[2] Similar diseases can be found on quince and hawthorn[3] and many species of juniper can substitute for the eastern red cedars.

Small, yellow-orange spots appear on the upper surfaces of the leaves, anytime from April to June.

In the spring these structures absorb water during rainy periods and elongate into orange gelatinous telial horns that are 10–20 mm long.

They maintain the orange gelatinous form after the first warm rains of spring but generally on a greatly reduced scale.

The complex disease cycle of cedar apple rust, alternating between two host plants, was first delineated by Anders Sandøe Ørsted.

[3] When swollen, teliospores will germinate and produce basidiospores which are forcibly discharged and travel along air currents to infect apple trees and other alternate hosts.

[8] The telial horns will dry out once the rain passes and will lose their gelatinous appearance, instead resembling dark brown threads.

[9] One to two months later, in July and August, orange-yellow aecia are produced in concentric rings on the bottom of the apple leaves or surrounding the pycnia on the fruit.

The wind carries the spores back to eastern red cedars, completing the infectious cycle.

Removing as many cedar trees within close proximity of an apple orchard will reduce potential sources of inoculum.

Resistant Crataegus (Hawthorn) include C. crus-galli, series Intricatae, C. laevigata, 'Autumn Glory', C. phaenopyrum, C. pruinosa, C. viridis, and 'Winter King'.

Fungicide sprays applied in a timely manner are highly effective against the rust diseases during the apple cycle.

[12] Most protective fungicide sprays are applied four times at 7- to 10-day intervals, starting with pink bud on crabapples.

Although curative fungicides also exist for cedar apple rust, they must still be applied before trees begin to develop symptoms.