What Is Cedar Apple Rust Disease?

Cedar-Apple Rust is a natural disease which affects apple trees, junipers and of course, cedar trees. It is distinct because for it to spread, it has to travel between an apple, cedar, or juniper tree. Therefore, it is critical to treat all cedar trees in an area. It doesn’t matter if they’re displaying symptoms or not.

Symptoms of Cedar Apple Rust

The symptoms of Cedar-Apple Rust disease are most recognizable on apple trees. In the springtime, little pale-yellow spots emerge on the upper part of the leaves. As the season continues, the spots increase in size and little brown or black spots grow in the middle of the more prominent yellowish spot. As the spots increase and the tree is under increased stress, fruit and leaves fall early. Cedar-apple Rust is regular on ornamental flowering apples and fruit-producing apple trees.

In the springtime, the fungal spores from the cedar or juniper trees are blown by the wind on to apple trees’ leaves. The spores contaminate the apple tree and quickly increase in the wet periods. As the season continues, the fungal spores on the apple tree are carried back to cedar and juniper trees, and a new virus occurs.

Cedar-Apple Rust on Juniper

Control of Cedar Apple Rust

Cedar-Apple Rust disease can’t be controlled in the active growing season after it has already affected the tree. However, it is a good idea to use a fungicide spray in the growing season on the infected tree, and surrounding juniper and cedar trees. This is how to diminish the level of re-propagation and infection.

In the growing season, make sure to have a tree specialist spray all uninfected and infected apple, juniper, and cedar trees. Keep spraying every two to three weeks.

The next spring spray the trees (the apple tree in particular) with a disease control spray. The first spray should be made when the tree flowers. The second application must be sprayed when around 70% of the flower petals have fallen. The third application must happen around two weeks later.

If you aren’t comfortable with doing your tree spraying or if you suspect your cedar or fruit tree is infected, contact an arborist to examine the tree and give you a diagnosis.