Orchard productivity
Crop yields and tree growth. Two harvests
were conducted each year (130 and 137 d
after full bloom in 2002, and 124 and 127 d
after full bloom in 2003). Harvest analyses
were conducted on the rst harvest in 2002
and on the second harvest in 2003 based on
the optimal maturity for ‘Gala’ apples in each
season (Plotto et al., 1995). Calculations of
yield, yield ef ciency, crop load (number of
fruit per tree), average fruit weight, and amount
of unmarketable fruit were calculated at each
harvest by counting and weighing all of the
fruit from each of the 12 sample trees per
plot and are reported as the cumulative value
of the two harvests in each year. Tree growth
was assessed by calculating the trunk cross-
sectional area (TCSA) from measurements
of trunk circumference, assuming a circular
geometry, at 20 cm above the graft union of
the rootstock. Return bloom was calculated
by oral intensity (ratio of total ower buds
to total ower + vegetative buds) on three
branches of each sample tree.