultural activities, the detection of disease using an Unmanned Aerial System (UAS) is a challenging task. Several Unmanned Aerial Vehicles (UAVs) and sensors have been used for this purpose. The UAVs’ platforms and their peripherals have their own limitations in accurately diagnosing plant diseases. Several types of image processing software are available for vignetting and orthorectification. The training and validation of datasets are important characteristics of data analysis. Currently, different algorithms and architectures of machine learning models are used to classify and detect plant diseases. These models help in image segmentation and feature extractions to interpret results. Researchers also use the values of vegetative indices, such as Normalized Difference Vegetative Index (NDVI), Crop Water Stress Index (CWSI), etc., acquired from different multispectral and hyperspectral sensors to fit into the statistical models to deliver results. There are still various drifts in the automatic detection of plant diseases as imaging sensors are limited by their own spectral bandwidth, resolution, background noise of the image, etc. The future of crop health monitoring using UAVs should include a gimble consisting of multiple sensors, large datasets for training and validation, the development of site-specific irradiance systems, and so on. This review briefly highlights the advantages of automatic detection of plant diseases to the growers

Quantifying corn emergence using UAV imagery and machine learning

Corn (Zea mays L.) is one of the important crops in the United States for animal feed, ethanol production, and human consumption. To maximize the final corn yield, one of the critical factors to consider is to improve the corn emergence uniformity temporally (emergence date) and spatially (plant spacing). Conventionally, the assessment of emergence uniformity usually is performed through visual observation by farmers at selected small plots to represent the whole field, but this is limited by time and labor needed. With the advance of unmanned aerial vehicle (UAV)-based imaging technology and advanced image processing techniques powered by machine learning (ML) and deep learning (DL), a more automatic, non-subjective, precise, and accurate field-scale assessment of emergence uniformity becomes possible. Previous studies had demonstrated the success of crop emergence uniformity using UAV imagery, specifically at fields with simple soil background. There is no research having investigated the feasibility of UAV imagery in the corn emergence assessment at fields of conservation agriculture that are covered with cover crops or residues to improve soil health and sustainability. The overall goal of this research was to develop a fast and accurate method for the assessment of corn emergence using UAV imagery, ML and DL techniques. The pertinent information is essential for corn production early and in-season decision making as well as agronomy research. The research comprised three main studies, including Study 1: quantifying corn emergence date using UAV imagery and a ML model; Study 2: estimating corn stand count in different cropping systems (CS) using UAV images and DL; and Study 3: estimating and mapping corn emergence under different planting depths. Two case studies extended Study 3 to field-scale applications by relating emergence uniformity derived from the developed method to planting depths treatments and estimating final yield. For all studies, the primary imagery data were collected using a consumer-grade UAV equipped with a red-green-blue (RGB) camera at a flight height of approximate 10 m above ground level. The imagery data had a ground sampling distance (GSD) of 0.55 - 3.00 mm pixel-1 that was sufficient to detect small size seedlings. In addition, a UAV multispectral camera was used to capture corn plants at early growth stages (V4, V6, and V7) in case studies to extract plant reflectance (vegetation indices, VIs) as plant growth variation indicators. Random forest (RF) ML models were used to classify the corn emergence date based on the days after emergence (DAE) to time of assessment and estimate yield. The DL models, U-Net and ResNet18, were used to segment corn seedlings from UAV images and estimate emergence parameters, including plant density, average DAE (DAEmean), and plant spacing standard deviation (PSstd), respectively. Results from Study 1 indicated that individual corn plant quantification using UAV imagery and a RF ML model achieved moderate classification accuracies of 0.20 - 0.49 that increased to 0.55 - 0.88 when DAE classification was expanded to be within a 3-day window. In Study 2, the precision for image segmentation by the U-Net model was [greater than or equal to] 0.81 for all CS, resulting in high accuracies in estimating plant density (R2 [greater than or equal to] 0.92; RMSE [less than or equal to] 0.48 plants m-1). Then, the ResNet18 model in Study 3 was able to estimate emergence parameters with high accuracies (0.97, 0.95, and 0.73 for plant density, DAEmean, and PSstd, respectively). Case studies showed that crop emergence maps and evaluation in field conditions indicated an expected trend of decreasing plant density and DAEmean with increasing planting depths and opposite results for PSstd. However, mixed trends were found for emergence parameters among planting depths at different replications and across the N-S direction of the fields. For yield estimation, emergence data alone did not show any relation with final yield (R2 = 0.01, RMSE = 720 kg ha-1). The combination of VIs from all the growth stages was only able to estimate yield with R2 of 0.34 and RMSE of 560 kg ha-1. In summary, this research demonstrated the success of UAV imagery and ML/DL techniques in assessing and mapping corn emergence at fields practicing all or some components of conservation agriculture. The findings give more insights for future agronomic and breeding studies in providing field-scale crop emergence evaluations as affected by treatments and management as well as relating emergence assessment to final yield. In addition, these emergence evaluations may be useful for commercial companies when needing justification for developing new technologies relating to precision planting to crop performance. For commercial crop production, more comprehensive emergence maps (in terms of temporal and spatial uniformity) will help to make better replanting or early management decisions. Further enhancement of the methods such as more validation studies in different locations and years as well as development of interactive frameworks will establish a more automatic, robust, precise, accurate, and 'ready-to-use' approach in estimating and mapping crop emergence uniformity.Includes bibliographical references

