Vine Weevil Potted Azalea

I have Vine Weevil eating my potted Azalea. Lots of leaf damage, found 2 adults at night. I noticed the leaf damage last year, but thought it was snails or slugs. It was very minor damage compaired to this year.

I will be using nematodes, I'm not comfortable using any chemicals, as it harms bees. But from reaearch the larvae are only active spring and autumn. Is this correct and do I wait until August before applying the nematodes.

 

I don't know, but looking on the RHS site, it advises -

Biological control

• Biological control for the larvae is available as microscopic insect pathogenic nematodes. Several species and combinations are available (Steinernema kraussei, Heterorhabditis megidis, H. bacteriophora and S. feltiae). They are available from suppliers of biological controls and as sachet formulations available from some retail outlets. They are suitable for use in containers and in the open ground. Nematodes have the potential to infect other animals. They should therefore be used with care and only when there is a specific problem to treat
• For best results apply in August or early September when the soil temperature or potting media is warm enough for the nematodes to be effective (Steinernema species 5-20ºC/41-68ºF Heterorhabditus species 12-20ºC/ 54-68ºF) and before the vine weevil grubs have grown large enough to cause serious damage
• The nematodes can give poor results in dry or heavy soils. They work best in lighter soils and open potting composts, such as peat or coir. Nematodes can be used safely on all edible and ornamental plants
• A trap containing nematodes (Steinernema carpocapsae), is available for controlling adult vine weevil. The traps should be placed on the ground below plants damaged by the weevils during the summer. The adults enter the trap during the day and are infected by the nematodes

 

Hi @peterpies

While it is commendable that you want to avoid chemicals, if you need to resort to it to save your plant, keep in mind that if you do it late in the evening, bees aren't very active then. With this being a potted plant, could you not also cover it for say 24 hours or move it to your shed? Also, I haven't had to use a product for vine weevil before, but presumably it's applied to the compost rather than the main part of the plant?

 

Is there a reason you have it potted @peterpies ? Is it because of your soil pH?
Do you have a photo and do you know what type of azalea it is? Much of the damage done to tough plants is aesthetic, so it can often come down to how you feel about it. A few vine weevils can be shrugged off quite easily by something like a healthy azalea, but the key is that word 'health'. What care do you give the plant, and what medium is it grown in, what feed/water does it get? Those are all very important.
Bear in mind that the nematodes will only work well if temps are right, so take note of the info @Pete8 has given. That's the reason they aren't really worthwhile using here where I am.

 

The most marketed spray was Provado Vine Weevil killer. That contained Neonicotinoids and all such sprays were banned in the UK in 2018 for non-commercial use.

Vine weevil sprays are available containing acetamiprid, but that is also a type of Neonicotinoid that can harm bees.

from Google-
Yes, acetamiprid can kill bees. While it's often considered to have lower toxicity to bees compared to some other neonicotinoids, it can still negatively impact bee health and survival, particularly at higher concentrations or when combined with other pesticides. Acetamiprid is a neurotoxic insecticide that can be harmful to beneficial insects like bees and butterflies.

As an alternative for adult vine weevil, Pyrethrum sprays are effective.
It's a contact insecticide made from a type of chrysanthemum.
That may help clear the adults you have atm, then use nematodes from August to get rid of the larvae.

 

It's potted because of a being small garden with a large gravel area. It's in a half whiskey barrel and flowers well every year, although growth is most likely stunted.

So temps for nemotodes are 5-20ºC, August will be too warm for them, so maybe September is better. I'm going the cardboard trap route and torch at night, to try and catch the adults from now.

I'm not touching sprays, I'm super bee friendly and grow plants just for them.

The photo shows the worst area, being near the barrel, other areas are affected, but not as bad.

I'm thinking it's quite serious as there was damage last year to the leaves and the grubs have been at the roots since.

 

To add. It's well cared for, watered and feed as needed, although I haven't added compost this year.

I only water this using rain water from a butt, helps the PH. All other plants get tap water.

Having never heard of the Weevil before and reading about it, it's too much risk leaving it. I'll go the nematodes route, but want to get the timing right.

 

Personally I would go down the nematodes route. I have used them for several years on my potted plants and (touch wood) haven't had any further trouble.

You will find information here that might help, September seems to be the best time for the first application.
(Just to add I have no connection to the company, but I find their service to be excellent. Other companies are available ).

Vine Weevil Nematodes | 12 sqm | Buy Online | Green Gardener

 

Thanks all.

Will go with 2 applications this year of nematodes starting Sep 1st. Use on all surronding pots and lawn border, as it covers 12sqm. Keep the ground moist and well watered after.

Mean time, try and catch as many adults as possible.

Then see what happens next year.

 

If you have noticed VWeevils on potted plants there is always the chance that you will end up with the grubs in the soil which will feast on the roots.
I have used Provado in the past but only diluted with water and used to soak the plant ( Heucheras and Strawberries in my case ) to kill the grubs. Removing any flowers which appear over the following 6 to 8 weeks prevents any damage to bees and insects.

 

If you've seen grubs on the root system, I guess you've taken it out the pot to look?
If so, the other option is to hose off all the soil from the root system, then repot using completely fresh material.
Then leave the soil spread out for the birds to get the grubs, or deposit in a council wast ebin if you have that option.

A very thick layer of grit on the surface of the soil in the pot can help prevent adults laying there too.