International Alternate Bearing Summit_ Phase one of alternate bearing solutions for avocado growers (AV09009)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

The effects of alternate bearing (AB) and irregular bearing (IB) created major challenges to growers and marketers of avocados throughout Australia and the world.

The AB problem was common to most tree fruit crops, and varies in intensity, AB could manifest countrywide, regionally, on a specific farm and even in the branches of a single tree. AB was typically initiated by an abnormally heavy or light crop in young trees, followed by a light or heavy subsequent crop. This pattern then became entrained and difficult to change unless severe climatic events intervened, or drastic management interventions were made. A heavy "on" crop results in reduced vegetative shoot and root flushing, and less carbohydrate (energy reserves) build-up. Seed gibberellins may have also reduced flower bud initiation. Fewer flowering and fruiting sites for next season's cropping were formed, and flowering intensity was reduced. Many complex interacting factors affect AB intensity.

The issue of AB in avocados was seen in varying degrees across all production areas in Australia and also globally.

This summit seeked to establish a large scale international project in partnership with New Zealand, USA, Mexico, Chile and South Africa, to challenge the understanding and develop solutions for the issue of alternate bearing in avocados.

Australian research capacity was limited in this area of science, as was the world. The ability to work jointly and draw on the avocado researchers and funding was the only way the Australian industry was able to achieve a positive improvement.