Pear Rust is on the Move

Here is the monthly educational post from the Bellevue Tree Board:

Pear Rust is on the Move:

Most gardeners have heard of cedar-apple rust and cedar-hawthorn rust, both caused by rust fungi that need two different host plants to complete their life cycle—usually a juniper (like Eastern red cedar) and a tree in the rose family. But here’s a surprise for many: that same fungus responsible for cedar-hawthorn rust can also infect ornamental pear trees, especially the widely planted (but now discouraged) Callery pear and its cultivars.

Rust on pears often appears suddenly in late spring or early summer. Gardeners are taken aback when orange to reddish leaf spots show up seemingly overnight, sometimes with little tubular growths on the undersides of the leaves. While the damage may look alarming, it’s mostly cosmetic—although repeated infections can stress the tree over time.

Unfortunately, the window for prevention has already closed for this season. Fungicides are only effective if applied before symptoms appear, typically in early spring. Once the bright orange spots are visible, there’s nothing that can be done to stop the disease that year.

Callery pear trees (including Bradford, Cleveland Select, and Chanticleer types) have fallen out of favor for several reasons: weak branch structure, invasive tendencies, and yes—even vulnerability to disease like pear rust. If your landscape still includes one of these trees, this may be yet another reason to consider removing and replacing it with something more resilient and environmentally friendly.

Thankfully, there are excellent alternatives that bring beauty and seasonal interest without the baggage. Consider planting a white fringetree (Chionanthus virginicus) for its airy spring blooms, a pagoda dogwood (Cornus alternifolia) for tiered elegance and wildlife value, or a paperbark maple (Acer griseum) for its gorgeous peeling bark and fiery fall color. Serviceberry (Amelanchier spp.) offers edible fruit and four-season appeal, while the seven-son flower (Heptacodium miconioides) provides late-season blooms that attract pollinators, followed by striking red calyces and exfoliating bark for winter interest.