Jorge Luis Flores-Sánchez

Precision agriculture is revolutionizing the management and production of agricultural crops. The development of new technologies in agriculture, such as unmanned aerial vehicles (UAVs), has proven to be an efficient option for spraying various compounds on crops. UAVs significantly contribute to enhancing precision agriculture. This review aims to determine whether integrating advanced precision technologies into drones for crop spraying enhances spraying accuracy compared to drones utilizing standard spraying technologies. To achieve this, 100 articles published between 2019 and 2024 were selected and analyzed. The information was summarized into five main areas: (1) improved spraying with agricultural drone technologies, (2) operational parameters, (3) spraying applications of chemical and natural compounds with agricultural drones, (4) evaluations of control pest efficacy, and (5) considerable limitations. Finally, considerations are presented on the advantages of drone technology with artificial intelligence (AI); the practical effects of reducing pesticides, which, in some cases, have reached a reduction of 30% compared to the recommended dose; and future directions for improving precision agriculture. The use of drones in precision agriculture presents technical and scientific challenges for the maximization of spraying efficiency and the minimization of agrochemical use.

Huanglongbing (HLB), a recent worldwide spreading disease on citrus, was detected in July 2009 in Yucatan State of Mexico. The objective of this study was to evaluate the fit of diffusion and classic disease gradient models to large-scale HLB spatial data originated from initial foci to improve sampling, monitoring, and control strategies for Diaphorina citri, vector of Candidatus Liberibacter asiaticus (CLas), putative agent of HLB. Four transect routes were selected: Yuc-1, Yuc-2, QRoo-1, and QRoo-2, based on the directionality of the prevailing winds and foci location of HLB infected plants. In these routes, 35 sites, 5 to 20 km apart, were selected for monthly evaluation during a 12-month period. A 10-insect sample and disease incidence and severity of HLB, further confirmed by PCR, were assessed per site. Mexican lime was more vulnerable (67.5%) than sweet orange (14%). Also, leaf symptoms were mostly found with homogeneous distribution but rarely reaching 100% of the tree canopy during the 12-month period. The diffusion model provided the best fit among the family of time-gradient curves (r 2 = 0.90 to 0.99) due to the flexibility of a three-parameter model. The gradients were well conformed to the model in a 25 to 82.6 km range, having the east-west direction the longest effect. Yuc-2 and QRoo-2 transects showed 82.6 and 43.9 km gradients with a diffusion coefficient (Do) of 0.15 and 0.09, respectively. This study constitutes the first quantitative evidence of the regional spread of CLas from a single focus and the application of a flexible model that improved the fit and allowed to better compare different gradients. These results are useful to determine the size of Regional Areas of Diaphorina citri Control (ARCO), a management program currently implemented in Mexico to combat HLB.

"El objetivo de este estudio fue estimar pérdidas productivas inducidas por el agente asociado al Huanglongbing, Candidatus Liberibacter asiaticus (CLas) en limón persa (Citrus latifolia Tanaka) en México, mediante la evaluación de variables morfológicas y organolépticas en frutos. En el estado de Yucatán, México, se seleccionó una huerta de limón persa de cuatro años, con árboles bajo un mismo manejo e infección, esta característica se verificó por PCR cuantitativo. El estudio se condujo bajo cuatro niveles de severidad (0=sano, 1=25, 2=50, 3=75 y 4=100, porcentaje de síntomas de HLB en dosel). Se evaluaron ocho variables morfológicas y organolépticas en un diseño de bloques con tratamientos apareados. Los valores de peso tamaño, grosor de cáscara, volumen de jugo (VJ) y pH fueron estadísticamente mayores en frutos de árboles sanos y en ramas asintomáticas de árboles positivos, en comparación con los frutos de ramas sintomáticas (Tukey, P=0.05). CLas indujo reducción en peso (17.3 %) y VJ (18.6%), con mayor daño en árboles con 100 % de síntomas de HLB en dosel; los modelos de regresión fueron: Ypeso=217.2-4.2x+0.03x2, R2=0.86; YVJ = 645.4-11.7x+0.09x2, R2=0.82. La reducción en peso implicó una pérdida en producción de 2.4 toneladas/ha. El efecto perjudicial se asoció al nivel de severidad y concentración de CLas, ya que se detectó que la intensidad de los síntomas de HLB están en función de la concentración bacteriana mediante el modelo Y[bacteria]=1.17+0.77x-0.0067x2, R2=0.91. El presente documento constituye el primer estudio cuantitativo del efecto de CLas en la producción delimón persa."