Plant tissue and soil nutrient analyses.
Leaf N concentrations were slightly higher
in the CON and INT systems in 2002, but no
difference was measured in 2003 (Table 3). In
both years, all three systems were above the
critical nutrient range (CNR) for mature apple
trees (Table 3). In 2002, zinc (Zn) levels were
highest in CON leaf tissue and lowest in ORG
leaf tissue, but no differences were found in
2003 (Table 3). ORG trees were Zn de cient
in 2002 (Table 3) with visible symptoms,
including small thin chlorotic leaves, leaf
rosetting, and branches with sections of non-
bearing blind wood (Martin, 2004; Swietlik,
2002), observed in both years. There were no
symptoms of Zn de ciency in the CON or INT
systems. In 2003, leaf boron (B) concentrations
were greater in ORG than CON trees (Table
3). Although no B was applied from 2000 to
2002, all three systems were within or above
the CNR in 2002 and 2003 (Table 3). Leaf
manganese (Mn) levels were considerably
lower in the ORG system in 2002 and in the
ORG and INT systems in 2003 (Table 3), but
in both years all three treatments were within or
above the CNR. All other leaf mineral nutrient
levels were within or above the CNR (Table
3), therefore statistical differences among them
may not be physiologically important.