Fruit size management of citrus

Page last updated: Monday, 18 November 2019 - 9:06am

Please note: This content may be out of date and is currently under review.

Fruit size is an important feature for accessing desired markets and is largely determined by crop load.  Tree manipulation practices can be used by orchardists at a number of key crop stages to influence the size of fruit at harvest.

Manipulation practices

Some of the manipulation practices are listed below. More information is provided in each heading in the pages that follow.

  • Flower suppression
  • Pruning
  • Chemical thinning
  • Hand thinning
  • Harvest timing
  • Nutrition
  • Irrigation

Flower suppression

In the south west of Western Australia floral initiation of citrus usually occurs between June and July however identifying the difference between vegetative and floral shoots cannot be determined until early spring.

Many factors can influence flowering of citrus such as:

  • past physiological history of the tree
  • temperature
  • water stress

Gibberellic acid (GA) inhibits flower initiation in citrus, and has been used in other citrus growing countries for this purpose for a number of years. Ralex® is presently the only registered gibberellic acid compound for flower suppression in Australia where it is registered for use in both navel oranges and mandarins.

Leafless inflorescences produce a lot of white blossom but few leaves and produce smaller and less desirable fruit than leafy inflorecences which produce fewer flowers but fruit of better size. GA applications during flower initiation have been shown to reduce the number of leafless inflorescences and increase the more desirable leafy inflorescences which produce larger fruit.

The objective of flower suppression is to manipulate the forming bud into a vegetative state before any determination of floral parts has occurred.

Applications of GA should be made as directed on the label and be trialed on small areas to fine tune the technique on your own property.


Contact information

Kevin Lacey