Data from: Fungicide efficacy and duration of protection against coffee leaf rust (Hemileia vastatrix) on commercial coffee farms in Hawaii

These data are from a study that characterized fungicide efficacy and duration of protection against coffee leaf rust (CLR, Hemileia vastatrix) on Hawaii Island. Field trials were conducted on three commercial coffee farms in 2022 and five commercial farms in 2023. We included four commercially available fungicides approved for coffee in Hawaii in 2022, and six fungicides in 2023. The preventative fungicides (two copper-based, two Bacillus-based, and one botanical-based fungicide) were applied twice during the field trial, at week 0 and week 5. The translaminar fungicide was applied once (week 0) or twice (week 0 and week 6) in combination with a copper fungicide (week 3) during the field trial. Data was collected on CLR incidence (presence of infection) and leaf retention (leaves per branch) for 12 (2022) to 15 (2023) trees per treatment on a weekly (2022) or bi-weekly (2023) basis. The cost of application was also estimated based on labor (USD$/hour), gas and oil used for the sprayer, and product cost (USD$/pound or Fl oz) and rate (amount of product/acre). Our results suggest that conventional coffee farms can control CLR by alternating applications of translaminar and copper-based fungicides, aiming to apply a total of 4-6 sprays between flowering and harvest to reduce impacts on leaf retention and yield. Without the option to use translaminar fungicides, organic farms will need to aim for 5-8 sprays, alternating between copper and biological fungicides to control CLR.