Posted: Monday 27 October 2014
by Adam Pasco
Walking past my pots of sedum one day, every single stem had come away from the compost, and I immediately recognised the cause. Vine weevil!
I’m very fond of growing plants in patio pots for seasonal colour. I like to move them about to ring the changes, and group them for added variety and impact.
Hardy perennials provide great value, producing long-lasting displays, and with luck returning year after year as they grow bigger and flourish. Some of my favourites in recent years have included miscanthus and other grasses, hardy gerbera, fuchsias and an increasing collection of sedum.
The succulent leaves of sedum vary widely, from deep purple to glaucous greys and greens. The striking flower heads attract an endless queue of insect visitors like bees and butterflies, enjoying nectar from late summer well into autumn.
But this autumn some of my succulent sedum, now in their third year, haven't perfomed very well. Walking past my pots one day, every single stem had come away from the compost, and I immediately recognised the cause. Vine weevil!
Beneath the surface, vine weevil grubs have been enjoying a diet of sedum roots all summer. Now that autumn has arrived their voracious feeding has actually completely destroyed the root system, severing every stem from the roots so they’ve simply lifted free of their anchorage and fallen away.
A little gentle excavation through the compost revealed dozens of fat C-shaped vine weevil larvae, satiated on the delicious sedum I’d so generously provided for them to dine out on!
It’s too late to save these particular plants. The damage is done, but I’ve emptied the pots into a deep tray for blackbirds to scratch away and feed on.
From experience I know vine weevil larvae are partial to tuberous begonias, strawberries and fuchsias, among many others. I do occasionally discover an adult vine weevil beetle, and as every one of these is female and capable of laying eggs it’s obvious that they’ll have discovered some suitable plants to infest.
I'm disappointed, yes, but I’ll take this as a warning to take measures to control and prevent vine weevil attack next year. Compost can be treated with either a chemical drench or with biological pest control nematodes, killing any larvae present before they destroy even more plants!
Once again I’ve learnt my lesson … prevention is better than cure.
10/11/2014 at 08:44
I stopped using primulas in my tubs for this reason, so I decided on a decorative small conifer and heuchera with a few cyclamen bulbs. Alas the heuchera had to be replaced, although one did last a year longer than the other, and most of the cyclamen went the same way.
10/11/2014 at 10:13
in my last garden I gave up on heuchera because of vine weevil.
Chrissy the gardener
10/11/2014 at 10:14
You can always use a product called Provada especially for treating against vine weevil unless you are apposed to using chemicals.
you just mix it with water and water the soil in the pots, it then seeps into the soil the vine weevil grub ingests it and dies.
10/11/2014 at 10:16
I have found them in Heucheras, Fuchsias, begonias, just tipped out the fuchsias to save for next year, always repot them as there is usually some in there. I put them all in a pot and put them out for the birds.
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10/11/2014 at 10:55
Also helps if you use a non-peat compost and put a grit layer of at least 2 inches depth on top of the pots.
Single stem plants may be protected by putting a circle of plastic (like the things used to protect cabbage plants against cabbage root fly) round the stem. The weevil lays its eggs on or just around the base of the plant and if it cannot reach soil, it goes elsewhere.
Both Sedum and Heucheras can be re-grown very easily from the eaten remains. Just treat the pieces as cuttings. They both root very easily.