See answers to trunk injection questions from Tom Johnson, owner of TJ BioTech, to optimize applications.

Trunk injection applications are showing promise in combating citrus greening, or HLB, in Florida citrus, but there is a wide learning curve to getting the applications perfect. A Citrus Industry article series with Tom Johnson, owner of TJ BioTech, the creator and manufacturer of ReMedium TI®, the product being injected to combat citrus greening, shares answers to application questions. The first concerns rootstock vs. scion injections. See it below.

Trunk Injection Answers: Rootstock Vs. Scion Injections

The first question in the trunk injection series of Q&As concerns injecting in the rootstock vs. the scion. In short, Johnson maintains that injections can occur at either spot, but that the rootstock is more desirable because there is more room for the injection drill holes, which should be moved to the opposite side each year. See the full answer:

Q: “Are there any advantages or disadvantages to making a Remedium TI® injection in the rootstock or the scion?”

Tom Johnson A: “To start, agronomically there is really no difference in a ReMedium TI® injection into the rootstock or the scion if we are talking about a single injection. However, there are distinct advantages to making the ReMedium TI® injection into the rootstock over the scion for multiple injections. As a practical matter, the rootstock is generally larger in circumference than the scion, which is better for intake of the ReMedium TI®. It also allows for a little better distribution of the drill holes moving around the tree as injections are repeated in subsequent years.

The injections should be done on the opposite side of the tree in year two as compared to the year-one injection. The ReMedium TI® label presently calls for no injection in year three as a resistance management tool. The third and fourth injections can be done on the opposite sides of injection one and two.

As time progresses and injections continue, the injections can be done moving the injection site an inch or two higher. In time, the injections may progress to the scion. Again, as a practical matter, if the scion is quite low to the ground it may not be practical to inject into the rootstock, and in that case, injection into the scion is fine. However, care should be taken to move the injection sites slightly higher on the scion with each injection on young trees to avoid allowing the drill holes to get too close to each other and weakening the trunk of the tree.”

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