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Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

Coconut bud rot (140)

Photo 1. Bud rot of coconut showing the collapse of the spear and younger leaves due to infection by Phytophthora palmivora, while the older leaves appear relatively healthy at this time.

Photo 2. Nuts are also infected by coconut bud rot causing premature nutfall. In this case, Phytophthora hevae was isolated from the rot.

Photo 3. Slices from nuts (Photo 2) showing internal infections by Phytophthora hevae.

Photo 4. Basal stem rot of coconut seedling, caused by Phytophthora palmivora.

Photo 5. Coconut seedling (Photo 4) cut open to show the internal infection by Phytophthora palmivora.

Summary

Worldwide distribution. On coconut and other palms (e.g., betel nut), cocoa (see Fact Sheet no. 006) and papaya (see Fact Sheet no. 152), as well as weeds. A water mould, an oomycete, not a fungus is the cause. A minor disease in the Pacific islands, although occasional outbreaks in nurseries.
In the field, first sign is a bending of the spear leaf, with light brown rots on the leaf stalks. Central leaves rot (there is a foul smell) and fall out together with the bud, and the palm dies. Outer leaves remain green for a few months. Outbreaks occur in nurseries too.
Cultural control: good drainage to keep humidity low to reduce the time for spore germination; remove diseased palms; space at least 10 m apart to help air circulation; varietal differences exist. Malayan Dwarf is susceptible.
Chemical control: not recommended but, if needed: (i) copper; or (ii) phosphorous acid or metalaxyl injections

Common Name

Coconut bud rot

Scientific Name

Phytophthora palmivora. Note, there may be more than one species of Phytophthora in the Pacific islands causing bud rot. For instance, Phytophthora hevae is also said to occur, causing a bud and nut rot of coconuts in New Caledonia (Photos 2&3).

AUTHOR Grahame Jackson
Information (and Photo 1) Gerlach WWP (1988) Plant diseases of Western Samoa. Samoan German Crop Protection Project, Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) Gmbh, Germany. Photos 2-5 Kohler F, Pellegrin F, Jackson G, McKenzie E (1997) Diseases of cultivated crops in Pacific Island countries. South Pacific Commission. Pirie Printers Pty Limited, Canberra, Australia.

Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community

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