Ash Trees

Ash Yellows: A Devastating Disease of Ash Trees

Introduction

Ash yellows is a serious disease that affects ash trees and other related plants, including lilacs. It can cause significant damage and even kill trees if left untreated. In this article, we will explore what ash yellows is, how to identify its symptoms, and what steps you can take to prevent and control it.

What is Ash Yellows?

Ash yellows is a plant disease caused by a tiny organism called a phytoplasma. It was first discovered in the 1980s, but it likely existed long before that. Ash yellows is unique to North America and only affects members of the ash (Fraxinus) family.

Symptoms of Ash Yellows

The symptoms of ash yellows can vary depending on the species of ash tree and the stage of infection. However, some common symptoms include:

• Yellowing and thinning of leaves
• Reduced leaf size
• Dieback of branches and twigs
• Formation of witches’ brooms (dense clusters of twigs)
• Slowed growth rate
• Reduced fruit production

How to Identify Ash Yellows

Diagnosing ash yellows can be difficult, as its symptoms are similar to those of other plant diseases and environmental stresses. However, there are a few key characteristics that can help you identify ash yellows:

• The symptoms are widespread throughout the tree, affecting multiple branches and leaves.
• The leaves turn yellow and thin, but they do not develop spots or other discoloration.
• The tree’s growth rate is significantly reduced.
• Witches’ brooms are present on the tree.

How to Prevent and Control Ash Yellows

There is no cure for ash yellows, but there are steps you can take to prevent and control its spread:

• Plant resistant species: Choose ash species that are resistant to ash yellows, such as white ash and green ash.
• Remove infected trees: If you have a tree that is infected with ash yellows, it is important to remove it promptly to prevent the disease from spreading to other trees.
• Control insects: Insects can spread ash yellows from tree to tree. By controlling insect populations, you can reduce the risk of infection.
• Avoid pruning infected trees: Pruning infected trees can spread the disease to other parts of the tree and to nearby trees.

Long-Term Management of Ash Yellows

Managing ash yellows over the long term requires a combination of prevention and control measures. By following the steps outlined above, you can help to protect your ash trees from this devastating disease.

Additional Tips

• If you are unsure whether your tree has ash yellows, consult with a certified arborist for a professional diagnosis.
• If you have an infected tree, remove it as soon as possible to prevent the spread of disease.
• Disinfect your tools after pruning or handling infected trees to prevent the spread of ash yellows.
• Plant new ash trees in areas where ash yellows is not present to reduce the risk of infection.
• Monitor your ash trees regularly for signs of ash yellows and take appropriate action if necessary.