Wednesday, February 20, 2008

Greenhouse - Manage to Reduce Botrytis

Botrytis is a major disease problem in greenhouse plants and can be seen infecting flower parts commonly. The following is a report from the University of Maryland on Botrytis.

We are seeing Botrytis on pansy, cyclamen, and primrose this week. Botrytis can invade the plant directly through unwounded plant parts, especially flowers or through wounds such as the stubs left when plants are pinched. Any areas of damaged tissue can be easily invaded by Botrytis.

The Botrytis fungus requires a film of water on plant surfaces to germinate and infect the plant. This film of water must remain on the plant surface for several hours. Any cultural practice that prevents continuous periods of leaf wetness will help prevent Botrytis infection. Proper spacing and sanitation, removal of spent flowers, periodic venting, horizontal airflow fans, and watering early in the day are recommended.

Some fungicide controls include: Decree (fenhexamid), Zerotol (hydrogen peroxide), Spectro (chlorothalonil), and Protect T/O (mancozeb).

Adapted from an article in the February 15, 2008 issue of the Greenhouse TPM/IPM Weekly Report from University of Maryland Cooperative Extension.

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