Cedar Rust Differences
| Cedar-apple Rust | Cedar-hawthorn Rust | Cedar-quince Rust | |
Deciduous hosts |
Apple/crabapple |
Hawthorn, apple/crabapple, sometimes pear, quince, serviceberry |
Many of the genera in the rose family. More common ones attacked in IL include mountain ash, hawthorn, flowering quince, and serviceberry. |
Affected plant parts |
Mostly leaves |
Mostly leaves occasionally fruit, stems and thorns |
Mostly thorns, new twigs and fruits. Sometimes petioles and veins of leaves |
Leaf spot symptoms |
Start as greenish yellow then yellow followed by orange (black spots may form in orange), there is generally a reddish halo between infected lesion and healthy tissue |
Start as yellow spot followed by orange (black spots may form in orange). |
Basically none except upon close inspection of veins and petioles that are swollen and occasional chlorotic spots on some rosaceae hosts. |
Infection to aecial stage |
70 to 80 days |
80 to 90 days |
45 — 60 days |
Aecial spore release |
As air dries out in a.m. |
As air dries out in a.m. & during rains |
As air dries out in a.m. & during rains |
Evergreen hosts |
Mostly Eastern red cedar in Illinois & a few other junipers not commonly grown in Illinois. |
Eastern red cedar; Rocky Mountain, common and prostrate junipers as well as a few not commonly grown in Illinois. |
Eastern red cedar, common, prostrate, Rocky Mountain, and savin junipers. |
Gall shape |
Kidney shaped to round |
Flat on one side to round |
Elongated swelling of the twig |
Gall appearance |
Dimples/depressions by fall where telial horns develop the following spring |
Raised "bubble/blister" like appearances by fall where telial horns develop the following spring. |
Spindle shaped that has rough bark appearance after telia production is finished. |
Telial horn appearance |
Long and thin |
Short and stubby |
Orange bark scum |
Number of years telia are produced |
One year (spring following gall development) |
May produce telia horns for several growing seasons or years. |
One or more years (4-6 but sometimes for 20) |
Death of twig |
Twig almost always dies |
Twig seldom dies |
Twigs often die but not always. |
Distance between hosts that spores can travel to cause infection |
Usually within several hundred feet but possible for several miles |
Usually within several hundred feet but possible to 14 miles |
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