Vine Weevil Issues...

[Dario]

Hi All
I have recently seen many adult vine weevils hiding in my cork oaks and I am not happy as they are munching on some new shoots pretty heavily.
I have been checking to see if they are hiding just under the soil surface during the day with no luck. Then at night I ambush them with my flash light and pick the ones I can see off the foliage and squash the buggers...they are quite strong and make a lovely crispy sound under my shoe...
It is difficult though as they sometimes are on the trunk of the subers and they blend in ever so well with the colour of the bark and hide it the crevises of the cork bark.
I am a little worried though because suber has very sensitive roots and I know that the lava can devour the roots.
The corks are due for their first post collection repotting in spring when their origional soil will be inspected and somewhat removed etc so I can get a look see then. But that is a while off, and I don't fancy doing an emergency repotting at any stage before then with this species of tree. So I hope they don't go down hill re the lava (if any) munching the roots.
They may have been in the collected soil of the trees (but it has been two years sinse I collected them and they are healthy), or they may just have a thing for cork oak leaves? Either is possible as I have found the lava in the soil in my court yard when digging the ground on previous occassions (and I have read that the adults can fly too).
Does anyone know if I submerge the containers in water (like you do when treating curl grubs etc), if this will drown any lava that may be present...and if so, for how long should I submerge them)?
And can anyone who has combated adult vine weevils before, recommend any sprays to eradicate these blighters?
Any help or advise is appreciated as I am very fond of my cork oaks!
Cheers, Dario.

[NBPCA]

I found this info on the internet. (GardenForum Horticulture)

Would be interested to hear how you get on.

Grant

Adults.
One of the most effective - but time-consuming - methods of controlling the adult vine weevil beetles is to check your plants at night when they are active and feeding. They can then be scooped up and disposed of.

Another way is to use a physical barrier as the adult beetles cannot fly from plant to plant. Stand potted plants on upturned pots sat in saucers of water - the adults can't swim. Or surround the pots with Barrier Glue available from Agralan - the adults cannot walk across it. With either of these methods it is important to move plants away from walls or greenhouse/conservatory walls as the adults can jump down onto them; they cannot fly.

Physical barriers on top of the soil or compost also work very well. Add a 2cm (0.75in) deep layer of sharp grit or gravel on top of the compost or around the base of the plant to prevent the adults from laying eggs; the egg-laying structure is irritated by the scratchy feel.

Grubs
Typical vine weevil grubs, which will eat the roots of a wide range of different plants.

They are creamy-white, up to 13mm (0.5in) long, C-shaped, with a brown head and no legs.

Often the first signs of damage are only spotted when a plant completely wilts and dies.


Commercial nurseries sometimes add a strong chemical called Suscon Green to the compost, which gives good control. It is worth asking when you are buying particularly susceptible plants if Suscon Green has been used.

There are a number of insecticides that can be used to treat plants and give protection against attack. Bayer Provado Vine Weevil Killer 2 and Scotts Miracle-Gro BugClear Ultra Vine Weevil Killer can be used for any container-grown plants (apart from edible ones); they are watered onto the compost.

BugClear Ultra for Pots and Westland Bug Attack Quick Sticks are insecticide pins that are inserted into the compost.

Provado Ultimate Bug Killer is sprayed onto plant foliage to kill leaf pests, but may also give some control of vine weevil grubs (some edible plants can be treated; check the label first). Scotts BugClear Ultra and Westland Plant Rescue Bug Killer for Ornamental Plants are similar but can only be used on ornamentals.

If you don't like using pesticides, use a biological control based on nematodes. These microscopic creatures enter the bodies of the grubs and release a specific bacteria that poisons and kills them. They then multiply and go on to attack other grubs. The nematodes are available from several mail order supplies, such as Defenders, Scarletts PlantCare, Just Green and Green Gardener. See the suppliers list for details.


Grant

[Dario]

Thanks for all the info Grant I will let you know what I decide to do and the outcome.
Glad to know that they don't fly! I hadn't seen wings on them at all but I read somewhere that they fly , so I am pleased to now know that is not the case.
I had read about the saucer/water deterent previously for aphid control as ants can't swim.
My soil mix is topped with a good inch of 100% diatomite but they still seem to crawl across it. I just hope that it does deter them from laying their bloody eggs!

Often the first signs of damage are only spotted when a plant completely wilts and dies.
Grant

Now that is worrying! But good motivation to try some of the methods in the article you posted.
Thanks for the help Grant!...I'm glad someone replied
Cheers, Dario.

[lindsay farr]

Weevilnem is available here
http://www.ecogrow.com.au/top10/Black_Vine_Weevil.html
A very effective and secure option.
These nemetodes can be applied in Spring and Autumn. I suggest hand removal of the grubs.

[Grant Bowie]

When i ran my nursery I treated for the grubs using the biological control; Nematodes.

I never really had a problem with the Adults so that is whu I would be interested to see how you go.

Grant

[Dario]

Thanks for the link Lindsay, I appreciate it
Thanks again Grant
I sure am sick of the late night weevil catching but it is well worth the effort!
I will be sure to let you know what I do and the results.
Thanks again

Cheers, Dario.

[Dario]

When i ran my nursery I treated for the grubs using the biological control; Nematodes.

I never really had a problem with the Adults so that is whu I would be interested to see how you go.

Grant

Hi Grant, I am sorry for not replying sooner, although not much to report.
I really appreciated the excellent advise from both yourself and Lindsay
As I try not to use pesticiides when it can be avoided I liked the option of using a biological control based on nematodes but I decided to keep monitoring the situation before acting. A mistake for sure...Often the first signs of damage are only spotted when a plant completely wilts and dies....but luckily for me so far everything seems ok.
I kept removing the adult weevils and in the last two months I have not seen/found any.
Will repot the cork oaks in spring.
Thanks again, Dario.

[Paulneill]

I found 2 weevils on my best Juniper bonsai . One was big the other small . I noticed them because they were eating chunks of bark. But haven't seen any since . I didn't know they produced root eating grubs. What a nIghtmare . Hopefully they don't like modern substrates

[Dario]

Hi Paul, yeah they sure are little buggers
You saw the adults, they start off as lava that live in the soil and devour the roots.
They are supposed to not like rough surfaces and free draining mixes of varying partical size that have rough edges etc...but I wouldn't put it past the mongrels!
Cheers, Dario.