Re. Byers et Rp. Marini, INFLUENCE OF BLOSSOM AND FRUIT THINNING ON PEACH FLOWER BUD TOLERANCETO AN EARLY SPRING FREEZE, HortScience, 29(3), 1994, pp. 146-148
Peach trees [Prunus persica (L.) Batsch.] blossom-thinned by hand were
overthinned due to poor fruit set of the remaining flowers; however,
their yield was equivalent to trees hand-thinned 38 or 68 days after f
ull bloom (AFB). Blossom-thinned trees had three times the number of f
lower buds per unit length of shoot and had more than two times the pe
rcentage of live buds after a March freeze that had occurred at early
bud swell the following spring. Blossom-thinned trees were more vigoro
us; their pruning weight increased 45%. For blossom-thinned trees, the
number of flowers per square centimeter limb cross-sectional area (CS
A) was two times that of hand-thinned trees and four times that of the
control trees for the next season. Fruit set of blossom-thinned trees
was increased four times. Flower buds on the bottom half of shoots on
blossom-thinned trees were more cold tolerant than when hand-thinned
68 days AFB. Fruit set per square centimeter limb CSA was 400% greater
the following year on blossom-thinned trees compared to controls. Rem
oving strong upright shoots on scaffold limbs and at renewal points ea
rly in their development decreased dormant pruning time and weight and
increased red pigmentation of fruit at the second picking. The number
of flower buds per unit shoot length and percent live buds after the
spring freeze were negatively related to crop density the previous sea
son for trees that had been hand-thinned to varying crop densities at
48 days AFB. According to these results, blossom thinning and fruit th
inning to moderate crop densities can influence the cold tolerance of
peach flower buds in late winter.