Dr. Yarnell recommends Desert Willow as a preferred alternative to Pau d'Arco. Pau d'Arco, derived from a tree also used for Ipe lumber, faces significant threats due to overharvesting for timber. Current trends indicate that these trees are likely to become endangered within the next 50 years. Fortunately, with highly effective alternatives like Desert Willow available, there is no need to increase the demand for Pau d'Arco.

Desert Willow is featured in our formula No Grow: Fungal. 

A few other alternatives to Pau d'Arco: 

Thuja plicata (Western Red Cedar) (PNW local)

Usnea spp. (Old Man's Beard)  (PNW local) 

Azadirachta indica (Neem)