Agriculture Reference
In-Depth Information
Sciarid fly (fungus fly)
This very common greenhouse and polytunnel pest can cause severe infections
in soil beds. If your area is prone to sciarid fly, then as a preventative measure
place grease-coated pieces of yellow card at a low level in your tunnel, perhaps
attached to seed markers; adult sciarid flies are attracted to the colour yellow,
and they will stick to it along with various other flying species. If you end up with
a serious infestation, stop surface watering for long enough for the top layer of
the bed to dry out completely and hoe it to provide a 'dust mulch'. If this fails,
using a biocontrol may be your only option.
In containers, sciarid fly can be physically removed by taking out the top 10cm
of compost and replacing it. During an infestation, containers can be protected
by covering the surface area around the plant with horticultural sand, making it
a less inviting area for eggs to be laid, and cutting back on watering as far as
possible without stressing the plant.
Slugs and snails
Slugs and snails are the two most serious vegetable pests, and, owing to our
unique climate, the UK is arguably the slug capital of the world. By far the most
important factor in controlling their numbers is to reduce the habitat available to
them. In the tunnel this means removing leaf litter, plant debris, weeds and so
on, but the area around the tunnel is important too: both slugs and snails hunt
by scent, and although they move slowly they can still cover a considerable dis-
tance (around 7 metres) in a night. Avoid having overgrown areas near the tunnel
if you possibly can.
The second most effective measure is performing a 'slug patrol' soon after dark
during times when the animals are active, which will be on warm, humid even-
ings throughout the year. If you see them on paths and grass outside, check the
tunnel. Peak activity is usually in May, but if you want to keep things under control
we suggest you start as early as March, otherwise clutches of eggs may be laid,
making work later in the year.
After habitat elimination and slug patrol, copper tape is also an invaluable slug
control method (see overleaf). Nematode biocontrols are also available, which,
though effective, are expensive to use. Total control through any method, however,
is extremely unlikely, so you also have to be able to protect individual plants,
particularly when they are young. That said, not all slugs are bad. The leopard
slug (pictured overleaf) is actually a friend to the gardener because it prefers eat-
ing other slugs to young plants, and will hunt them down.
Never use slug pellets
based on metaldehyde or methiocarb, which kill a wide
variety of other small animals including beetles and toads, which normally help
to control slug numbers by eating eggs and juveniles. Without rainfall to wash
