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Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.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?

Berry collapse was an important issue for the table grape industry and to gain a better insight into its cause and the mechanisms involved, the problem had been investigated by CSIRO Plant Industry in collaboration with DPI, Victoria.

This project had focussed on identifying the causes (environmental and or management practices) of berry collapse in order to prevent or effectively reduce crop loss as a result of berry collapse in Thompson Seedless table grapes at harvest.

A key part of the research project involved setting up glasshouse trials to investigate the link between gibberellin (GA) sprays and heat and water stress. Several field trials had also been conducted on properties at Sunnycliffs and Birdwoodton to understand the impact, if any, of girdling (cincturing), water stress and rootstock selection on berry collapse.

The data collected from two glasshouse experiments suggested a strong link between GA sprays and berry collapse when vines were subjected to heat stress. Water stress further increased the incidences of berry collapse under hot glasshouse conditions.

Microscopy was carried out on berries collected from the glasshouse and from field trials to observe the process of collapse throughout the growing season. Extensive microscopy results suggested that berry collapse was due to cell death. It also suggested that brown striations on berries might be a good indicator of whether or not a berry would succumb to collapse symptoms.

Foliar application of Surround®, which reflected sunlight and reduced sunburn and heat stress, was made and its effect on berry growth and berry collapse symptoms was assessed.

The application of some chemicals known to be involved in plant defence mechanisms (salicylic acid), resulted in the reduction of berry collapse symptoms.

Management practices with the potential to exacerbate berry collapse symptoms, e.g. GA sprays and water deficit during hot weather conditions at and around fruit set and early berry growth, needed to be avoided to reduce berry collapse.