What you will see:
- Yellow spots on the leaves of hawthorn
- Rust colored fingers on hawthorn fruits
- Big woody galls on juniper
- Orange finger-like goo coming out of galls
- Spores are spread by wind
- Spores move from hawthorn to junipers in late summer or fall
- Spores overwinter on junipers
- Fungal galls form in the Spring on juniper species
- Spores can be spread to apple hosts within several miles
- Most infections occur within a few hundred yards
- New leaves are susceptible to infection
- Reduce moisture around foliage
- Re-direct sprinkler heads so that irrigation does not hit foliage
- Don’t plant junipers near hawthorns
- Remove galls from infected junipers in the winter
Chemical treatments can effectively manage the disease. Ask your Consulting Arborist for details.
Additional Information Regarding Cedar-Hawthorn Rust
Cedar-hawthorn rust is a fungal infection that is currently spreading through a variety of softwood and fruit trees that causes discoloration, invasive growth, and it destroys otherwise delicious fruit. This name describes a type of fungus called Gymnosporangium globosum. This fungus spreads rapidly from its chosen host and can often jump species as it transmits.
How do you spot a tree infected with Cedar-hawthorn rust? Symptoms vary from evergreen trees to fruit trees, but they manifest in two major ways. Evergreen hosts develop small lumps and scarred galls that grow like balls on needles and flats on the tree itself. The fungal growths look reddish on the brown of the tree when immature and grayish when they are fully grown. During the rainy spring weather these lumps sprout little horns, which is when they spread their spores. Evergreen trees tend to fare well despite the infection and rarely die from this fungus.
Fruit tree hosts are not nearly as well adapted as their evergreen cousins. On these deciduous trees, the Rust looks like little yellow spots that eventually turn red with black specks on them near the middle of the legion. These lesions grow little tubes by mid-summer and will spread over twigs, leaves and fruit, making the fruit inedible from the infected trees. The trees severely infected with rust may suffer discoloration and the death of younger shoots and leaves.
Cedar-hawthorn rust, like many fungus infections, can spread rapidly and infect whole stands of evergreen and fruit trees. It can be a danger to the health of a forest, and it is something that anyone who cares for their trees should look for among the plants they cultivate.