Hyaloperonospora niessliana
A downy mildew which parasitises Hedge Garlic, Alliaria petiolata, forming dense, well-defined white patches on the leaf undersides. This is considered to be a gall-causer.
host 
Photograph both sides of the leaf and the downy mildew on the host plant; ensure you have noted the host species in your comments
Hedge Garlic, Alliaria petiolata
This species is part of the Hyaloperonospora parasitica s.lat. species complex; species in this group affect plants in the Brassicaceae
sue
Huncote, Croft Hill Road path
23 March 2026
Hedge Garlic (Alliaria petiolata)
white mildew on leaf undersides
sue
Huncote, Croft Hill Road path
23 March 2026
x400, Cotton Blue stain
from leaf undersides, Alliaria petiolata
sue
Huncote, Croft Hill Road path
23 March 2026
Upperside of affected leaves slightly distorted
sue
Huncote, Croft Hill Road path
23 March 2026
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Species profile
- Species group:
- fungoid
- Kingdom:
- Chromista
- Order:
- Peronosporales
- Family:
- Peronosporaceae
- Records on NatureSpot:
- 5
- First record:
- 30/05/2019 (lemmon, roy)
- Last record:
- 23/03/2026 (Timms, Sue)
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% of records within its species group
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