Cottonwood Leaf Rust in Spring: Same Disease, Wet Site

Yellowing Cottonwood in Wet Area? It’s Rust, Not Drowning

Your young cottonless cottonwood in a wet spot turns yellow in June and drops leaves. This is cottonwood leaf rust, not overwatering. The fungus needs a conifer alternate host (likely nearby). Some cottonwood families are resistant—explains variable infection.

Management

• Rake and destroy fallen leaves to reduce spores.
• No fungicide for yard trees.
• Tree won’t die, but repeated infections reduce growth.

See details here.