Girdling is a management practice carried out to increase the fruit size and dry matter in all
varieties. It was applied to kiwifruit in New Zealand by Katikati kiwifruit orchardist, Basil Cook.
In recent years there has been a larger emphasis on finding tools to aid in producing better
tasting fruit to keep up with the demand of the Taste Zespri Grade (TZG).
What is a girdle
Trunk girdling involves removing a narrow strip (usually 3-7mm) of the outer layers of the trunk
(bark + phloem) so that the phloem layer is completely separated. By cutting the phloem all the
sugars produced in the leaves can no longer travel to the roots and are available for the fruit.
Below the cambium is the xylem, this transports water from the roots throughout the plant,
these cells are lignified (like a pipe).
Getting it wrong
It is important to ensure plants are not girdled if they are showing any signs of stress, poor
health or on wood younger than two years old. Seasons that are hot and dry with no irrigation
can wipe out a crop.
The main risk associated with girdling is going too deep, the cost of getting it wrong per plant is
$500 every year of non-production, because of this Southern Cross Horticulture pays an hourly
wage, as opposed to a contract rate per plant so the girdlers don’t need to rush.
There are three months where girdling is carried out, December, January and February. The December girdle is generally done to increase size,
the second and third girdle are done to increase dry matter although there is a correlation between the two.
If done well, girdling has the potential for large financial gains. As you can see in figure 3. the December girdle on Gold3 added 1.0% dry matter;
and adding a February girdle to December and January girdles added a further 1.1% dry matter. A total of 2.1% dry matter was added by girdling
in both January and February. This increase has a significant impact on your TZG (Taste Zespri Grade) payments.