Is powdery mildew fatal?

It is rarely fatal if caught early, but it can severely stunt growth and seed production.

Should I remove the spotted leaves?

Yes, carefully snip off heavily infected leaves to reduce the spread of spores.

Thale cress: spots, causes and fixes

Check these first

Inspect the undersides of the leaves for signs of fungus.
Check if the leaves are staying wet after watering.
Ensure there is enough space between plants for air to move.

Likely causes

Powdery mildew
Most likely
How to tell: White, powdery patches appear on the surface of the leaves and stems.
What to do: Improve air circulation by using a small fan or moving the plant to a less crowded area. You can gently wipe leaves with a damp cloth or use a mild neem oil spray if the infection is widespread.
Water splashing
Possible
How to tell: Small, irregular spots appear after watering, often accompanied by leaf yellowing.
What to do: Always water at the base of the plant rather than overhead. Avoid getting water on the leaves to keep the foliage dry.

Leaf spots on other plants

Find out what's wrong with your thale cress

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

When to worry

If the spots cover most of the leaf surface, the plant will struggle to photosynthesize. Treat it immediately to prevent the fungus from spreading to other plants.

Stopping it coming back

Keep the foliage dry and ensure good ventilation in your growing space.

Thale cress: spots? Check yours with a photo

Every plant is a little different. Take a photo of your thale cress and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

Get the app · Or check it from a photo now, free

Questions people ask

Is powdery mildew fatal?: It is rarely fatal if caught early, but it can severely stunt growth and seed production.
Should I remove the spotted leaves?: Yes, carefully snip off heavily infected leaves to reduce the spread of spores.

Guides to these causes

Powdery Mildew

Why are there white spots on my Thale cress leaves?