The invaded tissues will disintegrate into a slimy brown rot if humidity remains high. The rotted tissues may also become a dry brown rot if the environment dries out after stems and leaves are invaded. If humidity remains high, very soon after visible lesions appear, they become covered with a dense mat of gray mold. Each conidiophore produces several hundred spores, so a mat of Botrytis can produce spores by the thousands, which are easily dislodged and airborne by even the slightest disturbance. Clouds of spores can be observed coming off a mat of gray mold fungus when a slight breeze rustles an infected plant.
Botrytis activity is favored by high humidity.
The fungus grows equally well in light or in darkness, but produces spores only in the light. These conditions can occur any day of year on the Central Coast. Free moisture in the form of liquid water is necessary for germination of Botrytis spores. Moisture is also necessary for growth within plant tissues, and low humidity helps arrest growth of the fungus. However, growth can resume when moisture again becomes available.