Vine
weevils
Symptoms
Irregular notches are taken from the margins of the leaves are made
by the adult damage. If a plant suddenly dies and appears to have
no roots, this is the work of the larvae.
Cause
Vine weevils are the scourge of the horticultural world because
they can be so devastating and it is so hard to protect your plants
against attack. The adults are nearly all female and reproduce parthenogenically
(they do not need a male partner). The bites that they take from
the leaves do very little harm but it is unnerving because it shows
that they are around and may have laid their eggs by the roots of
your plants. Each weevil can lay hundreds of eggs. It is the grub
stage of the vine weevil that is so destructive since they live
off roots.
Harm
The effect on your plants will depend on the size of the root system
and the number of grubs eating it. To start with the growth will
slow, the plant may then begin to wilt and finally die as it no
longer has sufficient roots to sustain it.
Treatment
Organic - adult vine weevils cannot fly, they walk and mainly
at night, so you can go out at night to find them and step on them.
Biological - nematodes are small soil worms which lay their
eggs in the vine weevil grub, which then hatch to feed on the vine
weevil. The nematodes come in powdered form and are watered on in
late summer, while the soil is still warm but the grubs are, hopefully,
still small enough not to have caused too much damage.
Chemical
- Bio Provado is a new product based on thicloprid that can
be used as a soil drench to control vine weevil grubs. For new container
plants try Levington Plant Protection Compost which also contains
the same chemical.
ps feeding within hours and will die a few days later.
Source:
Crocus
- The leading online garden centre
