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Washington State University
WSU Puyallup Ornamental Plant Pathology

Lavender Diseases

Lavender has few pests and diseases and is often promoted as a sustainable crop because growers do not commonly need to apply pesticides and fertilizers in its production. However, recently growers have been reporting plants with symptoms of Phytophthora root and crown rot (PRCR).

On this webpage, we aim to share information about PRCR of lavender and provide resources for managing the disease.

Lavender field

Phytophthora Root and Crown Rot

Phytophthora Diseases

Phytophthora species are microscopic organisms that cause disease in plants. Many species have been identified as the primary causes of root and crown rot of their host plants. Much of our research is focused on this group of microbes.

Click here to find resources about the Best Management Practices for managing Phytophthora in ornamental plant nurseries. Most of these management practices can be applied to control or limit the effects of Phytophthora in any system.


Presentations and Publications


Title Slide Image of Presentation

Click on the image above to view or download a presentation (pdf) we prepared for the Washington Lavender Association Meeting in Ellensburg, WA (March 24, 2017) .


Contact us for a copy of the research publications.



Have a Lavender Disease Concern?

Diagnostic services are available from the WSU Plant and Insect Diagnostic Laboratory. Contact Jenny Glass for more information about WSU’s diagnostic services.

Screenshot of Phytophthora DIY Test GuideWe have also prepared a guide for a technique to test your own samples for PRCR. You can view or download it by clicking the document image on the right.

Contact us or join our Mailinglist


You are welcome to contact us for more information.

If you are interested in participating in our lavender root rot research project and/or would like to subscribe to an email mailing list about this subject, fill out the form on the right.

Lavender Field - Photo Credit: Andrew Wilkinson (CC BY-SA 2.0)

Lavender growers information

  • Tell us about which lavender cultivars you grow and why.