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

Abstract

<jats:p>For 4 years, `Redchief Delicious' apple [<jats:italic>Malus</jats:italic> ×<jats:italic>sylvestris</jats:italic> (L.) Mill. var. <jats:italic>domestica</jats:italic> (Borkh.) Mansf.] trees were treated with ethephon and/or Accel (6-BA + Gibberellins <jats:sub>4+7</jats:sub>) when average fruit diameter was 5.0 to 11.4 mm. Effective thinning was obtained with ethephon at concentrations &gt;500 mg·L<jats:sup>-1</jats:sup> and with Accel at concentrations of 100 to 125 mg·L<jats:sup>-1</jats:sup>. 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 giberrellins <jats:sub>A4 + A7</jats:sub> (Accel).</jats:p>

Multiple season-long sprays of ethephon or NAA combined with calcium chloride on ‘Honeycrisp’ apples: I. Effect on bloom and fruit quality attributes

“…In 2009, flowering was assessed individually by three individuals, who rated bloom on the entire tree using a 4-point scale where 0 represented no bloom, and 1-3 represented low, medium, and high bloom, respect tively adopted from Marini (2004). To improve upon this method, a more refined 6-point scale was used in subsequent years, where 0 represented no bloom and 1-5 represented very low, low, medium, high, and very high bloom respectively.…”

Improving the Productivity, Quality, and Storability of ‘Katja’ Apple by Better Orchard Management Procedures

“…The international trend for organic cultivation practices rather than chemical has renewed interest in hand thinning (Pretorious et al, 2004). In most cases, thinning increases fruit size (Marini, 2004;Tomala, 1997), firmness, and sweetness (Basak, 1999;Bergh, 1990) and improves superficial color (Link, 2000). Although some studies report no visible effects of thinning on fruit storability (Krzewinska et al, 2002), others report a tendency for decreased storage potential related to thinning (Wójcik et al, 2001) and decreased yield (Basak, 1999).…”

Flower Abscission and Induction in North American Ginseng with Ethephon

“…Concentrations of 750 to 1500 mg•L -1 of ethephon were consistently successful in the experiments carried out over the two year period, achieving flower abscission and obtaining the desired root weight increase. However, response to applied ethephon was variable as found for other crops (Jones et al, 1989;Marini, 2004;Turnbull et al, 1999). In other studies the optimum concentration of ethephon to achieve desired results varied with the species and the plant organ being affected.…”

“…There was still some reddening of the leaves and early ripening of the seed head, but the severity of the injury was less than seen in the previous year. Erratic responses to ethephon as an apple thinner have been reviewed by Marini (2004).…”

“…Results from the highest concentrations of ethephon (3000 and 4000 mg•L -1 ) sprayed at this site were not as good as results from HR, even though they were the most successful treatment at removing the inflorescences. Jones et al (1989) and Marini (2004) reported that the concentration of ethephon, date of application, cultivar differences, temperature variation, blossom density and spray volume contributed to the variable results obtained when ethephon was sprayed at bloom time as a chemical thinner for apples. Some of these factors could apply to ginseng; other things may also apply.…”