FM first reported on a local infestation of the pest commonly known as box tree caterpillar last September. At that time, we were nearing the end of the growing season, which meant that there was limited time to take action. The most effective treatments are nematodes, which need to be applied to the leaves and ingested by the caterpillars – so the problem becomes not only invisible but untreatable during the pest’s hibernation period.
With the arrival of the warm weather, however, it is clear that the infestation has not gone away. There are now very few box hedges in Fairfield that do not show signs of it – it seems likely that the only ones that are still green are those whose owners are spraying them regularly. If you would like to do the same, many brands of nematode treatment are available; we know that several residents use and recommend XenTari from TopBuxus. It needs to be sprayed onto the plants very thoroughly to penetrate the caterpillars’ protective webbing.
Since there is no cure, reinfestation is a big problem. Anyone choosing to keep their box plants and control the pest will need to spray several times a year between March and October. Those who prefer not to invest the time and energy in doing that can help to limit the problem by removing their infected plants. It is best to seal these inside a bin bag or other container after removal, spray them to kill off any caterpillars and then leave sealed away for a week or so – checking that there are no caterpillars left alive before placing the plants into your garden waste bin for collection.
Box caterpillar has become such a widespread nuisance since its arrival in the UK 15 years ago that there are now plenty of suggestions from respected horticulturalists about what to replace it with – so removing your box doesn’t mean doing without a hedge. A quick google search will throw up a range of possibilities. If you have any suggestions of your own to share, please write in and let us know!
What are the management companies doing about it?
The Fairfield Park Resident Company, whose hedges are badly affected by caterpillars, has arranged for box trees under their management to be sprayed twice in the coming months. The spraying will be done early in the morning and will probably be completed before most people are up and walking dogs or taking children to school. However, if you are out and about when it is taking place it may reassure you to know that the solution being used is safe for children and animals (as is the one we mention above for use in your own garden). The Fairfield Hall Management Company took similar action last year, and other management companies around Fairfield are also monitoring the problem.
It may be that replacing the hedging with another variety is the best long-term solution, but since it will be extremely costly to do this across all the managed areas in Fairfield there is little appetite for that extreme measure at present.