Detection of huanglongbing of citruses (Citrus sp.) through Sentinel-2satellite images in Huimanguillo, Tabasco, Mexico

Objective: develop a fast, practical and economical methodology for the determination of plants with HLB symptoms, by exploring the potential use of Sentinel-2 satellite images. Design/methodology/approach: Sentinel-2 images were used to perform a supervised classification to discriminate healthy Persian lime trees and trees with HLB molecularly verified by qPCR, as well as other land uses in the citrus growing area of Huimanguillo, Tabasco. Results: The results showed that in the green (560nm), red (665 nm) and near infrared (705 nm) band regions the spectral response of trees with HLB is higher than that of healthy trees. An area of 26.96 and 12 981 hectares of Persian lime affected and free of HLB was found, respectively, with an accuracy of 0.84 % and a Kappa coefficient of 0.83. Field verification corroborated three plantations in which plants with HLB were previously detected and are currently in production. Limitations on study/implications: The study was carried out in the period of less cloud cover, as this is a limiting factor for the analysis of the image since it can lead to inadequate tracking of the affected area. Findings/conclusions: The results showed that using Sentinel-2 satellite images, it is possible to differentiate Persian lemon plants affected by HLB from healthy plants.Objective: Develop a fast, practical, and inexpensive methodology for determining plants with HLB symptoms by exploring the potential use of Sentinel-2 satellite images. Design/Methodology/Approach: Sentinel-2 images were used to perform a supervised classification to discriminate healthy Persian lime trees and trees with HLB molecularly verified by qPCR, and other land uses in the citrus growing area of Huimanguillo, Tabasco. Results: The results showed that in the green (560nm), red (665 nm), and near-infrared (705 nm) band regions, the spectral response of trees with HLB is higher than that of healthy trees. Likewise, there is an area of 26.96 and 12 981 hectares of Persian lime affected and free of HLB, respectively, with an accuracy of 0.84 % and a Kappa coefficient of 0.83. Field verification corroborated three plantations where plants with HLB were previously detected and are currently in production. Study Limitations/Implications: The study was carried out in the season of less cloud cover, as this is a limiting factor for the image analysis since it can lead to inadequate tracking of the affected area. Findings/Conclusions: The results showed that it is possible to differentiate Persian lime plants affected by HLB from healthy plants using Sentinel-2 satellite image

Fluctuación espacio-temporal de Diaphorina citri Kuwayama (Hemiptera: Liviidae) en limón Persa (Citrus latifolia) en la zona citrícola de Huimanguillo, Tabasco

En México se cultivan cerca de 600 mil hectáreas de cítricos, de los cuales, el cultivo de limón Persa representa el 19%, con un valor cercano a 3 mil 800 millones de pesos. Veracruz, Tabasco y Oaxaca son los tres principales productores a nivel nacional; sin embargo, esta producción se mantiene en riesgo por las pérdidas económicas que genera la enfermedad Huanglongbing y su vector el Psílido Asiático de los Cítricos Diaphorina citri (Kuwayama, 1907). En Tabasco, el patógeno y vector se detectaron desde el 2012 y 2005, respectivamente. Así, a cinco años del manejo mediante las Áreas Regionales de Control (ARCOs), es imperativo conocer la fluctuación poblacional de D. citri, por lo que el presente estudio tuvo como objetivo conocer la fluctuación espacio-temporal de Diaphorina citri en el ARCOs de la zona citrícola de Huimanguillo, Tabasco, y determinar los periodos de mayor densidad poblacional y de riesgo de dispersión del HLB. Se analizó la base de datos de la captura catorcenal de adultos en 2,820 trampas pegajosas amarillas en 141 sitios del monitoreo de D. citri de marzo a diciembre del 2019, realizado en la campaña contra plagas reglamentadas de los cítricos. Con la base de datos se generaron mapas geoestadísticos del promedio de D. citri por trampas y se determinó el patrón de dispersión del adulto mediante el cálculo de tres índices de agregación, además de su relación con las variables ambientales de temperaturas y precipitación mensuales. Se observó que D. citri está presente durante todo el periodo de estudio variando su densidad de manera mensual, las densidades poblacionales más altas se presentaron en el periodo de junio a octubre, con tendencia de mayor abundancia hacia la parte noroeste de la zona citrícola, presentando un patrón de distribución en agregados y del 20 al 30% de los sitios evaluados rebasan el umbral de intervención regional de un adulto de D. citri por trampa.In Mexico, about 600 thousand hectares are cultivated with citrus fruits, of which, Persian lime represents 19%, with a value close to 3.8 billion pesos. Veracruz, Tabasco, and Oaxaca are the three main producers nationwide; however, this production remains at risk due to the economic losses generated by the Huanglongbing disease and its vector, the Asian Citrus Psyllid Diaphorina citri (Kuwayama, 1907). In Tabasco, the pathogen and vector were detected since 2012 and 2005, respectively. Thus, after five years management through the Regional Control Areas (ARCOs), it is imperative to know the population fluctuation of D. citri, so the objective of the present study was to know the space-time fluctuation of Diaphorina citri in the ARCOs of the citrus zone of Huimanguillo, Tabasco, and to determine the periods of greatest population density and risk of HLB spreading. The fortnight adult-capture database from 2,820 yellow sticky traps in 141 D. citri monitoring sites from March to December 2019 was analyzed, carried out in the campaign against regulated pests of citrus fruits. With the database, geostatistical maps of the average D. citri per trap were generated and the dispersion pattern of the adults was determined by calculating three aggregation indices, as well as their relationship with the environmental variables of temperature and monthly precipitation. Diaphorina citri was observed to be present throughout the study period varying in density on a monthly basis, the highest population densities occurred in the period from June to October, with a trend of greater abundance towards the northwest part of the citrus zone, presenting a distribution pattern in aggregates and 20 to 30% of the evaluated sites exceed the regional intervention threshold of one adult D. citri per trap