What Are the Signs of Ash Tree Disease?

What are the signs of ash tree disease? If you worry about your beloved tree succumbing to a pesky malady, you’re not alone. Solidify your first line of defense by arming yourself with knowledge.

As the go-to arborist services in Phoenix, our crew at Tree Workers of Phoenix knows a thing or two about arboreal afflictions. Keep reading as we break down the nitty-gritty details, from deciphering early warning signs to taking preventative measures that could save your tree from an untimely demise.

The Common Culprits

Unfortunately, the destructive elements trying to lay waste to your precious ash come in various forms. Let’s delve into some of the most notorious offenders:

Ash Borer

This dastardly insect, better known as the emerald ash borer, is a vibrant green beetle that hails from Asia. 

Don’t let its tiny size fool you. The critter has become a veritable nightmare for American ashes, causing widespread destruction wherever it spreads its wings. In most cases, you need to have infected trees removed and destroyed to prevent further spread.

Symptoms include:

  • D-shaped exit holes
  • Dead branches and dieback
  • Vertical bark splits
  • Excessive sprouting from the base of the tree

Ash Anthracnose

Anthracnose refers to a fungus-driven disease that tends to infect trees during winter and manifest in the spring, especially when the weather gets wetter. Unfortunately, it can harm almost every variety, including black, red, velvet, white, and green ash.

Watch out for:

  • Blighted, brown leaves
  • Leaf drop during spring and early summer
  • Lesions or cankers on the twigs and branches
  • Twig death in severe infections

Ash Yellows

Did you know that trees can have viral infections, too? Ash yellows, a tree’s equivalent to a human’s flu, stems from phytoplasmas. This microscopic menace—a bacteria-like organism—wreaks havoc on your ash’s internal system.

Common warning signs include:

  • Yellowing and wilting foliage
  • Stunted growth
  • Smaller leaf size
  • Thick, dark bark that may crack or split over time

Ash Rust

Ash rust comes from a fungus called Puccinia sparganioides. This disease makes its appearance during mid to late spring when sporulation occurs on the leaves. While not usually deadly, you shouldn’t leave it to fester, either.

What are the signs of ash tree disease? Infected ones exhibit these symptoms:

  • Heavy leaf drop in late summer or fall
  • Brown to orange lesions on the leaves 
  • Deformed, twisted, or otherwise disfigured leaf
  • Curled petioles and twigs

Your Best Bet Against Pests and Disease

An ounce of prevention is worth a pound of cure, and this adage rings immensely true in the world of arboriculture. So, what can you do?

  • Supplemental watering: While ash trees are generally hardy and can withstand Arizona’s dry conditions, during extreme drought or for young, newly planted trees, extra moisture becomes a lifeline.
  • Regular pruning: Pruning not only gives your tree a robust structure that can handle strong winds but also increases air circulation and sunlight penetration, reducing the chances of disease spread.
  • Consistent monitoring: Keep an eagle eye on your tree. Early detection helps prevent disease progression.
  • Soil amendments: Not every yard has the ideal soil for ash trees. From installing drainage to adjusting pH levels, making these changes sooner rather than later can make all the difference.

Consult a Local Arborist

With so many types of ash trees and various pests and diseases to watch out for, it can feel a bit overwhelming. When in doubt, why not consult our green-thumbed specialists at Tree Workers of Phoenix? 

We can tackle anything from a regular check-up to an all-out emergency. Call 602-320-2797 today.

Beyond knowing what are the signs of ash tree disease, learning to identify common tree fungus may also become a boon to your vigilant efforts.   


Tree Workers of Phoenix has been in business since 1994 and is a member of the Better Business Bureau (BBB) and International Society of
Arboriculture (ISA).


18402 N. 19th Ave. #115

Phoenix, AZ 85023

Phone: 602-320-2797

Email : rickthetreeexpert@gmail.com

Hours of Operation :

Monday - Sunday : 9:00am-5:00pm


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