Agriculture Reference
In-Depth Information
CHAPTER TEN
Dealing with pests
and diseases
One of the ways in which polytunnel growing is different from managing an
outdoor plot is in the control of pests and diseases. The polytunnel environment
seems to deter some pests, but provides others with ideal conditions to breed
very rapidly, which means that without prompt action a minor infestation can
quickly become a serious problem.
Since there is no rain to wash chemical residues down to the subsoil, the use of
pesticides inside a tunnel is a really bad idea. Even organic options should be
treated as a last resort, since they typically affect many more species than their
intended targets. Happily, provided that you keep a close eye on the plants in
your polytunnel - and you most definitely should - intervention with insecti-
cides is very rarely, if ever, necessary - so long as you remember the key points
to pest management as follows.
Keep pest habitat to a minimum
Or, to put it another way, keep your tunnel free of all clutter. This includes
weeds, fallen leaves and flowers, unused plant pots, old grow bags and anything
else that isn't actively in use, as these give refuge to everything from woodlice
and slugs to mice.
Give plants a good start
Plants that are able to grow away strongly are much less likely to be attacked by
pests. Starting vulnerable seedlings such as brassicas in modules is a good idea,
but remember that plants grown without adequate heat or light will be much
more prone to problems. Keeping the tunnel beds in good health (see Chapter 11)
is also extremely important.
Watch what you bring in
When you bring any plant into the garden from outside, there is always a risk of
introducing disease. To be as sure as possible about the health of incoming
plants, quarantine them in a greenhouse or cold frame, or on a sunny windowsill,
for a couple of weeks. Take them into the polytunnel only once you are sure they
are healthy. Garden centres and other commercial sources have a professional
