Troubleshooting
Hogweed problems — and how to fix them
Hogweed (Heracleum sphondylium) is generally low-drama, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Leaf-miner (Phytomyza spondylii)
Larvae of this specialised fly mine distinctive pale tunnels through the leaves; generally cosmetic on mature plants but can weaken seedlings — remove heavily mined leaves to reduce the population.
Powdery mildew (Erysiphe heraclei)
White powdery coating on leaves appears in late summer, particularly in dry spells; can reduce seed production — improve air circulation and avoid overhead watering.
Prevent hogweed problems before they start
Most hogweed issues are care-mismatch, not bad luck. Dial in the basics:
Hogweed problems — FAQ
Why is my hogweed leaf-miner (phytomyza spondylii)?
Larvae of this specialised fly mine distinctive pale tunnels through the leaves; generally cosmetic on mature plants but can weaken seedlings — remove heavily mined leaves to reduce the population.
Why is my hogweed powdery mildew (erysiphe heraclei)?
White powdery coating on leaves appears in late summer, particularly in dry spells; can reduce seed production — improve air circulation and avoid overhead watering.