Vigilance can prevent spread of Phytophthora

Gardeners should follow best practices, experts say

Residents can help prevent the spread of plant disease such as Phytophthora, according to Igor Lacan, an urban horticulture adviser for U.C. Cooperative Extension San Mateo-San Francisco Counties.

"Basically, look in the nursery. Go to a reputable nursery and ask if they follow best-management-practices protocol. If you ask and the nursery person looks at you blankly, maybe you want to go somewhere else," he said.

Customers can also ask nurseries if the potting soil is pasteurized, which kills the harmful organisms. And look to see if the plant is in good shape, not wilting and not next to a plant that is wilting or drooping, he said.

Unfortunately, a Phytophthora infection won't cause symptoms in the early stages. When people bring home new plants, Lacan recommended putting them in quarantine from other plants for four to six weeks. Runoff from watering be contained so as not to contaminate other soil or plants, he said.

If plants show signs of wilting, develop oozing cankers or have rotten roots, the plants should be pulled and destroyed. They should not be composted, he said. If you think you have a Phytophthora-infected plant, the entire plant can be double bagged and taken to a local Cooperative Extension office for examination, he said.

Soil and pots should not be used again and can be bagged and disposed of in the trash. Phytophthora expert Ted Swiecki said that chemical treatment may help to suppress the activity of the microorganisms, but it will not make the pathogen go away.

"Infestations in urban sites pose a risk for spread if shoes or equipment get contaminated with inoculum in soil, especially when soils are wet, and subsequently transported elsewhere," he said. Unless transported along creeks, in urban areas the risk of transport downstream is not that high, he added.

Best practices for gardeners also include scrupulous cleaning of garden tools and equipment and even shoes. Spraying surfaces with 70 percent isopropyl alcohol can help disinfect tools and other surfaces, Lacan added.

Read the cover story, "Deadly disease plagues plants high above Silicon Valley"


Follow the Palo Alto Weekly/Palo Alto Online on Twitter @PaloAltoWeekly and Facebook for breaking news, local events, photos, videos and more.

We can't do it without you.
Support local journalism.


4 people like this
Posted by Baloney
a resident of Midtown
on Sep 23, 2016 at 11:15 am

Baloney is a registered user.

The best prevention is to bring back the ban on foreign plants and agricultural products-- period!

Sorry, but further commenting on this topic has been closed.

Be the first to know

Get the latest headlines sent straight to your inbox every day.

Peek inside the fine-dining Selby's, opening in Redwood City this summer
By Elena Kadvany | 6 comments | 4,098 views

Homestead Faire at Hidden Villa 4/27
By Laura Stec | 7 comments | 1,202 views

Premarital and Couples: "You're Not Listening to Me!" may mean "I don't feel heard."
By Chandrama Anderson | 1 comment | 1,066 views

All those things our city does – and doesn’t -- do
By Diana Diamond | 6 comments | 1,003 views

Migraines and motherhood
By Cheryl Bac | 0 comments | 593 views


Vote now!

It's time once again to cast your vote for the best places to eat, drink, shop and spend time in Palo Alto. Voting is open now through May 27. Watch for the results of our 2019 Best Of contest on Friday, July 19.