Botrytis blight

July 6, 2015

Fungal leaf spots


Botrytis cinerea.


Very large host range, some of the most susceptible include Delphinium, Hosta, Iris, Lilium, Primula, Rudbeckia and Viola. Blossoms are especially susceptible.

Botrytis on hosta
Severe leaf spotting. Infections developed during prolonged, wet weather


Seedling blight, leaf spots and blight, distortion of young leaves, crown rot and blossom blight.

Botrytis cinearea Lilium leaf spot
Severe leaf spotting on Lilium, a very susceptible host.


In high relative humidity, grayish, fuzzy mold on the surface of the affected tissue is visible with the naked eye.

stem with Botrytis
Basal ends of cuttings can be infected during propagation. The gray, fuzzy mold is characteristic of B. cinerea sporulation.


Spores are produced in mass under humid conditions and are readily released and moved by air currents. Additionally, overwintering structures (sclerotia) are formed and can persist in soil and plant debris. Sclerotia are found on the surface of heavily diseased plant material.

Stem with sclerotia
Sclerotia, the overwintering structure, on dead stem tissue.


Sanitation and aeration procedures that reduce humidity levels around plants and appropriate fungicide applications are recommended for disease control. Botrytis cinerea can sporulate on dead plant material; fallen leaves and petals should be carefully removed from production areas. Trash cans used for dead plant tissue should not be kept in production areas. Regular fungicide applications will likely be necessary to reduce losses on especially susceptible hosts grown in humid environments.

Botrytis rudbeckia
Foliar blighting of Rudbeckia.

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