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Ministry of Agriculture, Food and Rural Affairs

Gray Mold (Botrytis)

Gray mold symptoms on tomato plant Gray mold fruit symptoms Gray mold fruit symptoms Symptoms of gray mold on tomato stem
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Beginner

Scientific Name
Botrytis cinerea

Identification

  • Main symptoms on fruit are ghost spots- a pale halo or ring with a brown to black pinpoint spot in the centre
  • Occasionally fruit will rot
  • The fungus can appear as a grey, velvety covering of spores on leaves, stems, dying flowers, or fruit
  • Infection appears first on leaves in contact with the soil, damaged leaves, or flowers
  • Infection on stems may girdle the plant

Often Confused With
White mold

Period of Activity
Gray mold favour periods of prolonged high humidity. It can be present all season, but the main symptoms appear during fruiting. It is uncommon except during very wet seasons and is not usually a serious concern.

Scouting Notes
Both gray mold and white mold are most common during wet seasons. The fuzzy, grayish covering of fungal growth on lesions is diagnostic of gray mold. White mold lesions can be distinguished by the development of black fungal bodies (sclerotia).

Thresholds
None established.

Advanced

Scientific Name
Botrytis cinerea

Identification
The main symptoms of gray mold are ghost spots on fruit, and occasionally fruit rotting. Ghost spots show a pale halo or ring with a brown to black pinpoint spot in the centre. The fungus can appear as a grey, velvety covering of spores on leaves, stems, dying flowers, or fruit. Infection appears first on leaves in contact with soil, damaged leaves, or flowers. Infection on stems may girdle the plant.

Often Confused With
White Mold

Biology
The pathogen responsible for gray mold has a wide host range and can be spread by wind. It can also grow on organic matter in or on the soil. It generally needs a wound or dead tissue in order to begin an infection into live tissue.

Period of Activity
Gray mold favours periods of prolonged high humidity. It can be present all season, but the main symptoms appear during fruiting. It is uncommon except during very wet seasons and is not usually a serious concern.

Scouting Notes
Both gray mold and white mold are most common during wet seasons. The fuzzy, grayish covering of fungal growth on lesions is diagnostic of gray mold. White mold lesions can be distinguished by the development of black fungal bodies (sclerotia).

Thresholds
None established.

Management Notes

  • Control measures are rarely required.
  • Some registered fungicides have activity on this pathogen.