Ferguson, Louise

Burns, Jackie :

Barrett, Diane M

Glozer Dr, Kitren

Rosecrance, Richard :

Einhorn, Todd :

Krueger, William H

O'Connell, Neil V

Freeman, Mark W.

Sibbett, G. Steven

Screening and Testing Potential Abscission Compounds Project Leaders : Louise Ferguson , Department of Plant Sciences , 2037 Wickson Hall , Mail Stop II , University of California , 1 Shields Ave . , Davis CA 95616 ; ( O ) 530 - 752 - 0507 ; ( M ) 559 - 737 - 3061 ; LFerguson @ ucdavis.edu Jackie Burns , Department of Plant Sciences , Citrus Research and Education Center , University of Florida , 700 Experiment station Road , Lake Alfred Florida , 33850 - 2299 ; ( O ) 863 - 956 - 1151 ; Ext 1285 , ( M ) JKBU @ ufl.edu Cooperators : Diane Barrett , Extension Specialist , University of California , Davis ; DMBarrett @ ucdavis.edu Kitren Glozer , Associate Project Scientist , University of California , Davis ; kglozer @ ucdavis.edu Rich Rosecrance , Associate Professor , California State University â?? Chico ; Rosecrance @ CSUChico.edu Todd Einhorn , Assistant Professor , California State University â?? Fresno ; TEinhorn @ CSUFresno.edu William H . Krueger , UCCE Farm Advisor , Glenn County , CA ; WHKrueger @ ucdavis.edu Neil Oâ??Connell , UCCE Farm Advisor , Tulare County , CA ; NVOConnell @ ucdavis.edu Mark Freeman , UCCE Farm Advisor , Fresno County , CA ; MWFreeman @ ucdavis.edu Steven T . Sibbett , UCCE Farm Advisor Emeritus ; Sibbett @ lightspeed.net Reporting period : 2007 â?? 2008 ( Anticipated Duration of Project : Year 1 of 4 ) ABSTRACT The abscission trials demonstrated ethephon and a numbered compound , # 901 , had the best potential for decreasing fruit detachment force . However , ethephon was erratic in performance and had leaf loss . Developing an abscission agent remains a long term goal . INTRODUCTION Developing an abscission compound , which would decrease the amount of force required to detach olives from the olive tree could also increase harvester efficiency and decrease fruit damage . However , registering growth regulators for any crop , particularly a small specialty crop , is a long term process requiring 10 years or more . The first step is identifying potential abscission compounds . OBJECTIVES Our objectives for this section were : â?¢ Evaluaate the ERC ( Ethylene Releasing Compounds ) that demonstrated potential in 2006 â?¢ Screen new compounds for fruit detachment force reduction PROCEDURES All screening trials were done on replications of individually tagged branches . Individual branches were tagged , initial fruit number counted , and sprays applied with had held spray bottles . Within 10 days to 2 weeks fruit number were counted and fruit detachment force was measured using an Imada pull force tester . Leaf loss , fruit and leaf burn , and fruit shrivel and drop were evaluated visually using a 4 point scale ; 0 equaled no visible effect , 1 = mild , 2 = moderate 3 = severe . RESULTS In 2006 screening trials identified the ethylene releasing compound ( ERC ) , ( 2 - chloroethyl phosphonic acid ) ethephon , and HarvestVant , an Israeli product containing MPK and ethephon , as potential abscission agents . These and other compounds were tested in 2007 . The results of two screening trials are given in Tables 5 and 6 below . The