Coffee Rust Forecast Systems: Development of a Warning Platform in a Minas Gerais State, Brazil

This study aimed to develop a warning system platform for coffee rust incidence fifteen days in advance, as well as validating and regionalizing multiple linear regression models based on meteorological variables. The models developed by Pinto were validated in five counties. Experiments were set up in a randomized block design with five treatments and five replications. The experimental plot had six lines with 20 central plants of useful area. Assessments of coffee rust incidence were carried out fortnightly. The data collected from automatic stations were adjusted in new multiple linear regression models (MLRM) for five counties. Meteorological variables were lagged concerning disease assessment dates. After the adjustments, two models were selected and calculated for five counties, later there was an expansion to include ten more counties and 35 properties to validate these models. The result showed that the adjusted models of 15–30 days before rust incidence for Carmo do Rio Claro and Nova Resende counties were promising. These models were the best at forecasting disease 15 days in advance. With these models and the geoinformation systems, the warning platform and interface will be improved in the coffee grower region of the south and savannas of the Minas Gerais State, Brazil.

Strategies for Coffee Leaf Rust Management in Organic Crop Systems

Coffee is a crop of great economic importance in many countries. The organic coffee crop stands out from other production systems by aiming to eliminate the use of synthetic fertilizers and pesticides. One of the most important limitations in the organic system is the management of diseases, especially coffee rust, which is considered the main disease of this crop. Coffee rust causes a production slump of up to 50%, significantly affecting the profitability of coffee growers. This work aims to review the integrated rust management in organic coffee crop in different producing countries. Regarding the disease management strategies, this review addresses the use of rust-resistant cultivars, cultural management, biological control, use of plant extracts, and chemical rust control by cupric fungicides. Considering the importance of the organic system, the increase in world coffee consumption, and the potential market for this kind of coffee, this review may help researchers and producers looking for alternative strategies to control rust in an organic coffee cultivation system.

Web-based epidemiological surveillance systems and applications to coffee rust disease

El avance de la tecnología digital ha permitido concebir Sistemas de Vigilancia Epidemiológicos (SVE) automatizados con un enfoque <em>holístico-sistémico</em> favoreciendo la planeación, operación, gestión y procesamiento de datos fitosanitarios de manera efectiva y oportuna para toma de decisiones en la prevención y manejo regional de plagas. Este tipo de sistemas se enfocan en la salud del cultivo superando la visión reduccionista de plaga en la vigilancia normativa convencional. Un SVE web implica la definición clara del marco regional, objetivos, plaga(s) en su amplia acepción, recursos humanos/financieros, contexto normativo, líneas de investigación de soporte, estructura operativa y modelos de innovación. Estos elementos determinan la precisión, frecuencia y tipo de muestreo y monitoreo, así como las variables de medición relativas a un novel<em> sistema epidemiológico</em>. A diferencia de la vigilancia normativa, un SVE web <em>holístico-sistémico</em> tiene capacidad descriptiva y de pronóstico de riesgos, incluyendo alertas tempranas a partir de análisis espaciales y temporales. La interfaz web SVE asegura la generación flexible y dinámica de reportes y/o análisis automatizados. Un SVE operado en plataformas web, con énfasis en lenguajes de programación y herramientas de uso libre puede ser alojado en servidores genéricos o dedicados para almacenamiento de metadatos configurados con tecnologías Linux/Apache y funcionalidad 24/7 (h día-1). Programas de uso libre incluyen MySQL/MariaDB y otros como gestores de bases de datos; PHP / Node.js, y JavaScript, Ajax, HTML5 y CSS, como tecnologías web de maquetado base ‘back-end’ y ‘front-end’, respectivamente. Esta revisión se enfoca en principios, atributos conceptuales, enfoques metodológicos generales y objetivos de SVE base web. Aplicaciones generales se ilustran con un SVE desarrollado en México para el cafeto (<em>Coffea</em> spp.), el cual permitió operar la vigilancia de 19 plagas, nueve con estatus cuarentenario, mediante la generación, gestión y análisis de 87.4 y 15.7 millones de registros climáticos y epidemiológicos, respectivamente, obtenidos entre 2013-2019.

