Spray variable effects on deposition and harvesting efficacy of cmn-pyrazole

Ezzeddine Bensalem, Masoud Salyani, Jodie D. Whitney


The renewed interest in mechanical harvesting of Florida citrus has intensified the investigations on using abscission chemicals to enhance fruit loosening and assist mechanical harvesting. Four tests were conducted using 5- chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole) in two commercial orange groves in central and south Florida. In Tests 1 and 2 the spray was delivered at different flow rates to the top and bottom halves of 'Hamlin' orange tree canopies. The other two tests were conducted in 'Valencia' orange grove. In Test 3, spray application variables were sprayer type, spray volume, and application time. In Test 4, spray application variables were sprayer type and spray release height. Spray deposition was assessed by fluorometry and the abscission chemical efficacy was quantified by measuring the fruit detachment force and the percent of fruit removed by a trunk shaker. Spray release height had a significant effect on spray deposition along the canopy height. However, deposition at different canopy heights was not proportional to spray delivery rate directed to different heights. Depositions on the outside and at the canopy edge were generally higher than those on the inside and at the tree center. In general, spray release height had significant effects on fruit loosening and removal. Deposition decreased with increased application volume, but higher application volume produced better effects on fruit loosening and removal. At low volume, night time application resulted in higher deposition than daytime application.


spray volume; 5-chloro-3-methyl-4-nitro-1h-pyrazole; pyranine; fruit detachment force; trunk shaker; citrus

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283