At the beginning of July, I discovered I had vine weevil in my garden - I discovered a couple of grubs when I was about to plant where a heuchera had been. This was my first introduction to the pest.
I destroyed the grubs and subsequently found a few more throughout the garden. I destroyed what I found and also one or two plants which seemed to have a proliferation of eggs - also destroyed - at least what I could find.
Without digging up my plants, how do I know I have grubs?
As I live in Fife, should I be applying nemotodes earlier than in the south in case of early frosts?
Once applied, do nemotodes continue to destroy the grubs as long as there are grubs to be found, or do they die off themselves in a short period of time?
I am prepared to treat most of my garden but need to know I have a fairly good chance of grubs being around before I make the investment.
What happens to this year's beetles? I have fairly widespread leaf damage throughout the garden, and wonder if the beetles die once they have laid their eggs or do they hide until next year?
I suspect I have had fairly low level infestation for a year or two, but the problem only came to light when I had work done in the garden and planted quite a lot of young shrubs and perennials.
I do hope you can help me.
Looking forward to hearing from you
Thanks for your e-mail.
Vine weevil goes through a life cycle, where generally there are grubs present in the spring and late summer. Although the grubs can be found in warmer conditions for longer periods. I would expect grubs to be present from late August for the second generation.
To be safe I would apply Vine weevil killer nematodes in September, this will also ensure that the soil or compost is warm enough for the nematodes to be active. A successful application will kill about 70 percent. It is not possible to kill all of them.
The Vine weevil either goes through the winter as a grub deep in the soil or as an adult sometimes. There are no controls available for the adults. Soil temperatures are warm enough for nematode treatments again from about April to May.
The grubs will form new adults in June to July. I would focus on treating pots and containers, where the nematodes are very effective and any beds where you think there are high numbers of grubs. I would not treat the whole garden but focus on those areas and treat in late summer and the spring. I hope this helps.