Table 4.

Annual xylem ring increment (mm) 50 cm from the ground line for white and red oak for the year prior to treatment and for 4 years after treatment with paclobutrazol in April 1995 using the soil drench method, with total reduction expressed as a percentage of untreated controls.

TreatmentYearTotal 1995–98Percentage reduction
PriorAfter treatment
White oak
Control4.95 a4.43 a5.06 a4.50 a6.11 a20.10 a
Treated5.30 a1.60 b0.99 b0.70 b0.71 b  4.00 b80
Red oak
Control6.19 a4.65 a4.65 a4.03 a5.57 a18.90 a
Treated6.24 a2.68 b1.78 b1.37 b1.81 b  7.64 b60
  • Pairs of values followed by the same lowercase letter are not significantly different at the P ≤ 0.05 level.