Pest & disease or Laurel experts please!!

Andy163 · February 2022

Hi all, hope everyone's enjoying this lovely windy weather.
Here's a quick run down.
I planted a hedge of 2 metre laurels this time last year, they are planted in semi shade and have a drip irrigation to the roots. They seemed to take well, putting on a little growth throughout the year. All seemed well.

I have only just noticed this week that there seems to be some dieback on a run of particularly plants.
The majority of the plant is fine, with healthy growth and healthy leaves. Some branches however have wilting leaves, leaf drop and whole branch die back, which makes me think of some kind of fungus.

The surrounding soil is moist but not over or under wet.

I have pruned out infected branches which are dead. On some of these branches there was a flat brown fungus, not all of
them though as seen in the picture.

Some of the leaves have brown areas and are wilted.

No canker was visible and no other issues.
Have a look at the pictures and see what you think, hopefully someone may be able to advise?

Fairygirl · February 2022

I'm assuming you didn't cut them back on planting?
Large specimens always tend to struggle with establishment, and that could have been magnified if conditions weren't ideal through last year. I can't tell how you're growing them either, in terms of site, soil and drainage etc.
It's also quite normal to get leaves/branches/stems failing on any plant, evergreen or not. It's hard to see just from those close ups.
If the rest is generally healthy, I'd cut those back quite hard so that they can bush out properly and give you a better hedge.

There's a whole thread on laurels - it'll take a while to read, but it gives lots of info. More than you'll ever need

https://forum.gardenersworld.com/discussion/656523/help-needed-please-with-laurel-hedge-issues/p1

Andy163 · February 2022

Thanks for this fairygirl
I'll take a look at the thread.

Site soil conditions are generally good although they may be getting a little too much shade, however the issues seem to be only in on particular section of the hedge.

They are planted in a dappled shade woodland on sandy soil surrounded by lead mulch. There is a drip irrigation at the base of the plant. There were no major issues during the 1st year of establishment, the odd lead drop but as you say it can be expected.

The bit I can't figure out is why particular whole branches are affected rather that the whole plant or the top or bottom which makes me sway more towards a fungus infection.

I have removed all the infected growth, cleared the base of leaves and will feed in March to try and reinvigorate them.

GardenerSuze · February 2022

I have often seen this problem on laurel . Cold temperatures can produce blackened leaves. Also leaves that are further down the stems are older often brown and get less light so when you cut back they become more noticeable. You have cut out the nasty stem which is good .Best time to prune is April early May and ensure your secateurs are cleaned before and after. Cutting with shears can look very messy. I am sure they will grow like mad once the weather improves.

Fairygirl · February 2022

Sandy soil isn't the best medium for them, but if they've established well enough apart from that, I wouldn't worry too much. If you're adding some organic matter now and again, that'll certainly help, and will also help with water retention. They're virtually impossible to over water. Poorer, lighter soil isn't as good for growing them in, as good old heavy clay

It's more likely to be a bit of weather damage, or even a bit of damage from wildlife - sitting on, or chewing branches and stems. Cutting out the damaged bits is the best solution.
It's one of the toughest shrubs anywhere. Weather of any kind doesn't affect it. You occasionally get bits of damage when there's a freeze and then a sudden thaw if they're in the sun, but it doesn't affect them long term. It wouldn't grow so well up here if it did.

Andy163 · February 2022

Thank you all. I will monitor them over the coming months and hope growth improves.

I have just read about Botryosphaeria fungi, it can cause wilting and dieback of twigs and branches, and cankers in cherry laurel trees. Although no cankers were visible. There also isn't a cure for this other than pruning out infected branches.

Fairygirl · February 2022

With laurel, just cutting out damaged stuff usually sorts it

robairdmacraignil · February 2022

Damp conditions can help the transmission of fungal spores so if there is an element of this being your problem letting the area dry out a bit more by stopping the drip irrigation system might be worth considering. I much prefer to let shrubs and trees stretch for water and develop a stronger root system and not water them once they are established but I guess if you have sandy soil this would drain a bit better than the soil I have in the garden here. The last laurel hedge I got established here got no watering outside of rain which I know is contrary to some advice but over 90% of the plants settled in fine and filling the odd gap in the winter months since planting has been much easier than watering. Laurels are really tough so removing the dead material and trimming to encourage new shoots should be all you need to do to help generate healthy fresh growth.

Happy gardening!

Fairygirl · February 2022

I think the soil is a big factor in this @robairdmacraignil.
I hardly have to water plants once they're in either, and I often plant stuff without watering it at all, as it isn't necessary, but I'm always aware that many locations are very different from mine in terms of moisture and soil.
The way plants are watered is certainly important too. Light watering which doesn't get down into the ground does more harm than good, and it's something we often mention on the forum. As you say - the roots need to get right down so that the plants can fend for themselves once established.

Pest & disease or Laurel experts please!!

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