Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens & Weeds

Capsicum Phoma blight (239)

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Photo 1. Small, irregular spots 1-2 mm, on a capsicum leaf, brown at first, later maturing to light grey with brown border.

Photo 2. Close-up of a single spot showing the pycnidia (black dots) which contain large numbers of spores.

Photo 3. Large expanding spots on a mature capsicum fruit showing masses of spores that have discharged from the round spore-containing pycnidia.

Summary

  • Worldwide distribution. On capsicum, cotton, cowpea, eggplant, okra, soybean, tomato, and more. A minor disease when plants are wounded by weather or insects.
  • Spots, irregular, 1-2 mm, pale brown with brown borders, on leaves and stems. Large spots on fruits with black tiny fruiting bodies.
  • Spread in rain splash and wind; possibly, seed.
  • Cultural control: care during cultural operations; weed; control fruit flies; handle fruit with care; collect and burn trash after harvest; crop rotation.
  • Chemical control: not recommended for this disease; if required use copper or chlorothalonil.

Common Name

Capsicum blight

Scientific Name

Phoma species; commonly Phoma exigua. It was previously known as Ascochyta phaseolorum. It has been renamed Boeremia exigua var. exigua.

Photo 4. A single fruit body (pycnidium) under the microscope that has been squashed to release the large number of small oval spores (seen at the top of the photograph).

AUTHOR Grahame Jackson
Information from McKenzie E (2013) Boeremia exigua: PaDIL - https://www.padil.gov.au/; and from CABI (2019) Boeremia exigua var. exigua (leaf spot). Crop Protection Compendium. (https://www.cabi.org/cpc/datasheet/40426). Photos 1&2 Jacqui (Wright) Kami, formerly Plant Pathologist, Secretariat of the Pacific Community, Suva, Fiji. Photo 3 Phoma pycnidia Bruce Watt, University of Maine, Bugwood.org. Photo 4 Phoma sp. Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org.

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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