The Missouri Department of Agriculture, in coordination with the USDA Animal and Plant Health Inspection Service, has detected the presence of ramorum blight, (also known as Sudden Oak Death when affecting oak trees), on rhododendrons shipped to some retail nurseries in Missouri. Ramorum blight is caused by a fungus-like pathogen known as Phytophthora ramorum. Shipment of these rhododendrons has been traced back to a common out of state nursery, and were shipped to 18 states. The plant disease has caused mortality in some types of oak trees in California and Oregon since the 1990s and has a host list of over 100 species of trees and shrubs.

APHIS List of Regulated Hosts and Plants Proven or Associated with Phytophthora ramorum

Where were the plants shipped to?

The rhododendrons were shipped to Wal-Mart and Rural King stores throughout Missouri, as well as the Springfield Home Depot, Stark Bros. Nursery Garden Center and the Fort Leonard Wood PX. These plants were shipped from Park Hill Plants in Oklahoma and may have originated from nurseries in Washington State and Canada.

What is the Missouri Department of Agriculture and USDA doing?

Working together with USDA APHIS PPQ, the Missouri Department of Agriculture has visited these retail locations, collected samples, and placed plants on hold until lab results are confirmed. Any plants confirmed with ramorum blight, and any host species comingled with the confirmed positive plants will be destroyed. USDA has worked with Wal-Mart to organize a voluntary recall of the impacted plants, while the other locations have already isolated or destroyed the affected plants.

How do I know if I have an infected plant?

If you purchased rhododendrons or lilacs from these stores between March and June of 2019, labeled from Park Hill Plants, these plants may be infected with ramorum blight. Specific rhododendron varieties that have tested positive so far in destination states include: Cat Cunningham Blush, Firestorm, Holden, Nova Zembla, Percy Wiseman, Roseum Elegans, and Wojnars Purple. Investigations are ongoing, so other varieties may be at risk.

What should I do if I have an infected plant?

Varieties that have been determined to be infected should be disposed of immediately to prevent further spread of the disease. Plants may be destroyed by burning on site, deep burial or by double bagging the plant and its root ball in heavy duty trash bags and disposing into a sanitary landfill (where allowed). Consumers SHOULD NOT mulch or compost the plants, or dispose of these plants in municipal yard waste curbside pick-up or drop off sites. This would cause further spread of the disease. Garden tools used to dig up any affected plants should also be sanitized before they are used again. For more information on how to sanitize your garden tools.

What if I don’t know the source or variety of my rhododendrons?

Consumers who purchased rhododendrons or lilac plants labeled Park Hill Plants from these stores between March and June of this year should look for wilting or browning leaves, leaf spots and twig dieback. If consumers notice these symptoms, they should contact the Department’s Plant Pest Control team at (573) 751-5505. The University of Missouri Plant Diagnostic Clinic can also be reached at (573) 882-3019 or by email at plantclinic@missouri.edu.

What are the symptoms of Ramorum Blight?

Symptoms include wilting or browning of leaves, leaf spots and twig dieback. Photos of symptoms are available from USDA APHIS PPQ.

Is Ramorum Blight harmful to humans or animals?

No. Ramorum Blight has not been shown to cause any harmful effects to humans or animals.

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