Fauna
Fungus

Cedar-apple Rust

Gymnosporangium juniperi-virginianae

Also known as Cedar Apple Rust Fungus, Juniper Rust

Cedar-apple rust is a complex plant pathogen that requires two distinct host species to complete its lifecycle. During warm spring rains, round galls on red cedars swell and sprout striking, bright orange gelatinous tendrils that release millions of windborne spores. These spores travel to neighboring apple trees, forming yellow and orange spots on leaves and fruit that eventually release spores back to infect cedars.

FungusPlant PathogenOrange
Cedar-apple Rust reference1 / 7
(c) Sabrina Setaro, some rights reserved (CC BY) · cc-by
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Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyEastern Red Cedar, Apple, Crabapple
ThreatsFungicide applications and host plant removal
HabitatsOrchards, temperate forests, rural landscapes, and suburban yards where junipers and apples co-occur
Life spanPerennial inside host cedar galls; annual seasonal cycle on apple foliage
Classification
  1. OrderPucciniales
  2. FamilyGymnosporangiaceae
  3. GenusGymnosporangium
  4. SpeciesGymnosporangium juniperi-virginianae
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Harmless to humans; many wild fungi have toxic look-alikes, so never eat wild fungi based on app identification alone.
Responsible observation
  • Spring Rain Spotting: Look for bright orange gelatinous horns sprouting from juniper galls following warm spring rains.
  • Apple Leaf Check: Examine apple leaf undersides in midsummer for small tube-like spore structures.
  • Distance Management: Maintain a gap of several hundred meters between red cedars and apple orchards to minimize infection.
Related species
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