The production of ornamental plants in Mexico represents a job-generating activity that has grown in recent years; however, it is adversely affected by phytosanitary issues, notably those induced by Phytophthora. Studies of Phytophthora in ornamental nurseries are scarce in Mexico. The aim in this study was to identify Phytophthora species from selected ornamental plant nurseries in Mexico as potential new hosts. Samples of 13 genera diseased plant tissue and soil were collected from eight nurseries in Mexico during 2009–2010. Based on morphology and sequences of ITS rDNA, the 19 isolates obtained were identified as P. cactorum, P. capsici, P. cinnamomi, P. drechsleri, P. kelmanii, P. nicotianae, and P. tropicalis. Additional loci were sequenced to support species determinations within the P. capsici species complex; some of these isolates could not be confirmed as belonging to any described species, and one appeared to be an interspecific hybrid. This is the first report of P. kelmanii in Mexico; this is noteworthy due to being a broad host range, similar to most of the other species encountered. Evidence of nursery-grown plants serving as a Phytophthora vector to a home garden has been reported for the first time in Mexico. Cestrum nocturnum and Solanum ovigerum are new hosts for Phytophthora worldwide.

En México, la citricultura representa una de las actividades económicas más importantes para la fruticultura nacional, con una producción de 8.8 millones de toneladas y una derrama económica de más de 47 mil millones de pesos al año. Sin embargo, la producción se ve afectada por plagas y enfermedades, destacando el Huanglongbing (HLB), ‘dragón amarillo’ o enverdecimiento de los cítricos, como la enfermedad más devastadora a nivel mundial, ocasionada por una proteobacteria del género Candidatus Liberibacter (Ca. L.). Debido a que no existe un método efectivo para controlar esta enfermedad la correcta y oportuna detección puede reducir significativamente su diseminación. El propósito de la presente revisión es recopilar métodos que se emplean para la detección de la presencia de Ca. L. en plantas de cítricos, cubriendo aspectos generales sobre la sintomatología de la enfermedad, métodos moleculares para una precisa y rápida detección al realizar el muestreo tanto en plantas como en el vector. Asimismo, se mencionan diferentes protocolos que analizan algunos compuestos producidos durante la infección con Ca. L. e imágenes en cítricos con HLB.

Mexico is the world’s leading producer of avocado (Persea americana); however, its productivity is threatened by various diseases, especially root rot caused by Phytophthora. While P. cinnamomi is the most commonly reported species worldwide, this study identified P. mengei for the first time as a causal agent of root rot and trunk canker in avocado orchards in the state of Michoacán, México. The morphological and molecular characterization of four isolates (three from canker and one from root rot) confirmed their identity: semi-papillate sporangia and plerotic oospores with paragynous antheridia, with sequence identities of 99.87% (ITS) and 100% (COI) with type sequences of P. mengei. Pathogenicity tests demonstrated the ability to infect roots, stems, and fruits, although with a low reisolation percentage in roots (10%), suggesting an opportunistic pathogen behavior. Sensitivity tests to potassium phosphite (EC₅₀ of 3.67 μg/mL⁻¹ a.i.) and metalaxyl-M (0.737 μg/mL⁻¹ a.i.) revealed possible limitations for chemical control. These findings position P. mengei as an emerging pathogen with important implications for integrated crop management. To the best of our knowledge, this is the first report of P. mengei causing root rot and trunk canker in avocado in Michoacán, Mexico.

Conventional horticultural production is generating adverse effects on human health and the environment, mostly because of the vast amounts of agrochemicals that are widely applied (Atreya, 2008; E...