When sited properly there are rarely issues with Trautman Juniper. Usually, damage is the result of poor drainage, mechanical damage from people and animals, and/or lack of sunlight.
Trautman Juniper is not disease prone but there are several pests and problems that can damage an already stressed plant. Not all of these are fatal, and some are unavoidable with time. The following information shouldn’t be viewed as a litany of failures but as information for a responsible grower. Remember, there’s no such thing as a perfect plant that is disease-free!
Rusts (Gymnosporangium) are probably the most significant fungal disease of Juniper. Juniper acts as an alternate host for this fungus, which completes the other half of its life cycle on a variety of plants in the Rosaceae family. These include Serviceberry (Amelanchier), Apples (Malus), Hawthorns (Crataegus), Pears (Pyrus), and more. Usually, the damage on Junipers is limited to a few galls. Occasionally twigs may die back but these can be pruned. The damage is more pronounced on those alternate hosts and can cause unsightly foliage damage or weird growths on fruits.
Before you write off Juniper as a landscape plant due to rusts, let’s take a moment and reframe. Most references to Gymnosporangium management recommend to “avoid planting Junipers in close proximity to primary hosts.” This makes sense; if the fungus needs two plants to grow on, why not take out the common denominator of Juniper being the alternate host? Well, if you do a little digging, you’ll find that “close proximity” usually means ‘kill every Juniper within 1-3 miles of your planting location.’ This is the nuclear option that’s usually reserved for large-scale apple production. Unless you live on a 640+ acre lot AND you’re planting your apple/hawthorn/pear in the center of the lot AND you’re sure that there are no junipers on your property, you’re probably going to have rust at some point or another. And even if you don’t have any Junipers on your property, chances are your neighbors are going to plant one. The good news is that the damage on both hosts is usually negligible unless you’re heavily investing in fruit production – in which case, you’re probably already spraying your fruit trees for fungal diseases.
So, in conclusion to this long-winded diatribe on the non-issue that is Cedar Rust, you don’t have to worry about damaging your Crabapples, Serviceberries, Hawthorns, etc. by planting a Juniper. Should you plant a Juniper right next to your susceptible plant? Probably not. But if you’re putting them on opposite sides of the house or one in the backyard and one by the driveway, you’re likely not going to have an issue.
Now, aside from Rusts, there are a few other diseases that can attack Junipers if they’re in areas with poor airflow or constantly soggy soil. These are Phomopsis Tip Blight, Kabatina Tip Blight, and Abiotic Tip Blight. These diseases cause tips to brown in early spring or late winter and can progress inward if left unchecked. Phomopsis and Abiotic Tip Blight are caused by stress on the plant and are usually comorbid with overhead irrigation/sprinkler systems. In these cases, pruning the affected branches in winter and treating the plant with a fungicidal spray in spring can do the trick, but you have to increase airflow and reduce the moisture on foliage to prevent the disease from persisting. Kabatina Tip Blight has similar symptoms that show up a little earlier than Phomopsis in late winter. Kabatina differs from the other blights in that it usually needs an open wound to spread; therefore, pruning should be completed in winter as this will prevent spores from moving within the plant.