Willow trees, Salix spp., are deciduous trees suitable for cultivation in USDA Hardiness Zones 4 to 9.
They make imposing landscape specimens with heights from 20 to 140 feet and spreads of 30 to 60 feet, depending on the variety.
Cultural requirements include full sun to part shade, moderate to high moisture, and well-draining, loamy soil.
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Sometimes, you may notice galls – warty bumps on the leaves or growths that look like little pine cones at the ends of the branches, or even weird lumps on the trunk.
There may be few or many, and like me, you may find them fascinating.
In our guide to growing willow trees we provide all you need to know to cultivate these ornamental shade trees in your outdoor living space.
This article discusses galls common to trees in the Salix genus and suggests proactive steps you can take to avoid them.
Here’s what we’ll cover:
Let’s start.
What Are Willow Galls?
Willow galls are tumorous or wart-like growths that appear on the leaves, roots, and/or branches.
They can be caused by bacteria, fungi, insects, mites, nematodes, and viruses that secrete growth-regulating chemicals into emergent or young willow tissue.
Older foliage is not usually vulnerable to these parasitic organisms.
The chemicals cause increased hormone production and abnormal cell division in the plant tissue, resulting in tumor-like abnormalities.
In some cases, the galls nourish, protect, and shelter the progeny of the pests that caused them.
Common Causes
Let’s discuss some of the causative agents that can result in unusual growths on willow trees.
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