MAY 2024
CELEBRATING 145 YEARS AS CANADA’S PREMIER HORTICULTURAL PUBLICATION
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SOFT CHEMISTRY
Reducing labour by regulating plant growth in tender fruits
For many years, apple growers have had access to plant growth regulators, an aid in thinning blossoms and managing crop loads. Valent BioSciences has registered Accede PGR for peaches and nectarines, a breakthrough practice for tender fruit growers in the U.S. David Hipple has participated in product trials in his Beamsville, Ontario peach orchard with hopes that a label extension will be granted in Canada. Photo by Marcella DiLonardo.
KAREN DAVIDSON Always capricious but, in the mood, Mother Nature can also be quite forgiving. Consider tender fruit. Just 15 per cent of an orchard’s blooms need to be pollinated for yield to be profitable. This means that either the blossoms or the developing fruit need to be thinned. Apple and pear growers have access to chemical thinners to help manage crop loads to ensure good fruit sizing and quality while peach growers are restricted to thinning fruit by hand. And topping out at more than $1013/ acre, the long- held practice currently results in a peach production expense ranking second only to harvest labour costs. This recent metric from the Ontario Ministry of Agriculture, Food and Rural Affairs (OMFARA) provides a timely focus on new technologies targeted at helping to reduce labour costs. One such product is Accede, a new plant growth regulator (PGR) from Valent BioSciences,
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and the first chemical thinner registered in the United States for use on peaches and nectarines. Its active ingredient, ACC, encourages the plant to produce ethylene, a gas acting as a naturally occurring plant hormone to regulate fruit drop, colouring, and ripening. The product is already registered for use in Canadian apples. Depending on approval of Valent’s application to the regulators, the technology could be available to tender fruit growers as a minor use extension to the label in as little as a couple of years. University of Guelph pomology professor John Cline has hands-on experience with Accede, having just completed six trial growing seasons using the product’s soluble granular formulation. This project gained more hands on deck in 2022 with Kathryn Carter, an OMAFRA fruit crop specialist, and in 2023 with Sofia Franzluebbers, an MSc candidate at Guelph. The Canadian team has been encouraged by previous trials in the U.S. where Accede was shown to reduce peach fruit set by an average of 40 per cent and nectarine
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fruit set by an average of 25 per cent. When sharing these results at a product webinar in November 2023, Valent BioSciences noted that ACC can be applied from pink bud to petal fall to achieve these results. “The earlier the thinning, the better effect on size because you’re not wasting carbohydrates of the tree,” said Jozsef Rocsko, senior product development manager, Valent BioSciences. This points to chemical thinners possibly becoming a valuable tool to help overcome poor sizing for early-season peach varieties. As for labour benefits, Anna Wallis, IPM co-ordinator for fruit at Cornell University, noted, “A first application of Accede in peaches at 20 per cent bloom and a second application at 100 percent bloom can result in a significant reduction in fruit, cutting follow-up hand thinning almost by half. And using ACC can decrease the number of picks for some peach varieties, resulting in additional labour efficiencies.” Continued on page 3
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