Advanced stem rots also have sporangia on the surface on the diseased tissue. These sporangia are splashed onto other parts of the plant or to other plants. Rain and overhead irrigation favors diseased spread in nurseries. Fruit or seed infections have not been found but are likely since several commercial nurseries have lost many young seedling to this pathogen. The pathogen survives in diseased plant tissue in the absence of the host.
Oospores can also survive many months in soil or potting medium.
To begin a new crop, growers should carefully select seeds that are clean and firm. Avoid any seeds that are dented, soft or have dark blemishes. Plant seeds in new potting mix and produce the crop away from mature plants. A separate, clean greenhouse for new seedlings is highly recommended. Since moisture favors the pathogen life cycle and drives the disease cycle, moisture control is important.