OTC Optimization Discussed in Podcast

Ute Albrecht, associate professor of plant physiology with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), joined the February All In For Citrus podcast to discuss the latest learnings in optimizing trunk injections of oxytetracycline (OTC) aimed at reducing HLB in trees. She shared what has been discovered over the past few years in terms of application timing, rates and injection methods.

TREE AGE

One area of discussion has been how the age of citrus trees influences the performance of OTC. Albrecht noted that 4- to 6-year-old trees seem to respond better than older trees. She also cautioned growers to be careful with drill size on younger trees to avoid trunk damage.

Albrecht discussed a trial with 8- to 10-year-old trees with yields that more than doubled after two consecutive years of OTC treatments. She said in another trial, with 18-year-old trees, there were moderate yield improvements after the first treatment. This is an interesting finding because trees in that older age range have been observed to be less responsive to OTC treatments.

SPLIT INJECTIONS

Observations continue to show the benefit of splitting the OTC dosage by making injections on both sides of the tree. But Albrecht acknowledged that split injections might not be practical for all growers. Getting the clearance to make a third application after this season is important to continue to put pressure on the HLB bacteria in trees, she added.

APPLICATION TIMING

Albrecht advised against making OTC injections in Valencia trees in December because they have lower metabolic activity during that time of year and are less likely to translocate the active ingredient. Growers should be cautious with late summer and fall applications to avoid potential problems with residue levels being too high in the fruit at harvest.

To hear all of Albrecht’s OTC recommendations, don’t miss the February episode of All In For Citrus. The podcast is a partnership between UF/IFAS and AgNet Media.

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