Scouting for diseases: Botrytis blight

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.    

Editor’s note: This information is from the new field guide
A Pocket Guide for IPM Scouting in Herbaceous Perennials. For ordering information, call 517-353-6740 or visit: http://www.ipm.msu.edu/pdf/pocketGuidesLandsc07.pdf

Pathogen.
Botrytis cinerea.  (view images)

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

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

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

Spread.
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.

Management.
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.

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