First identified in the United States in the fall of 2011, boxwood blight has now been detected in at least 22 states. Boxwood blight is caused by the fungus Calonectria pseudonaviculata, and is a serious fungal disease of boxwood that results in major damage to infected boxwood and even surrounding plants.
Earlier this year, the Tennessee Department of Agriculture confirmed that a new boxwood blight quarantine would go into effect. The quarantine stated that any regulated material entering the state must comply with a boxwood blight cleanliness program and be accompanied by a phytosanitary certificate.
Nevertheless, boxwood blight continues to spread as researchers look for an effective way to stop the pathogen. Though boxwood blight rarely kills the plant, it eventually defoliates the shrub, leaving an unattractive bare plant in its wake. These are our best pieces of advice when it comes to fighting boxwood blight.
Mulching can help to reduce disease spreading in a unique way. The texture and absorption of the mulch can prevent the pathogen dispersal via rain splash. While it may sound trivial, rain splash is actually a primary cause of the boxwood blight’s spread.
PRO TIP: Boxwood requires a great deal of circulation at the root zone and the interior of the plants. Mulch should never be placed inside of the dripline and annual removal of the mulch Is critical.
Disinfection & Sanitation
These two factors are critical components of disease control. Soil in nursery beds can harbor boxwood blight microsclerotia- overwintering structures in dead leaves that are viable for years. Some commercially available sanitizers have proven to be effective in killing the spores.
Little data exists on what fungicides are best for boxwood control, but studies out of the Connecticut Agricultural Experiment Station have identified some as effective. There have been reports of products that were successful in their control, including pyraclostrobin and propiconazole. Both demonstrated good preventative control.
If you’re experiencing boxwood blight or are concerned about the potential, give us a call. We will work with your landscaping to find the best solution to preserve your plants and lawn.