Rotted in the Roots: Phytophthora 101

TreePeople’s gorgeous nursery is pristine. Its manager, Jack Smith, runs a tight ship in order to keep the plants inside safe and protected.  Those who enter must pass through a massive enclosure and wash their shoes in order to even go near the plants. This keeps deer, many herbivorous insects, and plant pathogens like Phytophthora from causing harm to our saplings.

Phytophthora (pronounced Fie-TOF-ther-uh) literally translates from Greek to “plant destroyer,” so we have good reason to do what we can to keep it out of the nursery. It causes root rot, stem cankers, and, finally, plant death

These organisms are microscopic, spreading via contaminated water, shoes, and equipment.  Once they become established in the wild, there is no way for humans to eradicate it. Symptoms appear above ground during the later stages of the disease, so early detection is very challenging.

To keep Phytophthora out of our nursery, we:

  • Keep our tools and equipment squeaky clean
  • Clean our shoes when we walk inside
  • Keep plants raised off the ground on tables to prevent contamination
  • Keep space between our tables of plants to avoid cross contamination between projects
  • Maintain a quarantine zone for plants that may be sick
  • Cover and properly store soil 
  • Steam soil to terminate any pathogens in it
  • Keep a gravel floor to reduce pooling water that can spread pathogens through splash

The plants in our nursery are precious because they’ll be used to restore Los Angeles’ wildlands. That’s why Jack takes such care to keep them healthy and happy. Make sure to visit to learn more about our forestry programs and about how you can help us restore the earth that protects us every day!