Penn State’s Dr. Jim Schupp says that the inconsistent results with chemical thinners led to researcher interest in mechanical thinners. After a decade of searching for effective chemical blossom thinners for Pacific Northwest stone fruit growers, researchers are still empty-handed. The Washington Tree Fruit Research Commission has evaluated chemical thinners for stone fruit since 2000, testing a variety of products, including ATS (ammonium thiosulfate), Tergitol (a polyglycol surfactant), NC 99, fish oil and lime sulfur, Armothin (ethoxylated propoxylated tallow alkyl amines), and vegetable oil. Nearly two dozen trials have been conducted in grower-cooperator plots to assess the effectiveness of chemical […]