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Tree Health :: Abscission Implications


Removal of mature and young green fruit could be differentiated by using fruit abscission compounds provided they are selective for mature fruit. Some abscission chemicals can cause typical herbicide-like phytotoxic symptoms on citrus leaves. We studied the abscission chemical CMNP that has shown promise in terms of selectivity of fruit loosening along with low leaf phytotoxicity. Results could provide information that may assist the ongoing commercial registration effort of CMNP as an abscission agent for citrus.


Determine the photosynthetic ability and water status of leaves of fruiting citrus trees to determine the effects of CMNP in comparison to ethephon, a commercially available abscission compound which often causes excessive defoliation and young fruit drop

Key Findings (Updated on 10/07)

Using foliar application, CMNP not only effectively reduced fruit detachment force of mature citrus with no effect on young fruit, but intact citrus leaves showed little response.

Activities Planned for 2007-2008

Finish data analyses and publications.

Publications and Extension Products


Kuo-Tan Li, Jim Syvertsen, and Jackie Burns. 2005. Mechanical harvesting of Florida citrus trees has little effect on leaf water relation or return bloom. Proceedings of the Florida State Horticultural Society. 118:22-24.

Syvertsen, J.P. 2006. Citrus Harvesting and Utilization Effects on Production: Barriers and Opportunities. Symposium at FSHS Annual Meetings, 4-6 June. Tampa, FL

Li, Kuo-Tan, Jackie Burns, Luis Pozo, and J.P. Syvertsen. 2006. Effects of 5-chloro-3-methyl-4-nitro-1H-pyrazole and ethephon on citrus leaf function and water relations. Annual Meetings of ASHS, 27 -30 July, New Orleans, La. HortScience 41: 1008.

Kuo-Tan Li, Jackie Burns and Jim Syvertsen. 2008. Recovery from phytotoxicity after foliar application of fruit loosening abscission compounds to citrus

For more information:

Jim Syvertsen
Jacqueline Burns

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