Portuguese Laurels - seriously prune/trim NOW?

[Pebs]

Hi.

Is it all right to seriously prune back Portuguese Laurels bushes right now (February), or should we wait till later, or should we not do it all?

2 years ago my street was seriously infested by Vine Weevils - small black beetles that feast on leaves and lay eggs in the soil beneath so that the grubs can feast on the roots! They devastated our Portuguese Laurels - more than any other plant.

So 30 three-foot high Portuguese Laurel bushes forming a hedge round our small garden are now looking unsightly and straggly - lots of branches and sub-branches have few or NO leaves on them at all. Most of the leaves which remain are at the tops of the bushes, where the Vine Weevils didn't much get to, probably because every night we were shaking them off (and squeezing them dead).

We have studied every garden in the road. LOTS of species have been badly attacked by the Weevils. The only ones which the Weevils have NOT touched in our road are:
choisya,
aucuba,
seneca (NZ yellow daisy bush),
and phormium (flax).

This winter we have had 2 really cold periods here in Shropshire, with the temperature down to -8C in our area. And this year, unlike last winter, we haven't seen a Weevil anywhere - whereas last winter we found the odd one sheltering inside the house in warm spots! So we are wondering whether or not it's likely that the cold has COMPLETELY killed off the weevils in our street.

We realise that there could be another Vine Weevil infestation this summer or next, or in years to come, and that we really ought to remove all the Portuguese Laurels NOW, and replace them with one of the above (and probably choisya or aucuba would look best in our situation).

But IF cutting all our Portuguese Laurel bushes down to about 9" above soil-level will help them bush again this spring into a healthy state, then we COULD at least postpone the much bigger task of replacing them all.

What would you advise in this situation?

Thank you for all opinions offered.

Pebs.

[Charlie Pridham]

Best times for cutting Hedges is April and August but be careful in
April as birds may well be nesting by then, in a milder location you can
cut pretty much any time. These also respond well to being cut back hard
into older wood the new growth can then be managed to get a lower
bushier plant

Re your Vine Weevil issues, cold slows them up but wont completely
eliminate them, However they can be effectively and safely treated by
using nemotodes you will need to wait until the soil warms up, there are
two types available one works better outdoors you will need to check but
I think its Nemasys H

https://www.nematodesdirect.co.uk/vine-weevil-killer-nematodes/12-nemasys-vine-weevil-killer-nematodes-small?gclid=CjwKCAiA78XTBRBiEiwAGv7EKpb83-BKlGxkCiNcvnAIh1evehl_7WXCG8E9XKGprLoNhWo9KeW7HxoCYsIQAvD_BwE

--
Charlie Pridham
Gardening in Cornwall
www.roselandhouse.co.uk

[Pebs]

Thanks, Charlie.

Shrewsbury is quite a mild location, so I gather from what you say we could opt for the pruning, and now.

Disappointing though to hear that the cold snaps won't have eliminated the vine weevils. This news really decides the issue. If the cold hasn't eliminated them, then any new growth we encourage will just be gobbled up, as before.

So it looks like we're going to have to eliminate the savaged Portuguese Laurels and replace them with a plant that the Weevils clearly don't like! But I like choisya!

Pebs.

[Pebs]

Charlie, thanks again for your help. Re. the suggestion that vine weevils "can be effectively and safely treated by using nemotodes", I forgot to provide some hopefully helpful information.

Using nematodes was one of the first "remedies" we turned to. Because we have so many tubs, and big ones too, containing Portuguese Laurels, the purchase of nematodes was expensive. No matter, we bought what was needed and used it. What's more, we repeated the procedure twice in the first year. It simply didn't solve the problem. When we dug out one tub that had been well and truly saturated with water containing nematodes, and the right saturation too, we were aghast to find the soil beneath the roots wriggling with vine weevil grubs!

In the second year we saturated the soil in the tubs with Bugclear Vine Weevil Killer! That seemed to make the weevils a bit dizzy. We began finding the odd one lying on its back on the paving around the tubs - after having munched on the leaves, and taken in some of the systemic killer. But it absolutely did not eliminate the populations.

Did some research on this. A study by University of Swansea researchers found that AT LEAST ONE THIRD of the nematodes in a pack are dead upon arrival! But more telling was that in 2016, the year in which our street was infested by vine weevils, Lord Heseltine called a "Vine Weevil Summit" of experts to gather at his estate and discuss how to deal with the problem . . . as clearly NO effective deterrent exists. There's a video of one of the presentations online.

Basically regulations about insecticides mean that there is currently nothing truly effective on the market! And I'm afraid that our determined shaking of the bushes each night while the weevils were feeding only reduced the population: it didn't eliminate them. This is why we were hopeful that a couple of really cold snaps this winter might kill them off, but you think not, and I think you're right. There are sheltered corners in this street, below gas flues etc., where a weevil or grub will have survived, and the rate at which they multiply is horrendous. One vine weevil lays 100s of eggs.

Pebs.

[Charlie Pridham]

It doesn't help that they are all girls so don't even have to waste time
looking for a mate!

surprised at your poor results with the nematodes, we took part in the
original trials with Cambridge university back in the early nineties, it
pretty much wiped them out, we stopped using it after it went commercial
as being in cornwall we needed to be supplied early and they used not to
supply until May.
There are very effective chemicals for control (although its true the
best have been withdrawn) but they only work when added to the compost
and are designed to nobble the grubs when they are newly hatched see
MET52 (organic) and IMADASECT (Chemical) (before damage occurs) No
insecticides currently work on the adults.

Since these weevils can not fly and have to come down to the ground to
lay eggs and move between bushes Toads and Frogs are very keen on them.
I am not sure changing the plants will work, there are not many things
they wont eat the roots of/off

[Pebs]

Thanks for the further interesting information, Charlie.

Re. vine weevils' reproduction, there's a lot of misinformation on the Internet, as a result of which at one point I was telling neighbours that vine weevils are hermaphrodites. But I was wrong. There are males and females. However, the females don't need the males in order to reproduce. So, as you say, they don't spend any time hunting for mates: they just get on with dropping 100s of eggs!

Some of our Portuguese Laurels are in the ground, so while most of the leaves of these have been nibbled, we don't believe that the roots have been badly attacked because of the density of the ground, which is also very clayish.

We think the reproduction is occurring in the soft and straw-like environment of the bagged compost with which, of course, we filled all our planters! The weevils have no trouble digging into this mixture, and neither do the grubs have any trouble moving from root to root inside it! In addition, when the sun hits the side of planters in warms up the compost, which pleases the Weevils and grubs even more.

Unfortunately we have no toads and frogs up on the balcony where most of our planters are located. And when the Vine Weevils are active, at night, birds are not about.

As for their method of transportation! We have come to learn that Vine Weevils are marathon walkers! They may have short legs but no distance is too far for them! They love warmth and follow the sun! So they are drawn to scale the sides of buildings, and the warmer it gets the higher they will climb. A fourth floor balcony in our street became infested.

In winter they've been found inside, keeping warm, for example underneath a lap-top!

I will look into MET52 and IMAADSECT. Thanks.