Sunday, 13 August 2017

Battle of the brassicas

The cabbage is the most ordinary and widely available of vegetables. Yet, for me at least, it has been difficult to get a decent crop. Despite its humble qualities I like cabbage very much. But it seems nearly all other creatures like it equally much and have no inhibitions about helping themselves to their share. The same goes for its more fancy relatives in the brassica family like broccoli, Brussel sprouts or cauliflower. (Someone once described the cauliflower as a cabbage with a college education).

To begin with there is the phytomyxea parasite that causes club root, then flea beetles that eat away at the leaves. But for many people the biggest sources of attack on brassica plants are pigeons and the caterpillar of the cabbage white butterfly. Pigeons will readily strip newly planted brassicas leaving behind a skeletal framework of leaf veins. If ruination by pigeons is avoided then the next wave of attack will surely come from the cabbage white butterfly. Its caterpillars have a voracious appetite and will soon turn cabbage leaves into doilies. In the world of brassica growing it is truly a Weapon of Mass Destruction.

In the arable field adjoining us there is a tall 100 yard long leylandii hedge planted as a windbreak. It is also shelter to squadrons of pigeons that carry out sorties on my vegetable plot, over which they have a perfect (literally) birds eye view and readily spot when the brassicas are planted out.

When I see shelves of perfect cabbages and cauliflowers in supermarkets I can only assume that they have had the life sprayed out of them and as smallholders we don’t like that do we? For this reason, if none other, I will continue the battle.

If I am to grow brassicas, then, it is essential that I have adequate defences in place. For very large areas one option is simply to drape fleece or netting over the crop. This can be a nuisance when it comes to weeding which is important to keep on top of for a healthy crop. Another alternative for smaller areas is a building something like a fruit cage, but that can be expensive. A number of smaller, movable cages might be the answer. The ones I built which I describe here are robust, withstanding strong winds, but at the same time easily lifted to carry out weeding or other operations. Watering is not a problem as it is easily watered through. They also look quite attractive and are cheap and easy to make. I now have half a dozen cages.

Here’s how you can go about constructing them for yourself.

What you need
You can make the size of your brassica cage to suit your own needs. Mine used the following materials (Fig. 1):-
Roll of scaffolding netting
4 x 2m x 15mm plastic plumbers’ tubing
2 x 2.4m x 38mm x 45mm treated timber lengths (roughly 8’x2”x1.5”)
One more of the above cut in half to create 2 x 1.2m lengths
1 x 2.4m x 38mm x 25mm timber length to be used a s a croosbeam
2 x 80cm x 38mm x 25mm timber lengths to be used as upright supports.
Tools: power drill, Phillips screwdriver, tape measure, staple gun, scissors, screws.

To start off, the two shorter timber lengths were screwed on to each end of the longer timber lengths to create a rectangular wooden base (Fig. 1).

Fig. 1

Next, the plastic tubing was screwed into place at 80cm intervals along the long lengths to form four arches to support the netting (Fig.2). Two screws were used for each end of the tubing to keep the arches vertical. Note that by reducing the width of the cage a higher arch is formed from the plastic tubing. This might be preferable, for instance, for taller crops such as Brussel sprouts.

Fig. 2

For extra strength a cross beam was fixed along the apex of the four arches and this was further supported by two uprights at each end of the cage (Fig. 3).

Fig. 3
Scaffolding netting was stapled in place over the cage. About a 4m length is required for this size cage. The rolls I buy are conveniently 6 feet wide which is just the right width needed. I find it easiest to keep the netting taut by starting in the middle on one side and working outwards to each end. The netting should be folded to create a neat finish on each end panel (Fig.4). Excess netting can be trimmed off.
It is important that when choosing netting to cover the cage that it is of small enough gauge to prevent butterflies from entering. Many of the horticultural nettings for sale are too big in this respect, hence the usefulness (and cost-effectiveness) of scaffolding netting. I have not found any problems in the light levels within the cage using scaffolding netting and I have also found that water can readily access through the netting whether that is from rain, hose or sprinkler.

Fig. 4
Here are some of the cages in situ.

These brassica cages can go a long way in defending your cabbages. To keep up your spirits in the battle of the brassicas you can do no worse than listen through headphones to a Churchill speech whilst hoeing:-

...we shall fight with growing confidence and growing strength, we shall defend our [cabbages], whatever the cost may be, we shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender…