Taking a guess (hope this isn't it because it's bad news):
Infection:
Botrytis is a weak pathogen that must have nutrients or some food source before it invades the plant. From this food base, the fungus becomes more aggressive and invades healthy tissue. A dark to light brown rot forms in the diseased tissue. High humidity conditions favor the growth of this fungus.
Sites of first infection:
Wounded tissue such as large stubs left after taking cuttings.
Fading flowers.
Leaves on which fading infected flowers have fallen.
Broken stems or injured leaves.
Leaves damaged by overfertilization, spray damage, or mechanical injury.
Seedlings grown under cool, moist conditions.
Cuttings taken from plants with heavy infestations of Botrytis.
Management:
Sanitation is the first important step. Remove dead or dying tissue from the plants and from the soil surface. Remove this refuse from the greenhouse. Do not throw debris under benches or on walks. Sanitation alone is not sufficient to control this fungus. The fungus can produce 60,000 or more spores on a piece of plant tissue the size of your small finger nail. Even one spore can infect a plant and cause disease.
