Autumn this year has been very wet and warm here in the UK. These are perfect conditions for fungal growth and outbreaks of box blight have been very common. Outbreaks can occur on the top or sides of the box and are identifiable by the browning and blackening of the foliage.
These outbreaks occur almost overnight. The damage caused can be minimised if treated early so best to check box plants regularly. I spray a fungicide on to an affected area as soon as I see the first signs of a box blight outbreak. Hopefully this will slow the spread of the infection and give the box a chance to recover when the weather dries out.
A fungicide such as Bayer Fungus Fighter works well and is readily available online or at the garden centre. It’s not as strong as the commercial fungicides that I use for my box blight treatments so will need to be reapplied every 10 days until the outbreak is under control.
When the weather dries out in Spring and Summer, focus on improving the health of the box. Stronger and healthier plants can fight off box blight infections better, without the need to use fungicides.
Topbuxus Health Mix is an excellent feed to apply during the growing months of March until October. Apply as a foliar feed every 4-6 weeks. The feed contains copper that can work as a natural fungicide and also hardens the cell structures of the plant, making the box more robust.
Box plants that have suffered with a blight outbreak will experience leaf drop. Try to clear up as many of these leaves as possible as they will have fungal spores on them. Some infected leaves may remain on the box so place a tarpaulin underneath and give the plants a good shake. Only do this when the weather and plants are dry. Dispose of all the infected material, ideally by burning. Do not put them in a compost as the fungus spores will remain active for some time afterwards.