The Garden Doctor

I went away for a few days. Okay a week. Okay, it was eight days, but I did arrange for someone to water the garden while I was gone! That was fine. On my return I found several cucumbers swelling and my tomatoes had grown so tall they really needed their supports… with which I have yet to provide them. Hey, have you ever seen a mechanic’s car? Yeah, well, same thing. Okay, anyway, the garden is looking great, despite my absence. Except when I went to look at my patch of broccoli…

My poor Broccoli plants

My Broccoli patch is in a teardrop shaped hole in the concrete in my backyard. I assume there was once a tree here, and the cement was laid around it in order to let it grow. Of course, this killed the tree, and now I just have a funny shaped garden bed. Anyway, they holy-ness of the leaves has nothing to do with the religious overtones to this time of year, and a lot to do with the life cycle of the Cabbage White Butterfly (Pieris rapae). The larvae, or caterpillars of this common garden visitor are the cause of all this damage, and will do the same to  any member Cabbage family (Brassicaceae).

Before I left for my break, I was hand picking them off the underside of the leaves each morning. And when I say picking, I mean squishing. I suppose it may seem a little harsh, but there is nothing more satisfying than popping the little green caterpillars and squirting their guts out. Of course, you may object to this on moral, hygiene or sooky-pants grounds, but the alternative is to pick them off by hand and deprive them of food, basically, and this is quicker.

The virtually invisible Cabbage White caterpillar - trust me, it's next to my index finger - before squishing!

The little chompers start off as tiny yellow eggs, which you can see on the underside of leaves if you look carefully. On hatching, the larvae are not much bigger than the eggs themselves, but they soon grow, and in a day or two you can have big fat caterpillars about the same colour as the plants on which they feed. This can make them hard to spot, but after a while they stop hiding under the leaves and will rest in the base of the leaf on the stalk, making them easier to search and destroy.

Now, there is another solution to hand picking them, and it is in the form of a spray or powder. Because it’s a naturally occurring chemical, it’s also approved by most organic certification bodies, and has pretty much no effect on anything other than leaf eating caterpillars. Available in several commercial preparations, the toxins of the bacteria Bacillus thuringiensis disrupt the digestive systems of caterpillars, and they stop feeding, and eventually starve. The preparation can be sprayed freely on leaves of susceptible plants, and only affects leaf eating larvae, including the Cabbage White caterpillars. The commercial versions usually contain both the toxins that kill the caterpillars, as well as the bacteria itself, so it can multiply on the plants after application.

Even though the toxin itself and the bacteria have no ill effects on humans, vertebrates, or even other insects, some people have objected to its use in genetically modifying Potato crops, amongst others, to protect them from attack by pests which usually require far more potent and toxic chemical deterrents. Despite the bacteria itself being used in almost every organic farming operation in the world, it appears some people have an issue with genetic modification technology itself, which may prevent any possible benefits being transferred to farmers and consumers.

Okay, well, I am off to the hardware store to buy some stakes. And some bacteria. And some fertiliser. And… who am I kidding, I’ll be there the rest of the day if you need me.