I was visiting a friend last week who lives next to Altadena Middle School. He has two very large, stately trees in his back yard that provide great shade during the summer. In February however, there are no leaves on the trees. Just packets of pollen clusters. The branches are heavy with them.
These Ash trees also line the sports fields of Altadena. And once you start to look for them, they are everywhere: in local parks, schools, green belts, and your neighbors yard. All heavy with the same pollen sacks. I took a few pictures while riding my bike and found a large number of Ash trees in Vista Canyon Park next to Desert Vista High School.
Interestingly, the logo for the Phoenix Parks and Preserves Initiative is an Ash leaf !
More than half a century ago, tree pollen counts in Phoenix skyrocketed. The culprit, the popular Olive tree. From an allergy standpoint the Olive tree is a monster. March through May, Olive pollen fills the air and is incredibly sensitizing with many new residents becoming allergic after just one season of exposure.
So notorious is the Olive for causing allergy problems that it has been banned in a number of cities including Tempe and Phoenix and so you will not see many in the newer communities in Ahwatukee. Unfortunately, the Olive happens to have a close allergy cousin, the Ash tree. Most people who react to Olive on allergy testing will also react to Ash, a form or cross-reactivity. Some allergy-control progress may have been made in limiting Olive tree planting, but this progress has likely been lost in the rising popularity of the Ash tree.