Abstract
In a 5-year study, available abscission chemicals were applied to 'Hamlin', 'Pineapple', and 'Valencia' orange trees, which were harvested with commercially available trunk shakers. In the first 2 years, abscission chemicals prosulfuron and metsulfuron- methyl were applied and loosened mature fruit, but were phytotoxic to the trees and young 'Valencia' fruit. Abscission chemical CMN-P (5-chloro-3-methyl-4-nitro-1H-pyrazole) was applied the last 3 years and it provided better loosening of mature fruit without being phytotoxic to the trees, young 'Valencia' fruit, or reducing yields. Trunk circumference growth was not affected by shaker and/or abscission chemicals. CMNP increased total fruit removal of the trunk shaker an average of 9%. Trunk shakers did not significantly reduce total yields compared to conventional manual harvesting methods.
