Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

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Passionfruit Phytophthora rot (154)

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Photo 1. Stem rot, water mould, Phytophthora nicotianae. Rots are purple at first, later brown. When they girdled the stem they cause a wilt.

Photo 2. Fruit rot caused by the water mould, Phytophthora nicotianae. Rots are grey-green at first and later light brown.

Summary

• Worldwide distribution. On passionfruit, cultivated and wild. Note, this is the same fungus that causes a similar disease on tomato (root rot, and a firm dark fruit rot; see Fact Sheet no. 157), and also attacks capsicum, citrus (see Fact Sheet no. 264), papaya (see Fact Sheet no. 152), pineapple, and tobacco.
• A water mould, an oomycete, not a fungus.
• A blight of young leaves, brown spots on older ones, rots on fruits and vines; root decay causing wilts.
• Spread by rain splash from spores in the soil; long distance spread is on wind-driven rain, and perhaps on nursery plants.
• Cultural control: yellow variety rootstocks with graft 30 cm above soil; avoid planting in poorly drained land; prune to aid air circulation and drying; grass barriers to stop rain-splash; collect trash and burn after harvest.
• Chemical control: copper or mancozeb (protectants); or phosphorous acid (systemic).

Common Name

Fruit rot, Phytophthora blight

Scientific Name

Phytophthora nicotianae; previously, Phytophthora nicotianae pv. parasitica. Note that in Fiji Phytophthora cinnamomi has also been reported as the cause of collar rot.

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