Cedar-quince rust
Cedar-quince rust is closely related to cedar-apple rust -- both are caused by Gymnosporangium species and require Eastern red cedar as an alternate host -- but the two diseases differ in which parts of the host plant they attack. Cedar-apple rust primarily attacks leaves; cedar-quince rust attacks.
—- title: "Cedar-quince rust" slug: cedar-quince-rust hub: problems category: "Disease-by-host" description: "Cedar-quince rust attacks fruit, stems, and thorns of apple family plants — not just leaves. Identify the orange tube masses on fruit and stems, understand the two-host lifecycle, and choose resistant plants." date: 2026-06-10 updated: 2026-06-10 author: "Thomas A." reading_time: 8 —-
Cedar-quince rust is closely related to cedar-apple rust — both are caused by Gymnosporangium species and require Eastern red cedar as an alternate host — but the two diseases differ in which parts of the host plant they attack. Cedar-apple rust primarily attacks leaves; cedar-quince rust attacks fruit, stems, and thorns. This shift in target tissue makes cedar-quince rust more economically significant for fruit production: infected fruit is unsalable, and infected stems may die back.
I don't grow quince or commercial apples at my Long Island property, so this guide draws on Penn State Extension, Clemson HGIC, and Cornell research.
The pathogen
Cedar-quince rust is caused by Gymnosporangium clavipes. Per Penn State Extension, this species has a broader host range on the rosaceous hosts (the apple family) than G. juniperi-virginianae. Hosts susceptible to cedar-quince rust include:
- Quince (Cydonia oblonga)
- Hawthorn (Crataegus spp.)
- Serviceberry (Amelanchier spp.)
- Apple and crabapple (Malus spp.) — primarily fruit, stems, and petioles rather than leaf blades
- Pear (Pyrus spp.) — less commonly
The alternate host is Eastern red cedar and other junipers (Juniperus spp.), particularly Juniperus virginiana.
Two-host lifecycle
Per Cornell Cooperative Extension, the lifecycle follows the same alternating pattern as cedar-apple rust:
On juniper: The fungus causes spindle-shaped, woody swellings on branches rather than the round galls of cedar-apple rust. In spring, orange to rust-colored gelatinous spore masses erupt from these swellings when temperatures exceed 40°F (4°C) and rain occurs. The swellings are perennial and can produce spores for several years.
On rosaceous hosts (quince, hawthorn, apple, serviceberry):
- Basidiospores from juniper swellings infect developing fruit, flower stems (pedicels), and young twigs during the pre-pink through petal fall period
- Orange to rust-colored lesions develop on infected tissue over 3–6 weeks after infection
- Tube-like aecia erupt from infected fruit and stems in early summer; these produce aeciospores that return to juniper
Identification
On juniper hosts
Per Clemson HGIC, cedar-quince rust on junipers produces:
- Elongated, spindle-shaped orange-yellow swellings on branches, rather than round galls
- Orange, gelatinous spore masses in spring
- These branch swellings persist for multiple years, unlike the single-use galls of cedar-apple rust
On quince, hawthorn, apple, serviceberry
Per Penn State Extension, symptoms differ from cedar-apple rust by location:
- Fruit lesions: yellow to orange discolored areas on developing fruit, often with small tube-like aecia erupting from the lesion surface; infected fruit may be deformed and drop prematurely
- Stem and twig cankers: lesions on young stem tissue that may enlarge and girdle the stem, causing dieback of the growth above the canker
- Thorn infections: on hawthorn, the thorns themselves may be infected, becoming swollen and distorted
- Petiole and leaf midrib lesions: on susceptible hosts, the disease can extend from fruit petioles into leaf petioles and midribs, causing entire leaves to die
Distinguishing from cedar-apple rust
Per Penn State Extension:
- Cedar-apple rust on apple primarily produces leaf spots (orange-yellow circular spots on leaf blades)
- Cedar-quince rust primarily attacks fruit, stems, and thorns rather than leaf blades
- Both can occur simultaneously on the same tree; distinguishing them requires attention to which plant parts are most affected
Conditions that favor infection
Per Clemson HGIC, infection requires:
- Spore release from juniper (requires rain and temperatures above 40°F, 4°C)
- Susceptible rosaceous host tissue (young fruit, stems, flower tissue) present at the same time
- Adequate moisture and mild temperatures during the infection period
The critical infection window on rosaceous hosts is pre-pink through petal fall. Infections occurring after fruit and tissue maturity rarely cause significant damage.
