|Authors: ||T.M. Yoon, T.L. Robinson, J.L. Osborne|
|Keywords: ||Prunus persica, ammonium thio-sulfate, ATS, lime sulfur, Tergitol, fruit set, crop load, fruit size|
The thinning response of ‘Redhaven’ and ‘Babygold 5’ peaches to rate and timing of ammonium thio-sulfate (ATS), lime sulfur plus fish oil (LS+FO) and Tergitol® sprays was studied in a field trial at Geneva, New York State, USA in 2007. With ‘Redhaven’, ATS showed increased thinning with increasing rate with the high rate of ATS (4.5%) resulting in over-thinning (11% fruit set). The lower rates of ATS 1.5% or 3% ATS resulted in intermediate fruit set but less thinning than the hand thinned controls.
Tergitol® also caused increased thinning as rate increased with excessive thinning at the highest rate (3%) which had only 4% fruit set.
At the lower rates of 1% or 2% Tergitol fruit set was similar to the hand thinned controls.
LS+FO did not show a rate response with similar thinning at 1, 2 or 3%. Two applications of ATS, LS+FO or Tergitol reduced fruit set more than one application.
Two sprays of 1% Tergitol burned most of the flowers and led to only 5% fruit set.
Considering both yield and fruit size, two sprays of 1% or 2% LS+FO, 2 sprays of 3% ATS or a single spray of 2% Tergitol seem to be promising to thin ‘Redhaven’ peach blossoms.
With ‘Babygold 5’, Tergitol and ATS caused greater thinning as the rate increased but the high rate of Tergitol (3%) burned almost all flowers.
Two sprays of 1.5% ATS and 2% LS+FO reduced crop load more effectively than a single spray.
Two sprays of 0.5% Tergitol effectively thinned blossoms but when the rate was higher (1%), the spray almost eliminated fruit set.
Considering both yield and fruit size a single spray of 4.5% ATS, 1% Tergitol or 3% LS+FO at 80% bloom, look promising as blossom thinning treatments for ‘Babygold 5’. Alternatively, two sprays of 1.5% ATS, 0.5% Tergitol or 2% LS+FO at 50% and 80% bloom, were also promising.
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