Agriculture Reference
In-Depth Information
prove to be invaluable, as next year you won't be able to remember exact times,
conditions and so on. The UK is full of little climate pockets that differ from their
surrounding areas, and if you're in one of them, whether warm or cold, the right
timings can be quite different from those recommended on seed packets. And
that's important, as the challenges of gardening are constant.
Treating fungal diseases
For early treatment of mildew and other fungi, make up a spray of 10g of bicar-
bonate of soda (baking soda) in one litre of water, with a few drops of plant-
based washing-up liquid (such as Ecover) or plant-safe detergent (Citrox) to
encourage the liquid to stick to the foliage. Always spray in the morning so that
the liquid dries quickly, making sure that you treat the undersides of the leaves
as well as the tops. This can be repeated weekly as needed (twice-weekly if you
use overhead irrigation), but should not be used as a routine preventative measure
because of the risk of salt building up in the soil.
Treated plants and fruits tend to look dusty when the spray dries, so harvest any
ripe fruit before you start. Always spray a small area of one plant before treating
the whole crop to check that it will be tolerated, unless you have successfully
used it on that variety before.
A fleece cloche
There will probably be lots of frost-sensitive plants in your polytunnel when the
first frost arrives. If you're lucky, this first blast of winter weather will just be a
warning, but if not, it may kill plants you wanted to keep for another month or
so. Horticultural fleece can help to protect an entire bed from several degrees of
frost, depending on the weight of fleece you use (light fleece, 15g, is good for up
to -3°C; heavier fleeces, 30g, up to -6°C) but it is not without problems.
Even heavy fleece is supposed to cut light by only 6 per cent, but this measure-
ment is based on a perfectly clean and flat sheet of it, held exactly perpendicular
to the light source. In practice the loss of light is probably substantially greater.
So, while fleece will save your plants from destruction by frost, if you just put it
up and leave it in place for days on end you will probably get leggy growth
caused by reduced light levels, and you will also be restricting the flow of air - so
you'll be very likely to get mould problems too.
The ideal fleece protection provides a single layer of covering, held reasonably
flat, which touches the plants as little as possible so as to minimise contact frost
burn. A fleece cloche - see box opposite - provides this and is easily adjustable,
so if the sun comes out and warms the tunnel, you can pull the fleece back,
allowing more light and air circulation without damaging things in the process.