Automatic Counting of Canola Flowers from In-Field Time-Lapse Images

The combination of plant phenotyping and computer techniques has gained popularity amongst breeders and computer scientists. The recent evolution of the latter has allowed High-Throughput Phenotyping (HTP) to play a significant role in filling the genotype-to-phenotype gap. While most of the related work in HTP is performed in controlled environments, such as greenhouses, that allow automatic devices to capture the data reliably, research in in-field phenotyping is not as robust due to environmental confounds (i.e., fog or sun-reflections). The usage of high temporal density data has not been exploited to the same degree as high spatial resolution information. However, many phenotypes (e.g., canola flowering) have a temporal component. In this document, we present an image-processing-based method that attempts to detect and count flowers of canola during the early flowering stage on in-field time-lapse images. This approach can be used to analyze the evolution of the flower density of canola plants over short periods of time during the first days of flowering thanks to the availability of high temporal resolution images. We used images extracted during Summer 2016 to generate ground truth, tune the flower detection method and count the flowers during the first days of the flowering period. We provide an overview and a discussion about additional steps that might be needed to overcome the impact of sunlight reflection on canola leaves in the detection of flowers

Image-based Microplot Segmentation/Detection and Deep Learning in Plant Breeding Experiments

In the coming years, the agricultural sector will encounter significant challenges from population growth, climate change, and evolving consumer demands. To address these challenges, farmers and plant breeders actively develop advanced plant varieties with enhanced productivity and resilience to harsh environmental conditions. However, the current methods for evaluating plant traits, such as manual operations and visual assessment by breeders, are time-consuming and subjective. A promising solution to this issue is image-based phenotyping, which leverages image-processing and machine-learning techniques to facilitate rapid and objective monitoring of numerous plants, enabling breeders to make more informed decisions. In order to perform per-microplot phenotypic analysis from the imagery and extract phenotypic traits from the field, it is necessary to identify and segment individual microplots (a small subdivided area within a field) in the orthomosaics. Nonetheless, the current procedures for segmenting and identifying microplots within aerial imagery used in agricultural field experiments necessitate manual operations, resulting in considerable time and labour investments. By automating this process, the evaluation of microplot phenotypes, such as physical traits, can be expedited, facilitating automated monitoring and quantification of plant characteristics. Our objective is to develop novel phenotyping algorithms to segment, detect, and classify microplots using image-processing and machine-learning techniques to achieve the goal. The thesis comprises four projects such as a comprehensive review of vegetation and microplot segmentation methods, the development of algorithms for the detection of both rectangular and non-rectangular microplots, and the utilization of deep learning techniques to predict lodging on microplots and highlighting the impact of deep learning on microplot phenotyping. These innovative approaches possess broad applicability in remote sensing field trials, encompassing diverse applications such as weed detection, crop row identification, plant recognition, height estimation, yield prediction, and lodging detection. Moreover, our proposed methods hold great potential for streamlining microplot phenotyping efforts by reducing the need for labour-intensive manual procedures

