Colletotrichum theobromicola - ???

Written on 01/12/2022
Lawnmasters Inc.

Now that we have your attention, let's break it down...

Boxwood dieback, scientifically known as Colletotrichum theobromicola, is a disease affecting English, Korean and Japanese boxwoods. The pathogen has been found to have been spread into new locations, including here locally, and within infected nursery stock. Once introduced into the landscape, spores of the pathogen are produced on the infected twigs. These spores are spread by splashing rain and overhead irrigation water. Poor pruning also seems to be associated with the development of the disease, possibly through the infection of pruning cuts.

“Boxwood dieback is a fungal disease that causes random dieback of twigs and branches,” says Chad Everage with Landscape Management. “Leaves initially turn light green and then turn more light tan colored as the disease progresses. Affected leaves do not defoliate, but rather tend to stay attached to the branches. The root and crowns of affected plants look normal.”

 Although the environmental conditions affecting disease development are not currently known, high humidity is believed to be contributing factor, which explains its spread across the southern states. Boxwood dieback is a recently discovered disease – first reported in the United States by LSU AgCenter plant doctor, Raj Singh.  Effective diagnostic tools and control measures such as fungicides are currently limited, but the experts at Lawnmasters can help with remediation and/or removal. “It is important for nursery growers and landscapers to be able to identify the disease correctly in order to manage it effectively,” says Singh. 

Since removing the dead and dying twigs from plants infected by the pathogen is not known to control this disease, once detected, all symptomatic plants in the landscape should be removed and destroyed. Our landscape professionals have attended training to help identify, isolate and remove the diseased plant. 

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