Evaluation of the Physicochemical Properties of Chitosans in Inducing the Defense Response of Coffea arabica against the Fungus Hemileia vastatrix

Chitosan is a natural polymer, and its biological properties depend on factors such as the degree of deacetylation and polymerization, viscosity, molecular mass, and dissociation constant. Chitosan has multiple advantages: it is biodegradable, biocompatible, safe, inexpensive, and non-toxic. Due to these characteristics, it has a wide range of applications. In agriculture, one of the most promising properties of chitosan is as an elicitor in plant defense against pathogenic microorganisms. In this work, four kinds of chitosan (practical grade, low molecular weight, medium molecular weight, and high-density commercial food grade) were used in concentrations of 0.01 and 0.05% to evaluate its protective effect against coffee rust. The best treatment was chosen to evaluate the defense response in coffee plants. The results showed a protective effect using practical-grade and commercial food-grade chitosan. In addition, the activity of enzymes with β-1,3 glucanase and peroxidase was induced, and an increase in the amount of phenolic compounds was observed in plants treated with high-molecular-weight chitosan at 0.05%; therefore, chitosan can be considered an effective molecule for controlling coffee rust.

Exogenous application of salicylic acid to control coffee rust

The exogenous application of salicylic acid can induce plant resistance against pathogens. However, little is known about the potential uses of this bioregulator for controlling coffee diseases. In this study, we assessed the effect of applying salicylic acid (SA – 150 mg L-1) on the management of coffee rust (Hemileia vastatrix) in a 7-year-old coffee plantation with low crop load (651.6 kg ha-1 in 2017). For comparison, plants were sprayed with protectant fungicide (copper hydroxide – CH) and standard fungicides (SF) used by local farmers (boscalid, pyraclostrobin + epoxiconazole, and copper hydroxide). Non-treated plants were included as a negative control. Five monthly applications were performed from November 2016 to March 2017. Rust incidence and severity, defoliation, and growth of plagiotropic branches were evaluated monthly. The activity of catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) and total proteins was assessed one day after the first, third, and fifth product applications. Compared to untreated plants, SA reduced the severity and incidence of rust from 36.3 to 54.7%, while CH and SF reduced disease from 31.8 to 54.6% and from 83.8 to 88%, respectively. SA reduced defoliation by 54.1%. SA increased the concentration of CAT, APX, and SOD after the first application. However, this effect was not observed after subsequent applications. Foliar application of SA reduces the severity and incidence of coffee rust and defoliation in plants with a low crop load.

Analysis of time series recurrence and cross recurrence in the relationship of climate with Coffee Leaf Rust

