Agriculture Reference
In-Depth Information
Moles
Moles can cause a great deal of damage as they burrow through the soil, and they
inevitably target the richest soil - the growing beds - because this is where
the worms are. Moles dislike vibration in the soil, so if they are nearby, get hold
of a 'mole-chaser' windmill (available from Northern Tool in the UK - go to
www.northerntooluk.com) and site it close to the tunnel. While you are trying to
persuade a mole to relocate, resist the temptation to disturb runs and molehills.
Most of the vandalism perpetrated by moles occurs during the digging out of new
tunnels, and once these are established relatively little damage is done.
The ornamental plant Allium moly is also reputed to deter moles, so it may be
worth planting some clumps of bulbs around the tunnel and replacing them
every two years. If all else fails you may need to consider trapping, but this is
tricky and best done by a professional.
Moulds
Treatment of moulds in the tunnel is as for botrytis (see page 162).
Onion fly
Onion fly is unlikely in a polytunnel but can be a pain nevertheless. The risk is
reduced by growing plants from sets rather than from seed. Affected plants will
usually yellow and die some time in May. If you see evidence of maggot damage,
cultivation of the soil around the plants until the end of May will help.
Peach leaf curl
Peach leaf curl is a fungal disease causing severe deformity of developing leaves
and the loss of both fruit and flowers. A single attack is unlikely to be fatal to the
tree, but as the disease overwinters in cracks in the bark it can re-infect the tree
the following year. Thankfully, peach leaf curl is much less likely in plants grown
under cover, and choosing a resistant variety means that you will probably never
see it. If you are unlucky enough to get it in the tunnel, remove all affected leaves
immediately and burn them. Trees that are otherwise in reasonable health will
produce a second flush of foliage that should not be affected, but don't allow
them to fruit until the following year.
Pea moth
Pea moth attack is very unlikely in the polytunnel, since the adults fly only
between May and August - months when there is no need to grow this vegetable
under cover. The moths are also largely nocturnal, and if you shut the tunnel
doors an hour before dusk they are unlikely to get in.
Powdery mildew
Courgettes and other cucurbits are especially prone to this fungal disease, which
is associated with inadequate or patchy watering. Keeping the soil in good
