Phytophthora root rot
DISEASE
When it's active · UK
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When it's active · Northern Italy
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When it's active · Central Italy
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When it's active · Southern Italy and islands
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How to recognise it
Wilting, yellowing and dieback of an otherwise well-cared-for plant, with dark, mushy roots and often a foul smell when the rootball is examined.
Life cycle and conditions
A water-mould pathogen thriving in waterlogged, poorly drained soil; spreads in standing water and can persist in soil for years.
Prevention
Improve drainage before planting susceptible species; avoid planting in areas prone to waterlogging.
How to treat it
🌿 ORGANIC · RECOMMENDED
Improve drainage immediately if caught early; severely affected plants usually can't be saved and should be removed, avoiding replanting the same species in that spot.
🧪 CHEMICAL · IF YOU CHOOSE
Products to treat this pathogen exist commercially but aren't practically available or recommended for amateur gardeners — improving drainage is the meaningful lever here.
PLANTS MOST AFFECTED
Rhododendrontrees and shrubs in poorly drained soil