screening results in Table 5 reinforce the data obtained in 2006 . Only ethephon at higher concentrations , 5000 ppm and above , continued to reduce fruit detachment force but leaf loss remained a problem . A new numbered compound , # 901 , reduced fruit detachment with only moderate leaf loss . Table 5 . Abscission Compound Screening Trials at Lindcove Field Station . Screening trials , table olives - Sept Oct 2007 Leaf loss , leaf burn , fruit burn and fruit shrivel subjective ratings : 0 - no visual effect ; 1 - slight ; 2 - moderate ; 3 - severe Applications Sept 28 & 29 - measurements October 9 & 10 , 2007 DATA OVERVIEW - Lindcove leaf burn FDF ( g ) leaf loss frt burn frt shvl % frt drop 0.0 402 0.0 0.0 0.3 4 control 0.0 125 1.5 0.3 0.3 6 1 ppm 901 0.0 165 2.3 0.3 0.5 2 2 ppm 901 0.0 362 0.0 0.3 0.3 0 200 ppm 589 0.0 408 0.0 0.5 0.0 7 1000 ppm 589 0.0 353 0.5 0.3 0.0 0 2000 ppm 589 0.0 349 0.5 0.8 0.5 0 200 ppm 111 0.3 405 0.0 0.5 0.5 0 1000 ppm 111 1.0 289 1.3 2.0 0.0 0 2000 ppm 111 0.0 182 2.0 0.5 0.0 28 5 mM TIBA + 5000 ppm ethephon 0.0 138 2.0 0.5 0.0 23 5 mM TIBA + 7500 ppm ethephon 387 0.0 0.0 0.5 0.0 0 5 mM TIBA 225 0.0 2.0 1.0 0.0 45 5000 ppm ethephon 49 0.0 2.5 0.8 0.0 47 7500 ppm ethephon 394 0.0 0.0 0.3 0.3 0 5 mM 2 - NAA 215 0.0 3.0 1.0 0.3 23 5 mM 2 - NAA + 5000 ppm ethephon 132 0.0 5 mM 2 - NAA + 7500 ppm ethephon 3.0 1.0 0.5 48 372 0.0 5 mM CPMPA 0.3 0.8 0.3 0 177 0.0 5 mM CPMPA + 5000 ppm ethephon 2.5 0.8 0.0 40 68 0.0 5 mM CPMPA + 7500 ppm ethephon 2.8 0.8 0.3 66 383 0.0 control 0.0 0.0 0.3 0 The results in Table 6 are similar . Ethephon at higher concentrations , 2500 ppm and above reduced fruit detachment force with moderate to severe leaf loss . However , results were erratic as one 2500 ppm application failed to decrease fruit removal force . Numbered compound # 901 again reduced fruit detachment force with a low leaf loss . Given the potential value of an abscission compound for mechanical - harvesting , attempts to further define ethephon performance , and screening for new compounds should continue . However , it should be recognized this is a long term objective , and development of mechanical harvesting should proceed as if we will not obtain an abscission agent in the near future . Table 6 . Abscission Compound Screening at Nichols Estate . Screening trials , table olives - Sept Oct 2007 Leaf loss , leaf burn , fruit burn and fruit shrivel subjective ratings : 0 - no visual effect ; 1 - slight ; 2 - moderate ; 3 - severe application October 14 - measurements October 26 , 2007 DATA OVERVIEW - Nichols Estate FDF ( g ) leaf loss frt burn % frt drop 4 % MPK 297 1.5 0.5 13 2500 ppm ethephon 415 1.8 0 6 2500 ppm ethephon + 4 % MPK 99 2.3 0 42 5000 ppm ethephon 151 2.8 0.5 38 5000 ppm ethephon + 4 % MPK 56 3 0.3 68 0.1 % RNAsi silicon adjuvant 404 0 0.5 3 1X HarvestVant ( 40 g / L ) 376 0.8 0 0 0.5X HarvestVant ( 20 g / L ) 394 0.3 0 5 2 ppm 901 298 0.5 0.3 4 1 ppm 901 264 0.8 0.3 2 0.5 ppm 901 367 0.5 0.5 2 2000 ppm dikegulac 1 ( 18.5 % ai ) 421 0 0.3 0 4000 ppm dikegulac 1 ( 18.5 % ai ) 332 0 0.5 0 2000 ppm dikegulac 2 ( 9.45 % ai ) 222 2 0.5 5 4000 ppm dikegulac 2 ( 9.45 % ai ) 142 2.8 0.5 15 2000 ppm dikegulac 3 ( 4.47 % ai ) 102 2.5 0.5 18 4000 ppm dikegulac 3 ( 4.47 % ai ) 75 3 0.5 45 0.1 % dikegulac adjuvant 408 0 0.5 0