Flower thinning of apple cultivar Braeburn using ammonium and potassium thiosulfate: Short communication

Abstract

Milić B., Magazin N., Keserović Z., Dorić M., 2011. Flower thinning of apple cultivar Braeburn using ammonium and potassium thiosulfate -Short communicaton. Hort. Sci. (Prague), 38: 120-124.Ammonium and potassium thiosulfate are used commercially or experimentally as flower thinners because they are considered user, environment and consumer safe. The thinning trials were conducted in 2009 and 2010, on three-and four-year-old Braeburn Mariri Red* trees. The chemicals were applied at 1%, 2% and 3% rates of ammonium and 0.5%, 1% and 1.5% of potassium thiosulfate. Both thinning agents reduced fruit set, but were more efficient in 2009, when applied at 20% full bloom, than in 2010, when they were applied at 80% full bloom. Flower thinning with ammonium and potassium thiosulfate increased the average fruit weight, but the highest chemical rates retarded fruit growth. Ammonium and potassium thiosulfate did not affect fruit shape and firmness, but they increased starch degradation, total soluble solids content and titratable acidity. The treatments increased the percentage of flower buds, except at the highest chemical rates, where leaf damage reduced flower bud formation. Ammonium or potassium thiosulfate application may be recommended as the first step in a chemical thinning program.

Fruit set and quality of self-fertile sweet cherries as affected by chemical flower thinning

“…A negative linear relationship exists between fruit weight and diameter on the one hand and fruit to leaf area ratio on the other (Whiting, Lang 2004), which is why a healthy leaf area is a crucial factor that affects fruit size. It is previously reported by Milić et al (2011) that phytotoxicity occurred on apple leaves after 3% ATS application and caused a decrease in fruit weight. It is assumed that more leaf damage occurred on apple than on sweet cherry because, at the time of flowering, an apple tree develops a larger leaf area susceptible to burning than sweet cherry.…”

“…Although ammonium thiosulfate (ATS) successfully thins apple (Milić et al 2011) and peach flowers (Coneva, Cline 2006), its application on cherries, although effective in reducing fruit set, did not improve fruit size, weight and soluble solids contents (Schoedl et al 2009). Surfactant Armothin (Southwick et al 1996) and Tergitol-TMN-6 (Ambrožič Turk et al 2014) showed a promising flower thinning efficacy in peach while Silwet 408 significantly reduced fruit set in peach (Baugher et al 2008) and apple (Bound, Klein 2010).…”

Ammonium thiosulfate as blossom thinner in 'Maxi Gala' apple trees

“…At 1.5%, ATS shows a strong thinning which is capable of decreasing half of the amount of flowers produced by European plums, reducing yield and fruit set more severely than hand thinning, and as a consequence, increasing the fruit weight and quality (Meland, 2007). On apple, ATS at 2% significantly reduced fruit set and increased fruit weight (Milić et al, 2011). In the United States and Europe, the use of ATS is consolidated and there are plenty of research on this theme.…”

“…The lack of effective options other than hormonal thinners are still one of the main discussions among apple producers. There is plenty of information about the potential use of ATS as a chemical blossom thinner in cropping systems around the world (Meland, 2007;Milić et al, 2011;Maas, 2016), and it may have potentially promising results in Brazil.…”

Timing and rates of application of NAA as blossom and fruitlet chemical thinner on apple cv. and #712;Braeburn and #712;

“…Braeburn as it produces flowers abundantly and has a high fruit set as well. Since, high crop load leads in decreasing fruit size especially in young apple trees (Milić et al, 2011).…”