A Review of the Challenges of Using Deep Learning Algorithms to Support Decision-Making in Agricultural Activities

Deep Learning has been successfully applied to image recognition, speech recognition, and natural language processing in recent years. Therefore, there has been an incentive to apply it in other fields as well. The field of agriculture is one of the most important fields in which the application of deep learning still needs to be explored, as it has a direct impact on human well-being. In particular, there is a need to explore how deep learning models can be used as a tool for optimal planting, land use, yield improvement, production/disease/pest control, and other activities. The vast amount of data received from sensors in smart farms makes it possible to use deep learning as a model for decision-making in this field. In agriculture, no two environments are exactly alike, which makes testing, validating, and successfully implementing such technologies much more complex than in most other industries. This paper reviews some recent scientific developments in the field of deep learning that have been applied to agriculture, and highlights some challenges and potential solutions using deep learning algorithms in agriculture. The results in this paper indicate that by employing new methods from deep learning, higher performance in terms of accuracy and lower inference time can be achieved, and the models can be made useful in real-world applications. Finally, some opportunities for future research in this area are suggested.This work is supported by the R&D Project BioDAgro—Sistema operacional inteligente de informação e suporte á decisão em AgroBiodiversidade, project PD20-00011, promoted by Fundação La Caixa and Fundação para a Ciência e a Tecnologia, taking place at the C-MAST-Centre for Mechanical and Aerospace Sciences and Technology, Department of Electromechanical Engineering of the University of Beira Interior, Covilhã, Portugal.info:eu-repo/semantics/publishedVersio

A survey of image-based computational learning techniques for frost detection in plants

Frost damage is one of the major concerns for crop growers as it can impact the growth of the plants and hence, yields. Early detection of frost can help farmers mitigating its impact. In the past, frost detection was a manual or visual process. Image-based techniques are increasingly being used to understand frost development in plants and automatic assessment of damage resulting from frost. This research presents a comprehensive survey of the state-of the-art methods applied to detect and analyse frost stress in plants. We identify three broad computational learning approaches i.e., statistical, traditional machine learning and deep learning, applied to images to detect and analyse frost in plants. We propose a novel taxonomy to classify the existing studies based on several attributes. This taxonomy has been developed to classify the major characteristics of a significant body of published research. In this survey, we profile 80 relevant papers based on the proposed taxonomy. We thoroughly analyse and discuss the techniques used in the various approaches, i.e., data acquisition, data preparation, feature extraction, computational learning, and evaluation. We summarise the current challenges and discuss the opportunities for future research and development in this area including in-field advanced artificial intelligence systems for real-time frost monitoring

Nuevas estrategias basadas en geotecnologías de aplicación a la agricultura y ganadería de precisión

