Pacific Pests, Pathogens, Weeds & Pesticides - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Lettuce Sclerotinia collar rot (129)

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Photo 1. Sclerotinia on soybean. Note the fungus has destroyed the roots of these three plants, and large balls of the fungus called sclerotia have formed on the stem and tap root. These will germinate to produce a mushroom-like body that produces spores.

Photo 2. Severe wilt of lettuce caused by Sclerotinia soft rot fungus. The fungus produces sclerotia (see Photo 1) and these can survive in the soil for many years.

Photo 3. Close up of lettuce showing the basal rot, with the cottony growth of the soft-rot fungus, Sclerotinia.

Summary

  • Worldwide distribution. On many vegetables, fruit and field crops. Important disease in sub-tropical countries.
  • Cottony growth causes rots of roots, stems, leaves and fruits; also, damping–off. Black, survival bodies ('sclerotia') form, later producing a toadstool and liberating spores infecting dying leaves and flowers.
  • Cultural countries: wide spacing; trellis; prune lower leaves/branches; crop rotation; soil sterilisation; add manures; mulch, do not harvest and pack in wet weather; plough in trash or collect and burn.
  • Chemical control: seed treatments: thiram or captan; in the field: benzimidazole, strolbilurin or triazole fungicides.

Common Name

Cottony soft rot, Sclerotinia soft rot, collar rot, white mould, lettuce drop.

Scientific Name

Sclerotinia sclerotiorum

AUTHOR Grahame Jackson
Information from (and Photo 1) Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, et al.. CSIRO Publishing; and from CABI (2019) Sclerotinia sclerotiorum (cottony soft rot). Crop Protection Compendium. (https://www.cabi.org/cpc/datasheet/49124). Photos 2&3 Kohler F, et al. (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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