Application Timing Recommendations
- For oranges and tangerines with small amounts of dead wood, one to two applications per season are adequate.
- Start in early May.
- Applications for grapefruit should start when fruit are 0.25 inch to 0.5 inch (0.64 cm–1.3 cm) in diameter.
- Often beginning of May but can be as early as mid-April.
- Fruit no longer susceptible at 2.5–3.0 inches (6.4 cm–7.6 cm) in diameter, usually in mid-July.
- If using calendar application schedule for copper, time applications no more than 21 days apart.
- Strobilurin-containing (FRAC MOA 11) should be made at shorter intervals, particularly when there is high rainfall.
- Copper applications can be more effectively timed with the Citrus Copper Application Scheduler.
Fungicide resistance is a known problem with the strobilurin fungicides (FRAC MOA 11). While Diaporthe citri does not have a history of resistance, it may develop. Therefore, these materials should never be used more than twice in a row, and no more than two strobilurin-containing applications should be used for melanose control in a season.
Web Addresses for Links
Citrus Copper Application Scheduler: http://agroclimate.org/tools/citrus-copper-application-scheduler/
UF/IFAS publication PP289, "A Web-Based Tool for Timing Copper Applications in Florida Citrus": https://doi.org/10.32473/edis-pp289-2012
Recommended Chemical Controls
READ THE LABEL.
See Table 1.
Rates for pesticides are given as the maximum amount required to treat mature citrus trees unless otherwise noted. To treat smaller trees with commercial application equipment including handguns, mix the per-acre rate for mature trees in 125 gal of water. Calibrate and arrange nozzles to deliver thorough distribution, and treat as many acres as this volume of spray allows.
Table 1. Recommended chemical controls for melanose.