Tree-of-heaven control using stem injection treatment with undiluted imazapyr as an emulsifiable concentrate (Stalker) or water-soluble (Arsenal) formulationz.
| Treatment | Cutting date | Evaluation 8 MAT* | Percent of stumps with sprouts | Evaluation 21 MAT | |||
|---|---|---|---|---|---|---|---|
| Mean number of sprouts | Mean crown reduction (%) | Mean number of sprouts on sprouting stumps | Mean height of sprouts (m) | Crown reduction (%) | |||
| Imazapyr (Stalker) | |||||||
| Small trees (4–8 cm diameter) | 4 MAT | 0 | — | ||||
| 8, 12 MAT | — | 97.9 ±5.2 | |||||
| 12.5 | 1.0 | 0.4 | — | ||||
| Medium trees (8–16 cm diameter) | 4 MAT | 0 | — | ||||
| 8, 12 MAT | — | 96.9 ± 4.4 | |||||
| Clumps, 1/2 dose | — | — | 84.2 ± 14.6 | — | — | — | 99.3 ± 0.6 |
| Clumps, 1/4 dose | — | — | 76.0 ± 8.9 | — | — | — | 81.7 ± 18.9 |
| Untreated small trees | 4 MAT | 2.75 ±3.10 | — | ||||
| 8, 12 MAT | — | 0 | |||||
| 70.8 | 3.8 | 1.6 | — | ||||
| Untreated medium trees | 4 MAT | 2.75 ± 2.50 | — | ||||
| 8, 12 MAT | — | 0 | |||||
| Imazapyr (Habitat) | |||||||
| Medium trees (8–16 cm diameter) | 4 MAT | 0 | — | 8.3 | 1.0 | 0.6 | — |
| 8, 12 MAT | — | 94.8 ± 5.8 | |||||
| Untreated medium trees | 4 MAT | 9.25 ± 4.27 | — | 75.0 | 4.0 | 2.0 | — |
| 8, 12 MAT | — | 26.3 ± 37.4 | |||||
↵*Months after treatment (4 MAT = February 1999; 8 MAT = June 1999; 12 MAT = October 1999, 21 MAT = July 2000).