In summer 2003, Peronospora lamii was observed for the first time in Switzerland on a greenhouse crop of Basilico (Ocymum basicicum). The origin is thought to be contaminated seeds and that high temperatures and a excessive spray irrigation favoured the sread of the disease. It is an obligate parasite which can only survice in plant tissue. Its preferential hosts come from the Lamiacee family that includes Basilico, Mint (Menta), Sage (Salvia spp.) and other aromatics. Outbreaks of this disease in Italy was first notified in Italy in 1999. In the absence of appropriate fungicides, seed companies can guarantee seed completely free from the pathogen in question through a specific DNA test of the seed coat. Early morning irrigation rather than in the evening will help to avoid the development of the pathogen and the same applies to drip irrigation. "Colture Protette" fax 051 6575856 E-mail: cp@gce.it