What to do about stressed/browning Bottle Brush (Callistemon)
We are dealing with 2 dying large bottle brush trees (possibly the "weeping" variety) in Northwest Harris County, TX (planting zone 9a.) One has some new growth on ends of limbs and in suckers emerging near the base. The other doesn't have any green leaves but the branches still have some elasticity/resilience (not all brittle and breaking.) What is the best course of action to attempt to save these trees? This has happened to several others in the neighborhood as well. I'm concerned that any pruning in this current heat (high 90s) will kill them altogether. Any advice is appreciated.
Without knowing more about the growing conditions, soil and water management, I would guess that water deficit - drought stress during your hot dry spell had caused the drying and browning of foliage.
Watering is the key factor. Immediatley give the plants a deep flooding in the entire planting bed and root zone, not just a sprinkle and not just at the base of the stem, drench the entire soil surface under the foliar canopy and a little beyond. Try to achieve 8-inches to 12-inches depth of water infiltration into the soil profile. Do that again in a couple of days, and then once a week throughout the dry hot season. Mulch the soil surface with compost or other organic matter material, to help retain soil moisture.
You're right, don't prune now except for confirmed dead material that snaps off when you bend it, or shows no green growing layer when you slice off a shallow layer of outer bark on the stems.
If and when the plants start to put out substantial new green growth, you can prune out the dead material back to the new growth.