WITH limited trial work completed in Western Australia on stonefruit using the new plant growth regulator prior to registration, the workshop brought together a group of growers who will be participating in small-scale demonstration sites to share practical knowledge and establish a consistent approach to this new technology for stonefruit producers.

Chemical thinning has the potential to become an important management tool for the stonefruit industry.

As one of the most labour-intensive and costly orchard operations, effective thinning plays a significant role in achieving profitable yields, improved fruit size and quality.

Understanding how this new crop thinning tool performs under Western Australian conditions will be an important part of its adoption.

The aim of the day was to provide producers with expert support in sprayer calibration across two different spray setups, nozzle selection and positioning, and application techniques. Ensuring the sprayers were correctly calibrated, and the plant growth regulator applied in accordance with label instructions, will provide greater confidence that ongoing observations throughout the season reflect product performance rather than differences in application.

Before any product was applied, water-sensitive paper was mounted across the full crop height within the target zone. The two spray units then completed a test run, allowing participants to visually assess droplet distribution and canopy penetration before confirming the final setup.

Once the calibration was confirmed, baseline assessments were completed within the demonstration blocks. Participating growers then worked together to identify treated and untreated control trees while recording flower bud numbers and blossom stage prior to the application. These observations will provide an important reference point, as crop response is monitored from application through to harvest.

The first demonstration site was established on an early nectarine variety. Later in the day, a second demonstration site was established at another participating orchard in the Perth Hills, which will host the WA Stonefruit Presents: Thinning Showcase on 9 September.

Additional participating producers will be included in future small scale demonstration sites within their own orchards.

As part of the next stage, an Ammonium Thiosulfate (ATS) will also be included. Stonefruit producers are familiar with ATS, although its effectiveness can vary depending on crop, location and timing. Including ATS will provide a useful point of comparison, giving producers additional information and more tools to consider when looking to minimise thinning costs while maximising fruit quality and production outcomes.