Does Cedar-Apple Rust Kill Trees?

Does cedar-apple rust kill trees? If left untreated, cedar-apple rust can get out of hand and result in severe damage or death. 

Rick’s PHC Certified Arborists offers a tree wellness program to maintain the health of trees and shrubs on your property. 

What is Cedar-Apple Rust?

Cedar-apple rust is an unsightly disease. It needs the perfect set of circumstances to form. It requires one infected evergreen tree in the Cyprus family and another in the apple family. 

The harm caused by cedar-apple rust is more severe in years when spring and summer are wet and humid. A professional arborist can help you identify host trees on your property if you are unsure of which species you have. If one species has symptoms of rust, check the other species to prevent further development of the fungus.

In severe cases, cedar-apple rust can kill trees. 

The Life Cycle of Cedar-Apple Rust

In the Evergreen Cyprus family, cedar-apple rust appears most commonly on Eastern red cedar and Rocky Mountain juniper trees. It is not life-threatening, but it can kill individual tree branches.

• Small, round growths called galls form on tree branches during the fall season. They have a woodlike texture and can grow up to two inches in diameter. 
• During early spring rain, the galls develop orange, fingerlike tentacles that can extend up to ¾ inch long. The tentacled gall produces spores that can migrate to apple trees hundreds of feet away. 
• As they dry out, the orange tentacles dehydrate, reforming into galls. This process can repeat several times during the spring season.

Cedar-apple rust on apple trees is more of a cosmetic issue. An untreated apple tree will grow fewer leaves year after year. Infection occurs in the spring season when spores from juniper trees adhere to the leaves of the apple tree, forming yellow rust spots. 

• Infected leaves often go undetected until the summer, when the fungus thrives, turning each infected spot bright orange.. 
• Black spots form on the upper surface of a fully mature leaf spot.
• Tiny, fungal tubes grow on the underside of each leaf spot.
• The tubes release chalky spores which travel to juniper trees to perpetuate infection.

As this process continues, the infection grows, and you may find yourself wondering, “Does cedar-apple rust kill trees?”

Treating Cedar-Apple Rust

For Evergreens, treatment is as simple as removing galls as they appear. Fungicide application may slightly reduce the appearance of galls.

For apples, preventative treatment is the only way to ensure the fungus is not present. In spring, fungicide applied to flowering buds is effective. Spraying the soil below can treat fallen spores and prevent them from spreading.

Professional Tree Health Care 

Tree health problems require an arborist tree assessment in order to identify and treat potential diseases. A professional arborist can offer a personalized treatment plan to maintain the health of your trees. 

Rick’s PHC Certified Arborists in West Chester, PA, answers all tree-related questions, including “Does cedar-apple rust kill trees?” Call 610-840-2655 to speak with one of our professional arborists.