Only a percentage of avocados ever make it to harvest but CSIRO research is working on ways to combat what is called immature fruit abscission or early fruit drop, a major challenge faced by growers.
A five-year research project from CSIRO , Australia's national science agency, supported by Hort Innovation uncovered results suggesting that hormonal changes in the seed coat of the fruit were initiating immature fruit drop.
The findings have now been published in the Journal of Experimental Botany with the next step, research to develop responses to the problem.
CSIRO project lead Dr Harley Smith said the first stage of the project focussed on understanding the developmental and physiological factors that mediate immature fruit abscission when a tree will shed a majority of fruitlets.
"Our research indicated that hormonal reprogramming in the seed coat (the maternal organ that envelops the seed) was the deciding factor that initiated immature fruit abscission, in response to reduced carbohydrate availability," Dr Smith said.
Avocado growers are now turning their interest to R&D investment aimed at managing fruitlet abscission.
Dr Smith said the findings of research into new management tools to reduce fruitlet drop would support an industry that produces more than 130 thousand tonnes of avocados annually and is worth around $800m to the Australian economy.
"During the summer months, it is really frustrating for growers to be walking through an orchard, listening to the thumping of immature fruit hitting the ground and not having any way to manage that loss in yield," said Dr Smith.
"Further, the fact that immature fruit abscission is influenced by the environment, means this process is an underlying factor that contributes to fluctuations in annual yield, which impacts market development."
In the second phase of the research, the team leveraged the research results and identified plant growth regulators that have potential to reduce immature fruit drop.
Avocados Australia CEO John Tyas said growers welcomed the findings around the cause of early fruit drop and are looking forward to the outcomes of the new research into management of the issue.
"This research is very important for the Australian avocado industry, especially in Queensland and Western Australia where immature fruit abscission is a major factor that reduces yield."
With avocado growers reporting as much as 80 per cent fruit drop in their annual crops, Mr Tyas said any actions that can increase and stabilise yield will be welcome.
"We've been trying to get to the bottom of this fruit drop challenge since the late 70s, so it's great to understand the challenge and move forward with work looking at a response for growers."
