No abstract

Mango anthracnose, caused by Colletotrichum spp., is the most significant disease of mango (Mangifera indica L.) in almost all production areas around the world. In Mexico, mango anthracnose has only been attributed to C. asianum and C. gloeosporioides. The aims of this study were to identify the Colletotrichum species associated with mango anthracnose symptoms in Mexico by phylogenetic inference using the ApMat marker, to determine the distribution of these species, and to test their pathogenicity and virulence on mango fruits. Surveys were carried out from 2010 to 2012 in 59 commercial orchards in the major mango growing states of Mexico, and a total of 118 isolates were obtained from leaves, twigs, and fruits with typical anthracnose symptoms. All isolates were tentatively identified in the C. gloeosporioides species complex based on morphological and cultural characteristics. The Bayesian inference phylogenetic tree generated with Apn2/MAT intergenic spacer sequences of 59 isolates (one per orchard) revealed that C. alienum, C. asianum, C. fructicola, C. siamense, and C. tropicale were associated with symptoms of mango anthracnose. In this study, C. alienum, C. fructicola, C. siamense, and C. tropicale are reported for the first time in association with mango tissues in Mexico. This study represents the first report of C. alienum causing mango anthracnose worldwide. The distribution of Colletotrichum species varied among the mango growing states from Mexico. Chiapas was the only state in which all five species were found. Pathogenicity tests on mango fruit cultivar Manila showed that all Colletotrichum species from this study could induce anthracnose lesions. However, differences in virulence were evident among species. C. siamense and C. asianum were the most virulent, whereas C. alienum and C. fructicola were considered the least virulent species.

Persian lime (Citrus latifolia Tan.) is an important and widely cultivated fruit crop in several regions of Mexico. In recent years, severe symptoms of gummosis, stem cankers, and dieback were detected in the Persian lime-producing region in the states of Veracruz and Puebla, Mexico. The aims of this study were to identify the species of Lasiodiplodia associated with these symptoms, determine the distribution of these species, and test their pathogenicity and virulence on Persian lime plants. In 2015, symptomatic samples were collected from 12 commercial Persian lime orchards, and 60 Lasiodiplodia isolates were obtained. Fungal identification of 32 representative isolates was performed using a phylogenetic analysis based on DNA sequence data of the internal transcribed spacer region and part of the translation elongation factor 1-α and β-tubulin genes. Sequence analyses were carried out using the Maximum Likelihood and Bayesian Inference methods. Six Lasiodiplodia species were identified as Lasiodiplodia pseudotheobromae, Lasiodiplodia theobromae, Lasiodiplodia brasiliense, Lasiodiplodia subglobosa, Lasiodiplodia citricola, and Lasiodiplodia iraniensis. All Lasiodiplodia species of this study are reported for the first time in association with Persian lime in Mexico and worldwide. L. pseudotheobromae (46.9% of isolates) was the most frequently isolated species followed by L. theobromae (28.1%) and L. brasiliense (12.5%). Pathogenicity on Persian lime young plants using a mycelial plug inoculation method showed that all identified Lasiodiplodia species were able to cause necrotic lesions and gummosis, but L. subglobosa, L. iraniensis, and L. pseudotheobromae were the most virulent.

During the spring of 2015, fruit rot symptoms were observed on pomegranate fruit in an orchard located in Oaxaca, Mexico. Characteristic lesions were collected and a fungus was isolated from these lesions. Based on morphological characteristics, analysis of rDNA-ITS sequences, and pathogenicity tests on pomegranate fruits, the causal agent was identified as Pilidiella granati. This is the first report of P. granati causing pomegranate fruit rot in Mexico.

Tomato brown rugose fruit virus (ToBRFV) is an emerging pathogen affecting tomato-production systems in several countries, including Mexico. This situation involves challenges due to the negative impact on yield and the lack of disease-management measures. This work analyzes the spatiotemporal distribution of ToBRFV in commercial tomato greenhouses. The presence or absence of diseased plants was evaluated weekly, assigning a location in space (x, y). Temporal analysis consisted of fitting the incidence to the monomolecular, logistic, log-logistic, Gompertz, exponential, Weibull, and Richard models, evaluated using the Akaike information criterion, significance, correlation, coefficient of determination, and root mean square error. Spatial analysis consisted of determining spatial aggregation using the Moran, Fisher, and Lloyd indices. In addition, spatial distribution was assessed by sequence observations, point patterns using the inverse distance index, and analysis by SADIE distance indicators. Results indicated that the logistic models (log-logistic and logistic) best described the temporal progress of ToBRFV. This disease also had slightly aggregated patterns in the initial phase, highly aggregated in the exponential phase, and uniform in the deceleration and stationary phases. This study demonstrates that the spatial and temporal dynamics of ToBRFV have important implications for the monitoring, diagnosis, management, and risk prediction of this disease.