&lt;p&gt;Agroindustry in South and Central America is positioned as a traditional production sector, where exists a need for integration of processes for the implementation of contingency measures in a timely manner against events that create a risk for crops. Diseases affecting agricultural sectors are often closely related to weather conditions and crop management. In particular, for the coffee production, the Coffee Leaf Rust (CLR) is a disease that affects quality and production costs for farmers greatly.&amp;#160;&lt;/p&gt;&lt;p&gt;Detecting the patterns that affect the disease can lead to early actions that lessen its impact. In this sense, some researchers in the sector have focused their efforts on determining over time the relationships between weather conditions and agronomic properties of crops with episodes of epidemics of diseases as coffee rust.&amp;#160;&lt;/p&gt;&lt;p&gt;Different natural processes, such as the climate, can have different and recurrent behaviors in time. Despite its periodicity, climate change has impacted on recurring events, both in their temporality and intensity. Thus, climate variables have properties of dynamic deterministic or nonlinear systems. The recurrence analysis of states in these systems is one of the solutions to carry out a study of their behavior in the time-domain.&amp;#160; Eckmann et al. proposed the Recurrence Plots (RP) for the visualization of state recurrence, allowing to see the space phase trajectories in a bidimensional representation. This analysis, initially applied to a single time series and its recurrence with itself, can also be extended to compare two time series by Cross Recurrence Plots (CRP) and find the recurrence between them. Moreover, the elements of PR and CRP can be quantified, obtaining direct elements of comparison between series or pairs of time series.&lt;/p&gt;&lt;p&gt;The aim of this analysis was to find the times and conditions in which the time series of the climatic variables present events related to anomalies or extreme values in the CLRI time series. In addition, the recurrence analysis allows to know the time delay for which each climatic variable affects the disease.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;J. Avelino et al., &amp;#171;The coffee rust crises in Colombia and Central America (2008&amp;#8211;2013): impacts, plausible causes and proposed solutions&amp;#187;, Food Secur.,&amp;#160; 7(2), 303-321, 2015.&lt;/p&gt;&lt;p&gt;&amp;#160;J. M. Waller, M. Bigger, y R. J. Hillocks, Coffee pests, diseases and their management. CABI, 2007.&lt;/p&gt;&lt;p&gt;&amp;#160;A. C. Kushalappa y A. B. Eskes, &amp;#171;Advances in coffee rust research&amp;#187;, Annu. Rev. Phytopathol., 27(1), 503&amp;#8211;531, 1989.&lt;/p&gt;&lt;p&gt;&amp;#160;E. Lasso, D. C. Corrales, J. Avelino, E. de Melo Virginio Filho, y J. C. Corrales, &amp;#171;Discovering weather periods and crop properties favorable for coffee rust incidence from feature selection approaches&amp;#187;, Comput. Electron. Agric., 176, 105640, 2020.&lt;/p&gt;&lt;p&gt;&amp;#160;J. P. Eckmann, S. O. Kamphorst, y D. Ruelle, &amp;#171;Recurrence plots of dynamical systems&amp;#187;, World Sci. Ser. Nonlinear Sci. Ser. A, 16, 441&amp;#8211;446, 1995.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Technical support of Telematics Engineering Group (GIT) of the University of Cauca, the Tropical Agricultural Research and Higher Education Center (CATIE) and the InnovAccion Cauca project of the Colombian Science, Technology, and Innovation Fund (SGR- CTI) for PhD scholarship granted to MSc. Lasso is acknowledge. Financial support by Fundaci&amp;#243;n Premio Arce (ETSIAAB, UPM) financial support under contract FPA18PPMAT08 is greatly appreciated.&lt;/p&gt;

Virulence genes of new population of coffee rust (Hemileia vastatrix) affecting coffee variety 'Lempira', in Honduras; resistant and susceptible varieties.

The coffee variety 'Lempira', released in Honduras in 1998, was classified 100% resistant to races I and II of coffee rust identified by Portugal's Centre for Research into Coffee Rusts (Centro de Investigação das Ferrugens do Cafeeiro) (CIFC) in 1997. However, since 2007, the disease has been reported in seed foundation plots and producer farms, the most recent epidemic report being in April 2016 in Vegas de Jalan, Juticalpa Olancho, affecting 210 ha. Since this variety constitutes 45% of the cultivated area under coffee in the country, there is a need to identify the virulence genes of the new strain and to determine the resistance and susceptibility of other cultivated varieties. For these purposes, mass samples of rust were inoculated on leaf discs of the differential clones 1343/269, 110/5, 147/1, 152/3, 33/1, 419/20, 832/1 and 832/2, together with 87/1, 1006/10, 420/10 and 420/2 from the Federal University of Vicosa, as well as on the two main cultivated resistant varieties ('Parainema' and 'IHCAFE- 90'), and seven promising genotypes, under controlled temperature conditions and relative humidity. After 20-60 days of inoculation, seven virulence genes were identified (v1, v2, v4, v5, v6, v7, v9), of which v1, v4, v6, v7 and v9 had not been reported in Honduras previously. It is inferred that this rust population arose by recombination of race v5 with v6, v7 or v9. Races with 3, 4, 5, 6 or 7 virulence determinants were identified as the most complex and aggressive strains described but they lacked the v3 and v8 determinants. In addition, it was found that 'Parainema', 'H27', 'T5296-170', 'Central American', 'Pacamara yellow' and 'Anacafe-14' are resistant because they possess the SH8 gene, absent from 'Lempira'. 'IHCAFE-90' and 'Obatá' showed 20% susceptibility, and 'Ruiru 11' was susceptible. The results reveal the diversity of rust virulence genes in Honduras and emphasize the importance of the SH3 and SH8 genes as sources of resistance.