Asked June 20, 2021, 2:32 PM EDT
Polk County Iowa
This response to your question is from our Iowa State University Extension and Outreach horticulture specialist.
Quaking aspen can be a difficult tree to grow in Iowa. It is native to high elevations with well-drained, rocky soils. The warm, humid Iowa summers are hard on this species and our heavy soils can sometimes hold more water than this tree species appreciates. I suspect that the soil conditions are holding too much water for this tree. Quaking aspen would be less tolerate of these wet soil conditions than other trees. The symptoms for too much water look much like the symptoms for too little water and would include leaf browning often starting on the ends of branches and then moving inward.
It is important to check the soil moisture each day, but rarely will the tree need water every day. Only water the tree when the original root ball and/or the surrounding soil is dry. Cut back the watering and only water when needed (the top couple of inches of soil is dry to the touch). If there is not already mulch around the base of the tree, apply mulch and do not fertilize. Then wait to see if the tree can recover and grow out of the damage it received to its roots from the wet soil conditions.