Two kinds of plant pathosystem

Plant pathosystems can be divided into the two categories of wild pathosystems and crop pathosystems. Perhaps the essential difference between the wild plant pathosystem and the crop pathosystem is a question of control. The wild plant pathosystem is self-organised and self-regulated. It is an incredibly complex adaptive system. Indeed, it is so complex that we cannot begin to understand it in terms of conventional analytical science. We can only recognise, and accept, its complexity, its resilience, its overall stability, and its adaptability. And, in terms of complexity theory, we can recognise a few of the many mechanisms, such as negative feedback, which contribute to that complexity.

The crop pathosystem, on the other hand, has been over-controlled to the point of considerable hazard to both the human population and the environment as a whole. Much of this artificial control is clearly necessary, and it is not inevitably hazardous. For example, we need the agricultural properties of cultivars, such as high yield and high quality of crop product. We also need host population uniformity in our crops. However, these features can lead to pathosystem imbalance, and a loss of resilience.

Much of the current imbalance and instability in our crop pathosystems is unnecessary. This shows, for example, in the loss of horizontal resistance in most modern cultivars, and the consequent necessity for crop protection chemicals. The message of this book is that much of the balance, stability, and resilience of the crop pathosystem can be restored if we allow a healthy gobbet of self-organisation to operate (see 2.4 & 11).

0 0

Post a comment