Cedar apple rust and arborvitae
I have 6 apple trees and am unsure if arborvitae (specifically green giant) would be a host for the apple cedar rust galls since they have a foliage like junipers. I don't want to destroy my apple trees, but I want to create a screen about 25 feet from the apple trees. Any help would be appreciated!
Livingston County Michigan
Plants now called arborvitae, Thuja occidentalis and Thuja plicata, were once commonly called types of cedars, though they are not true cedars. The Thuja genus plants do not host rust diseases. The issue with arborvitae is they are a favorite food of deer, and they have some pests and diseases to monitor, though these do not affect apples.
Another consideration is mature size- depending on how they are sited, you don’t want your screen to shade your apple trees when they become tall.
There are other evergreens to use in hedges, and planting a variety is recommended so that in future, if a disease or pest wipes out a species, the whole hedge isn’t lost. Black Hills spruce and Canadian hemlock are examples of plants for wind screens. Again, mature size is a consideration as are the other growing requirements such as soil pH and moisture.
Rust spores can travel on wind several hundred yards, so you still need to monitor your apple trees. Rust diseases are hosted by Juniperus genus, such as eastern red cedar, Rocky Mountain juniper, and Chinese junipers. Here is a detailed discussion of the four rust diseases: