Works Best:
On huisache that are bushy, have many stems at ground level, and are less than 8 feet tall. This method is also known as high-volume foliar spraying.
When to Apply:
Begin in September after any late-summer growth has stopped; then continue through November or until soil temperature drops below 75 degrees.
1. Prepare Equipment
Small pump-up garden sprayers, backpack sprays, cattle sprayers, or sprayers mounted on 4-wheel all-terrain vehicles (ATV) work well. Garden sprayers are best for small acreages; backpack sprayers are usually the most efficient in dense huisache; and ATV sprayers become more efficient in large acreages or as the distance between plants increases. Make sure your sprayer has an adjustable nozzle that can deliver a coarse spray (large droplets) to the top of an 8-foot tree. Conejet™ 550 x-6 or x-8 adjustable cone nozzles work well.
2. Mix Herbicide Spray
You can achieve 76 to 100 percent rootkill by spraying with Grazon P+D™, which is a restricted use pesticide. A certified applicators license is needed to buy or apply the product.
To prepare the spray mix, add Grazon P+D™ at a concentration of 1 percent to water. To make sure the foliage is coated thoroughly, add either liquid dishwashing detergent or a surfactant to the spray mix (see tables below). It may be helpful to add a dye, such as Hi-Light™ Blue Dye, to mark the plants that have been sprayed.
Recommended spray mixture using a surfactant or liquid dishwashing detergent.*.
| Ingredient | Concentration in spray solution | Tank Size | ||
| 3 gal. | 14 gal. | 25 gal. | ||
| Grazon P+D™ | 1% | 4 oz. | 18 oz. | 1 qt. |
| Surfactant | 1/4% | 1 oz. | 3 oz. | 8 oz. |
| Hi-Light Blue Dye™ | 1/4-1/2% | 1-2 oz. | 3-6 oz. | 8-16 oz. |
*All spray solutions are mixed in water.
3. Spray the Huisache
The best time to begin spraying is in the fall. Continue spraying until the soil temperature drops below 75 degrees. The spray period may last through November. Wet the foliage of each huisache plant until the leaves glisten, but not to the point of dripping.
Keep these points in mind:
- Follow herbicide label directions.
- For best results, don’t spray when:
- rains have stimulated new growth in tree tops.
- leaves are wet.
- foliage shows damage from hail, insects or disease.
- you are working upwind of desirable trees, shrubs or crops.
- The cost of treatment rises rapidly as the brush becomes bigger and more dense. Also, controlling huisache is not a one-time job. You’ll need to go over your land now and then to get rid of unwanted huisache sprouts.