Understanding plant diseases

ILEIA Newsletter • 5 nº 3 • October 1989

Understanding plant diseases

Before he retired, Jaap Bakker worked with the Plant Protection Service in Wageningen, the Netherlands and with the Dutch Ministry of Agriculture. During that last job, he had to monitor the use of chemicals in agriculture. He got increasingly in conflict with himself: "is the environment not paying too high a price for the use of chemicals?" In his vegetable garden at home, he uses no chemicals. This article has been translated and reprinted with kind permission from 'Vruchtbare Aarde' (Fertile Soil), July 1989.

Sylvia Borg and Bart Hommersen

"Do you see that lupine over there? Things do not get that bad very often in this garden: the plant is completely covered with lice. I had two such plants, I removed the other one just yesterday. Like this one, it all withered. They just don't grow on these grounds. Now if you were to use pesticides, it would only take one louse not destroyed -something that always happens- to rebuild the complete pest. And after three weeks, the lupine is all covered with lice again. Probably more so than at the moment."

"You suggest I should spray again in three weeks? To really control the pest, one would have to spray once every seven or ten days. Sometimes, wheat is sprayed seventeen times per season with all kinds of pesticides. Ten to twelve times is nothing unusual. In this way, you just keep spraying. There's no end to it."

"In the end you have to ask yourself why the lupine is all covered with lice. If not, you'll be caught in a vicious circle. Why does the foxglove over there flourish so well? Why this year, but not other years? These are the questions that matter. At last, we should stop looking at plants and the pathogens they carry as if they were "things". One "thing" we like, the other "thing" we don't like, so we get rid of "things" not welcome.

But once you start to learn and look at a plant, you start to understand why the plant is bothered by pathogens. You start to understand the mechanisms that cause all this. With this lupine, it's very simple. It does not belong here. Normally speaking, it grows in England and Ireland, on rocky grounds: poor soil. Here the soil is extremely rich. Just look at how luxuriantly this plant grows. That cannot be. This plant won't survive here. There's too much nitrogen in the plant juice, to which the lice are attracted. The environment is just not right. That's always the main point."

Wrong image

In Jaap Bakker's huge garden in the Netherlands, the lupine is indeed the only example of a withering plant. Plants covered with lice are not to be seen during the elaborate tour we get. Nor are they to be seen in the official world of agriculture, thanks to pesticides. But during Bakker's garden tour (illustrated with many examples and anecdotes) one realises again how distorted the image of pesticides really is. Of course, pesticides are poison. It is garbage. Bad for the environment and unhealthy to work with. But it's also marvellous stuff. It frees you in no time of all these weeds and juice sucking little animals. It helped the farmer to stay in business. Bakker: "Economically speaking yes.

But for a very different reason than the one known to the public. Pesticides made it possible for farmers to leave out multiple cropping systems, to ignore environmental circumstances, to stop growing rye, which pays poorly, and grow sugar beet or potatoes once more instead, which are more profitable.

Cauliflower

The old principle of extensive crop rotation was set aside. For purely economic reasons. Here, in this region, it's nothing but cauliflower. Cauliflower is continuously grown. In the old days, cauliflower was grown once every four or sometimes even six years. Now it's cauliflower every year. When summer cauliflower has been harvested, winter cauliflower is planted on the same plot. I'm sorry, but that's impossible. Farmers fall in a trap, which they think they can escape with the help of pesticides.

I said "think", because the soil here is completely poisoned with fusarium, a fungus existing in the soil that affects the roots of cauliflower plants. It has become the largest problem in the cultivation of cauliflower. Although it doesn't have to be this way, because in the thirties and forties farmers didn't even know of this problem. Farmers do not care about the cauliflower, they only care about the money received for it. We accept knowingly that this one-sided economic approach causes diseases. We have pesticides to take care of that. The introduction of chemicals in agriculture did not help the farmer to control diseases. Indirectly, chemicals created diseases."

Jaap Bakker
Oosteinde 87
1647 AD Berkhout
The Netherlands