Trunk or scaffold girdling is performed on early season peaches and nectarines to increase fruit size, advance maturity and reduce the number of harvests. It is most effective when the seed length in the fruit is about 10 mm (3/8"), which generally occurs around one month after bloom.
The procedure involves removing a strip of bark completely around the trunk or scaffold. It is important to remove the bark just down to the cambial layer - a more shallow cut renders the girdle ineffective and a deeper cut can kill the tree.
If done correctly, the girdling wound heals over in 6 to 8 weeks, even though some gumming may occur and leaf nutrients may be decreased for a period of time. The practice should be treated with caution as some varieties do not respond well or show negative effects such as increased split pits, poor coloration or decreased fruit quality.
Girdling Mayfire Nectarine
Girdling Chapter in Stone Fruit Manual
Water Relations of Girdling