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Pacific Pests & Pathogens - Mini Fact Sheet Edition

Papaya Phytophthora fruit & root rot (152)

Photo 1. Papaya fruits infected by Phytophthora palmivora. Note the white cottony growth of the water mould, and that the disease is spreading from the older, lower, fruits upwards.

Photo 2. Close-up of a papaya fruit showing the cottony growth of fruit rot, Phytophthora nicotianae, identical in appearance to that caused by Phytophthora palmovora (Photo 1).

Photo 3. Tree shown in Photo 3 with basal stem rot caused by Phytophthora palmivora.

Photo 4. Lower stem or "foot" rot on papaya caused by Phytophthora palmivora.

Photo 5. Stem rot on papaya caused by Phytophthora palmivora.

Photo 6. Root rot and/or basal stem rot caused by Phytophthora palmivora, resulting in a wilt and rapid death of the trees.

Summary

Worldwide distribution. On coconut, cocoa, avocado, citrus and breadfruit, papaya and more. An important disease, worse in waterlogged soils at high temperatures.
Large areas of rot on lower fruit with white fungal growth, progressing upwards. Rots occur on stems via leaf and fruit scars. Roots rots cause wilts.
Spread in rain splash, wind, machinery, ground water.
Cultural control: improve drainage - plant on ridges or raised beds; mulch to stop rain splash; collect and burn infected fruit and stems; 4-year crop rotation.
Chemical control: chlorothalonil, copper, mancozeb (protectants); or alternate with metalaxyl or phosphorous acid (systemics).

Common Name

Papaya fruit and root rot, Phytophthora fruit rot

Scientific Name

Phytophthora palmivora. Note, Phytophthora nicotianae has also been recorded as the cause of this disease in e.g., Australia and Fiji. This fact sheet assumes the symptoms and management for both are similar.

AUTHOR Grahame Jackson
Information (and Photos 1,3,6) Gerlach WWP (1988) Plant diseases of Western Samoa. Samoan German Crop Protection Project, Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) Gmbh, Germany; and from Diseases of fruit crops in Australia (2009). Editors, Tony Cooke, Denis Persley, Susan House. CSIRO Publishing. Photo 2 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. Photos 4&5 Liberato JR, Suzuki MS, Denth A (2006) Phytophthora Fruit Rot and Root Rot of Papaya (Phytophthora palmivora) PaDIL - (http://www.padil.gov.au).

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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