6 Most Common Tree Diseases Found in Philadelphia

Trees are an investment in your property, so most people want to ensure they grow healthy and live to old age. Trees also contribute to the overall health and beauty of your environment, providing shade and clean air.

Understanding the most common tree diseases goes a long way to helping you look after your trees because it can help you identify diseases in time for an arborist to help.

If you suspect your tree has a disease because it displays signs such as powdery mildew and yellow leaf spots, read on to learn about the most common tree diseases that may require you to call in a trusted and certified Philadelphia arborist.

Apple Scab

Apple scab is a fungal disease that affects cultivated and wild crabapple trees. It manifests as lesions around the leaves near flower buds. These lesions progress over time, appearing as yellow, olive-green, or brown leaf spots.

As the disease affects the tree, it may infect the fruit and cause the leaves to dwarf, twist, and fall off.

Fire Blight

Fire blight is a bacterial infection commonly found in apple and pear trees. This disease causes the leaves to look scorched as if by fire, hence its name. It attacks new growth areas such as buds and travels down tree stems, eventually causing dieback.

There is no known cure for this disease, but a professional arborist can successfully prune affected areas and save the healthy parts of the tree. Severely damaged trees may require complete removal.


This disease typically affects ash, maple, oak, dogwood, and sycamore trees. The most common symptoms of anthracnose include premature defoliation, dead leaf spots, and dying buds and twigs.

Arborists will usually recommend tree removal as the only remedy to solve this problem, especially if they have tried pruning or spraying a copper fungicide with no success.

Powdery Mildew

One of the most common tree diseases in Pennsylvania is powdery mildew. This fungal disease thrives in warm climates with substantial humidity. The telltale sign of this tree disease is leaves that look like they have a coating of fine white powdery circles.

Fortunately, treatment is simple: a half teaspoon of dishwashing liquid mixed with a tablespoon of baking soda or mouthwash sprayed on affected parts should do the trick.

Thousand Cankers Disease

Cankers disease occurs due to fungal infections from walnut twig beetles. These beetles tunnel into the bark of walnut trees, creating tiny cankers that disrupt the trees’ ability to absorb the nutrients and water they need.

Over time, the tree branches, and eventually the tree, die. There is no known cure for cankers disease.

Verticillium Wilt

Verticillium wilt is a fungal disease that affects deciduous trees. Affected trees have smaller leaves, heavy seed production, a characteristic brown margin on the leaves, and wilting on only one side of the foliage. In addition, the wood under wilting branches will be streaked and discolored.

Pruning tree branches affected by this disease often halts it from spreading further.

Contact a Professional Philadelphia Arborist for Certified Tree Services

Whatever is affecting the trees on your property, whether it’s one of the most common tree diseases or something rarer, a certified arborist can diagnose the problem and help you determine the next steps. There may be many other causes ailing your tree, including environmental stressors and pests.

If you need experienced tree service experts in Philadelphia to help you deal with infected trees, Mercado’s Landscaping and Tree Service is available to help. We provide professional tree services at affordable rates and with the utmost care and professionalism. Get in touch with our professional arborists today at (215) 764-5509 for a free estimate.

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