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The first sign of problems - often unnoticed and
unheeded - will be the damage caused to plant foliage by the adult vine
weevil beetle. (As seen in the image below). thereafter, plant will be
found wilting, or simply falling over once their root system has been
eaten away by the Vine Weevil Beetle's maggots!
The right hand image shows the 'business end of the Vine
weevil, with it's narrow jaw structure which cuts the 'slices' out of
leaves. Strangely, it is not normally the plant that that has been fed
upon that suffers the most damage. It is often plants some distance away
- and totally unrelated to the damaged foliage plant - that often get
attacked by the larvae.
Control
The only effective 'spray' that we have been happy with
is Provado Vine Weevil Killer 2 (Bayer) which contains thiacloprid. This
is normally applied as a drench to the soil. It is probably effective
for up to 4 months for a single treatment, so further treatments may be
necessary in areas where Vine Weevil Beetle are a severe problem.
There is normally just one generation each year -
thankfully - and the larvae overwinter below soil level - having a feast
at the same time, so Spring is often the first sign of trouble, as some
prized plants either do not come into growth, or simply look very limp -
as a result of having their root system attacked
Hunting the adult beetle by night, and torchlight is also
effective! (Do warn your neighbours and local Neighbourhood Watch
committee!). A dry evening is best, for then any offending adult beetles
will show up better against the light coloured soil. Simply shake the
shrubs - particularly those that seem to be the feeding area - and the
beetles will fall to the ground. How you dispose of them is a matter of
choice. They never seem to recover from being trodden into the ground!
Also, lift container plants to see if the Vine Weevil
Beetles are hiding underneath - this is particularly good practice in
the greenhouse.
Biological controls are available for those who do not
wish to use chemicals. The most effective being the nematode
Heterorhabditis megidis. Don't worry about remembering the name. It will
be found at most good garden centres as Vine Weevil Killer - under
Biological control. Be aware that you only buy a pretty box at Garden
Centres! The box will contain a ticket/voucher, which you then send off
to the lab to get your supply of the nematodes.
Plants Affected Most
alpine and rockery plants - Primulas in particular - also
violas/pansies.
Fuchsias
Most Container Plants
Rhododendrons
Euonymus
I have recently discovered a mature containerised Liriodendron (Tulip
Tree) to have been attacked. Ignore the signs of
Vine Weevil Beetle at your own peril!
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