Scientific studies have demonstrated that numerous declines and diebacks affecting horticultural crops, forests and natural ecosystems in Europe, Australia and the Americas are primarily caused by invasive soil- or airborne pathogens from the genus Phytophthora. Extensive surveys conducted in more than 2,500 nurseries and a similar number of restoration and planting sites across Europe revealed near-ubiquitous infestation with over 120 Phytophthora species, most of them exotic.
Nursery accreditation schemes have been operating successfully for years in Australia, California and recently the United Kingdom. They showcase that the spread of invasive plant pathogens can be drastically reduced through effective biosecurity standards, improving plant quality while ensuring the economic viability of the nursery sector.

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