About a month ago I began to notice driving around Surrey that almost all Boxwood (Buxus) hedges I passed had been reduced to near skeletons having been attacked by the much feared Boxwood moth caterpillar.
In the horticultural industry there are many discussions being had about alternatives to Box topiary and hedging and whether it can be saved.
We chatted to one of our main suppliers of topiary and larger plants and trees near Florence, Italy who stated that Italy had almost completly eliminated the Boxwwod moth caterpillar, which gives us some hope.
The fact is that although many gardeners and garden owners are ripping out their Box hedging in droves, with some careful management, they can continue to thrive.
The European Boxwood and Topiary Society (EBTS) recently invited members to an open discussion regarding this issue to gain some feedback and found that the main issues came down to access to products and education.
The Boxwood plant has been around a long time, it was used in Ancient Egypt from around 4000 BC where it was grown and clipped to create formal hedges. Henry VIII added Box topiary at Hampton Court Palace in the form of cones, spheres, running greyhounds, deer, bears, urns, vases and boats. With so much history, many gardeners and owners feel very passionately about protecting this versatile heritage plant.
So how can we save it?
Be Prepared
Educate yourself on what to look for so you can establish whether any obvious issues are down to the Box caterpillar or Box Blight (see our post on Box Blight here). Research ther products available to buy and keep a stock ready so when you see the signs, you’re ready to know any infestations on the head.
Professional Spraying
Professional spraying for caterpillar can be done using pesticides such as DECIS (active ingredient: deltamethrin) which lasts for around 5-6 weeks and is in a stronger concentrations than is available to domestic gardeners (needs to be used with care around bees).
Search Google for suitably qualified professional in your area.
Domestic Spraying
Biological Insecticide (least damaging to other wild life)
XenTari is a biological insecticide based on Bacillus thuringiensis subsp. Aizawai. It is sprayed on the leaves of the of the plants and works by ingestion. Once the caterpillar has eaten the sprayed leaves, the toxic proteins disrupt the insects gut causing it to stop eating within minutes and thus prevent further damage. The caterpillar will die after a couple of days. XenTari is safe to beneficial insects & is Bee-friendly. Weekly sprayng during the caterpillar season will keep your plants healthy.
Chemical Insecticide (use with care around other plants & beneficial animals like bees)
Garden centres sell a BAYER garden product called PROVADO Ultimate Bug Killer, which is effective but requires constant repeat spraying.
Pheromone Traps
Pheromone traps are a good indicator of moth activity in your garden and also as a preventative measure. Depending on which trap you buy it will last between 6 weeks & 3 months per dose of pheromone. Some traps covers an area of 0.40h / just under an acre, whilst others cover 180 square meters (which is 7.5m radius around the trap). Given the variety of ranges covered it is important to read the information on the trap you buy and use the appropriate number for the area to be covered.
Although there are many alternatives to using Buxus for your formal hedging and topiary, there is nothing quite like it. By spreading the word and helping our clients look after their plants we hope to play a part in eliminating the threat to part of our national heritage.
