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.
| Treatment | Year | Total 1995–98 | Percentage reduction | ||||
|---|---|---|---|---|---|---|---|
| Prior | After treatment | ||||||
| 1994 | 1995 | 1996 | 1997 | 1998 | |||
| White oak | |||||||
| Control | 4.95 a | 4.43 a | 5.06 a | 4.50 a | 6.11 a | 20.10 a | |
| Treated | 5.30 a | 1.60 b | 0.99 b | 0.70 b | 0.71 b | 4.00 b | 80 |
| Red oak | |||||||
| Control | 6.19 a | 4.65 a | 4.65 a | 4.03 a | 5.57 a | 18.90 a | |
| Treated | 6.24 a | 2.68 b | 1.78 b | 1.37 b | 1.81 b | 7.64 b | 60 |
Pairs of values followed by the same lowercase letter are not significantly different at the P ≤ 0.05 level.