Swedish columnar aspen
This tree has a white film on the leaves which is causing them to dry out and die
Denver County Colorado trees and shrubs
We don't have enough information to diagnose the white film on your Aspen leaves. It may be a fungal issue - could you send us a picture?
Aspen are beautiful but prone to a number of different problems when grown on the High Plains: too hot, too dry, humidity from irrigation, poor air circulation, clay soils, poor drainage, pollution ... life in the big city makes it tough to replicate the gorgeous aspen stands we see in the mountains! Unfortunately, the Swedish Columnar form (Populus tremula 'Erecta') is as susceptible as any other.