Ma. Rettke et Ap. Dahlenburg, Effect of timing of hand thinning on productivity of Moorpark apricots destined for drying, AUST J EX A, 39(7), 1999, pp. 885-889
Thinning at full bloom was compared with thinning at 3 stages of fruit deve
lopment and the effects on size, total soluble solids level (TSS) and yield
of apricots are reported. In 2 seasons separate branches of 9-year-old Moo
rpark apricot trees were hand-thinned to a density of 1 blossom or fruit pe
r 50 mm of fruiting wood. Times of thinning were at full bloom, 5-15 mm siz
e fruit, stone tip hardening and 21 days post stone tip hardening. These tr
eatments were compared with an unthinned control. Experimentation was carri
ed out at Loxton, South Australia. All thinning treatments reduced the yiel
d of fresh fruit. Thinning reduced yield of dried fruit irrespective of tim
ing in the first season but only at the 5-15 mm diameter fruit timing in th
e second season. Total soluble solids level of the fruit was increased by t
hinning which tended to improve drying ratio. Compared to the unthinned con
trol all thinning treatments increased the size of fresh fruit. Mean fruit
weight and diameter progressively decreased as thinning was delayed from fu
ll bloom till stone tip hardening. Thinning at full bloom produced higher y
ields of 35-mm-grade dried fruit than other treatments. To achieve the grea
test benefit from thinning it should be carried out at blossoming.