The Crux of Fruit Tree Care: Part II-Disease

The Crux of Fruit Tree Care: Part II-Disease

Blight Breakdown

Fruit trees can be a beautiful and productive asset on any landscape; tenacious, sweet smelling blooms provide aesthetic appeal while also attracting pollinators and fruit can be harvested or left as wildlife forage. However, they can be susceptible to diseases which will compromise aesthetic value, growth and fruit production.  Detection, identification, prevention and treatment are integral steps to preserving the health and value of your fruit trees. Discussed below are the most common diseases found on fruit trees, it is, by no means, an all-inclusive list, please have your arborist assess your property to accurately identify any diseases present and develop the proper treatment plan.


Apple scab is a fungal disease which affects both leaves and fruit of apple trees. Pictured here are the symptomatic leaf scabs.


Pictured here is severe fruit scab, a symptom of apple scab. Apple scab is caused by the fungus Venturia inaequalis and is common in wetter, inland areas.


Powdery mildew appears on fruit as spreading cracks on the skin. This disease reduces vigor, flower production and fruit quality.


Powdery mildew caused by Podosphaera leucotricha fungus, affects the leaves, twigs, fruit and flowers of apples, crabapples and pears. Symptoms are most noticeable on leaves and fruit, seen here is the greyish layer of mildew on the leaves.

cedar apple rust

Once spores find apple leaves they will infect causing orangish-yellow pustules. These pustules affect the leaves’ ability to collect sunlight for photosynthesis.

cedar apple rust-cedar

Cedar apple rust, caused by the fungus Gymnosporangium juniperi-virginianae, needs 2 hosts to complete its life cycle. Above is the gall with extruded telia formed on the eastern red cedar. During dry conditions spores will be released.


Fire blight produces several symptoms affecting, leaves, fruit, twigs, bark and blossoms. Apple, pear, quince and raspberry are all very susceptible.




Fire blight is caused by the bacterium, Erwinia amylovora and can be one of the most destructive fruit tree diseases. Intensity of outbreak will depend on weather patterns and plantings but needs to be closely monitored and appropriately treated.

 Remedial Recourse

Time and again, Integrated Pest Management (IPM) is mentioned in this blog.  It is important to understand and utilize all the available options in order to get the most effective results in the most efficient manner, which is the core principle of IPM. There are cultural practices which can aid your landscape plants in resisting diseases such as pruning, fertilization, liming (for pH balancing), plant positioning, proper watering and mulching.  Combining cultural methods with fungicides and/or bactericides, applied where and when necessary by a trained technician (this cannot be stressed enough, fungicides and bactericides are highly controlled and need to be applied responsibly) can provide all around prevention and control in an effective and environmentally accountable fashion.  Make an appointment with your arborist, have them evaluate your fruit trees and establish an integrated plan customized for your landscape.