[ES]Las geotecnologías han emergido como la piedra angular del nuevo paradigma digital en el que están actualmente inmersas la agricultura y la ganadería contemporáneas, es decir, la nueva revolución agrícola, conocida como Agricultura 4.0, en la que se enmarcan las denominadas agricultura y ganadería de precisión. La obligada modernización a la que se ven sometidas las prácticas agroganaderas tradicionales viene desencadenada por el incipiente crecimiento demográfico y la consecuente demanda de productos agroalimentarios. Esta drástica transformación del mundo rural se torna imprescindible no solo para conseguir abastecer las necesidades de una población creciente, sino para rescatar a un sector primario cada vez más castigado por los elevados precios de los insumos y los escasos beneficios que se perciben. Como avales también de esta necesaria reconversión de los sistemas de manejo agropecuarios, entran también en juego pilares fundamentales de la productividad agrícola y ganadera como son la sostenibilidad medioambiental y el bienestar animal, ambos muy demandados en los productos de primera necesidad por una sociedad cada vez más concienciada con la producción respetuosa con el medio y con los animales. En este contexto, las geotecnologías no deben ser tomadas como herramientas que amenacen con sustituir los conocimientos agroganaderos tradicionales o que promuevan su desaparición. El enfoque es categóricamente opuesto, ya que tratan de perfeccionar la toma de decisiones de los agricultores y ganaderos, fundada en dicha sabiduría tradicional. Esta complementariedad resultará en nuevos modelos de gestión de los sistemas agropecuarios, que serán ostensiblemente más respetuosos con el medio que los sustenta, a la par que se maximizará el respeto hacia los principios básicos de sostenibilidad y bienestar animal. Por lo tanto, en este trabajo se plantea la siguiente hipótesis: la implementación de nuevas estrategias metodológicas basadas en geotecnologías en el sector agroganadero contribuirán a reducir los costes de producción, el tiempo empleado por agricultores y ganaderos en sus labores y el impacto medioambiental que dichas labores pudieran ocasionar, generando beneficios de corte económico, social y medioambiental. Considerando la hipótesis anteriormente expuesta, el objetivo de la presente tesis doctoral se centró en demostrar el potencial de las geotecnologías como herramientas alternativas y complementarias destinadas a la mejora de la gestión de los sistemas de manejo agroganaderos en el ámbito económico, medioambiental y desde el punto de vista del bienestar animal. Así mismo, se planteó que dichas estrategias geotecnológicas sirvan también para ahondar en el aprendizaje de nuevos conocimientos agrícolas y ganaderos. Para lograr este objetivo, se plantearon una serie de aportaciones que permitieran dilucidar la idoneidad de dichas geotecnologías en la gestión agroganadera

Sustainable Agriculture and Advances of Remote Sensing (Volume 1)

Agriculture, as the main source of alimentation and the most important economic activity globally, is being affected by the impacts of climate change. To maintain and increase our global food system production, to reduce biodiversity loss and preserve our natural ecosystem, new practices and technologies are required. This book focuses on the latest advances in remote sensing technology and agricultural engineering leading to the sustainable agriculture practices. Earth observation data, in situ and proxy-remote sensing data are the main source of information for monitoring and analyzing agriculture activities. Particular attention is given to earth observation satellites and the Internet of Things for data collection, to multispectral and hyperspectral data analysis using machine learning and deep learning, to WebGIS and the Internet of Things for sharing and publishing the results, among others

Artificial Neural Networks in Agriculture

Modern agriculture needs to have high production efficiency combined with a high quality of obtained products. This applies to both crop and livestock production. To meet these requirements, advanced methods of data analysis are more and more frequently used, including those derived from artificial intelligence methods. Artificial neural networks (ANNs) are one of the most popular tools of this kind. They are widely used in solving various classification and prediction tasks, for some time also in the broadly defined field of agriculture. They can form part of precision farming and decision support systems. Artificial neural networks can replace the classical methods of modelling many issues, and are one of the main alternatives to classical mathematical models. The spectrum of applications of artificial neural networks is very wide. For a long time now, researchers from all over the world have been using these tools to support agricultural production, making it more efficient and providing the highest-quality products possible

Proceedings of the European Conference on Agricultural Engineering AgEng2021

This proceedings book results from the AgEng2021 Agricultural Engineering Conference under auspices of the European Society of Agricultural Engineers, held in an online format based on the University of Évora, Portugal, from 4 to 8 July 2021. This book contains the full papers of a selection of abstracts that were the base for the oral presentations and posters presented at the conference. Presentations were distributed in eleven thematic areas: Artificial Intelligence, data processing and management; Automation, robotics and sensor technology; Circular Economy; Education and Rural development; Energy and bioenergy; Integrated and sustainable Farming systems; New application technologies and mechanisation; Post-harvest technologies; Smart farming / Precision agriculture; Soil, land and water engineering; Sustainable production in Farm buildings