Potential and Challenges of Branched Secondary Alcohol Ethoxylate and Fish Oil Applications as Blossom Thinners in Apples

Thinning excessive fruit in apples is an essential but expensive cultural practice and the use of blossom thinners can facilitate this practice. To assess the potential and challenges of branched secondary alcohol ethoxylate (Tergitol TMN-6) and Crocker Fish Oil (CFO) as blossom thinners, their impacts on fruit set, yield, and fruit quality of Delicious , Top Export Fuji and Early Spur Rome apples (Malus domestica Borkh)were studied. Application of Tergitol TMN-6 at all rates reduced fruit set, yield per tree, and fruit weight in Top Export Fuji . Applications of Tergitol TMN-6 at all rates in Delicious and at the rate of 3.12 mL.L-1 in Top Export Fuji apples were challenging and caused phytotoxicity, induced fruit russeting in both cultivars and resulted in smaller fruit and lower yield in Top Export Fuji . The exent of russeting was diercetly proporotional to the Tergitol TMN-6 rate. The use of CFO at 30 mL.L-1 alone did not have any significant effects on yield per tree, fruit weight, or fruit color, while significantly reduced fruit sunburn and increased fruit russeting in Top Export Fuji . In Early Spur Rome apple, application of Tergitol TMN-6 at or higher than 1.87 mL.L-1reduced fruit set. Despite fruit set reduction, application of Tergitol TMN-6 at the rate of 1.87 mL.L-1 did not reduce total yield per tree, fruit weight, fruit color, or fruit russeting when compared to Un-treated Control and thus, this rate can be recommended for blossom thinning in Early Spur Rome apple.