Application Timing Recommendations
- Managing citrus canker where it is endemic has three main methods:
- Slow the wind speed with windbreaks.
- Manage citrus leafminer to minimize wounding of the leaves (see chapter 22 of booklet 1, “Citrus Leafminer,” and chapter 5 of booklet 2).
- Protect canopy with copper or an integrated program of copper with plant immune system activators.
- Copper applications should be made every 21 days on average. Copper residue levels can be assessed with the Citrus Copper Application Scheduler.
- For early processing oranges, applications should start early April and go to late June or early July.
- For late hanging or midseason processing oranges, applications should start mid-April and continue until late May or early June.
- Fresh-market grapefruit applications should start on the mostly expanded spring flush until fruit are completely grown in October.
- Copper applications for scab, melanose, and greasy spot will also manage citrus canker.
- Detailed timing information is given in booklet 1.
- Plant immune stimulators can reduce the amount of inoculum and make copper more effective.
- Actigard: Nonbearing trees (drench applications)
- Make the first application once trees have recovered from transplant shock.
- Adjust doses based on tree age and size (Table 2), starting with the lowest for category.
- Continue applications at 60-day intervals throughout the spring, summer, and fall.
- Actigard: Bearing trees (drench applications)
- Make the first application post-bloom but prior to weather favorable for canker.
- Adjust doses based on tree age and size (Table 2), starting with the lowest for category.
- Continue applications at 45- to 60-day intervals throughout the spring, summer, and fall, depending on tree size and planting density.
- Aura Citrus: Foliar applications
- Only recommended for canopy management of citrus.
- Recommended to apply with a copper hydroxide product.
- Apply during the major flush events of spring, summer, and fall.
The rules and regulations regarding canker are changeable. For current information on disease status and regulations, see the website of the Florida Department of Agriculture and Consumer Services or the UF/IFAS CREC website.
Contact your local UF/IFAS Extension citrus agent for additional information, training materials, and programs at https://citrusagents.ifas.ufl.edu/.
Web Addresses for Links
Citrus Copper Application Scheduler: http://agroclimate.org/tools/citrus-copper-application-scheduler/
Citrus Health Response Program, Florida Department of Agriculture and Consumer Services website: https://www.fdacs.gov/Agriculture-Industry/Pests-and-Diseases/Plant-Pests-and-Diseases/Citrus-Health-Response-Program/CHRP-Resources-for-Industry
UF/IFAS publication FOR227, “Windbreak Designs and Planting for Florida Agricultural Fields”: https://edis.ifas.ufl.edu/publication/fr289
UF/IFAS publication PP289, “A Web-Based Tool for Timing Copper Applications in Florida Citrus”: https://doi.org/10.32473/edis-pp289-2012
UF/IFAS CREC website: https://crec.ifas.ufl.edu/research/citrus-production/disease-identification/citrus-canker/
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.
For applications of Actigard (drench or chemigation), use rates are expressed as the amount of Actigard per tree. Recommended drench water volume is 8 to 16 fl oz/tree.
Table 1. Recommended chemical controls for citrus canker.
Table 2. Recommended rates and use patterns for Actigard 50WG/100 trees.