Issues with Portuguese Laurel Hedge

Hi all. I have come in need of guidance with regard to my hedge please.

I moved into a new house with landscaped gardens just coming up to a year ago. The gardens were planted for display probably around a year prior to that with relatively established plants.

I have a Portuguese Laurel hedge to the front and side, which I suspect was planted not much smaller than you see today. It is for the most part looking healthy with obvious growth and shoots in the spring.

A healthy section of the hedge just so you can see what I have.



However even sections where it's looking healthy have leaves in places that look bitten, but without any sign of anything eating it.



The above is not my concern, actually I have read this to be not unusual with a laurel.

The problem is this:






















So in a few sections, luckily to the side of the property, the plants have developed either really bad cases of the leaves with holes, or the leaves have gone brown and dead or a combination of both.

I wouldn't have said the ground any more wet or dry than the locations the hedge doing better.

So far I have tried (over the last 6-8 weeks):

• Kept the plants watered in any dry spells
• Fed with Miracle Gro
• Sprayed with Proranto Fungus Fighter Plus
• Applied a Bone Meal fertiliser to the top soil
• Removed dead leaves from the affected plants and ground

No signs of improvement and actually the issues seems to have spread to the plants either side of the originally affected ones.

Ideally I would like to try and determine:

What has likely caused this?
Can I save the affected plants and if so what would the best steps be to try?
Can I stop this spreading?

Your collective guidance would be much appreciated.

 

Well having had a quick read Vine Weevil certainly looks to create this damage and root damage would explain the impact to some plants.

For best results do I go insecticide or Nematode?

 

Nematode will kill any grubs in the ground but they probably be turning into adults now, I am not a fan of insecticides but they will kill off the adults. They probably done there worst for now have a look late summer / autumn when they are looking for suitable candidates for their young

 

Preventing further root damage is my priority, it seems that's what's losing the plants, although treating the larvae and adults would be good.

Actually I cant find an insecticide spray that specifically states it covers Vine Weevils.

Both the insecticide I can find (Bug Clear Ultra Vine Weavil Killer) and the Nematodes are water on products applied to the compost not the plant.

Also what I cant find is why the insecticide states for use in pots only not open ground. I wonder if it somehow not effective in open ground or if it more an environmental consideration. Any idea?

 

I had exactly these problems with my laurels. They were so bad that in Spring, I decided to give them one last chance before removing them. Now, they look like this...


(ignore the weeds surrounding them!)

Being unsure as to the cause, I decided to "attack" them on two fronts. First, I sprayed the leaves with a mix of neem oil, green soap (its made from pine oil, and I dont know if its available in the UK) and water.

Second, I found an natural/ecological fertiliser for evergreens, and applied it at half the recommended rate.

Within a short time, they looked as they do in the photo.

 

If I was going to use nematodes to catch vine weevils, then a trap is certainly the way I would go. Before using anything, I would first check that it is actually weevils that are the cause of the problem. Its easily done. A little bit of a dig in the soil around the plants should show up some of the grubs. If they are adult, then going out to the plant at night, and they will be seen in the light from a torch or mobile phone.

In regards to nematodes, I have a couple of concerns. Even if there are literally thousands of different species, these fall into two groups. Beneficial and Detrimental. The beneficial ones are those that are needed, but how do we know that the ones bought actually are from this group? I've no doubts whatsoever that there are unscrupulous people or companies selling Detrimental as Beneficial. Remember also that detrimental ones are known to feed off plant roots. Its probable that my fears are unfounded, but even so, they still must be considered.

Killing off Vine Weevils also kills off a source of food for certain animals. Hedgehogs for example. I'm under the impression that the numbers of these are declining, so is it correct that we should help this decline by removing a source of their food? Perhaps rather than using nematodes, we should be finding ways to encourage creatures that eat weevils as food into our gardens?

Just thoughts, that hopefully will promote a discussion....

 

It's definitely looking like Vine Weevil, there are larvae in the ground. Big fat ones!

Large pack of nematodes arriving tomorrow, with a trap to follow by the weekend hopefully. Also got some general bug spray in case I find any adults this evening, but not sure how effective this is on Weevils and haven't seen any yet either (although not checked after dark).

I am pleased I know the cause at least. I wish I had asked sooner. I just hope I can get it under control now. Gives me time to save for some more laurel hedge I suppose! Some will definitely need replacing, the plant is loose in the ground there cant be much in the way of roots left. Others not so bad.

 

Thanks to the guidance above, things seem to be more under control at present. I used nematodes and a trap. I still visit the trap and manually pick off the odd sleeping weevil in the mornings. A plant pot on a tile or similar would work just as well if honest.

Reduced leaf damage up top and fingers crossed no other plants dying at present. Digging around, no larvae evident in the ground now.

I will retreat with Nematodes Autumn and Spring.

I have 5 of the Portuguese Laurel plants reduced to bare woody trunks and branches. I have trimmed off what went black. There are some roots left. What are the chances these will have new shoots and signs of life next year? They are unsightly at present, but prepared to give them a chance if there is one. If they are unlikely to ever recover I would rather replace now and get new plants establishing.