Boxwood Blight

At the Tennessee Master Gardener Winter School last week, we heard a presentation from Dr. Frank Hale and Dr. Alan Windham, of the University of Tennessee Institute of Agriculture, on some potential diseases/pests to be aware of for the upcoming growing season.  The first one we want to alert you to is Boxwood Blight.  The following discussion is abstracted from a paper written by North Carolina Extension Specialists Dr. Kelly Ivors, Dept. of Plant Pathology, and Dr. Anthony LeBude, Dept. of Horticultural Science, North Carolina State University, Mountain Horticultural Crops Research and Extension Center, Mills River, NC.  The entire paper can be found by clicking HERE.

Boxwood Blight (Cylindrocladium buxicola) is a fungus that first appeared in the UK in the mid-1990's.  It was recently discovered in a small region in North Carolina, forcing the grower to destroy more than 30,000 container plants!  You can see that it can have devastating economic effects.  It can be dispersed naturally through water (splashing rain, flood water, overhead irrigation, droplets carried by rain), by animals, on contaminated tools and equipment or through movement of contaminated nursery stock.

Once a plant is infected, death comes very quickly - often in less than an week.  The leaves have tan to brown spots on the top, with a white fungus on the bottom side.  Quickly the whole leaf turns brown, then all the leaves drop off. 



White Fungus



Brown leaves and denuted branches

 Infected stems can have dark brown or black lesions, either linear or diamond shaped.



Lesions on stems



Carefully inspect any boxwood plant before you purchase it.  Make sure that you or your landscape company sterilize any equipment before and after you prune your boxwoods.  At this point, to limit spread and movement of the pathogen, all infected plants should be destroyed. Infected plants should be burned to ash or sealed in heavy, black plastic trash bags and taken to an approved landfill. DO NOT RECYCLE PLANTS OR MEDIA. Containers should be sanitized before reuse.

Next:  Impatiens at risk!