Spotting early signs of box blight

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The weather recently has been quite humid so I was not surprised to spot the first indications of box blight.

When clipping I noticed the blackening of a few leaves on top of the box plant. This is an early sign of a box blight outbreak.

Early sign of box blight

If ignored the blackening would spread across the top of the box, leading to leaf loss. What’s worse is the blight gets into the stems and is more difficult to treat.

At this earlier stage I have found there are two things that can be done. The first is to cut out the infected leaves. Can be tricky to remove all the leaves with blight and does result in the box looking very tatty.

My preferred course of action is to spray a fungicide on to the infected area. Doesn’t have to be a strong commercial fungicide as one from the garden centre will work just as well. I’ve found Provanto Fungus Fighter Plus to be very effective at slowing down the spread of blight. Important to catch the infection early though and you may need to repeat the application in 10 days.

Provanto Fungus Fighter Plus
Spraying with Provanto Fungicide

Extra care should be taken when clipping to avoid spreading the blight to other plants. I add a splash of bleach to a bucket of water and regularly dip my shears and clippers in there when working. The bleach helps disinfect the tool’s blades and also removes the box sap that can affect the clipping action.

Disinfecting shears

Last autumn was a really bad one for blight outbreaks and unfortunately the weather patterns indicate this may be the same this year. So be extra vigilant for spotting any unusual discolouration of the box leaves and treat early with a fungicide.

By James Todman

Topiary Specialist based in The Cotswolds, UK.

6 replies on “Spotting early signs of box blight”

Todd, provanto isn’t available on amazon here in the States. Do you have another recommendation for a product we can get here?

Sorry Linda, I don’t know the fungicides available in the U.S. Hopefully a garden retailer maybe able to advise. Most fungicides are effective against blight but it is worth asking as some are better than others. Let me know if you find a good one 🙂

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