Inter-seasonal irregular bearing (AV23000)

What was it all about?

This project built new knowledge to help manage irregular bearing in avocados by targeting summer fruit drop, a major cause of yield variability. It identified plant growth regulators (PGRs) with potential to reduce fruit loss during summer without harming fruit development. The work also confirmed that maintaining good canopy leaf area is critical for supporting fruit development and reducing fruit drop.

The project tested several PGRs over two seasons to understand how they affect fruit drop, seed coat function and tree physiology. Researchers measured fruit retention, yield, hormones and sugars in developing fruitlets, and examined how the summer vegetative flush aligns with peak fruit drop. Extension activities supported industry uptake, including an article in Talking Avocados and presentations at regional avocado forums to explain the findings and practical implications for growers.

Irregular bearing is a significant challenge that negatively impacts productivity and limits market development for the Australian avocado industry. The irregular bearing nature that underlies variation in annual yield is because avocado experiences poor fruit set, high fruitlet abscission and biennial bearing, all of which are influenced by the environment. Currently, there are no effective tools to manage the drivers of irregular bearing, including the summer fruitlet abscission event.

The findings from this research provide a foundation for future R&D to develop practical orchard tools that improve yield consistency. With further testing and validation, this work is expected to support more reliable production, better orchard management decisions and stronger long-term industry sustainability.