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Coffee Leaf Rust (CLR) is caused by Hemileia vastatrix in Coffea spp. It is one of the most dangerous phytopathogens for coffee plantations in terms of coffee productivity and coffee cup quality. In this review, we resume the problem of CLR in Mexico and the pathogenesis of H. vastatrix. The review abord plant-pathogen interactions which lead a compatible or incompatible interactions and result in CLR disease or resistance, respectively. The review abord Coffea spp. defense response pathways involved in H. vastatrix pathogenicity. Additionally, current measures to control H. vastatrix proliferation and germination were aborded focused on phytosanitary actions, and biological and chemical control. Finally, new trendlines to reduce the impact of CLR as nanoparticles and nanotechnology were analyzed. [ABSTRACT FROM AUTHOR]

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Coffee leaf rust (CLR), caused by Hemileia vastatrix , is considered a highly important phytosanitary problem in Mexico. Currently, there are few microorganisms used as biocontrol alternatives to chemical control of CLR in organic coffee fields in Mexico. This study evaluates the use of Paenibacillus sp. NMA1017 as a biocontrol agent to inhibit the development of H. vastatrix in in vitro and in vivo (greenhouse) experiments. Hemileia vastatrix urediniospores were placed on water agar plates, and then Paenibacillus sp. NMA1017 was inoculated simultaneously or 8 h later. Urediniospores germination rate was reduced by 94% when the NMA1017 strain was inoculated simultaneously with the urediniospores and reduced by 38% when NMA1017 was inoculated 8 h later. Experiments with 8-month-old Bourbon coffee plants that were infected with H. vastatrix showed that disease incidence was reduced by 38, 90, and 50% when NMA1017 was applied 8 days before, simultaneously, or 8 days after the application of H. vastatrix , respectively. Paenibacillus sp. NMA1017 also reduced the severity of CLR on the leaves by up to 62%. The germination urediniospores of other rust pathogens such as Puccinia sorghi (maize leaf rust), Puccinia triticina (wheat leaf rust), Puccinia graminis f. sp. tritici (black stem rust of wheat), Uromyces striatus (alfalfa leaf rust), and Phragmidium sp. (rosebush leaf rust) were also inhibited. Use of the potential biocontrol agent Paenibacillus sp. NMA1017 might help reduce the application of chemical fungicides for the control of CLR, making coffee a more sustainable crop and providing management options for organic coffee growers., Competing Interests: The author(s) declare no conflict of interest.

The advancement of digital technology has made it possible to conceive automated Epidemiological Surveillance Systems (ESS) with a holistic-systemic approach allowing effective operation, management, and processing of phytosanitary data for fast decisionmaking applied to regional prevention and pest management. This surveillance type focuses on plant health, overcoming the reductionist pest vision of the conventional normative surveillance. An ESS implies the precise definition of the regional framework, objectives, pest(s) in widesense, human/financial resources, regulatory context, support research planning, operational structure, and innovation models. These elements determine the precision, frequency, and type of sampling and monitoring and the selection of variables related to a novel epidemiological system. In contrast to the normative surveillance, a systemic ESS has descriptive and risk forecasting capabilities, including early warnings, based on spatial and temporal analyses. A web-based ESS assures a flexible-dynamic generation of reports and automated analysis. An ESS operated on web platforms, emphasizing open source software and tools, can be hosted on generic or dedicated servers for metadata storage configured with Linux / Apache technologies with 24/7 (h day-1) functional capabilities. Open source tools include MySQL / MariaDB and other systems as database managers; PHP / Node.js, and JavaScript, Ajax, HTML5 and CSS as web design base 'back-end' and 'front-end' programs, respectively. This review focuses on principles, conceptual attributes, general methodological approaches, and objectives of web-based ESS. An overview is presented with an ESS developed in Mexico for coffee plantations (Coffea spp.), which allowed the surveillance of 19 pests, nine under quarantine status, through the generation, management, and analysis of 87.4 million climatic data and 15.7 million epidemiological records over 2013-2019. [ABSTRACT FROM AUTHOR]

Highlights • We compare shade coffee management before and after coffee leaf rust (CLR) outbreak. • Before CLR, Arabica coffee was grown in agroforests without agrochemical use. • After CLR, farmers adopted hybrid coffee varieties (HCV) resistant to CLR. • Farmers' certification status is uncertain due to agrochemical use to combat CLR. • CLR, as an environmental shock, triggered an agro-technological response fostered by external agents. Abstract Coffee agroforestry systems are a promising approach to the challenge of sustaining both biodiversity and livelihoods in tropical landscapes. However, coffee farmers' response to the unrelenting coffee leaf rust (CLR) outbreak may have repercussions for the potential of coffee agroforestry systems to contribute to biodiversity conservation. Adaptations in management practices could affect the extent to which farmers rely on ecological processes vs. external inputs (e.g., agrochemicals) to support production. This study investigates farmers' response to CLR outbreak through a study in a forest frontier in a Biosphere Reserve in Chiapas, Mexico. We conducted household surveys and fieldwork before the CLR outbreak in 2011-2012 (n = 59), and follow-up surveys after the outbreak in 2016 (n = 48). Before CLR outbreak, farmers were cultivating Arabica coffee varieties in agroforestry systems and generally following agroecological approaches. Most farmers (82%) were certified organic and did not employ synthetic agrochemicals. Farmers (66%) had plans to expand their Arabica coffee agroforests either into forest (35%) or fallow (31%) in response to high farm gate prices. After CLR outbreak, 94% of farmers had CLR-resistant hybrid coffee varieties (HCV) in their possession and were either incorporating them by substituting affected Arabica coffee plants in existing fields, or by establishing new coffee fields with HCV at lower elevations. In attempts to control CLR, farmers (54%) also applied agrochemicals at least once and, to a lesser extent (19%), removed shade trees. Among the farmers (63%) who were planning on expanding coffee production with HCV, more farmers were planning on expanding on fallow (46%) than forest (17%) compared to the period before CLR outbreak (p-value < 0.05). Public and private actors promoted and distributed saplings of HCV and agrochemicals along with technical assistance. The promotion of HCV along with fertilizers may result in a substitution of ecosystem functions with agrochemicals, and the need to acquire seeds and saplings outside of farmers' own resource base and networks. This shift in management strategies generates new instabilities and risks by introducing a new market for HCV about which little is known and by making external agents the holders of productive resources and knowledge. [ABSTRACT FROM AUTHOR]

Coffee is one of the most important commercial traded commodities in the international market, as well as the most popular beverage around the world. In Mexico, organic coffee cultivation (specifically, Arabica coffee crops) is a highly demanded that generates up to 500,000 employments in 14 federal entities. Among various coffee producers, Chiapas, Veracruz, and Oaxaca are responsible of 80% of the total coffee production in the country. Currently, Mexico is the leading producer of organic coffee in the world. However, there have been a slow recovery due to the large production losses since 2012, caused by earlier and highly aggressive outbreaks of coffee leaf rust (CLR), in the country, where the infectious agent is known as Hemileia vastatrix (HV). This phenomenon is becoming frequent, and climate change effects could be the main contributors. This spontaneous proliferation was generated in Mexico, due to the precipitation and temperature variability, during the last decade. As result, in Mexico, the biological interaction between coffee crops and their environment has been harmed and crucial characteristics, as crop yield and quality, are particularly being affected, directly by the negative effects of the greenhouse phenomenon, and indirectly, through diseases as CLR. Therefore, this review discusses the contribution of climate change effects in the early development of CLR in Mexico. The focus is also given on possible schemes and actions taken around the world as control measures to adapt the vulnerable coffee varieties to tackle this challenging issue., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)