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New research supports use of ACTIGARD post-harvest

Kiwifruit
23.03.2021

ACTIGARD® is unique in that it interacts directly with the plant, triggering its natural self-defence mechanisms to help the plant protect itself from Psa infection.

Until recently, most research into the effectiveness of ACTIGARD focused on spring applications prior to flowering, where visual effects can be measured by how well leaf spotting and shoot dieback symptoms are controlled a few weeks after the application of ACTIGARD.

In 2019, Syngenta, Zespri/Kiwifruit Vine Health and Plant & Food Research collaborated on a research project using mature Hayward vines to get a better understanding of post-harvest use of ACTIGARD, and what impact (if any) it was having on kiwifruit vines during the post-harvest growth stage.

Tony Reglinski, Senior Research Scientist at Plant & Food Research explains: “The best way to understand the effect of ACTIGARD in the post-harvest window is to look for changes in the defence gene expression in the ACTIGARD treated vines compared with the untreated vines. Because an increase in gene expression is likely to equate to an increase in protection against Psa.”

The good news is both early and late harvested Hayward vines were responsive to ACTIGARD, as the gene response patterns were similar.

This highlights the value in using ACTIGARD post-harvest to help protect vines against Psa infection that can occur from fruit scars and leaf-fall scars during autumn. It also indicates good flexibility in the application timing of ACTIGARD in relation to leaf condition at the time of application.

A maximum of four sprays of ACTIGARD can be applied on kiwifruit per season at 21-day intervals.

This normally allows two sprays post-harvest (prior to leaf-fall) if the first is made immediately post-harvest.

To avoid risk of residues on fruit when spraying ACTIGARD post-harvest, extreme care must be taken to prevent spray drift into unharvested fruit in adjacent blocks.

For more information on the use of ACTIGARD post-harvest and new research results click here