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PLNA e-News: Protecting Values In Pennsylvania

Beware Boxwood Blight and Sudden Oak Death

Sunday, August 11, 2013   (0 Comments)
Posted by: Gregg Robertson
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HARRISBURG, PA - The Pa. Department of Agriculture (PDA) is warning wholesale nurseries, retail garden centers, landscape contractors and rewholesalers to be careful of their sources of boxwoods and species susceptible to sudden oak death (SOD), such as Rhododendrons.

Boxwood Blight 

This summer, PDA has found two additional cases of boxwood blight in Pennsylvania, both traced back to distributors outside of Pennsylvania. Earlier, in May, PDA announced that it had found boxwood blight in Cumberland County in a residential setting. Boxwood blight is a fungal disease caused by Cylindrocladium pseudonaviculatum (syn. Calonectria pseudonaviculata). Once infected, a boxwood will quickly yellow and drop its leaves. There is no treatment or cure and the infected plants and surrounding leaf litter must be burned and the soil sterilized to prevent reinfection.

PDA's plant regulatory official, Dana Rhodes, is cautioning wholesale nurseries, retail garden centers, landscape contractors and rewholesalers to be sure that the source of their boxwoods is following phytosanitary protocols established by ANLA and the National Plant Board. Companies should also be sure that they themselves are following best practices. Download the best management practices (BMP's) by clicking here.

"We are urging green industry companies that are purchasing boxwoods to ask a lot of questions of their vendors," said Rhodes. "Are they following established industry best practices to assure that their boxwoods are not being infected by boxwood blight? Where has their stock come from?" For more information, go to

Sudden Oak Death

Recently, PDA has been busy tracking down over 100 potential cases of sudden oak death (SOD) in Pennsylvania. Some have involved commercial operations, some residential consumers. Caused by the plant pathogen Phytophthora ramorum, the disease affects oaks and a wide variety of other plant species, including those in the Rhododendron and Viburnum genera. If plants are found to be infected, they must be destroyed. For an up-to-date list of susceptible species from USDA APHIS, click here.

SOD is not yet present in the wild in Pennsylvania (that we know of), but forests in the far west have been infected. Certain forested areas in California and Oregon have been devastated by the disease. Some nurseries in the far west also have been infected, as the trace backs done by PDA on the Pennsylvania cases have shown.

Again PDA's Dana Rhodes is urging Pennsylvania green industry companies that are purchasing product that could carry the P. ramorum pathogen from nurseries in affected areas to be sure that their source is disease-free. For more information on Sudden Oak Death, follow this link to the USDA website.

Contact PDA

If you suspect that you have found plants infected with boxwood blight or sudden oak death, please contact your local PDA regional office immediately. Contact information for your local PDA regional office can be found by clicking here.

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