Cottonwood

Apples, Peaches, Cherries, Celery, Carrots, Hazelnuts

Cottonwood is one of Arizona’s most recognizable native trees and one of its most significant spring allergens. Growing naturally along rivers, streams, washes, and irrigation canals throughout the state, Fremont Cottonwood is a fixture of Arizona’s riparian landscape — from the Salt River corridor through the Phoenix metro to the Verde River Valley around Cottonwood and Sedona, and throughout the waterways of southern and eastern Arizona.

Season begins earlier than most people expect. Cottonwood starts releasing pollen in January in warmer parts of the Valley, building through February and reaching peak intensity in March and April. The fluffy white seeds that drift through the air in spring are often blamed for triggering symptoms, but it is actually the fine, invisible pollen released weeks earlier that causes the allergic response. By the time the cotton is visible, the worst of the pollen season is already winding down.

What makes cottonwood particularly challenging in Arizona is its close relationship with willow. Both belong to the Salicaceae family and share highly cross-reactive allergenic proteins, meaning patients sensitized to cottonwood are almost always also reactive to willow. The two trees grow in the same riparian environments across the state and pollinate in an overlapping window, making it nearly impossible to separate their contributions without specific allergy testing.

In the Phoenix metro area, cottonwood is found primarily along canals, parks, and the Salt River, but pollen travels significant distances on Arizona’s dry spring winds, reaching neighborhoods well beyond where the trees are visibly growing. In communities along the Verde River like Cornville, Camp Verde, and Cottonwood, exposure can be particularly intense during peak weeks.

If your symptoms begin in January or February and worsen through March, cottonwood is very likely a primary factor. The team at Carefree Allergy can confirm your specific triggers through targeted testing and build a treatment plan tailored to you. Options range from medication management to long-term immunotherapy to reduce your sensitivity to cottonwood and the related tree pollens that share its season across Arizona each year.