6 October 2026

Customer Question – Box Blight or Caterpillar?

Q. “I called yesterday and you suggested I send photos – see below. I want to understand if I need to buy TopBuxus ‘health mix’ or ‘grow’ to help restore my caterpillar eaten box hedge. I am not sure if I have box blight or not. Many thanks for the advice.” Jacki

A. Thanks for the message and for the pictures. You only need the Topbuxus Health Mix if you have blight. Caterpillar and blight are 2 separate problems and looking at your pictures, yellowing areas are more likely to be blight whereas if you have had caterpillars (not sure if you have spotted them / treated for them this year?) then you will get areas that have lost their leaves i.e. the leaves have been eaten and the caterpillars spin webbing, so you see areas of that as well?

This pest over-winters as a caterpillar, so its likely if you have Box Moth Caterpillars then they will be there now, so its best to inspect the hedge and look for the caterpillars. They use their webbing to spin leaves together and hide inside, so look for clumps of leaves with webbing and look inside for the distinctive green and black caterpillars. Depending on what you find then treatment would be :-

• Inspect for caterpillars and if you find them treat your hedge with Box Tree Caterpillar Nematodes. Treating now will kill any over-wintering Caterpillars so your hedge is clear of caterpillars for the winter / Spring.

• If you have areas of yellowing leaves with no evidence of caterpillars then this is likely to be blight and you should spray with Topbxus Health Mix. Blight spores lay dormant in the soil under the hedge so it is a good idea to rake up any fallen leaves abd debris under the plant and destroy it i.e. don’t compost it. The Health Mix also contains a foliar feed which will help the plants recover.

• If you have had caterpillar damage and are NOT spraying with Health Mix then you need to feed separately to help the plants recover from the caterpillar attack, so apply Topbuxus Grow Fertiliser as a granule around the base of the plants. You can apply this as well as the Health Mix if you want to give it both a root and foliar feed, but normally one or the other is enough.

Then next spring wait for new growth to appear and then monitor the plants to see if caterpillars / blight return and treat at the 1st signs

I hope this helps.

Kind regards Jon @ Green Gardener

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