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Box Caterpillar: How shall I deal with it?

Gardening and Landscaping

Box Caterpillar: How shall I deal with it?

by Hamish Kemp on 02/09/19

Box Caterpillar: How shall I deal with it?

 

The explosion in box caterpillar is the biggest problem we encountered last year around North London.  It can take hold quickly turning a healthy box to something like this in less than a week.



If you have a garden, like so many people do, where box is the fundamental plant in the garden forming neat low hedges and focal topiary plants it can completely ruin the garden and end up costing a lot of money to replace. 

 

You may be left with 2 options to consider if your garden shows signs of being attacked by box caterpillar. 

 

On the one hand, you can stick with your plants and try and keep on top of it. 

 

Let us look at this alternative of trying to keep on top of the problem.  I maintain around 30 gardens in North London in many of them Box is the fundamental plant in the garden.    We managed to keep on top of it last year.  Ok we lost a few plants but the vast majority of the box we managed to save by following these 4 steps.

 

Firstly, detect early the first signs of box caterpillar.  Here it is:




The browning of the leaves which from a distance just looks like brown patches on the plants and is very easy to just pass off as dryness.  This is the first sign of the damage being inflicted to the plant from the box caterpillar.

 

Secondly, spray the infected plants thoroughly as soon as possible with an off the shelf garden caterpillar spray. We found it no use trying to pick the caterpillars off by hand as there are so many of them and they are difficult to see. 

 

Thirdly, check the plant throughout the summer at regular intervals for any signs of reoccurring caterpillar activity. We found that they did reoccur.  If so, spray again.  

 

Forth, regularly feed the infected plants to encourage them to green up again.

 

We found that this worked and saved the box in the gardens we maintain.

 

We also monitored the recovery of some of the box that had been attacked and this is what we found.

 

Some of them were so badly eaten they died and had to be thrown out.  Like this example:






Others we monitored, so if you have box which has been attacked this may help you in your decision whether to replace the plants or stay with them.

 

This picture was taken in May:






Here is the same plant six months later you can see it has recovered the leaves are starting to grow back.  By next summer, with more feeding the plant should look respectable.



 

So, if you have box which has been damaged it’s often worth sticking with it as it will recover.  You’ll have to spray and feed them throughout the growing season.  How quickly they will recover will depend on how much damage the plant has sustained.

 

On the other hand, if your box plants are beyond recovery or you decided to finish with Box altogether, there are alternatives which we will look at.

Taxus bacatta (topiary)

Euonymus japonicas ‘Jean Hugues’ (hedging)

Saracococca confusa (hedging and greenery)

Euonymus japonicas (topiary and hedging)

Ligustrum ovafolium (topiary and larger hedging)

The above plants I have seen will make good alternatives in gardens. Taxus bacatta (below) is often used for topiary in the form of cones, balls, pyramids and other complex shapes. 




Saracococca confusa (below) will form into a neat low growing hedge and is good just as a small evergreen bush.



Euonymus japonicas ‘Jean Hugues’ (below) is almost identical to Box and is very suitable for low hedging.  





 



Ligustrum ovalifolium, too, can be shaped into various shapes like balls, squares and animals.



To sum up, whatever route you take to deal with the problem will depend on your individual circumstances.  You may decide to do away with Box altogether then some of the alternatives may be the answer for you.  Or you may decide to invest in controlling the problem by following the four steps outlined earlier.  Either way I hope this article will be of use.

 

For more insights into gardening visit Hamish’s Youtube channel.