Are you curious about the lackluster appearance of the aspen and cottonwood trees across the landscape this summer?   Leaves are turning brown and falling early without transitioning to their lovely fall colors. This has been especially noticeable in the South Pass area, along North Fork Popo Agie, and even in the Dubois area.  
 
At least two fungal diseases are to blame for the leaves showing significant spotting or dark splotches. Marssonina leaf spot is caused by the Marssonina fungus and is the more common leaf disease of aspen and cottonwoods.  It is often associated with wet spring weather, and can persist over several years if conditions allow.  The good news is that these diseases rarely cause any permanent tree damage or death, and appear to affect some stands of trees more than others. 
 
Luckily, this means at least some of the usual splendor of the changing aspen trees will still be visible in the coming weeks.