Galls – Definition & Detailed Explanation – Tree Diseases and Pests Glossary

What are galls?

Galls are abnormal growths that form on various parts of trees, including leaves, stems, branches, and roots. These growths are typically caused by the tree’s response to an irritant, such as an insect, mite, fungus, or bacteria. Galls can vary in size, shape, and color, depending on the type of irritant and the tree species affected. While galls are generally harmless to trees, they can be unsightly and may indicate an underlying issue that needs to be addressed.

What causes galls on trees?

Galls are caused by the tree’s response to an irritant, which can be a variety of organisms including insects, mites, fungi, or bacteria. When these irritants come into contact with the tree, they trigger a hormonal response that results in the formation of a gall. The irritant may lay eggs, feed, or inject toxins into the tree, causing the tree to produce abnormal growth in an attempt to protect itself. Different types of irritants can result in different types of galls, each with its own unique characteristics.

How do galls affect trees?

While galls are generally harmless to trees, they can affect the tree’s overall health and appearance. In some cases, galls can interfere with the tree’s ability to photosynthesize, transport water and nutrients, or grow properly. Severe infestations of galls can weaken the tree and make it more susceptible to other pests and diseases. Additionally, galls can be unsightly and may reduce the aesthetic value of the tree, especially in ornamental landscapes. It is important to monitor galls on trees and take appropriate action to prevent or treat them if necessary.

How can galls be treated or prevented?

There are several methods for treating or preventing galls on trees. One common method is to prune and remove affected branches or leaves to reduce the spread of galls. In some cases, applying horticultural oils or insecticidal soaps can help control the pests that cause galls. Properly watering, fertilizing, and maintaining the health of the tree can also help prevent galls from forming. In severe cases, it may be necessary to consult with a professional arborist or horticulturist to determine the best course of action for treating galls on trees.

What are common types of galls found on trees?

There are many different types of galls that can form on trees, each caused by a specific irritant. Some common types of galls include:

– Leaf galls: These galls form on the leaves of trees and can vary in size, shape, and color. They are often caused by insects or mites that lay eggs or feed on the leaves.
– Stem galls: These galls form on the stems or branches of trees and can cause swelling or distortion of the affected area. They are typically caused by insects or fungi that inject toxins into the tree.
– Root galls: These galls form on the roots of trees and can interfere with the tree’s ability to absorb water and nutrients. They are often caused by nematodes or bacteria that infect the roots.

Each type of gall has its own unique characteristics and may require different methods of treatment or prevention.

How can galls be identified on trees?

Galls can be identified on trees by their appearance, location, and the type of irritant causing them. Some common signs of galls include abnormal growths, swelling, discoloration, or distortion of leaves, stems, branches, or roots. Galls may also have a unique shape, color, or texture that sets them apart from normal tree growth. It is important to inspect trees regularly for signs of galls and take appropriate action if they are detected. Consulting with a professional arborist or horticulturist can help identify the specific type of gall and determine the best course of action for treating or preventing it.