• Worldwide distribution. On bele (see Fact Sheet no. 149), citrus, papaya (see Fact Sheet no. 152), passionfruit (see Fact Sheet no.154), pineapple, tobacco, tomato (see Fact Sheet no. 157) and many other hosts. An important disease.
• A water mould, an oomycete, not a fungus. Worse in wet soils. Root are infected and rot; collar rots occur causing the bark to dry, die and fall away, and the trunk to ooze gum.
• Above-ground, leaves yellow, dry and fall, and branches dieback. Lower fruit become infected.
• Cultural control: drainage; bud high on root stock; ensure nursery plants are disease free; weed; prune low-hanging branches; importantly, seek local advice on root stock varieties.
• Chemical control: copper - against lower fruit infections and collar rots; phosphorous acid after times of flowering and main leaf flushes.

Citrus root and collar rot, Phytophthora foot and root rot (Phytophthora nicotianae), and brown rot of citrus fruit (Phytophthora citrophthora).

Two species are commonly found causing root and collar rots on citrus: Phytophthora nicotianae, and Phytophthora citrophthora.