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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Publications at this Location » Publication #430217
Research Project: Conservation and Utilization of Tropical and Subtropical Fruit, Cacao, Coffee, and Bamboo Germplasm and Associated Descriptive Information

Location: Tropical Crops and Germplasm Research

Title: Dynamics of coffee leaf rust (Hemileia vastatrix) in Puerto Rico: associations with season, cultivar, altitude, and hyperparasites

Author
item MARIÑO, YOBANA - University Of Puerto Rico
item BUITRAGO, DIANA - University Of Puerto Rico
item Serrato Diaz, Luz
item ALMONTE-JAVIER, EMILY - University Of Puerto Rico
item NEGRON, SEBASTIAN - University Of Puerto Rico
item BAYMAN, PAUL - University Of Puerto Rico

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2026
Publication Date: 3/9/2026
Citation: Mariño, Y.A., Buitrago, D., Serrato Diaz, L.M., Almonte-Javier, E., Negron, S., Bayman, P. 2026. Dynamics of coffee leaf rust (Hemileia vastatrix) in Puerto Rico: associations with season, cultivar, altitude, and hyperparasites. Frontiers in Plant Science. 17:1768440. https://doi.org/10.3389/fpls.2026.1768440.
DOI: https://doi.org/10.3389/fpls.2026.1768440

Interpretive Summary: Coffee Leaf Rust (CLR) is a disease that harms coffee plants and is caused by a fungus called Hemileia vastatrix. The relation of this fungus with the weather and other fungi called hyperparasites was studied during three years at 15 different locations. This study found that CLR was more common and caused higher levels of damage during the dry season in Puerto Rico and during post-harvest. The disease was worse at higher altitudes, and was likely spread due to high humidity and leaf wetness. CLR-susceptible cultivars had significantly more CLR than resistant cultivars, but the resistant cultivars also had CLR damage and followed the same seasonal pattern. This information helps farmers and researchers to understand when and where CLR is most likely to occur based on environmental conditions, and to select varieties with superior resistance for Puerto Rico.

Technical Abstract: Coffee leaf rust (CLR), caused by the fungus Hemileia vastatrix, is the most serious disease of coffee worldwide. CLR has been present in Puerto Rico since 1989, yet its incidence and severity have not been reported. We surveyed CLR incidence and severity for three years in fifteen sites and tested associations with environmental variables. CLR hyperparasites were also surveyed. CLR incidence ranged from 0% to 100% and severity from 0% to 60%. Both incidence and severity increased during the dry season following harvest. Environmental variables were important drivers for CLR and its hyperparasites in the field. The incidence and severity of both CLR and its hyperparasites were negatively correlated with temperature and rainfall. While CLR was positively correlated with mean relative humidity and leaf wetness, hyperparasites showed a negative correlation with both minimum and maximum relative humidity. CLR-susceptible cultivars had significantly more CLR than resistant cultivars, but the resistant cultivars also had CLR damage and followed the same seasonal pattern. The resistant cultivar with the most CLR damage was Marsellesa, widely planted to replace CLR-susceptible cultivars lost to Hurricanes Irma and Maria in 2017. CLR incidence and severity both increased significantly with altitude (range 400-951 m). Hyperparasite incidence and severity followed the same seasonal pattern as CLR. Some of the patterns reported here are like previous studies in other areas. They form a baseline for management decisions on cultivars and control, and a point of comparison for future studies.