What is it?
- Box blight is a fungal disease that affects the leaves and stems of Buxus plants, it doesn’t attack the roots. Unlike other fungal diseases that also affect box, it can be fatal for the plant
- The fungal spores are activated by water
- The spores are most active at 23.7c but are infectious when temperatures are between 5-28c
- Not all Buxus plants are as susceptible as each other
- Some other plants in the Buxaceae family can also be infected with Box Bight such as Pachysandra and some non-Buxaceae plants can also be affected, particularly Geranium sanguineum
Top 5 Most Susceptible Varieties
- Buxus sempervirens ‘Memorial’
- Buxus sempervirens ‘Suffruticosa’
- Buxus sempervirens ‘Morris Midget’
- Buxus sempervirens ‘Blauer Heinz’
- Buxus sempervirens ‘Ingrid’
Top 5 Least Susceptible Varieties
- Buxus microphylia ‘Belvédère’
- Buxus harlandi
- Buxus microphylia ‘Trompenburg’
- Buxus microphylia ‘National’
- Buxus bodinieri
How to spot it
- Early stages of development
- Leaves end up black before falling off
- Plants end up defoliated
- Black stem liaisons
How to deal with an infection
Use a fungicidal spray
Professional gardeners (with spraying licence)
- Signum
Domestic gardeners
- Fungus Clear Ultra (Triticonazole)
- Provanto Fungus Fighter Plus (Tebuconazole and Trifloxystrobin)
- Provanto Fungus Fighter Concentrate (Tebuconazole)
How to avoid it
- Make sure you tools are clean – regularly re-clean as you move along a hedge or when you move between plants – a 5-10% bleach/water mix or garden disinfectant in a bucket works well for hand shears and other tools, a spray can be used for powered clippers – make sure you wipe off excess before reusing the shears to avoid affecting the plants
- Use a light weight mulch like Strulch or Topbuxus Carpet to reduce splash and keep any fallen leaves covered – mulching can reduce box blight spreading by 97%
- Make sure your plants have enough air flow through them by regularly thinning them and avoid too many plants growing close and reducing the air flow
- Raise the canopy to around 150mm to avoid rain splashing any spores back into the plants
- After clipping clear all leaf debris from inside and around the plants – a garden vacuum is better than a blower which could spread the problem by moving infected leaves to a new area
- If you need more plants it’s best to take cuttings from your existing plants
- If you bring Buxus plants into your garden put them in a quarantine area for at least 4 weeks to check for symptoms that might have been masked by fungicides used by nurseries or growers
- Don’t let watering system spray onto box hedging or topiaries
- Avoid over stimulated growth caused by over use of fertilisers