Pocket BotanistSymptoms by part
Leaves
Small, dark brown or black spots appear on the leaf blades, often followed by the leaves wilting, curling, and turning brown as the infection spreads to the leaf stalks.
Stems
Dark, sunken cankers form on the twigs and branches, which eventually girdle the stem and cause the tips to bend into a characteristic shepherd's crook shape.
Causes
- Prolonged periods of cool, wet weather during the spring.
- Poor air circulation within the tree canopy.
- High humidity levels that allow fungal spores to germinate on wet foliage.
Could be confused with
- Willow Anthracnose · Anthracnose typically causes larger, more irregular blotches on leaves and does not usually cause the distinct shepherd's crook twig distortion seen in blight.
- Frost Damage · Frost damage affects new growth uniformly across the tree after a cold snap, whereas blight appears as localized spots and cankers that progress over time.
Treatment
- Prune out all infected twigs and branches at least 6 inches below the visible canker during dry weather.
- Sterilize your pruning shears with rubbing alcohol between every single cut to avoid moving spores to healthy wood.
- Gather and destroy all fallen leaves and debris from beneath the tree to remove overwintering fungal spores.
- Thin out the inner branches of the tree to improve airflow and allow the canopy to dry out faster after rain.
Without chemicals
- Pruning to improve air circulation.
- Sanitation by removing and burning or bagging all infected plant material.
- Avoiding overhead irrigation that keeps the foliage wet.
Chemical options
- Sulfur, apply as a preventative spray to the foliage during the early spring, follow the label.
Preventing it
- Select willow varieties known for better resistance to fungal pathogens.
- Space trees far enough apart to ensure good air movement.
- Water at the base of the tree rather than using sprinklers that wet the leaves.
- Clean up all leaf litter every autumn to prevent spores from surviving the winter.
Season
The warm growing season, particularly during wet spring weather.
Spread risk
High
Severity
High
When to act
Act as soon as you notice the first signs of leaf spotting or twig dieback to prevent the fungus from reaching the main branches. If the tree is large and the infection is high in the canopy, contact a professional tree surgeon to safely remove the diseased wood.
Think it's Willow Blight?
This guide covers the general picture. Pocket Botanist looks at your actual plant from a photo and tells you what's really going on, how serious it is, and what to try first. Identification and a health check are free.
Questions people ask
- Will my willow tree die from this?
- If the infection is caught early and the tree is otherwise healthy, it can recover. However, if the blight is allowed to girdle major branches or the main trunk, it can eventually kill the tree.
- Can I compost the infected leaves?
- No, do not compost infected leaves or branches. The fungal spores can survive the composting process and will reinfect your garden when you spread the compost later.
Plants it affects
This guide was generated with AI and is general information, not horticultural advice. Read about how we build these guides.