Protecting your garden greenery from boxwood blight

Like a sneaky stowaway, boxwood blight first hitched a ride from across the seas, believed to have originated in Europe and Asia. It found its way to our shores and has since spread across the country, wreaking havoc wherever it goes.

Picture this: Your once-vibrant boxwood hedge suddenly starts to wilt. The leaves develop brown spots, and then their lush, green foliage turns a sickly brown. That, my friends, is the handiwork of boxwood blight, a stealthy infiltrator attacking the leaves and stems of boxwood plants, leaving them weakened.

So, what exactly is boxwood blight? Well, it’s a sneaky little fungal disease, caused by the pathogen Calonectria pseudonaviculata, that’s been causing a ruckus among our beloved boxwood shrubs. You might hear it called box blight or boxwood leaf drop, but no matter what you call it, it spells trouble for our gardens. This pesky fungus can turn those lush, green boxwood leaves into a sad, brown mess faster than you can say “pruning shears.”

Like a sneaky stowaway, boxwood blight first hitched a ride from across the seas, believed to have originated in Europe and Asia. It found its way to our shores and has since spread across the country, wreaking havoc wherever it goes.

Now, you might be wondering, “Is this blight knocking on my garden gate?” While boxwood blight hasn’t made itself at home in every nook and cranny of California, it has been spotted in various counties across the state, including Santa Clara, San Mateo and Monterey. But don’t let your guard down just yet; this crafty fungus could be lurking in your neighborhood, waiting for the perfect opportunity to strike.

Now, you might be wondering what causes this blight to rear its ugly head. Turns out, a combination of factors can create the perfect storm for boxwood blight to thrive. Warm, humid weather? Check. Crowded planting conditions? Check. Oh, and let’s not forget about good old-fashioned neglect — yes, that’ll do it, too.

First things first, how do you know if you’ve got boxwood blight on your hands? Well, keep an eye out for those telltale signs — dark brown spots or lesions on the leaves often accompanied by yellowing or browning of the foliage. Check for black streaks or lesions on the stems and a general droopiness that just isn’t normal. If your once-green boxwood bushes start shedding leaves, it could be a sign of boxwood blight.

Now, prevention is the name of the game when it comes to boxwood blight. So, what can you do to keep this pesky fungus at bay? Start by giving your boxwoods plenty of space to breathe — think of it like social distancing for plants. Good air circulation is key to keeping those fungal spores from settling in and causing trouble.

Next up, keep those pruning shears clean and sharp. Regularly snipping away any dead or diseased foliage will help stop the spread of boxwood blight in its tracks. And don’t forget to give your tools a good scrub with some disinfectant between trims — nobody wants to be spreading fungus around the garden!

But what if, heaven forbid, you do find yourself face to face with boxwood blight? Well, don’t panic just yet. There are steps you can take to fight back and reclaim your garden. Start by removing any infected plants and disposing of them far, far away from your other greenery. Keep your garden clean and tidy; remove fallen leaves and debris regularly to minimize the risk of fungal spores lingering in the soil. Treating your remaining boxwoods with Propiconazole can significantly reduce their chances of becoming infected and, perhaps more importantly, prevent the production of fungal spores that can transmit the disease in your garden. When replanting, opt for boxwood varieties that show resistance to boxwood blight, such as Buxus microphylla or Buxus sinica var. insularis.

Remember, prevention is key! By staying vigilant and taking proactive measures, we can safeguard our precious boxwood bushes and keep our gardens thriving. So, roll up your sleeves, dust off your gardening gloves and let’s show boxwood blight who’s boss! For more information, check out ucnfanews.ucanr.edu/Articles/Disease_Focus/DISEASE_FOCUS__Boxwood_blight.

Sponsored by UC Cooperative Extension, the University of California Marin Master Gardeners provides science- and research-based information for Marin home gardeners. Email questions to helpdesk@marinmg.org. Attach photos for inquiries about plant pests or diseases. Please call 415-473-4910 to see when a master gardener will be at the office or drop off samples 24/7 in the sample box outside the office. To attend a gardening workshop or subscribe to Leaflet, a free quarterly e-newsletter, go to marinmg.ucanr.edu.