Combinations of Ethephon and Accel for Thinning 'Delicious' Apple Trees

Richard P. Marini

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


For 4 years, 'Redchief Delicious' apple [Malus xsylvestris (L.) Mill, var. domestica (Borkh.) Mansf.] trees were treated with ethephon and/or Accel (6-BA + Gibberellins4+7) when average fruit diameter was 5.0 to 11.4 mm. Effective thinning was obtained with ethephon at concentrations >500 mg·L-1 and with Accel at concentrations of 100 to 125 mg·L-1. In only 1 year out of 4 did combinations of Accel plus ethephon reduce fruit set more than either material applied alone. Repeat applications of either material alone or in combination reduced fruit set no more than single applications. Fruit weight was negatively related to the number of fruit per tree. After adjusting fruit weight for number of fruit per tree at harvest with analysis of covariance, ethephon did not improve fruit weight at harvest, but Accel improved fruit weight in two of three experiments. The effect of combinations of Accel and ethephon on fruit weight was inconsistent Chemical names used: 2-chloroethyl phosphonic acid (ethephon); polyothyethylleneploypropanol dihydroxy-propane 2, butoxyethanol (Regulaid); N-(phenylmethyl)-1H-purine-6-amine plus giberrellinsA4+A7 (Accel).

Original languageEnglish (US)
Pages (from-to)175-181
Number of pages7
JournalJournal of the American Society for Horticultural Science
Issue number2
StatePublished - Mar 2004

All Science Journal Classification (ASJC) codes

  • Genetics
  • Horticulture


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