Cause The fungus, Botrytis cinerea. This fungus has a wide-host range and is common throughout the year in western Oregon. Plants with injury to the flower bracts due to frost, slugs, snails, or insect damage, are especially susceptible to Botrytis infections.
Symptoms Leaves and flower bracts turn brown, and may take on a water-soaked appearance. Characteristic grayish-black moldy growth appears on infected plant parts.
Cultural control
- Remove dying leaves and bracts. Removal of tissues injured by frost can help plants overwinter in western Oregon.
- Protect plants from feeding injury due to slugs, snails, or insect pests.
Chemical control
- Pristine at 18.5 to 23 oz/A on 7- to 14-day intervals for up to three (3) applications per year. Do not tank-mix with any other product (see label). Can be applied the day of harvest. 12-hr reentry.
Biological control
- Stargus at 2 to 4 quarts/A plus a nonionic surfactant on 7- to 10-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
- Serenade Opti at 14 to 20 oz/A on 7- to 10-day intervals. Applications can be made up to and the day of harvest. 4-hr reentry. O