TITLE:
Branched Secondary Alcohol Ethoxylate, Ammonium Thiosulfate, Calcium Polysulfides-Thiosulfate, and Fish Oil Effects on Blossom Thinning, Fruit Set and Quality of Peaches and Nectarines
AUTHORS:
Esmaeil Fallahi, Amir A. Khoddamzadeh, Bahar Fallahi, Shahla Mahdavi
KEYWORDS:
Bio-Regulator, Crop Regulation, Fruit Thinning, Stone Fruit, Regular Cropping, Prunus persica
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.11 No.12,
December
11,
2020
ABSTRACT: Total crop load has an inverse relationship with fruit size, while larger
fruit size is often demanded by the peach and nectarine markets. Hand-thinning
is extremely expensive, and thus, crop load adjustment, using blossom thinners
is a crucial practice to ensure production of commercially acceptable fruit
size and yield efficiency in stone fruit. In this study, the influence of
branched secondary alcohol ethoxylate (Tergitol TMN-6) and/or ammonium
thiosulfate (ATS), Crocker Fish Oil (FO), and a mixture of calcium polysulfides and
thiosulfate (lime sulfur) on fruit set and quality attributes in peaches (Prunus persica) and nectarines (P. persica var. nectarina) were studied. All
blossom thinners reduced fruit set in “Summer Lady” peach in both 2016 and
2017. Fruit sets in “Summer Lady” peach trees with a
double application of Tergitol TMN-6 at the rate
of 7.5 or 10 mL ·Lˉ1, each rate applied at 40% and 80% bloom, were
lower than those receiving the same rates of this chemical only at 80% bloom,
but they were similar to those receiving a single Tergitol TMN-6 spray at 15
mL·Lˉ1 at 80% or 100% bloom. “Summer Lady” peach trees receiving FO
at 20 mL·Lˉ1 plus lime sulfur at 25 mL·Lˉ1, once at 40%
bloom and again at 80% bloom had lower fruit set as compared to Untreated
Control but the fruit set was higher than those with any Tergitol-TMN-6 spray.
Tergitol TMN-6 at 12 m·Lˉ1 at 100% bloom or 10 mL·Lˉ1 all
stages of bloom reduced fruit set in “Zee Lady” and “Snow Giant” peaches. In “Snow Giant” peach, trees receiving Tergitol
TMN-6 at all concentrations and blossom stages had significantly higher fruit
weight as compared to the trees of Un-treated Control. Applications of Tergitol TMN-6 at all concentrations at 80%
bloom reduced fruit set in “Red Globe” and “Elberta” peaches in Utah. ATS and
FO slightly reduced fruit set in peaches but they were less effective than
Tergitol TMN-6 in all cases. Overall, it is concluded that efficacy of blossom
thinners depends on the rate of thinners, temperature, cultivar and stage of bloom
development.