Let’s look at the other side of the coin for a moment. Ever since I started gardening, I have come across some extraordinary and imaginative remedies for plant ills and some cultivation techniques that stretch credibility well beyond its breaking point. Moreover, organic gardening does have more than its fair share of eccentrics. And that can be disconcerting. On the other hand, Christopher Columbus was held to be eccentric for saying that the world was round until he actually proved it. And that has been my solution.
Over the past 10 years I have been conducting various experiments. I’ve tried to keep an open mind (and that has not always been easy). However outlandish the theory seemed, I’ve tried it under as near scientifically experimental conditions as possible. It’s important to set up proper trials because, in many cases, when an organic gardener has reported complete success with a pest or disease control, he has not grown a control plot at the same time. The gardener may think, for example, that carrot fly was defeated by surrounding the rows with creosoted string, but how does anyone know that there would have been an attack in the first place? Unless a nearby row is attacked, the experiment proves nothing. I have tried the creosoted string method and it didn’t work.
I set up trials to test the many suggested organic controls for cabbage root fly. I grew one row with a bit of rhubarb stem underneath the plants, one row with a few mothballs, one with a layer of comfrey spread over the soil, and another watered with extract of nettle leaves. In order to be as comprehensive as possible, I grew other rows treated with the chemical insecticides dianzon and bromophos. Most outlandish of all, I surrounded each plant in one of the rows with a bit of carpet pad. And, of course, I grew a control row with no treatment at all.
The cabbage root fly did attack and the rows with rhubarb, mothballs, comfrey, and nettles all suffered, as did the control row. Those that were treated with soil insecticides were about 80 percent free, but the row with the carpet pad was completely unscathed. I use it every year now and it doesn’t cost me anything. I now have a row of four identical plots about 15 × 20ft (5 × 6.5m), each growing identical plants, ranging from apple trees and fruit bushes down to cauliflower, cabbages, carrots, and other vegetables. One plot is treated organically, one inorganically, one traditionally using a mixture of the two methods and, of course, there is the obligatory control plot, which gets no added organic matter or chemicals at all. I thought at first that the experiments would be invalidated by having the plots so close together: wouldn’t their close proximity mean that the insects would simply hop from one plot to another, that weeds could creep under the fences, and microbes move through the soil?
Well, of course, that may be so, but I realized that this was the way it had to be. If the experiment was to benefit the average gardener, the organic plot would have to be able to cope with the ills sent from next door. After all, few of us are lucky enough to be completely isolated, and converting the entire street to organic gardening would take much more than gardening skills.
But, amazingly, I found not the slightest problem. Weeds tried to creep in from the next plot but I dealt with those by installing a plastic barrier beneath the fence. Most marvelous of all, the hoverflies attracted by the marigolds in the organic plot, ate the greenfly in the next door plot as well, and the frogs hopped in and took care of their slugs too.