Grower Observations on OTC Trunk Injection

Josh McGillHLB Management

Highlands County Citrus Growers Association (HCCGA) President Aaron Nelson recently shared observations about trunk injection of oxytetracycline (OTC) for trees with HLB. The first formulations for citrus trunk injection became available in January. His observations follow:


Over the course of the last six months there have been countless hours spent injecting millions of trees all over the state. What follows comes from what I’ve experienced as well as conversations I’ve had with other growers about their experiences with OTC trunk injections.

One of the most surprising things to me has been how much variability there has been in uptake from tree to tree. While some trees take up the product in less than half an hour, others take several hours and, in some cases, don’t take the material at all.

Tree health is generally a good indicator of whether or not a tree will take in product. In general, the weaker the tree is, the slower it sucks up product. Factors like hole drilling location, time of day, soil moisture content and temperature also play a role in uptake.

Initial estimates for the number of injections one man could do in a day were in the 200–300 range. It turns out that in many cases one worker can double that estimate or more in a day!

While it has no doubt been a major undertaking to cover as much acreage as we have, I’m thankful it has gone a little quicker than anticipated.

Because crews have been able to move through groves so quickly, it has necessitated more injectors than many of us thought we’d need. Efficiencies are severely hampered when you must go back through the grove two and three times to find empty injectors to keep the men drilling supplied. Another reason having plenty of injectors is a must is that they break — and break a lot! Repairing and redeploying injectors back into service can be a full-time job.

Early in the year, when temperatures were cool, and soil moisture was adequate, I saw little to no phytotoxic effects from the OTC treatments. It didn’t seem like you could give a tree enough to hurt it.

When the temperatures started climbing and the soil started drying out in March and April, I began noticing what I’ve been calling “bronzing” in groves shortly after they’d been treated. Other than having discolored yellowish leaves, which can last a few weeks, the trees seem otherwise fine. Is this a big deal? Yet another question that needs answering.

These are just a few of the practical things I’ve learned since starting trunk injections. I suspect, as things usually do, that the way in which we tackle this job in the future will evolve and look different than it does today.

I’m optimistic that this new OTC therapy will manifest itself in healthier trees, better yields and improved quality this year. We could certainly all use it!

Source: HCCGA

Share this Post

Sponsored Content