Three University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers recently issued the document Suggested Use Pattern of Injectable Antimicrobials for Huanglongbing (HLB) Management. The authors are Ute Albrecht, associate professor of horticulture; Ozgur Batuman, associate professor of plant pathology; and Megan Dewdney, associate professor of plant pathology.
The antimicrobials for Florida citrus are ReMedium TI and Rectify; both contain oxytetracycline. Some document highlights follow.
APPLICATION TIMING
Only one application per year is allowed for bearing trees, but non-bearing trees can be injected twice annually with a four-month interval.
The most desirable timings of injection for various citrus varieties are:
- Early-season varieties such as Hamlin, Navel and Fallglo: March, April and May. June is a less desirable injection time.
- Mid-season varieties such as Murcott, Pineapple and Midsweet: March, April, May and June. July is a less desirable injection time.
- Late-season varieties such as Valencia: March, April, May, June and July. August is a less desirable injection time.
- Grapefruit such as Ray Ruby, Flame and Ruby Red: March, April and May. June is a less desirable injection time.
APPLICATION GUIDELINES
- Do not apply during bloom.
- Do not apply during leaf flushing.
- Apply when leaves are fully expanded for efficient uptake and distribution.
- Trees should be well watered before and at the time of application.
- Do not apply during drought conditions.
- Leaf yellowing (phytotoxicity) may occur on the side of injection.
- Only inject once the product is fully dissolved.
- Only use freshly prepared solution.
INJECTION SITES
- Do not re-use injection sites.
- The rootstock is the recommended location for injection, but scion injections are also effective.
- Subsequent injections should be above or below the initial site by 2 inches and on the opposite side, or to the right or left by 2 to 3 inches.
- Do not use any post-wounding treatments as these may interfere with wound healing.
OTHER CONSIDERATIONS
- Injection into the trunk can cause significant damage to the tree.
- Trees with a trunk diameter of less than 2.5 inches are prone to more damage.
- Minimizing the hole size by using a smaller injector tip will minimize tree damage.
The document also contains information about pre-harvest and re-entry intervals, maximum amount of product per tree per year, dose per tree by trunk diameter, and personal protective equipment.
Source: UF/IFAS
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