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Abscission :: Harvesting Management


Fruit response to an abscission agent depends on numerous factors including application method, active ingredient concentration and volume of delivery, environmental variables and fruit maturity. We are working to define citrus harvesting management scenarios that will assist the citrus industry in defining where, when and how to apply abscission agents for optimum removal with mechanical harvesting technologies.


  • Define effective abscission compound application methods, rates and timing.
  • Examine the effect of abscission agent application on yield.
  • Examine the role of temperature’s effect on efficacy of CMNP.

Key Findings (Updated on 09/10)

The abscission agent CMNP is a mature fruit abscission agent that disrupts fruit source-sink relationships and causes premature senescence, resulting in abscission of the organ. Other non-selective abscission agents such as ethephon cause excessive leaf drop; however, leaf drop can be greatly reduced by using 1-MCP, an ethylene perception blocker. We found that the fruit’s sensitivity to any abscission agent changes markedly during the day, and this knowledge of proper timing can be used to increase efficacy of abscission sprays.

We are providing information identifying environmental factors that control abscission. Together with previous research, this can be used to better predict and control the abscission process. Our expertise in abscission and mechanical harvesting has been used to assist other fruit crop commodities that are seeking to control abscission and mechanize the harvesting process.

Activities Planned for 2010-2011

  • Early and mid-season abscission agent and harvesting trials at several locations. Research will focus on varying active ingredient concentration and application volume.
  • Follow return yield of previous years’ harvest trials to determine the effect of abscission agent application combined with mechanical harvesting on yield.
  • Develop a data base of previous and current studies to define the role of temperature on efficacy of CMNP
  • Evaluate CMNP application and variable tractor speeds on harvest efficiency.
  • Develop a series of EDIS documents for CMNP and mechanical harvesting settings.

Publications and Extension Products


Alferez F, Alquezar B, Burns JK, Zacarias L (2010) Variation in water, osmotic and turgor potential in peel of 'Marsh' grapefruit during development of postharvest peel pitting. Postharvest Bioi Technol 56:44-49.

Liao H-L, Burns JK (2010) Light controls phospholipase A2a and phospholipase B gene expression. J Exp Bot doi:10.1093/ jxb/erq083.

Castro-Garcia S, Rosa UA, Gliever CJ, Smith D, Burns JK, Krueger WH, Ferguson L, Glozer K (2009) Evaluation of table olive damage during harvest with a canopy shake-and-catch system. HortTech 19:260-266.

Ebel RC, Burns JK, Morgan KT (2009) Spray volume, distribution, and efficacy of 5-chloro-3-methyl-4-nitro-1H. pyrazole for loosening sweet orange. HortScience 44:1895-1899.

Pozo, L, Burns JK (2009) Organ loss and yield impacts of 'Valencia' sweet orange in response to fruit abscission agents. HortScience 44:83-88.

Ebel RC, Burns JK, Morgan K, Roka FM (2009) Interaction of CMNP concentration and canopy shaker setting on fruit removal of sweet orange. Proc. Fla. State Hort. Soc. 122: 132-135.


Burns JK (2007) What’s shakin’. Abscission program update. Citrus Industry 88 (May):18.

Hyman B, Roka FM, Whitney J, Burns JK, Burks TF (2007) The past, present and future of mechanical harvesting. Florida Grower (in press).

Roka FM, Burns JK (2007) Benefits of an abscission agent for mechanically harvested citrus. Citrus Industry 88 (4):22-24.

Roka FM, Burns JK (2007) Needing Separation. Florida Grower Magazine, March 2007.

Presentations associated with 2009-10 efforts:

Burns JK (2009) Current state of the science related to fruit abscission. American Society for Horticultural Science Annual Conference, Ju ly 25-28, 2009. SI. Louis, Missouri. Oral presentation.

Ferguson L, Rosa U, Castro S, Burns JK, Glozer K, Krueger WH, O'Connell N, Ortiz JM, Ladux JL, Fernandez FJ, Searles PS, Ferguson JH, Kulakow P, Rosecrance R (2009) Developing mechanical harvesting for California Black Ripe Process Table Olives Olea europaea cv. Manzanillo. American Society for Horticultural Science Annual Conference, July 25-28,2009, St. Louis, MO. Poster Presentation.

Brochures and Posters:

Evaluating The Use of an Abscission Agent with Citrus Mechanical Harvesting Systems, Barbara Hyman, Jacqueline Burns, and Fritz Roka. Brochure

Evaluating The Use of an Abscission Agent with Citrus Mechanical Harvesting Systems, Barbara Hyman, Jacqueline Burns, and Fritz Roka. Poster

For more information:

Jacqueline Burns
Bob Ebel
Kelly Morgan

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