Question: We have a wild palo verde in our front yard that has several branches near the outer edge of the crown that are dense broom like in appearance. I’m wondering if this is a type of mistletoe or some other disease and if so any suggestions on long-term survival?
Answer: Palo verde trees (Parkinsonia species) are sometimes affected by what is called a witches’-broom. This abnormal growth is not mistletoe but rather another problem. These brooms have for many years been attributed to a plant response to mites feeding on the branches. In recent years, further research was initiated and continues at the University of Arizona to determine if there is another cause and a solution. I am sure that the results of this research will be publicized as soon as they are available. Until then, there is little to do about the brooms except pruning them out of the tree. They often grow back so it isn’t a very satisfying remedy.
Peter L. Warren is the Forest Health Program Coordinator for the Arizona Department of Forestry and Fire Management. Questions, photos and videos may be emailed to tucsongardensage@gmail.com.
