CDFA Pest Prevention Plant Regulation Practice Exam

In which California county is the pear-juniper rust known to occur?

1. San Mateo

2. Contra Costa

3. Marin

4. San Joaquin

The correct answer is: Contra Costa

The pear-juniper rust, a plant disease caused by the fungus *Gymnosporangium sabinae*, is known to affect both pears and junipers and has been monitored in various locations. In California, its occurrence has been documented, particularly in Contra Costa County. This area provides suitable environmental conditions for the disease to thrive, including the presence of both the pear and juniper hosts that allow for the fungus to complete its life cycle. Understanding the biological requirements of the pear-juniper rust is essential, as it requires both hosts for infection and reproduction. These factors help determine the regions where the disease is likely to occur, and extensive surveys and studies are conducted to track its distribution. The identification of Contra Costa County as the location where this rust is known to occur highlights the importance of regional monitoring for plant health management and pest prevention within California's diverse ecosystems.