Boxwood Blight Update: October 10, 2018

Boxwood Blight Update

We are being inundated with calls, emails, and texts from individuals and businesses that are facing boxwood blight for the first time. We are spending a great deal of time answering questions and making recommendations and we thought everyone would benefit from an update.

2018 will go down as one of the wettest years many of us can ever remember.  My father Paul will soon be 85 (he is doing fine and is in the office daily!).  Recently, he said he cannot remember a summer and fall as wet as this.  We are about 10 inches over our normal rainfall and most of the excess rain has come in the past 60-75 days following a very dry winter and early spring.  We have had the ‘perfect storm’ for an explosion of boxwood blight in the landscape, garden center, and any place boxwood are growing.  The overwhelming victim has been English Boxwood (Buxus semp. ‘Suffruticosa’).  Daily, we are learning of new infections throughout the Mid-Atlantic.   In Lynchburg VA, just 30 miles south of us, there have been 58 confirmed cases.  Who knows how many more have just ended up at the curb unreported.  

What do I do if I suspect boxwood blight?   

  • Immediately limit access to the suspected area.  Take samples and get them to a lab for testing.  We recommend using the Cooperative Extension Service in your area.  When taking a sample, take foliage that is slightly infected as well as some that highly infected.  It will allow easier diagnosis.  Double bag samples.  While waiting for test results, educate yourself on the disease.

If boxwood blight is confirmed, what do I do?

  • Be smart and make good decisions to not further spread the disease.  We hear of so many examples of hasty action that caused further problems.  When hiring landscape firms to clean up infected plants, it is important to only hire reputable firms who are educated on the disease and take steps not to spread the disease to other landscapes.  Recently we have witnessed uneducated individuals and landscape companies perform very poor (to say the least) methods of removal that will undoubtedly only further spread the disease.    

Should I spray for the disease?

  • Researchers are recommending, in neighborhoods or areas of high boxwood blight breakout, you should spray unaffected boxwood preventatively with fungicides to lessen the chance of getting the disease as long as warm, wet weather persists.  Take care to keep the spray hose clean and not let it be a source of spreading the disease.  
  • If you have confirmed boxwood blight, we recommend the use of fungicides during cleanup to lessen sporulation of the disease when moving infected debris. 
  • A list of fungicides is available through your local extension service.  Remember NO fungicide is curative, they are only preventive. 

Should I remove infected plants immediately?

  • It depends on variety and severity of infection.  English Boxwood (Buxus semp. ‘Suffruticosa’) is the most susceptible.  It is then followed by a group of plants including, Jensen, Justin Brouwers, Elegantissima, Morris Dwarf, and Morris Midget.  If you find the disease in one of these varieties, we highly recommend you remove the plant.  Also, remove other boxwood near the infected plants and closely monitor the area for additional outbreaks.   
  • If it is a boxwood variety that is somewhat tolerant, there are some options available to salvage the plant.  We have seen American Boxwood (Buxus sempervirens) salvaged when fungicide is applied, the infected foliage is removed, lower limbs are also removed to prevent splashing from the ground, pruning is done to create airflow within the plant, leaf debris on the ground is cleaned up, and the plant is mulched.  Afterwards, close monitoring should be done to prevent and avoid flare ups. 
  • Depending on severity of infection most very tolerant varieties can be salvaged and not removed.  Those varieties include Dee Runk, Fastigiata, Franklin’s Gem, Golden Dream, Green Beauty, harlandii, Insularis Nana, Jim Stauffer, John Baldwin, Little Missy, Richard, Winter Gem, and Wintergreen.  Again, decisions on removal of highly tolerant varieties must be made on a case-by-case basis.  A full list of our observations on tolerance can be found in the 5th Edition of the Boxwood Guide 

How do I keep from spreading the disease when removing the diseased plant?

  • It is best to do cleanup on sunny dry days when sporulation is lessened.  Consider using fungicides in advance of cleanup.
  • Remove the plant top/foliage first while taking care not to spread leaf litter.  If possible place a garbage bag over the plant prior to removal.  Clean up all leaf litter that may have dropped to the ground. 
  • Double bag debris and either burn or take it to the landfill.  Again, be careful not to spread leaf debris.  Then, remove the root system. 
  • Thoroughly wash and disinfect clothing, tools, and equipment.

Will the disease continue all winter and next year?

  • The disease ebbs and flows with weather conditions.  It thrives in prolonged periods that are wet and warm (70’s), with little air movement, thus, the outbreak of summer and fall of 2018. 
  • When temperatures get down to normal October temperatures of 60’s and 40’s and we get sunny, windy days, we will certainly see the disease slow down. 
  • The disease will not disappear or die this winter, it will only go dormant waiting for optimal environmental conditions. When it reappears, the severity of infection will be based on weather and variety.  Plants with high tolerance will be affected differently from highly susceptible ones.  Thus, we suggest when highly susceptible plants are infected, you should remove them.  
  • The Europeans who have been fighting this disease for over 25 years, say that in hot dry summers, the disease will not be prominent, but in prolonged wet, warm periods it is likely to reappear.  

What do I do in my garden center or holding yard to lessen my chances of seeing boxwood blight?

  • Space boxwood so they are not touching.
  • Water only when needed and preferably in early morning so plants are dry at night.  Avoid watering foliage when possible and apply water directly to root zone.
  • Holding space for boxwood should have a landscape fabric base to allow easy cleanup of leaf debris.
  • If possible keep boxwood in sunny locations where foliage will dry faster, except in midst of summer when shade is likely a necessity.  
  • Buy from suppliers who are educated about and take steps to avoid the disease.
  • Isolate symptomatic plants immediately.
  • Extra care should be taken with highly susceptible varieties. Limit their time ‘on the ground’.  Many businesses are only ‘cross docking’ them or eliminating them (especially English) from sales. 

What is Saunders Brothers continuing to do?

  • We are investing a great deal of time and money resources into understanding the disease and finding new tolerant varieties.  We are seeing some great promise on the varietal side.
  • We visited with university researchers last week in New England.  We saw promising results but it is early in some of the tests.
  • We have a team in Europe this week meeting with growers and researchers.  
  • We are making all efforts possible to keep the disease out of our nursery as long as we can.  We also are creating and practicing an action plan in the event it is found.  Make a plan, if you don’t have one.
  • We are being inspected regularly by Virginia Dept. of Agriculture and recently were recertified in the Virginia Boxwood Blight Compliance Agreement.  Also, we are doing thorough in-house inspections regularly. 
  • We are changing boxwood production to varieties that are tolerant to the disease.  
  • We irrigate only as needed in early morning so plants are dry during the day and at night.
  • We are spraying fungicides to lessen the chance of becoming infected if inoculum is introduced.
  • We are limiting access to any production area by outsiders and limiting staff entry to necessary jobs only.

Sources for more information.  

Virginia Cooperative Extension.  Numerous links and articles.

Saunders Brothers 5th Edition Boxwood Guide.  See page 24 for more information on blight.

We are fighting a nasty disease that is wreaking havoc on some boxwood, especially the historic English Boxwood.  We don’t have all the answers, but will tell you that an enormous amount of money and time is being committed in private and public research across the country to combat the Boxwood Blight.  In the meantime, everyone must do what they can to learn about the disease, so if/when you find the disease you will have a plan to deal with it.  Lastly, we believe better management practices by homeowners, landscapers, re-wholesalers, retailers, and growers coupled with varietal tolerance will be the long-term answer. 

Best of luck and keep fighting!

Robert Saunders​​​​​​​​​​​​​​

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