Ilex vs Boxwood Blight (Calonectria pseudonaviculata)

Boxwood Blight, also called Box Blight and Boxwood Leaf Drop (Calonectria pseudonaviculata) is a serious and deadly, fungal disease that mainly affects boxwood (Buxus), but can also hit Japanese Pachysandra (Pachysandra terminalis).

Boxwood Blight was first discovered in the Eastern United States in 2011. Presently, it has been identified in 18 states. It is being managed at a state level, which means states have different regulations on how they are dealing with it. Illinois and other states require nurseries to practice boxwood blight cleanliness programs to ensure the plants they sell are disease free.

This statement from the Illinois Department of Agriculture and where they stand on the issue.

It is generally agreed upon that the pathogen is not demonstrating the ability to move quickly or long-distance via air travel, or otherwise natural means. However, the overwhelming means of rapid and long-distance conveyance (interstate) is movement of infected plant material. The potential for more localized movement (i.e. within a production setting, from property to property, etc.) exists via plant to plant contact, contaminated tools, clothing, or other associated equipment that may have made contact with infected plants, in addition to local movement of infected plants or plant materials. This seems to be a โ€œcultural practicesโ€ issue versus natural spread like EAB which we are all too familiar with.

In my opinion, us pink apes don’t understand nature enough. I think they are treating this a bit passively. I completely agree that there are many landscapers and gardeners that are not using good cultural practices. However, there are also forces of nature we don’t understand yet.

When I saw these blight alerts popping up in every blog, newsreel, etc that I follow, I became a bit distraught! On average, I plant about 1,000 boxwood a season on my clients’ properties ๐Ÿ˜ฏ I trained my crews to be on the lookout for this menace and to bring in any samples they suspected of having the fungus. It didn’t take long before one came in. My clients boxwood were installed by us 10 years ago, using a ‘clean nursery’. She has had no other landscapers but us. The fungus had to have arrived in a natural way, not by bad practices. I had to tell my client the bad news. Not only is this a death sentence, this fungus habitats the soil, making it inhabitable forever to boxwoods. We are now going to use a small arborvitae for her hedge.

I was also talking to the salesman where I purchase my clean boxwood from. He was telling me he was golfing at the prestigious Medinah Country Club where he noticed a groundskeeper whacking away at a hedge of brown boxwood. He walked over to the guy and told him that these boxwood had blight, and he may not want to continue pruning diseased boxwood and then moving on to healthy ones. The groundskeeper paid no never-mind to him and continued to spread the disease.

So whether you’re going to contract Boxwood Blight on your boxwoods is a gamble. You can favor the house by buying clean stock and being sure your tools or your landscapers tools are clean. However, Mother Nature knows how to draw off the bottom of the deck sometimes…

ย ย ย ย ย 

Best management practices:

  • Monitor your existing boxwood – Look for the following:
    • Leaf spots – Light to dark brown circular lesions, often surrounded by a yellow halo.
    • Stem cankers – Dark brown or black cankers on the stem, diamond shaped or vertical streaks.
    • Defoliation – Sections of the plant dropping leaves.
    • If you feel your boxwoods have blight, you should contact your local Extension or send samples to your respective states plant clinic.
    • Do not prune suspect plants.
  • Planting suggestions:
    • Avoid planting a boxwood all together! There are many alternatives.
    • Ask the nursery or your landscaper to see the boxwoods’ certificate of Cleanliness.
    • Plant where there is good air circulation.
    • Prune regularly to keep good air circulation.
    • Sanitize pruning equipment before going from one plant to another. Dip tools in a 10% bleach solution between plants.
    • Water plants in the morning, so the sun will dry them off.
    • Avoid overhead watering if possible, use drip-lines or watering bags.

Here are some wonderful references to continue your education on the deadly Boxwood Blight!

The Connecticut Agricultural Experiment Center

Virginia Cooperative Extension

American Nurseryman


ยฉ Ilex ~ Midwestern Plant Girl


12 thoughts on “Ilex vs Boxwood Blight (Calonectria pseudonaviculata)

  1. I hate the Blighters! ๐Ÿ˜€
    Sorry, couldn’t help myself!
    Just reminds me of my poor roses that I nearly killed in hacking off the blighted parts. Update on that – the one I was really worried about has grown over 2 feet and has a rose bud! 12 days to winter solstice! ๐Ÿ™‚


  2. That’s very sad. Boxwood not only made great hedges/topiary, but is a wonderful wood to carve, very hard, with a very fine and even grain that can be carved from any direction, unlike softer hardwoods like maple or walnut. My first wood carving assignment in art school was to carve a pear out of a 3″ cube of boxwood. That’s an old shrub, to have a 4″ diameter trunk!

    I just came out of the Sierra Nevada, camping in the back country. I went to Sequoia National Forest, where the sea of green has turned into a sea of ugly rust color. The past 20 years of drought has killed most of the younger trees. The drought is over, for the next few years anyway, but too late to save the forest. Now we wait for the inevitable fire to clean up that particular mess. Won’t help the pines with their beetle problem…

    As I wound my way through the browned-off forest, I spoke to the ghost of my muse, Mr. Muir: “Oh Mr. Muir, I’m sorry I can’t meet you, but on the other hand, I’m glad you can’t see this sad mess.”

    Liked by 1 person

    • So sad about the Sierra Nevada trees. I’m going to hope that this is a normal cycle of the forest ane things will bounce back soon….
      Yes! I 4″ block of boxwood would have to be 100 years old! When clients birch about the price of a 21″ boxwood, I tell them they are at least 15 years old. There is 15 years of a farmer’s investment in there, that is why they are $170. whereas a fast – growing viburnum is $35. The clients feel it is a status symbol to have it front of your home. Yup, you’re rich, I get it. ๐Ÿ˜›

      Liked by 1 person

      • I can’t help thinking about all that beautiful topiary….๐Ÿ˜ฃ

        Well, it will happen “soon,” but in forest terms, that could be a few centuries. At some point there will be a hellacious burn, because the sheer quantity of dry, standing fuel is outrageous. I imagine the upper echelons of USFS are banging their heads together trying to figure out whether to bring in the tree cutters. They could certainly lessen the possibility of wildfire with judicious clearing of fuel, and much good wood could be salvaged.

        Since Sequoias are one of the trees that requires fire to germinate, that’s an inevitable blessing that has to come the hard way. Yosemite was devastated in 2013 when drought met illegal campfire

        It still looks like hell, but there are thousands or millions of lil baby Sequoias peeping up in light breaks among the fire succession vegetation. Many of the grand old giant trees survived, thankfully, albeit horribly scarred.

        Liked by 1 person

        • Just like little Phoenix, they rise from the fire!
          I just finished reading The Hidden Life of Trees. What an awesome read. Puts things in perspective with ‘tree time’ and how slow they pass the time. I highly suggest reading it.
          The ashes are wonderful, rich soil given back to the forest. Trees are magnificent things. Many times they can know more than us and what’s good for them. ๐Ÿ˜Š

          Liked by 1 person

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