A blight that can cause sudden oak death has been detected in rhododendrons across the state, the Missouri Department of Agriculture said Thursday.

Rhododendrons with the ramorum blight were shipped from Park Hills Plants in Oklahoma to Walmart and Rural King stores throughout Missouri. The Springfield Home Depot; Stark Bros. Nursery Garden Center in Louisiana, Missouri; and the Fort Leonard Wood PX have also received the diseased plants.

Over 2,000 plants were shipped to 113 locations throughout the state. Any remaining plants at these stores have already been quarantined or destroyed. The agriculture department urges consumers who have the plants to dispose of them immediately.

Sudden oak death is caused by a fungus-like pathogen known as phytophthora ramorum. It is a soil-born pathogen and tends to remain localized with its host plant.

In Missouri, the most susceptible tree is the northern red oak. Researchers are unsure how the pathogen might affect forests in the state.

Anyone unsure of their plants’ origins should look for wilting or browning leaves, leaf spots and twig dieback, which are signs of the ramorum blight.

Infected plants can be destroyed by burying them deep, burning them or double-bagging the plant with its root ball in heavy duty trash bags and throwing them away. Consumers should not mulch, compost or dispose of the plants in any municipal yard waste, as that would allow the pathogen to spread to other plants.

The agriculture department said it’s also a good idea to dig up and get rid of soil surrounding the plants.

Rhododendrons that have tested positive include:

  • Cat Cunningham Blush.
  • Firestorm.
  • Holden.
  • Nova Zembla.
  • Percy Wiseman.
  • Roseum Elegans.
  • Wojnars Purple.

Common purple and Persian lime lilacs have tested positive for the blight elsewhere but not in Missouri.

For questions concerning the pathogen or possible diseased plants, contact the Missouri Department of Agriculture or the University of Missouri Plant Diagnostic Center.

  • General Assignment Reporter, Summer 2019 Studying magazine journalism Reach me at lrtcx6@mail.missouri.edu, or in the newsroom at 882-5700

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