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 “cultural practices” 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 😯 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…
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!
Ilex ~ Midwestern Plant Girl