Annual xylem ring increment (mm) for the year prior to treatment and for 3 years after treatment with paclobutrazol in April 1996 using the soil injection method on eight tree species growing in Indiana, with total reduction expressed as a percentage of untreated controls.
| Treatment | Year | Total 1996–98 | Percentage reduction | |||
|---|---|---|---|---|---|---|
| Prior | After treatment | |||||
| 1995 | 1996 | 1997 | 1998 | |||
| Black walnut | ||||||
| Within crown | ||||||
| Control | 1.36 a | 1.38 a | 1.06 a | 1.08 a | 3.52 a | |
| Treated | 0.82 a | 1.28 a | 0.99 a | 0.94 a | 3.21 a | 9 |
| Mid-trunk (2—4 m high) | ||||||
| Control | 2.05 a | 2.44 a | 1.46 a | 1.67 a | 5.57 a | |
| Treated | 1.74 a | 1.54 a | 1.14 a | 1.40 a | 4.08 a | 27 |
| Base of trunk (10 cm above ground line) | ||||||
| Control | 1.86 a | 1.42 a | 1.25 a | 1.66 a | 4.33 a | |
| Treated | 2.06 a | 1.61 a | 1.05 a | 1.04 a | 3.70 a | 15 |
| European black alder | ||||||
| Within crown | ||||||
| Control | 2.06 a | 1.84 a | 1.46 a | 1.50 a | 4.80 a | |
| Treated | 2.59 a | 1.20 a | 1.11 a | 1.29 a | 3.60 a | 25 |
| Mid-trunk (2—4 m high) | ||||||
| Control | 5.80 a | 5.00 a | 3.90 a | 6.27 a | 15.17 a | |
| Treated | 3.15 a | 2.16 b | 1.27 b | 2.40 b | 5.83 b | 62 |
| Base of trunk (10 cm above ground line) | ||||||
| Control | 5.19 a | 3.85 a | 3.30 a | 4.45 a | 11.60 a | |
| Treated | 5.00 a | 3.25 a | 2.73 a | 2.25 b | 8.23 a | 29 |
| Red oak | ||||||
| Within crown | ||||||
| Control | 3.14 a | 2.16 a | 2.07 a | 3.36 a | 7.59 a | |
| Treated | 4.54 a | 2.38 a | 1.80 a | 2.85 a | 7.03 a | 7 |
| Mid-trunk (2—4 m high) | ||||||
| Control | 4.32 a | 2.82 a | 2.37 a | 3.38 a | 8.57 a | |
| Treated | 4.17 a | 2.23 a | 1.79 a | 2.60 a | 6.62 a | 23 |
| Base of trunk (10 cm above ground line) | ||||||
| Control | 5.87 a | 4.39 a | 3.39 a | 4.91 a | 12.69 a | |
| Treated | 5.97 a | 3.19 b | 2.04 a | 3.57 a | 8.80 a | 31 |
| Sweetgum | ||||||
| Within crown | ||||||
| Control | 4.68 a | 4.23 a | 3.78 a | 4.26 a | 12.27 a | |
| Treated | 4.18 a | 1.99 b | 1.66 b | 1.54 b | 5.19 b | 58 |
| Mid-trunk (2—4 m high) | ||||||
| Control | 4.50 a | 4.42 a | 3.51 a | 3.58 a | 11.51 a | |
| Treated | 3.54 a | 2.46 b | 2.17 b | 2.07 a | 6.70 b | 42 |
| Base of trunk (10 cm above ground line) | ||||||
| Control | 4.10 a | 4.44 a | 4.97 a | 4.93 a | 14.34 a | |
| Treated | 3.78 a | 3.37 b | 3.45 b | 4.13 a | 10.95 b | 24 |
| White ash | ||||||
| Within crown | ||||||
| Control | 1.55 a | 1.63 a | 1.95 a | 2.07 a | 5.65 a | |
| Treated | 1.09 a | 1.27 a | 1.32 a | 1.48 a | 4.07 a | 28 |
| Mid-trunk (2—4 m high) | ||||||
| Control | 2.21 a | 2.11 a | 2.21 a | 2.15 a | 6.47 a | |
| Treated | 1.39 a | 1.62 a | 1.55 a | 1.66 a | 4.83 a | 25 |
| Base of trunk (10 cm above ground line) | ||||||
| Control | 2.03 a | 2.25 a | 1.92 a | 2.25 a | 6.42 a | |
| Treated | 1.67 a | 1.57 a | 1.30 a | 1.71 a | 4.58 a | 29 |
| White oak | ||||||
| Within crown | ||||||
| Control | 2.42 a | 2.17 a | 1.84 a | 2.68 a | 6.69 a | |
| Treated | 2.46 a | 1.08 a | 0.80 b | 0.97 b | 2.85 b | 57 |
| Mid-trunk (2—4 m high) | ||||||
| Control | 3.02 a | 2.98 a | 2.69 a | 3.26 a | 8.93 a | |
| Treated | 2.30 a | 1.04 a | 0.90 b | 1.11 b | 3.05 b | 66 |
| Base of trunk (10 cm above ground line) | ||||||
| Control | 4.11 a | 2.94 a | 2.91 a | 4.36 a | 10.21 a | |
| Treated | 3.63 a | 1.40 a | 0.95 b | 1.16 b | 3.51 b | 66 |
| White pine | ||||||
| Within crown | ||||||
| Control | 4.71 a | 4.95 a | 8.67 a | 10.50 a | 24.12 a | |
| Treated | 5.35 a | 5.67 a | 4.42 b | 5.29 b | 15.38 b | 36 |
| Mid-trunk (2—4 m high) | ||||||
| Control | 9.77 a | 9.05 a | 10.39 a | 10.77 a | 30.21 a | |
| Treated | 8.48 a | 8.79 a | 8.42 b | 10.17 a | 27.38 a | 9 |
| Base of trunk (10 cm above ground line) | ||||||
| Control | 9.17 a | 11.32 a | 9.84 a | 12.08 a | 33.24 a | |
| Treated | 8.95 a | 9.33 b | 8.22 a | 11.46 a | 29.01 a | 13 |
| Yellow poplar | ||||||
| Within crown | ||||||
| Control | 2.83 a | 2.64 a | 2.98 a | 3.65 a | 9.27 a | |
| Treated | 2.74 a | 1.92 a | 2.57 a | 3.83 a | 8.32 a | 10 |
| Mid-trunk (2—4 m high) | ||||||
| Control | 3.28 a | 2.55 a | 2.71 a | 3.99 a | 9.25 a | |
| Treated | 2.68 a | 1.88 a | 2.33 a | 3.62 a | 7.83 a | 15 |
| Base of trunk (10 cm above ground line) | ||||||
| Control | 2.47 a | 2.25 a | 2.20 a | 3.90 a | 8.35 a | |
| Treated | 2.25 a | 2.16 a | 2.63 a | 4.16 a | 8.95 a | (−7) |
Pairs of values for each set of control and treated trees followed by the same lowercase letter are not significantly different at the P ≤ 0.05 level.