CHEMICALLY INDUCED ABSCISSION AS A TOOL IN THE MECHANICAL HARVESTING OF FLORIDA CITRUS

Driven by increasing labor costs the Florida citrus industry is gradually adopting mechanical harvesting of juice oranges.
A variety of trunk and canopy shakers have been developed and are in various stages of commercialization.
Fruit removal with these machine ranges from 60–95%, depending on type of harvester.
Chemical fruit loosening would improve the removal rate.
In the past, a number of abscission compounds were tested with varying success but none was registered for commercial use.
In field sprays we screened 10 Jasmonate derivatives and 25 chemicals with structural similarities to 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole) for their abscission activity.
Some of the jasmonates showed abscission activity, with methyl-jasmonate (MJ) and methyl-dihydro-jasmonate achieving the best loosening.
Several CMN-pyrazole analogs caused a reduction in fruit detachment force (FDF). However, high activity was coupled with high phytotoxicity.
None of the tested chemicals from either group loosened fruit as effectively as CMN-pyrazole.

II ISHS Conference on Fruit Production in the Tropics and Subtropics

U. Hartmond, W. Kender, J. Burns

CMN-pyrazole, fruit, harvest, jasmonic acid, methyl-jasmonate

https://doi.org/10.17660/ActaHortic.2000.531.22