Garden Q&A: Our hedge has black, withered leaves. What will help?

Whether you're a gardening beginner or expert, Irish Examiner columnist Peter Dowdall has the answer to your questions

Red robin hedge.

Question

We planted a Photinia 'Red Robin' hedge six years ago, and since then, we have let it grow slowly to five feet high. 

It gets trimmed back in March and September.

As you can see from the pictures, it's not looking healthy at the moment; it has black, withered leaves and sections that have not grown.

Answer

Your 'Red Robin' hedge is showing classic aphid damage on new growth. The soft red leaves are being fed on as they emerge, which causes them to curl, blister and distort. 

As the damage develops, the leaves often darken or blacken, and the shoot tips can look scorched or shrivelled. The older green leaves are unaffected, which helps me be certain. 

This is very common in spring when fresh growth is most vulnerable. It looks severe, but it rarely harms the plant long-term. 

Photinia evergreen is ideal for hedges. File picture

Lightly trim off the worst-affected tips and check for aphids on the undersides of leaves. The hedge will push fresh, clean growth once conditions settle. 

Feed the entire hedge with a good quality biochar-based plant food, and this will help the bare patches to fill out whilst improving the structure of the soil that it is growing in.

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