Watch out for the evil weevil
Some of my Heucheras in pots have been looking more tired than they should even at this time of year. I know the signs now, past experience tells me that the evil weevil has been at work. It is said that adult Vine Weevils can't fly. If that's true then how come they seem to find every succulent planty morsel that I grow and lay their eggs there. A few weeks later hey presto! look no roots. The answer is that they are sneaky little climbers, crawling along the ceiling is no challenge, they can even clamber up clean dry glass so the side of a pot is all in a days work.
Leaves nibbled round the edges are a dead give-away that adults have been at work, especially tough leaves, the kind that slugs and snails don't bother with. Bergenias, Rhododendrons, Heucheras, Azaleas that kind of thing are good indicators. Bergenias are especially favoured and are used by some nurseries in the same way that miners used canaries. Adult weevils look just like slightly speckled beetles with long noses - they are tough. If you are intent on squidging them you'll need to be firm - it's more of a job for a heel than thumb and forefinger.
Don't be fooled into thinking you have weevil grubs when what you really have is either Perlite granules or slow release fertiliser - it does happen. The test of weevil grubs is that they move, maybe not quickly but they do writhe about a bit and they squish rather than just crushing.
The root eating grubs of Vine weevils are so different to the adults, they are soft bodied, vulnerable little things and very squashable...but first you have to find them. Vine weevil grubs eat small roots and the tender 'bark' from larger roots. Sickly plants with wilted leaves are often a sign that the grubs are at work. They have favourite plants, Heucheras, Fuchsias, Primroses (the Primula family in general) Ivies and Heathers top their list so these are the ones to keep an eye on. If any of these favoured plants become detached from their roots you should dig in to the compost and look for grubs - it's easiest to knock the remains of the plant out of the pot and break the rootball apart - the grubs will be near the top, sometimes skulking in the nooks and crannies of the root system. Vine weevil grubs are off-whte in colour and 'c' shaped, they don't move around much and they are about the size of a small pea, if you don't want to squidge them you'll find that birds love them. Offer them to the garden Robin or, to really get your own back feed them to Chickens and turn them into eggs.
So, what can be done to counteract the work of the weevil? First off, some simple precautions are well worthwhile - if you see a plant that looks infested, deal with it and get rid of the pesky grubs. Plants that have had their roots chewed can often be saved by carefully getting rid of the pests - you have to pick them off the roots and re-pot into fresh compost. If you plan reusing compost in patio pots be sure there are no weevils - if in doubt use all fresh compost that you know is 'clean'. Affected Heucheras can often be increased several fold when they have been attacked, even pieces with no roots at all will soon get going if replanted.
There are treatments you can use, both chemical and biological and they do work. Go to your Garden Centre explain the problem and they will advise you.
