Symptom development is limited or absent during hot and dry weather and may be suppressed by fungicide applications. The disease is moved from infected stock to healthy plants primarily by splashing water that contains spores. Free water on the leaves is necessary for spore development. Under optimal conditions, new infection can be established in as little as five hours. CWR can also be spread to unifected plants on contaminated soil, litter, dead leaves, gardening equipment, clothes, shoes and hands.
Infectious spores can live for up to eight weeks on contaminated objects.
When CWR has entered the United States, survey, sanitation, modified cultural practices and fungicides have been employed to eradicate the disease. Since infectious spores can only live for up to eight weeks, the disease cycle can be broken by a host free period of equal duration. Management of the humidity and water can also limit disease spread.