Agriculture Reference
In-Depth Information
Rabbits
Rabbits are a problem in rural areas but are unlikely to be encountered in an
urban environment. If you do have rabbits around, you can be sure that if you
leave the polytunnel open while you're away (or if you forget to close it one
evening), they are extremely likely to pay it a visit. Once they know there's a
source of food available, you'll have to fight for your share.
The answer to this problem is to stop them from discovering what's inside the
tunnel in the first place. It's easy enough to create a sturdy barrier that you can
stretch across the inside of the tunnel doorway using some wire netting held into
place with short pieces of batten - see Chapter 10, page 168, for more details.
This kind of barrier will also deter most dogs.
Cats
Polytunnels are comfortable and warm, and it doesn't take cats long to figure out
that they make a good place for a quiet daytime nap. Usually they don't do very
much damage, but if they decide to use the beds as a toilet, you will have to
exclude them, and they can also cause damage if they are accidentally closed in
at night. We also heard from one tunnel owner whose dog spotted a cat inside
her tunnel, and went straight through the side of the cover to chase it.
Cats are agile and difficult to physically exclude without building a full-height
inner door covered with mesh (which also works for butterflies), but they dislike
walking on chopped trimmings from holly or gorse. These can be scattered just
inside the doors, and last for two or three years before eventually rotting down.
Caterpillars
Here's the dilemma: do you leave the tunnel open enough to allow bees to get in?
If pollination by insects needs to be encouraged, butterflies will get in too. And
if you have brassicas growing in the tunnel, that's where they will lay their eggs.
Once you have a caterpillar problem it's extremely difficult to deal with, espe-
cially on plants such as cauliflowers. The leaves are brittle and even before the
flowerhead has started to develop, they turn inwards to protect it. That, of course,
is where the caterpillars like to live too. The leaves are young and tender, and
predators can't get at them easily. Trying carefully to pull leaves back usually
results in tears and breaks, and rarely results in actually finding any caterpillars.
When disturbed, they tend to release their grip on the plant and fall to the bottom
of the leaf stem, where they are not only difficult to see but almost impossible to
get hold of.
You can easily exclude butterflies from the tunnel by hanging netting across the
doorways (thus still allowing air to circulate), but this also excludes many pollin-
ators (see Chapter 6, page 53). The solution is to cover crops at risk (mainly
