Quote from bob on 12th September 2022, 6:30 pm

Hello Rosafay, 

Dont worry its probably just getting rid of it's old leaves, looking at your pictures, have you given it enough grow room in the corner of your garden?

Bob

Quote from Michael B on 24th October 2022, 3:10 pm

Hi, I have a similar problem with a Magnolia Grandiflora since April this year when it got planted. What was a healthy tree when planted it has slowly been losing a lot of its leaves since June. What I thought was maybe Weevils as leaves appeared to have holes and eventually falling, I treated the base of the tree with Weevil killer but it seemed to continue. I was giving it alot of water and fertiliser during this time. I have attached pictures of tree from both June and today. Keen to hear if this is common. 

Quote from bob on 25th October 2022, 8:40 am

Hello Michael, you have treated the soil, but this to no effect, personally I would not feed the plant this time of year, and don't water too much, weevils like  moisture.

There are a couple of things you could try, there are what I think are called nematodes?? something like that, which predate the weevil, I'm first to admit I know very little on this type of subject, they can be purchased on line, and placed on and around plants, do they work in the cooling temperatures, I'm not sure? but it may be worth a Google.

You could also try digging away a fair amount of soil from around your plant, as this is where the adults would be, replacing of course with new top soil, and adding a bit of ericaceous compost with it.

I dont know the size of it, but If it were my plant, to try and save it, I would dig it up, wash the complete plant down, clean off all the roots using water, and re-plant in a container using say John Innes No3 and some ericaceous compost, and move it away from that planted area, you don't need an expensive container, just a cheap holding container that will do the job until next year.

I hope Lee can pick up on your post as he is the organic expert on getting rid of pests.

I hope it all goes well for you.

Bob

 

Quote from Lee Garden Ninja on 27th October 2022, 8:29 am

Hi @michael-b

The damage certainly looks like vine weevil. They are a real pain to get rid of given their lifecycle. 

Whilst Bob's advice to lift and move is sound, in my experience vine weevil will travel and trying to get rid of them manually can be so tricky.

Nematodes are the best option which are watered into the soil and cause the least damage to other flora or insects. They just target the weevil. To help you fight this mini beast understanding the life cycle is vital.

Lifecycle of Vine Weevils and how to stop them

Black vine weevils develop through four life stages:

1. Egg laid by adult Weevil -May to Oct - The eggs are laid in the soil near the roots of the plant or Magnolia. They are a yellow colour if dug up turning brown as they develop. Like tiny beads or pearls.

2. Weevil Larva emerge - August to May. This is where vine weevils overwinter as larvae under the soil. Once warmer spring weather emerges they start to eat through the plant's roots to consume energy before they pupate.

3. Pupa of new Vine Weevil - March to May. The larvae pupate ready to then emerge as an adult who causes the lead damage.

4. Adult vine weevil emerges - June - Oct. Which then chews through leaves causing damage.

This cycle repeats each year which can be a real pain.

When to use Vine weevil nematodes?

Nematodes are tiny worms that seek out the vine weevil larvae enter their bodies and then emit a bacteria that kills them. The nematodes then reproduce inside the dead larvae and then seek out other larvae. So they offer great targeted protection. Vine weevil nematodes are Steinernema kraussei and are usually watered in during autumn to target the larvea. For severe infestations a Autumn and Spring application may be required.

Hopefully, this helps you in targeting this pest without resorting to chemical sprays which kills other beneficial insects. 

Happy gardening!