Boxwood Blight

Boxwood Blight in Greenwich Connecticut

Boxwood Blight

Boxwood

It is important that gardeners who use boxwoods in their landscape keep an eye open for a disease that is new to our area.  Called boxwood blight, it spreads rapidly and is very destructive.  The fungus causes boxwoods to defoliate quickly after symptoms appear.  Since there are no known fungicides that cure it, preventative measures are important.

Informative Video About Boxwood Blight

Symptoms begin with light or dark brown spots on the leaves that will often have dark borders.  The spots enlarge and merge together forming a concentric pattern.  These leaves then become totally brown or straw colored.  Dark brown to black lesions will develop anywhere along the length of the stems.  Infected plants take on a “blighted” look and there is extensive leaf debris on the ground.  The fungus can remain in this debris for at least five years.  The disease does not seem to infect the root system, so plants may attempt to regrow, only to be infected again.  This repeating cycle will eventually lead to plant death.

Boxwood Blight Infected PlantB

Boxwood

Since no direct curative measures are available, the best management program is prevention.  Check boxwoods in the landscape on a regular schedule.  Be aware that other boxwood diseases have symptoms similar to boxwood blight.  Proper cultural procedures for growing boxwoods should be followed.  Keep plants healthy, avoid overhead watering, never work among wet boxwoods, and increase air circulation.  Good plant sanitation is a must.  Remove leaf debris immediately.  Preventative sprays with fungicides (daconil or mancozeb) can be tried when weather favors disease development and spread.  Timing for sprays is difficult and results are not consistent.  Infection readily occurs during warm (64-77degrees), humid weather.  The pathogen can exist in a temperature range of 41 to 86 degrees and is sensitive to high temperatures.  Remember that fungicidal sprays must be applied prior to disease outbreak.

This has the potential to be a challenging situation because boxwoods have been heavily planted in the local landscape.  Since boxwoods have already been experiencing numerous problems, a substitute for this garden mainstay may have to be found.

Written By: Jim Zanetti, McArdle's Personal Plant Doctor for over 30 years.

2 thoughts on “Boxwood Blight”

  • Sophie Wynne

    Thank you for the article. I noticed the start of this problem two summers
    ago and have lost many plants including a huge one over 20 years old !
    Potential remedies were unsuccessful.
    What evergreen do you recommend to replace it in a structured landscape?
    Many thanks again.

    Reply
  • [...] cultivate boxwoods, start getting into the habit of scouting them on a regular basis for signs of Boxwood blight.  Look for plants that are thinning out with a large amount of dead leaves at their base, leaves [...]

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