Distribution of ⁶⁵Zn in pear trees following bark injection

Abstract

Two-year-old pear trees (cv. Packham Triumph) growing in 15-gal drums, were bark-injected with 65Zn 2 months after bud burst. To some injection doses nonradioactive zinc with or without EDTA was also added.

The ⁶⁵Zn only moved from the injection point when extra zinc was included in the dose. EDTA further enhanced this movement. The ⁶⁵Zn was distributed to spurs and laterals on the injected leader, situated above and on the same side as the point of injection. Limited downward movement was also evident. ⁶⁵Zn was detected in new growth formed after injection, and also in blossom, leaves, and new lateral growth produced on the injected leaders in the following season. It was found that ⁶⁵Zn accumulated at the nodes on laterals, and in the petioles, midrib, and major veins of the leaves.