Management
Fungicide applications during the critical window
Per Penn State Extension, fungicide applications must cover the pre-pink to petal fall window. Apply every 7–10 days during this period on susceptible hosts. Registered active ingredients include:
- Myclobutanil — effective triazole fungicide; good protective and some curative activity
- Propiconazole — effective; apply per label
- Mancozeb — effective protectant
- Copper-based fungicides — organic option; apply every 7 days during spore-release periods
Resistant cultivars
Per NC State Extension, significant differences in susceptibility exist among cultivars:
- Hawthorn: Crataegus viridis 'Winter King' shows good rust resistance; Washington hawthorn (C. phaenopyrum) is very susceptible
- Serviceberry: most Amelanchier species show good resistance to cedar-quince rust compared to other hosts
- Apple: the same disease-resistant apple cultivars that resist cedar-apple rust (Liberty, Enterprise, Freedom, GoldRush) also show better resistance to cedar-quince rust
Prune juniper swellings
Per Penn State Extension, pruning the elongated orange-yellow swellings from junipers in late winter before spore release reduces local inoculum. The swellings on junipers are more persistent than the single-season galls of cedar-apple rust, producing spores for multiple years; regular monitoring and pruning during winter is more productive than a single removal effort.
Distance from junipers
Per Cornell Cooperative Extension, spores from juniper swellings travel significant distances on wind. Removing junipers from the immediate vicinity of susceptible plantings reduces but does not eliminate disease pressure in landscapes where junipers are common.
Common problems table
| Symptom | Likely cause | Action |
|---|---|---|
| Orange tube masses on quince fruit | Cedar-quince rust aecia | Remove fruit; apply fungicide next spring during bloom |
| Stem dieback on hawthorn from orange lesions | Cedar-quince rust stem canker | Prune below lesion; disinfect tools |
| Spindle-shaped orange swellings on juniper | Cedar-quince rust on alternate host | Prune swellings in late winter |
| Orange spots on apple leaf blades | Cedar-apple rust (not quince rust) | See Cedar-apple rust |
| Distorted, dropping fruit in spring | Rust fruit infection | Fungicide at pre-pink through petal fall next year |
Frequently Asked Questions
Is cedar-quince rust the same as cedar-apple rust?
Per Penn State Extension, no — they are distinct species of Gymnosporangium with overlapping but distinct host preferences. Cedar-apple rust (G. juniperi-virginianae) primarily attacks apple leaves; cedar-quince rust (G. clavipes) primarily attacks fruit, stems, and thorns of quince, hawthorn, and serviceberry.
My hawthorn has both orange stem lesions and orange leaf spots. Which rust is this?
Per Clemson HGIC, hawthorn is susceptible to multiple Gymnosporangium species. Orange stem and thorn lesions point to cedar-quince rust; orange circular leaf blade spots more typically indicate cedar-apple rust or cedar-hawthorn rust (G. globosum). Both can occur simultaneously.
Does cedar-quince rust harm Eastern red cedars?
Per Penn State Extension, the disease does not seriously harm Eastern red cedar or other juniper hosts. The swellings on juniper branches are unsightly but rarely affect tree vigor.
What is the best ornamental hawthorn to plant in a landscape with cedar-quince rust pressure?
Per NC State Extension, Crataegus viridis 'Winter King' is widely recommended for its ornamental value (white flowers, persistent red fruit, attractive bark) combined with good disease resistance. It outperforms Washington hawthorn in rust resistance and is a better choice for landscapes with abundant Eastern red cedar.
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Recommended gear: Best serviceberry cultivars — our buyer's guide covering picks for every budget, ranked by Extension publication consensus and personal use.
Sources
- Penn State Extension — Cedar-Apple and Related Rusts
- Clemson HGIC — Cedar-Apple Rust
- Cornell Cooperative Extension — Apple Disease Management
- NC State Extension — Hawthorn Selection and Disease